Dissertations / Theses on the topic 'Behavior Imaging'
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Matson, Douglas Marcus. "Imaging the recalescence behavior of undercooled nickel." Thesis, Massachusetts Institute of Technology, 1996. http://hdl.handle.net/1721.1/41412.
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Thesis (Ph. D.)--Massachusetts Institute of Technology, Dept. of Materials Science and Engineering, 1996.Includes bibliographical references (leaves 114-117).
by Douglas Marcus Matson.
Ph.D.
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Wekselblatt, Joseph. "Imaging Neural Circuits Underlying Learning and Behavior." Thesis, University of Oregon, 2018. http://hdl.handle.net/1794/23176.
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Sensory perception is context dependent and is likely modulated by task demands, learning and engagement to best serve specific goals of the organism. Sensory-driven behaviors also engage a cascade of cortical regions to process sensory input and generate motor output. To investigate the temporal dynamics of neural activity at this global scale, we have improved and integrated tools to perform functional imaging across large areas of cortex using a transgenic mouse expressing a fluorescent activity sensor. Imaging during an orientation discrimination task reveals a progression of activity in different cortical regions associated with different phases of the task. After cortex-wide patterns of activity are determined, we demonstrate the ability to select a region that displayed conspicuous responses for two-photon microscopy, and find that activity in populations of individual neurons in that region correlates with locomotion in trained mice.
We also found that learning a visual discrimination reduced population activity in visual cortex. To further investigate this phenomenon, we used two-photon microscopy to image mice before or after they had learned a visual discrimination. We find that excitatory neurons in layer 2/3 show striking diversity in their temporal dynamics during the behavior and classify them into transient, sustained, and suppressed groups. Notably, these groups exhibit different visual tuning and modulation by locomotion. The functionally defined cell classes are also differentially modulated by training condition: showing both a cell class specific decrease in fraction responsive to visual stimuli after learning, and an increase in modulation by task engagement specific to trained animals. The characterization of pyramidal neuron subtypes in layer 2/3 of V1, and quantification of their distinct changes over learning, provides new insight into the circuit elements and pathways that enable goal-directed sensory processing.
This dissertation includes published and unpublished co-authored material. This dissertation also includes four supplemental movies related to functional imaging techniques described in chapter II.2019-01-09
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Neumann, Martin. "Time-resolved imaging of the micro-mechanical behavior of elastomeric polypropylene." Doctoral thesis, Universitätsbibliothek Chemnitz, 2015. http://nbn-resolving.de/urn:nbn:de:bsz:ch1-qucosa-182113.
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Ziel dieser Arbeit ist es, eine Verbindung zwischen der Mikrostruktur teilkristalliner Polymere und derer mechanischen Eigenschaften auf der Mikro- und Nanometerskala aufzubauen. Dazu wurden Methoden der Rasterkraftmikroskopie verwendet um sowohl orts- als auch zeitaufgelöst Kristallisations-, Deformations- und Diffusionsprozesse in der Mikrostruktur von elastomerem Polypropylen (ePP) abzubilden. Die mechanischen Eigenschaften wurden simultan mit Mikrozugversuchen bestimmt. So konnte beispielsweise ein Zusammenhang zwischen abnehmender Kristall-Kristall-Distanz und einem Ansteigen des Elastizitätsmoduls während der Kristallisation nachgewiesen werden. Weiterhin war es möglich die Veränderung der nano-mechanischen Eigenschaften während der Kristallisation einzelner kristalliner Lamellen in deren direkter Umgebung mit MUSIC-mode Rasterkraftmikroskopie zu untersuchen. Laterale Querexpansion (auxetisches Verhalten) konnte bei uniaxialen Zugversuchen für die Kreuzschraffur-Struktur elastomeren Polypropylens auf der Größenskala einiger Mikrometer nachgewiesen werden. Zusätzlich wurde eine Orientierungsabhängigkeit dieses Effekts beobachtet. Außerdem wurde die Diffusion einzelner Kristalle in der Mikrostruktur von ePP beobachtet. Die Heterogenität dieser Diffusion lässt auf eine kristallin-amorph Grenzschicht um alle Kristalle schließen.
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Symonds, Deanelle T. "Fish population and behavior revealed by instantaneous continental-shelf scale imaging." Thesis, Massachusetts Institute of Technology, 2008. http://hdl.handle.net/1721.1/46492.
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Thesis (Ph. D.)--Massachusetts Institute of Technology, Dept. of Mechanical Engineering, 2008.Includes bibliographical references (leaves 221-229).
The application of a technique to instantaneously image and continuously monitor the abundance, spatial distribution, and behavior of fish populations over thousands of square kilometers using Ocean Acoustic Waveguide Remote Sensing (OAWRS) is demonstrated with data from its first implementation in a 2003 field experiment off the US Continental Shelf south of Long Island, NY. Conventional methods for monitoring fish populations rely on highly-localized, point measurements made from slow-moving research vessels that survey along widely spaced line transects to cover the vast ocean environments that fish inhabit and so significantly under-sample fish populations in time and space. This leads to incomplete, ambiguous and highly-aliased records of fish abundance and behavior. In contrast, OAWRS surveys at a rate roughly one million times greater than that of conventional fish-finding methods. Within a minute and a half, OAWRS images the ocean environment over more than ten thousand square kilometers, an area similar to the state of Massachusetts. This is possible because OAWRS exploits the natural capacity of the continental-shelf environment to act as a waveguide where sound waves are efficiently propagated over long ranges (tens of kilometers) via trapped modes that suffer only cylindrical spreading loss rather than the spherical spreading loss suffered in the short-range (hundreds of meters), waterborne propagation paths employed by conventional fish-finding sonar (CFFS). In this thesis, a method is developed for estimating the instantaneous population density and abundance of fish populations from wide-area OAWRS imagery.
The OAWRS population density estimates are calibrated with simultaneous local CFFS measurements, and are used to estimate the expected scattering cross section of an individual fish at OAWRS frequencies so that population density may be estimated in regions where CFFS measurements were not made. It is shown that the OAWRS population density estimates have uncertainties of less than 25% at each pixel or spatial resolution cell, for statistically stationary populations. Instantaneous abundance estimates then have much lower uncertainties when OAWRS population density is integrated over tens to hundreds of independent spatial resolution cells by the law of large numbers. A number of discoveries are also documented about the instantaneous horizontal structural characteristics, temporal evolution, short-term volatile behavior and propagation of information in very large fish shoals containing tens of millions of fish and spanning several kilometers in spatial extent. The OAWRS approach should enable new abilities in the study and assessment of fish populations and their behavioral dynamics.
by Deanelle T. Symonds.
Ph.D.
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Chiu, Sheng-Kuei. "Photoluminescent Silicon Nanoparticles: Fluorescent Cellular Imaging Applications and Photoluminescence (PL) Behavior Study." PDXScholar, 2015. http://pdxscholar.library.pdx.edu/open_access_etds/2455.
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Molecular fluorophores and semiconductor quantum dots (QDs) have been used as cellular imaging agents for biomedical research, but each class has challenges associated with their use, including poor photostability or toxicity. Silicon is a semiconductor material that is inexpensive and relatively environmental benign in comparison to heavy metal-containing quantum dots. Thus, red-emitting silicon nanoparticles (Si NPs) are desirable to prepare for cellular imaging application to be used in place of more toxic QDs. However, Si NPs currently suffer poorly understood photoinstability, and furthermore, the origin of the PL remains under debate.
This dissertation first describes the use of diatomaceous earth as a new precursor for the synthesis of photoluminescent Si NPs. Second, the stabilization of red PL from Si NPs in aqueous solution via micellar encapsulation is reported. Thirdly, red to blue PL conversion of decane-terminated Si NPs in alcohol dispersions is described and the origins (i.e., color centers) of the emission events were studied with a comprehensive characterization suite including FT-IR, UV-vis, photoluminescence excitation, and time-resolved photoluminescence spectroscopies in order to determine size or chemical changes underlying the PL color change. In this study, the red and blue PL was determined to result from intrinsic and surface states, respectively.
Lastly, we determined that the blue emission band assigned to a surface state can be introduced by base addition in originally red-emitting silicon nanoparticles, and that red PL can be restored by subsequent acid addition. This experimentally demonstrates blue PL is surface state related and can overcome the intrinsic state related excitonic recombination pathway in red PL event. Based on all the data collected and analyzed, we present a simple energy level diagram detailing the multiple origins of Si NP PL, which are related to both size and surface chemistry.
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Motavalli, Sayyed Mostafa. "DEPTH-DEPENDENT BIAXIAL MECHANICAL BEHAVIOR OF NATIVE AND TISSUE ENGINEERING ARTICULAR CARTILAGE." Case Western Reserve University School of Graduate Studies / OhioLINK, 2014. http://rave.ohiolink.edu/etdc/view?acc_num=case1390313405.
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Borg, Jacqueline. "Molecular imaging of the serotonin system in human behaviour /." Stockholm, 2007. http://diss.kib.ki.se/2007/978-91-7357-134-0/.
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Antalek, Brian J. "Magnetic resonance imaging studies of the behavior of fluids in gelatin and other porous materials /." Online version of thesis, 1991. http://hdl.handle.net/1850/10996.
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Semaan, Marie. "Characterization of the mechanical behavior of growing bone based on new imaging methods." Thesis, Aix-Marseille, 2019. http://www.theses.fr/2019AIXM0129/document.
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De nos jours, l’étude biomécanique des structures osseuses représentent un enjeu pour différents domaines: accidentologie, prise en charge des pathologies osseuses, confort des personnes âgées, conception de prothèses innovantes, etc. Le but de cette thèse est de fournir des valeurs de référence représentatives de la qualité de l'os enfant en caractérisant des propriétés mécaniques et morphométriques du tissu osseux en croissance à différentes échelles. Les propriétés mécaniques ont été mesurées à 2 échelles différentes – mésoscopique et microscopique – selon 2 modalités expérimentales – spectroscopie à résonance ultrasonore et microindentation. Un autre volet de cette thèse concerne le développement d’une procédure d’analyse morphométrique adaptée au tissu osseux pour le traitement d’images obtenues par micro-tomographie (RX). Mieux connaître le tissu osseux juvénile est indispensable pour développer des modèles dédiés et ainsi mieux comprendre les mécanismes pathologiques caractéristiques de l'os en croissance (fracture en bois vert) pour améliorer le diagnostic et adapter les choix thérapeutiques pour les jeunes patientsNowadays, the biomechanical study of bone structures is a challenge for different fields: accidentology, management of bone pathologies, comfort for the elderly, design of innovative prostheses, etc. The aim of this thesis is to provide reference values representative of the quality of child bone by characterizing the mechanical and morphometric properties of growing bone tissue at different scales. Mechanical properties were measured at 2 different scales - mesoscopic and microscopic - in 2 experimental modalities – resonant ultrasound spectroscopy and microindentation. Another part of this thesis concerns the development of a morphometric analysis procedure adapted to bone tissue for the treatment of images obtained by micro-tomography (RX). A better knowledge of juvenile bone tissue is essential to develop dedicated models and thus better understand the pathological mechanisms characteristic of growing bone (greenstick fracture) to improve diagnosis and adapt therapeutic choices for young patients
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Zhang, Wen. "Characterizing, imaging, and quantifying the environmental behavior and biological interactions of metal-based nanoparticles." Diss., Georgia Institute of Technology, 2011. http://hdl.handle.net/1853/44822.
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Due to the rapid expansion of nanotechnology and the increasing applications of nanomaterials under production and development, it is essential evaluate the potential impacts on human health, ecosystems and the environment. This study is specifically focused on the interactions between metal-based nanoparticles (NPs) and target cells, aiming at exploration of the fundamental knowledge essentially useful for understanding nanotoxicity and its connections with particle properties. The whole structure of this study can be divided into three levels: the first level is to quantitatively understand physicochemical properties of NPs of interest and their dynamic changes under varying environmental conditions. The second level is to evaluate the biological interactions of representative NPs with a specific focus on the size-dependent adsorption processes, interfacial forces, cellular disruption, and membrane damages. The third level is to develop effective, accurate, and valid tools based on atomic force microscopy (AFM) to characterize NPs in terms of the nanoscale hydrophobicity and the nanoscale electric properties, which are most relevant and important properties in the bio-nano interactions. Overall, this study systematically investigated the kinetic environmental behaviors, biological interactions, and unique nano-properties of metal-based NPs, which should be of interest to people in application and implication of nanotechnology.
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Chen, Zhengguang. "Experimental and clinical perspective on stroke : evaluation by behavior, magnetic resonance imaging and morphology /." Stockholm, 2001. http://diss.kib.ki.se/2001/91-628-4807-0/.
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Wixson, Sandra Werre. "The Effects of Imaging Ability, Guided Imagery, and Source of Themes on Interview Verbal Behavior." Thesis, North Texas State University, 1985. https://digital.library.unt.edu/ark:/67531/metadc331357/.
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Eighty four female undergraduate students participated in a psychotherapy analog study to determine the effects of imagery ability, guided imagery therapy treatments, and personal versus supplied constructs upon self-disclosure variables in a 2 x 3 x 2 Anova design, with repeated measures on the final factor. Dependent variables were measured by reaction time, total talk time, speech duration, silence quotient, and Doster's (1971) Self-Disclosure Rating Scale. Subjects were divided into two imagery ability levels on the basis of local mean scores on Sheehan's (1967) modification of Betts' (1909) Questionnaire upon Mental Imagery. Three treatment procedures were employed: a guided focal imagery treatment, which encouraged imagery involving the interpersonal topics to be discussed, a guided relaxation imagery treatment which used standard sensory relaxation scenes, and a treatment which imparted ambiguous instructions. The final factor was repeated measures of the eight negative topics the subjects were asked to discuss. Four were chosen from the subjects' Role Construct Repertory Test grid (Kelly, 1955; Landfield, 1971), and four were selected from the Semantic Differential (Snider & Osgood, 1969).
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Hwang, Bohyun. "Fluid Behavior in Nano to Micro Confinement Systems." The Ohio State University, 2020. http://rave.ohiolink.edu/etdc/view?acc_num=osu1593454113844453.
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Hägglund, Stina. "Development of a Tool for Imaging the Pumping-Out Behavior of Poly- Vinyl Alcohol Shelled Microbubbles." Thesis, KTH, Skolan för kemi, bioteknologi och hälsa (CBH), 2020. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-281980.
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For many years, microbubbles have been used as ultrasound contrast agents to improve the quality of diagnostics, seeing that they produce more backscattering ultrasound than blood does. Novel types of microbubbles and increased knowledge about their different behaviors have led to other suggested areas of use. One notable example is the poly-vinyl alcohol (PVA) microbubble, which has been discovered to have a unique fracturing mechanism referred to as the pumping-out behavior. The PVA microbubble has the potential to be used, for instance, in local drug delivery of therapeutic gases, but further studies are needed. In this study, the aim was to develop a tool for imaging the pumping-out behavior of the PVA microbubbles. A linear transducer connected to the programmable Verasonics Research System operated by MatLab software was used to achieve it. The designed ultrasound sequences were tested on a tissue-mimicking phantom containing one vessel filled with PVA microbubbles and one with degassed water. The design was divided into two steps. First, an ultrafast imaging sequence, based on plane waves, was developed to achieve adequate acquisition rate for detecting escaping air from the microbubbles. Furthermore, coherent compounding was implemented to compensate for some of the loss in image quality due to the use of plane waves instead of focused waves. The second step of the design was to combine the imaging sequence with destruction pulses so that the pumping-out behavior could be imaged. The designed ultrasound sequence was evaluated by calculating the mean pixel intensities, contrast-to-tissue ratio (CTR), and contrast-to-noise ratio (CNR) of different regions of interest (ROI) in the acquired images. The results of this project agree with the result previously reported in a study of PVA microbubbles made by Kothapalli et al.. Thus, the developed tool can image the pumping-out behavior. However, further improvements to the imaging tool, such as use of a contrast specific method, is recommended for it to become more reliable and useful. In conclusion, the developed imaging tool works for imaging the pumping-out behavior, but improvements should be made. With a useful imaging tool, further studies can be performed to understand the parameters affecting the pumping-out behavior. In the end, the PVA microbubbles can possibly be used as, for example, local drug deliverers in the clinic.
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Beckwith, Travis J. "A Magnetic Resonance Imaging Study of the Developmental Consequences of Childhood Lead Exposure in Adulthood." University of Cincinnati / OhioLINK, 2015. http://rave.ohiolink.edu/etdc/view?acc_num=ucin1439309120.
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Belke, Marcus [Verfasser], and Susanne [Akademischer Betreuer] Knake. "Diffusion Tensor Imaging (DTI) bei Patienten mit REM Sleep Behavior Disorder (RBD) / Marcus Belke. Betreuer: Susanne Knake." Marburg : Philipps-Universität Marburg, 2013. http://d-nb.info/1045729868/34.
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Malik, Saima. "Neural substrates of feeding behavior : insights from fMRI studies in humans." Thesis, McGill University, 2008. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=115850.
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Feeding behavior is a complex phenomenon involving homeostatic signals, and non-homeostatic inputs such as visual cues. In primates, exposure to food-related sensory cues has been shown to elicit cephalic phase responses as well as trigger central appetitive processing, in a motivationally-dependent manner. Neural structures consistently implicated in such responses and/or in the regulation of ingestive behavior in general, in both monkeys and in humans, include the amygdala, insula, striatum, hypothalamus, and frontal and occipital cortices. In humans however, the cerebral response to visual food stimulation remains minimally explored.Functional Magnetic Resonance Imaging (fMRI) provides information about state-dependent changes in local neuronal activity in vivo. Using fMRI, the present dissertation examined changes in human brain activity to food and nonfood pictures following the pharmacological induction of hunger with the orexigenic hormone ghrelin (Study 1), and following manipulation of the cognitive state of food expectation (Study 2).
Our data reinforce the involvement of a distributed frontal-limbic-paralimbic circuit in the central processing of food imagery, under both experimental conditions. The first study revealed that intravenous ghrelin administration potently modulated food-associated neural responses III areas involved in reward, motivation, memory, and attention (amygdala, insula, orbitofrontal cortex, striatum, hippocampus, midbrain, visual areas). This suggests that metabolic signals such as ghrelin may promote food consumption by enhancing the appetitive response to food cues via engagement of the hedonic network.
The second study revealed that brain regions activated in the 'expectant' state (i.e. when subjects were anticipating food reward) were at least partially dissociable from those in the 'not expectant' state. In particular, recruitment of the dorsolateral prefrontal cortex, a principal component in the cognitive control network, exclusively in the 'not expectant' condition, may signal an attempt to suppress appetite in the absence of food expectation. Areas of convergence were observed in the amygdala and insula.
Obesity is rapidly becoming the major cause of excess mortality worldwide; therefore, understanding how the central nervous system controls appetite and nutrient consumption is of considerable interest. The projects in this thesis offer significant insights regarding the effects two select factors (one intrinsic and the other extrinsic) on the neural reaction to visual food stimuli, in healthy male participants.
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Musselman, Brian Jay Davis David Scott. "A study of the diffraction behavior and resolution criteria for pattern recognition for a proposed multiplexed imaging technique." Monterey, Calif. : Springfield, Va. : Naval Postgraduate School; Available from the National Technical Information Service, 1991. http://handle.dtic.mil/100.2/ADA245066.
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Musselman, Brian Jay. "A study of the diffraction behavior and resolution criteria for pattern recognition for a proposed multiplexed imaging technique." Thesis, Monterey, California. Naval Postgraduate School, 1991. http://hdl.handle.net/10945/26795.
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Bergel, Antoine. "Cerebral vascular patterns associated with theta and gamma rhythms during unrestrained behavior and REM sleep." Thesis, Sorbonne Paris Cité, 2016. http://www.theses.fr/2016USPCC239/document.
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Le rythme thêta est un rythme cérébral associé à l’activité locomotrice et au sommeil paradoxal. Bien que son implication dans la communication entre régions du cerveau et processus mnésiques ait largement été démontrée, il persiste un manque de données extensives dû à la difficulté d’imager l’ensemble de l’activité cérébrale dans des conditions naturelles de locomotion et d’exploration. Dans cette thèse, j’ai développé une approche qui combine l’enregistrement des potentiels de champs locaux à l’imagerie ultrasonore fonctionnelle (fUS) sur l’animal en mouvement libre. Pour la première fois, j’ai pu révéler les réponses hémodynamiques associées au rythme thêta dans la plupart des structures du système nerveux central avec de bonnes résolutions spatiale (100 x 100 x 400 μm) et temporelle (200 ms). Pendant la locomotion et le sommeil, les variations hémodynamiques de l’hippocampe, du thalamus dorsal et du cortex (rétrosplenial, somatosensoriel) corrèlent fortement avec la puissance instantanée du signal thêta hippocampique, avec un décalage temporel variant de 0.7 s à 2.0 s selon les structures. De manière intéressante, les rythmes gamma hippocampiques moyen (55-95 Hz) et rapide (100-150 Hz) expliquent la variance des signaux hémodynamiques mieux que le seul rythme thêta, alors que le rythme gamma lent (30-50 Hz) est non pertinent. L’hyperémie fonctionnelle de l’hippocampe suit séquentiellement la boucle tri-synaptique (gyrus denté - région CA3 - région CA1) et se renforce considérablement à mesure que la tâche progresse. Lors du sommeil paradoxal, j’ai observé une hyperémie tonique globale ainsi que des activations phasiques de grande amplitude initiées dans le thalamus et terminant dans les aires corticales, que nous avons appelées “poussées vasculaires”. De fortes bouffées d’activité gamma rapide (100-150 Hz) précèdent de manière robuste ces poussées vasculaires, l’inverse n’étant pas vrai. Dans l’ensemble, ces résultats révèlent la dynamique spatio-temporelle des signaux hémodynamiques associés à la locomotion et au sommeil paradoxal et suggèrent un lien fort entre rythmes thêta, gamma rapide et activité vasculaire globaleTheta rhythm is a prominent oscillatory pattern of EEG strongly associated with active locomotion and REM sleep. While it has been shown to play a crucial role in communication between brain areas and memory processes, there is a lack of extensive data due to the difficulty to image global brain activity during locomotion behavior. In this thesis, I developed an approach that combines local field potential recordings (LFP) and functional ultrasound imaging (fUS) to unrestrained rats. For the first time, I could image the hemodynamic responses associated with theta rhythm in most central nervous system (CNS) structures, with high spatial (100 x 100 x 400 μm) and temporal (200 ms) resolutions. During running and REM sleep, hemodynamic variations in the hippocampus, dorsal thalamus and cortices (S1BF, retrosplenial) correlated strongly with instantaneous theta power, with a delay ranging from 0.7 to 2.0 s after theta peak. Interestingly, mid (55-95 Hz) and high gamma (100-150 Hz) instantaneous power better explained hemodynamic variations than mere theta activity, while low-gamma (30-50 Hz) did not. Hippocampal hyperaemia followed sequentially the trisynaptic circuit (dentate gyrus - CA3 region - CA1 region) and was considerably strengthened as the task progressed. REM sleep revealed brain-wide tonic hyperaemia, together with phasic high-amplitude vascular activation starting in the dorsal thalamus and fading in cortical areas, which we referred to as “vascular surges”. Strong bursts of hippocampal high gamma (100-150 Hz) robustly preceded these surges, while the opposite was not true. Taken together, these results reveals the spatio-temporal dynamics of hemodynamics associated with locomotion and REM sleep and suggest a strong link between theta, high-gamma rhythms and brain-wide vascular activity
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Lark, Arianna Ruth Stini. "The roles of a unique G-protein coupled dual receptor for dopamine and steroids in neuronal physiology and behavior." Diss., University of Iowa, 2016. https://ir.uiowa.edu/etd/2107.
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Steroid hormones are known to have significant effects on a wide variety of biological processes. In particular, they serve as critical modulators of neural function and behavior and play critical roles in stress responses and neurologic disorders. Until recently the biological actions of steroid hormones were believed to operate primarily through activation of cognate nuclear hormone receptors or the allosteric modulation of ion channels (Majewskaet al., 1986). However, new signaling pathways involving G-protein coupled receptors (GPCRs) for steroid hormones have been recently identified in multiple different species, implicating steroid hormones in direct fast modulation of intracellular signaling and in turn behavior (Thomas et al., 2006, Gabor et al., 2015). In mammals G protein-coupled estrogen receptor 1 (GPER), also known as G protein-coupled receptor 30 (GPR30), is expressed throughout the body including in the nervous system and has been suggested to play a variety of roles in health and behavior (Prossnitz and Barton, 2011). Despite recent progress in this area from studies using rodent models, the mechanisms underlying "non-genomic” actions of steroids remain largely elusive. This gap in our understanding presents a significant scientific and clinical challenge to a comprehensive view of the role of steroid hormones in regulating both neural function, behavior and overall health of the organism. To understand the mechanisms for this unconventional steroid signaling we sought to use a simpler system to explore the functions of GPCR’s for steroid hormones.
In 2005, Peter Evans’s group identified DopEcR, a unique GPCR in Drosophila melanogaster, which responds to ecdysone—the major steroid hormone in insects (Srivastava et al. 2005). This unconventional GPCR for steroid hormones is particularly interesting because it is a dual receptor that also responds to a structurally dissimilar compound, dopamine. DopEcR is preferentially expressed in the nervous system and has recently been implicated in modulating multiple behaviors including starvation-induced enhancement of sugar sensitivity (Inagaki et al., 2012), experience-dependent courtship suppression, habituation of the giant fiber pathway (Ishimoto et al., 2013) and ethanol-induced sedation (Petruccelli et al. 2016) in flies. DopEcR also plays a role in perception of sex pheromones in moths (Abrieux et al., 2013). More recently the mammalian GPCR for estrogen GPER has also been found to bind dopamine indicating that this unique attribute may be more prevalent among these novel GPCRs for steroids (Evans et al. 2013). Despite these previous findings, we still know little about how GPCRs for steroids modulate neurons at the cellular level and how they modulate behaviors.
Therefore we sought to forge a more comprehensive understanding of the function of steroid signaling by characterizing DopEcR function in neuronal and behavioral modulation through GPCR’s. To characterize DopEcR’s function we looked at the consequences of DopEcR signaling at three levels: behavior, neuronal morphology and finally physiology. Because changes steroid hormones levels are often associated with environmental stressors we assayed the role of DopEcR in a stress related behavior: starvation-induced sleep suppression and hyperactivity. To look at DopEcR’s role in neuronal physiology we used bioluminescent calcium imaging to measure its effect on the stimulated calcium response in a brain structure critical for behavior. Finally we used principal clock neurons in the brain (PDF+ l-LNv neurons) as a model to examine DopEcR’s role in modulating plasticity and neuronal structure.
In our present work described in Chapter 2, we found that the D1-like receptor, DopR1, modulates sleep and activity independent of starvation while DopEcR plays a role in mediating starvation-induced sleep suppression and enhanced activity. We found that knocking down EGFR in a DopEcR mutant background restored starvation induced changes in behavior, suggesting that DopEcR normally suppresses EGFR signaling to suppress sleep under starvation.
In Chapter 4, we show that the nicotine-induced Ca2+-response was selectively enhanced in the medial lobes either in DopEcR mutant or in flies with DopEcR selectively knocked down within the MBs. Using a pharmacological approach, we show that the endogenous ligands of DopEcR mediated two different responses in the MBs: the steroid ligand ecdysone enhances activity in the calyx and cell body region, whereas monoaminergic ligand dopamine reduced activity in the medial lobes. In Chapter 5, we find that reducing DopEcR in PDF neurons results in reduced basal levels of bouton numbers. The reduction in bouton number is independent of cAMP signaling but instead relies on inhibition of EGFR signaling. Signifying that DopEcR may modulate EGFR associated signaling to make changes in the in the brain.
These results demonstrate that DopEcR is able to modulate neuronal excitability, physical structure of neurons and the behavior of the organism. Interestingly it also indicates that DopEcR’s different ligands, dopamine and ecdysone, may have unique and spatially distinct effects on different brain structures or within the same structure. Overall, this study provides a solid foundation for understanding the roles and action mechanisms of GPCR-mediated steroid signaling in regulation of neural development, physiology and behavior.
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Khorshidi, Mohammad Ali. "Live Single Cell Imaging and Analysis Using Microfluidic Devices." Doctoral thesis, KTH, Proteomik och nanobioteknologi, 2013. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-129278.
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Today many cell biological techniques study large cell populations where an average estimate of individual cells’ behavior is observed. On the other hand, single cell analysis is required for studying functional heterogeneities between cells within populations. This thesis presents work that combines the use of microfluidic devices, optical microscopy and automated image analysis to design various cell biological assays with single cell resolution including cell proliferation, clonal expansion, cell migration, cell-cell interaction and cell viability tracking. In fact, automated high throughput single cell techniques enable new studies in cell biology which are not possible with conventional techniques. In order to automatically track dynamic behavior of single cells, we developed a microwell based device as well as a droplet microfluidic platform. These high throughput microfluidic assays allow automated time-lapse imaging of encapsulated single cells in micro droplets or confined cells inside microwells. Algorithms for automatic quantification of cells in individual microwells and micro droplets are developed and used for the analysis of cell viability and clonal expansion. The automatic counting protocols include several image analysis steps, e.g. segmentation, feature extraction and classification. The automatic quantification results were evaluated by comparing with manual counting and revealed a high success rate. In combination these automatic cell counting protocols and our microfluidic platforms can provide statistical information to better understand behavior of cells at the individual level under various conditions or treatments in vitro exemplified by the analysis of function and regulation of immune cells. Thus, together these tools can be used for developing new cellular imaging assays with resolution at the single cell level. To automatically characterize transient migration behavior of natural killer (NK) cells compartmentalized in microwells, we developed a method for single cell tracking. Time-lapse imaging showed that the NK cells often exhibited periods of high motility, interrupted with periods of slow migration or complete arrest. These transient migration arrest periods (TMAPs) often overlapped with periods of conjugations between NK cells and target cells. Such conjugation periods sometimes led to cell-mediated killing of target cells. Analysis of cytotoxic response of NK cells revealed that a small sub-class of NK cells called serial killers was able to kill several target cells. In order to determine a starting time point for cell-cell interaction, a novel technique based on ultrasound was developed to aggregate NK and target cells into the center of the microwells. Therefore, these assays can be used to automatically and rapidly assess functional and migration behavior of cells to detect differences between health and disease or the influence of drugs. The work presented in this thesis gives good examples of how microfluidic devices combined with automated imaging and image analysis can be helpful to address cell biological questions where single cell resolution is necessary.QC 20130927
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Hiler, Daniel James. "Bioluminescence Imaging of Transgene Expression at the Wholemouse Level and in the Mesencephalic Trigeminal Nucleus." Bowling Green State University / OhioLINK, 2009. http://rave.ohiolink.edu/etdc/view?acc_num=bgsu1245693947.
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Kliemann, Dorit [Verfasser]. "Implicit and explicit facial emotion recognition in autism spectrum disorder : Insights from behavior, gaze and functional magnetic resonance imaging / Dorit Kliemann." Berlin : Freie Universität Berlin, 2013. http://d-nb.info/1031667075/34.
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Neumann, Martin [Verfasser], Robert [Akademischer Betreuer] Magerle, Robert [Gutachter] Magerle, and Borczyskowski Christian [Gutachter] von. "Time-resolved imaging of the micro-mechanical behavior of elastomeric polypropylene / Martin Neumann ; Gutachter: Robert Magerle, Christian von Borczyskowski ; Betreuer: Robert Magerle." Chemnitz : Universitätsbibliothek Chemnitz, 2015. http://d-nb.info/121381376X/34.
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Bajaj, Sahil, Stephen N. Housley, David Wu, Mukesh Dhamala, G. A. James, and Andrew J. Butler. "Dominance of the Unaffected Hemisphere Motor Network and Its Role in the Behavior of Chronic Stroke Survivors." FRONTIERS MEDIA SA, 2016. http://hdl.handle.net/10150/622772.
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Balance of motor network activity between the two brain hemispheres after stroke is crucial for functional recovery. Several studies have extensively studied the role of the affected brain hemisphere to better understand changes in motor network activity following stroke. Very few studies have examined the role of the unaffected brain hemisphere and confirmed the testretest reliability of connectivity measures on unaffected hemisphere. We recorded blood oxygenation level dependent functional magnetic resonance imaging (fMRI) signals from nine stroke survivors with hemiparesis of the left or right hand. Participants performed a motor execution task with affected hand, unaffected hand, and both hands simultaneously. Participants returned for a repeat fMRI scan 1 week later. Using dynamic causal modeling (DCM), we evaluated effective connectivity among three motor areas: the primary motor area (M1), the premotor cortex (PMC) and the supplementary motor area for the affected and unaffected hemispheres separately. Five participants manual motor ability was assessed by Fugl-Meyer Motor Assessment scores and root-mean square error of participants tracking ability during a robot-assisted game. We found (i) that the task performance with the affected hand resulted in strengthening of the connectivity pattern for unaffected hemisphere, (ii) an identical network of the unaffected hemisphere when participants performed the task with their unaffected hand, and (iii) the pattern of directional connectivity observed in the affected hemisphere was identical for tasks using the affected hand only or both hands. Furthermore, paired t-test comparison found no significant differences in connectivity strength for any path when compared with one-week follow-up. Brain-behavior linear correlation analysis showed that the connectivity patterns in the unaffected hemisphere more accurately reflected the behavioral conditions than the connectivity patterns in the affected hemisphere. Above findings enrich our knowledge of unaffected brain hemisphere following stroke, which further strengthens our neurobiological understanding of stroke-affected brain and can help to effectively identify and apply stroke-treatments.
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Guendelman, Simon. "Emotion Regulation, Social Cognitive and Neurobiological mechanisms of Mindfulness, from Dispositions to Behavior and Interventions." Doctoral thesis, Humboldt-Universität zu Berlin, 2021. http://dx.doi.org/10.18452/22265.
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Achtsamkeit wird mit vielen positiven Effekten für das psychische Wohlbefinden assoziiert, wobei Fähigkeiten wie Emotionsregulation (ER) und soziale Kognition (SC) zu den wichtigsten Mechanismen gehören. In der vorliegenden Doktorarbeit wurde die Beziehung zwischen Achtsamkeit, ER und SC mit verschiedenen methodischen Ansätzen untersucht. In Studie I wurde mithilfe von Literatur und empirischen Modellen die Beziehung zwischen Achtsamkeit und ER ausgearbeitet und verschiedene psychologische und neurokognitive Mechanismen diskutiert. Studie II zielte darauf ab den ER-Mechanismus bei „Trait-Achtsamkeit“ zu entschlüsseln. Hier zeigte sich, dass es sowohl bei Probanden mit einer Borderline-Persönlichkeitsstörung als auch bei gesunden Teilnehmern einen mediierenden Effekt von Selbstmitgefühl gab, der Achtsamkeit mit ER-Merkmalen verband. Studie III untersuchte den Zusammenhang zwischen ER und SC mit Hilfe von Verhaltens- und Neuroimaging-Experimenten, mit Fokus auf dem Konzept der sozialen ER (die Fähigkeit, die Emotionen anderer zu modulieren). Es zeigte sich, dass bei der Regulierung der Emotionen anderer der eigene Stress reduziert wird, wobei wichtige "soziokognitive" Hirnregionen (z.B. Precuneus) an der Vermittlung dieser Effekte beteiligt sind. Studie IV untersuchte im Rahmen einer Neuroimaging-basierten randomisierten Kontrollstudie ER-Mechanismen während einer achtsamkeitsbasierten Intervention (MBI). Die Studie zeigte eine durch die MBI induzierte ER-Verhaltensplastizität im Gehirn, sowohl für die Eigen- als auch für die soziale ER. Ein Effekt im Vergleich zu SC (kognitive und emotionale Empathie) wurde nicht gezeigt. Unter Einbezug aller Ergebnisse wurde ein Modell postuliert, das den Austausch und die Regulierung von Emotionen im Kontext von sozialen Interaktionen integriert. Die Dissertation bietet neue Einblicke in die ER-Mechanismen der Achtsamkeit und beleuchtet die individuellen Determinanten sozialer Prozesse durch das Zusammenbringen von ER und SC.Mindfulness, the capacity to fully attend to the present experience, has been linked to a myriad of mental health benefits, being abilities such as emotion regulation (ER) and social cognition (SC) of the main potential active mechanisms. The current doctorate thesis investigated the relationship between mindfulness and ER and SC using a range of methodological approaches from trait level individual differences to behavioral and brain mechanisms. Study one explored the relationship between mindfulness and ER by examining the diverse literature and empirical models, discussing different psychological and neuro-cognitive mechanisms. Study two intended to unravel the ER mechanism of trait mindfulness, showing in both borderline personality and healthy subjects the mediating effect of self-compassion linking mindfulness and ER traits. Study three further investigated the link between ER and SC using behavioral and neuro-imaging experiments, addressing the notion of social ER (the capacity to modulate others’ emotions). It showed that when regulating others’ emotions, an individual’s own distress is reduced, being key ‘sociocognitive’ brain regions (i.e. precuneus) engaged in mediating these effects. Study four investigated the fine-grained ER mechanisms of a mindfulness-based intervention (MBI), comparing the MBI with a reading group (READ), in the context of a neuroimaging-based randomized controlled trial. This study revealed ER brain behavioral plasticity induced by the MBI, for both self and social ER. It also showed a lack of effect over SC (cognitive and emotional empathy). Articulating overall findings, a model that integrates exchanges and regulation of emotions in the context of social interactions is proposed. The dissertation offers new insights into mindfulness’ ER mechanisms, from dispositions to neuro-behavioral levels, and also sheds light onto individual level determinants of social processes, linking ER and SC.
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Olofsson, Per. "Microwell-based Collagen Matrix Migration Assays for NK:target Cell Interactions : Three-dimensional Imaging and Analysis of Transient Migration Behavior of NK Cells in vitro." Thesis, KTH, Cellens fysik, 2011. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-43456.
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Natural killer (NK) cells are lymphocytes of the innate immune system responsible for lysing tumor and virally-infected cells. Investigating NK cell heterogeneity can inform the development of more efficacious immunotherapeutic treatments. Cell motility is an essential aspect of NK cell function. Moreover, the cell migration behavior within cell populations displays a marked heterogeneity. For some time it has been clear that cell-matrix interactions can radically alter the behavior of certain types of cells. (1) However, conventional studies of cell migration have relied on flat (2-D) surfaces, and thus do not take this potentially game-changing third dimension into account. Still, migration studies using ECM-mimicking biomaterials such as collagen and Matrigel may employ volume imaging, but often fail to quantify and analyze the vertical direction of migration. This project used silicon microchip-based technology, extracellular matrixlike type I collagen hydrogel, and fluorescence laser scanning confocal microscopy to study the migration behavior of single cells in 3-D. NK and targetcells were embedded in a collagen gel matrix deposited inside sub-mm scale microwells. The microwell provides natural barriers to cell migration, and so ensures that the cells remain confined within the imaging volume. The entire volume of the microwell was scanned for two hours by time-lapse fluorescence microscopy. A total of N = 14 NK cell migration trajectories were quantified using fluorescence centroid measurements. Results suggest that NK cells retain their cytotoxicity when embedded in the collagen matrix used for the 3-D migration assay. The average migration speed of the studied NK cells in three dimensions was found to be 3.7 ± 0.5μm/min (mean± SEM). Additionally, the NK cells exhibited a directional bias in migration, slightly preferring horizontal migration over vertical migration. In conclusion, this assay readily lends itself to short-term imaging of the migration behavior and cell-cell interactions of NK and target cells embedded in collagen gel in microwells. This microwell-gel system shows promising prospects for future applications at the interface of immunology and engineering.NK-celler är lymfocyter tillhörande det ospecifika immunförsvaret vars uppgift är att uppsöka och avdöda tumör- och virusinfekterade celler. Genom att undersöka heterogeniteten inom NK-cellspopulationer öppnas en möjlighet att förbättra effektiviteten hos immunoterapeutiska behandlingar. Cellmotilitet är en viktig aspekt av NK-cellers funktion. Därutöver uppvisar cellmigrationsbeteendet inom cellpopulationer en märkbar heterogenitet. Det har under en tid stått klart att cell-matris-interaktioner kan ha en genomgripande effekt på beteendet hos vissa celltyper.(1) Emellertid grundar sig traditionella studier av cellmigration på användandet av tvådimensionella, plana ytor, och frånser på detta vis den potentiellt avgörande effekt som den tredje dimensionen kan ha på resultatet. Likväl kan studier som använder extracellulär matrix-liknande biomaterial, såsom kollagen och Matrigel, och som därutöver drar nytta av volymsavbildning för cellmigration ändå ofta bortse från att kvantifiera och analysera cellmigrationen i vertikalled. Detta projekt använde kiselbaserad mikrochipteknologi, extracellulär matrixliknande hydrogel typ I kollagen, samt fluorescensmikroskopi för att undersöka cellmigrationbeteendet hos enskilda NK-celler i 3-D. NK- och målceller bäddades in i en kollagenmatris vilken i sin tur gjöts in i en mindre än millimeterstor mikrobrunn. Mikrobrunnen utgör en naturlig barriär för cellmigration och kan således försäkra att cellerna stannar inuti avbildningsvolymen. Hela mikrobrunnens volym avbildades under två timmar med hjälp av tidsfördröjd fluorescensmikroskop. En tidsserie av mätningarna sammanställdes sedan. Totalt sammanställdes och kvantifierades N = 14 NK-cellers cellmigrationsbanor genom att uppskatta cellernas fluorescenta mittpunkter i den återskapade 3-D-volymen. Resultaten ger vid handen att NK-celler behåller sin cytotoxiska förmåga när de är inbäddade i 3-D-matrisen som används i mikrobrunnsuppsättningen. Den tredimensionella medelhastigheten för cellmigrationen hos de undersökta cellerna var 3.7±0.5 μm/min (medelvärde±standardfelet). Därutöver uppvisade NK-cellerna en bias i den genomsnittliga riktningen hos cellmigrationen, där horisontell cellmigration föredrogs framför vertikal cellmigration. Avslutningsvis kan sägas att denna experimentella uppsättning utan större problem kan användas för korttidsavbildning av cellmigrationsbeteende och cell-cell-interaktioner hos NK- och målceller inbäddade i en mikrobrunnsingjuten kollagenmatris. Detta mikrobrunn-gel-baserade system uppvisar lovande möjligheter för framtida tillämpningar i gränsytan mellan immunologi och ingenjörskonst.
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Alvari, Gianpaolo. "Fine-Grained Analyses of Early Autism-related Social Behavior in Real-World Scenarios by Machine Learning." Doctoral thesis, Università degli studi di Trento, 2022. http://hdl.handle.net/11572/331002.
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Autism Spectrum Disorder (ASD) is a condition that carries high costs for families and the healthcare system, requiring extensive management both in terms of diagnosis and treatment. The implementation of AI-based systems in clinical practice represents a possible supportive solution that can help clinicians by providing more systematic meth- ods to monitor child behavior. The main advantage over more traditional observational approaches is to offer quantitative and refined analysis solutions that can be ecological at the same time. The relevance of AI in clinical applications can have a role both in the challenge of early detection and in designing intervention programs better tai- lored to the specific functioning of children with ASD. The research project presented in this dissertation focused on developing AI-based systems for fine-grained analysis of autism-related social behaviors and their validation in concrete clinical environments. Specifically, in Chapter 2, our first study is presented, which targets on implementing a computational phenotyping system to address the need for new early markers of the condition. Through fine-grained analytics of facial dynamics in videos, we identified a set of features that distinguished young (6-12 months) infants with ASD (18 ASD, 15 non-ASD) during unconstrained at-home interactions. In Chapters 3 and 4, we introduce EYE-C, a Behavior Imaging model for robust analysis of eye contact episodes in eco- logical therapist-child interactions. The system was validated in the clinical setting for personalized early intervention. First, we investigated the influence of extracted features in categorizing spectrum heterogeneity across a sample of 62 preschool (<6 years) chil- dren with ASD. Further, we tested our metrics as predictors of early intensive treatment outcomes in a sub-sample of 18 subjects with ASD. The project aims to demonstrate the feasibility of effective computational systems that are robust to the high variability of unstructured interactions, with emphasis on the applicative value in real-world scenar- ios. Even though based on limited sample sizes, the work presented may offer interesting insights into the perspective of integrating AI into clinical practice.
The research project was funded by an FBK scholarship and developed in a double in- ternship at ODFLab (University of Trento) and the FBK Data Science for Health (DSH) research unit.
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Cerio, Donald Greene. "The Visual Apparatus of Avian Dinosaurs and Other Diapsids: Anatomical Correlates of Behavior and Evolution." Ohio University / OhioLINK, 2019. http://rave.ohiolink.edu/etdc/view?acc_num=ohiou1565617073174635.
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Boudiaf, Naïla. "Effets du vieillissement normal sur la production lexicale : approche pluridisciplinaire." Thesis, Université Grenoble Alpes (ComUE), 2016. http://www.theses.fr/2016GREAS029/document.
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Le vieillissement normal est associé à des difficultés cognitives même en absence de pathologies sous-jacentes. Les fonctions cognitives sont connues pour être sensibles à l’effet de l’âge, à l'exception de la fonction langagière qui fait débat. Cependant, les personnes âgées rapportent des difficultés de production lexicale qui sont également présentes dans des maladies neurodégénératives comme la maladie d’Alzheimer. L’objectif de ce travail de thèse a été de caractériser l’évolution des processus cognitifs impliqués dans la production lexicale sur le plan comportemental puis de caractériser les modifications cérébrales neurofonctionnelles et vasculaires associées. Dans une première étude en psychologie comportementale incluant 72 participants sains, âgés de 30 à 84 ans, nous avons montré un effet différentiel de l’âge sur les processus de dénomination orale et les processus d’associations sémantiques. La dénomination orale était bien préservée dans le vieillissement normal en termes de compétence, mais elle semblait être affectée par un ralentissement cognitif généralisé. Par contre, nous avons observé un ralentissement plus important des processus d’associations sémantiques qui est probablement dû à un contrôle exécutif moins efficace. Une deuxième étude en IRM fonctionnelle a confirmé ces résultats et a suggéré la mise en place de mécanismes compensatoires pour palier ces difficultés cognitives. Enfin, nous avons caractérisé les modifications de perfusion cérébrale basale et fonctionnelle dans une dernière étude en IRM fonctionnelle vasculaire. Nous avons montré le lien entre ces modifications et les capacités cognitives chez les mêmes participants sains, ainsi que chez des patients atteints de troubles cognitifs à des stades précoces. Cette approche multimodale combinant la psychologie expérimentale, la neuropsychologie, la neuroimagerie et l’imagerie de perfusion cérébrale a permis d’obtenir un tableau neurocognitif plus complet afin de décrire les modifications cognitives, cérébrales et vasculaires qui interviennent dans le vieillissement normal lors de la production du langageNormal aging is associated with cognitive difficulties in many domains except for language, which is still under debate. However, older adults report difficulties in lexical production, which are also known to be associated with pathological aging, such as Alzheimer’s disease. This work aimed first to characterize the changes in the cognitive processes involved in lexical production using a behavioral approach, then to characterize the associated neurofunctional and vascular changes using fMRI. In the first study including 72 healthy participants, aged between 30 and 84 years, we showed a differential aging effect on lexical production and semantic processing. Naming was well preserved in terms of competences in normal aging; nevertheless, it was affected by the general cognitive slowdown. However, semantic processing was more affected by aging, probably due to inefficient executive control. The second study using fMRI confirmed these results and suggested the establishment of compensatory mechanisms to overcome cognitive difficulties. Finally, in the third study using vascular fMRI we described basal and functional cerebral perfusion modifications in normal aging as well as at early stages of pathological aging. We showed a strong relationship between the hemodynamical properties and the cognitive abilities. This multidisciplinary approach combining behavioral, neuropsychological, neurofunctional and cerebral perfusion imaging studies, provided a more complete picture of cerebral and cognitive changes in lexical production during normal aging
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Campabadal, Delgado Anna. "Idiopathic REM sleep behavior disorder and olfactory dysfunction in Parkinson's disease and premotor stages. MRI and neuropsychological studies." Doctoral thesis, Universitat de Barcelona, 2020. http://hdl.handle.net/10803/671022.
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BACKGROUND:
The present Doctoral Thesis is focused on Rapid-eye-movement (REM) sleep behavior disorder (RBD) and olfactory dysfunction as biomarkers of Synucleinopathies, such as Parkinson’s disease (PD), dementia with Lewy bodies (DLB), and multiple system atrophy (MSA). RBD is a parasomnia characterized by loss of atonia during REM sleep that provokes dream-enacting behaviors. Clinically isolated RBD (IRBD) is considered a prodromal stage of alpha-Synucleinopathies since almost 75% of patients after 12 years of the disease develop a PD or atypical parkinsonism. Specifically, in a multicentric study,
56.5% of IRBD patients converted to parkinsonism as the first manifestation, while 43.5% developed dementia first. Subtle motor symptoms, hyposmia, and cognitive impairment are the best predictors of phenoconversion in IRBD.
OBJECTIVES AND HYPOTHESES:
The main objectives of this Thesis are: 1) To characterize structural and functional brain substrates underlying Idiopathic REM sleep behavior disorder as well as to relate these findings to cognitive performance; 2) To study olfactory dysfunction as a preclinical and clinical biomarker of alpha- Synucleinopathies, and its progression throughout the disease; 3) To investigate progressive brain degeneration throughout IRBD, and to investigate how these changes relate to cognitive decline.
The main hypotheses are:
1) IRBD will be characterized by specific changes in brain structure and functional connectivity that will be associate with olfactory and cognitive impairment,
2) IRBD patients will show structural brain changes over time and a cognitive decline superior to that seen in normal aging,
3) Smell dysfunction will be identified in IRBD and PD, and it is expected to progress slightly with the disease course.
MATERIAL AND METHODS:
This Doctoral Thesis is presented as a compendium of six studies that were carried out to achieve the above-mentioned objectives.
RESULTS:
In studies 1, 2, and 5, IRBD patients differed from controls in several cognitive domains, namely attention and executive functions, mental processing speed, verbal memory, and semantic fluency. Besides, studies 1 and 5 identified for first-time impairment in facial recognition and visuospatial functions. Contrary to our hypothesis in study 1, we did not find significant correlations between cognitive performance and brain atrophy. However, there was coherence between the structural changes detected by MRI and neuropsychological impairment. For instance, IRBD subjects had facial recognition impairment and cortical atrophy in the fusiform gyrus, a region that is known to be critical for such function. In the same way, patients showed memory impairment and hippocampal atrophy, a core structure for learning and memory. On the other hand, study
2 evidenced the potential role of altered brain functional connectivity in IRBD’s cognitive impairment. We found a positive correlation between mental processing speed and temporoparietal functional connectivity in the IRBD group. In study 5, we reported visual form discrimination decline in IRBD relative to normal aging after less than two years. More importantly, we identified that visual form discrimination worsening over time was explained by progressive reductions of the cortical thickness in the superior parietal.
CONCLUSIONS:
The present Doctoral Thesis has identified new cognitive deficits in IRBD patients and has shed some light on its progression throughout the course of the disease. In particular, our work has shown the importance of VS/VP functions as a measure able to identify cognitive changes across time in IRBD, and its potential in identifying those patients with progressive neurodegeneration in posterior cortices. Besides, we have exhaustively described the characteristics of severe and early olfactory dysfunction in IRBD and described for the first time its neuroanatomical correlates. The neuroimaging data from this Thesis points towards an early implication of the temporal-occipital-parietal cortices in IRBD. Additionally, our longitudinal work has shown that IRBD patients have brain degeneration of the occipitoparietal and orbitofrontal cortex over time, in line with the degenerative changes reported in PD and DLB. Abnormalities in such regions are supported by the association between impaired cognition and both functional and structural brain changes.
Cortical atrophy and disrupted cortico-cortical functional connectivity highlight that cortical degeneration and functional abnormalities already exist in patients with IRBD before they are diagnosed with DLB, PD, or MSA. Thus, suggesting that in prodromal PD, the alpha-synuclein pathology is already involving these structures earlier than would be expected according to the Braak degeneration model proposed form neuropathological data. Cortical atrophy and dysfunction may explain why some patients present neuropsychological impairment before the motor onset. We hope that our research will serve as a basis for further multicentric studies that confirm our findings, and to identify the optimal neuropsychological and neuroimaging markers for diagnostic, prognostic, and efficacy of future neuroprotective therapies.MARC TEÒRIC: La present Tesi Doctoral estudia el trastorn del comportament del son REM (RBD, per les seves sigles en anglès) i la disfunció olfactiva com a biomarcadors de les alfa- Sinucleinopaties, com ara la malaltia de Parkinson (PD, per les seves sigles en anglès), la demència per cossos de Lewy (DLB, per les seves sigles en anglès) i l’atròfia multisistèmica (MSA, per les seves sigles en anglès). El RBD és una parasòmnia caracteritzada per la pèrdua d’atonia durant el son REM que provoca episodis on els pacients mostren moviments que reflecteixen el contingut dels seus somnis. El RBD que es presenta clínicament aïllat (IRBD, per les seves sigles en anglès), es considera un estadi prodròmic de les Sinucleinopaties, doncs s’ha vist que gairebé el 75% dels pacients després de 12 anys amb diagnòstic d’IRBD acaben sent diagnosticats de malaltia de Parkinson o parkinsonismes atípics. Concretament, en un estudi multicèntric el 56.5% dels pacients amb IRBD varen desenvolupar parkinsonisme com a primera manifestació, mentre que el 43.5% va presentar demència en primer lloc. La simptomatologia motora, la hipòsmia i el deteriorament cognitiu han demostrat ser els millors predictors de conversió en aquests pacients. En aquest context, la comunitat científica ha demostrat un interès creixent en definir els canvis cognitius associats a l’IRBD. Els estudis publicats fins ara conclouen que entre el 15-50% dels pacients tenen deteriorament cognitiu lleu. Malgrat l’evidència ben documentada sobre la presència d’afectació neuropsicològica en pacients amb IRBD, cal una recerca addicional que valori de forma aïllada i específica les funcions visuoespacials i visuoperceptives (VS/VP), ja que l’alteració d’aquestes funcions és característica del perfil neuropsicològic dels pacients amb PD i DLB. Pel que fa al declivi cognitiu al llarg de la malaltia, encara hi ha una gran incertesa. OBJECTIUS I HIPÒTESIS: Els objectius principals d'aquesta Tesi són: 1 Caracteritzar els substrats cerebrals estructurals i funcionals subjacents a l’RBD, així com relacionar aquestes troballes amb el rendiment cognitiu, 2 Estudiar la disfunció olfactiva com a biomarcador clínic i preclínic de les alfa- Sinucleinopaties, i la seva progressió al llarg de la malaltia, 3 Investigar la degeneració cerebral progressiva al llarg de l’IRBD i com aquests canvis es relacionen amb el declivi cognitiu. Les principals hipòtesis són: 1 L'IRBD es caracteritzarà per canvis específics en l'estructura cerebral i la connectivitat funcional que estarà associada a un deteriorament olfactiu i cognitiu, 2 Els pacients amb IRBD mostraran canvis cerebrals estructurals amb el pas del temps i un declivi cognitiu superior a l’observat en l’envelliment normal, 3 S'espera identificar reducció de la capacitat olfactòria en l'IRBD i la PD, així com que progressi lleugerament amb el curs de la malaltia. MATERIAL I MÈTODES: La present Tesi Doctoral consta de sis estudis realitzats per donar resposta als objectius esmenats anteriorment. CONCLUSIONS: La present Tesi Doctoral ha identificat nous dèficits cognitius en pacients amb IRBD i ha perfilar la seva progressió al llarg de l’evolució de la malaltia. En particular, el nostre treball ha demostrat la importància de les funcions VS/VP com a mesura capaç d’identificar els canvis cognitius a través del temps en l’IRBD i el seu potencial per identificar aquells pacients amb neurodegeneració progressiva en el còrtex posterior. A més, hem descrit de forma exhaustiva les característiques de la disfunció olfactiva precoç i greu de l’IRBD i hem descrit per primera vegada els seus correlats neuroanatòmics.
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Ramadoss, Balaji. "Vector Flow Model in Video Estimation and Effects of Network Congestion in Low Bit-Rate Compression Standards." [Tampa, Fla.] : University of South Florida, 2003. http://purl.fcla.edu/fcla/etd/SFE0000139.
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Isaacson, Matthew David. "Using new tools to study the neural mechanisms of sensation : auditory processing in locusts and translational motion vision in flies." Thesis, University of Cambridge, 2019. https://www.repository.cam.ac.uk/handle/1810/288741.
Full textAbstract:
This thesis describes work from both the University of Cambridge in the lab of Berthold Hedwig and from the HHMI Janelia Research Campus in the lab of Michael Reiser. At the University of Cambridge, my work involved the development and demonstration of a method for electrophoretically delivering dyes and tracers for anatomical and functional imaging into animals that are not amenable to genetic labelling techniques. Using this method in locusts and crickets - model systems of particular interest for their acoustic communication - I successfully delivered polar fluorescent dyes and tracers through the sheath covering the auditory nerve, simultaneously staining both the peripheral sensory structures and the central axonal projections without destroying the nerve's function. I could label neurons which extend far from the tracer delivery site on the nerve as well as local neuron populations through the brain's surface. I used the same method to deliver calcium indicators into central neuropils for in vivo optical imaging of sound-evoked activity, as well as calling song-evoked activity in the brain. The work completed at the Janelia Research Campus began with the development of a modern version of a modular LED display and virtual reality control system to enable research on the visual control of complex behaviors in head-fixed animals. The primary advantages of our newly developed LED-based display over other display technologies are its high-speed operation, brightness uniformity and control, precise synchronization with analog inputs and outputs, and its ability to be configured into a variety of display geometries. Utilizing the system's fast display refresh rates, I conducted the first accurate characterization of the upper limits of the speed sensitivity of Drosophila for apparent motion during flight. I also developed a flexible approach to presenting optic flow scenes for functional imaging of motion-sensitive neurons. Finally, through the on-line analysis of behavioral measures, image rendering, and display streaming with low latency to multi-color (UV/Green) LED panels, I demonstrated the ability to create more naturalistic stimuli and interactive virtual visual landscapes. Lastly, I used this new visual display system to explore a newly discovered cell-type that had been implicated in higher-order motion processing from a large genetic screen of visually-guided behavior deficits. Using genetic silencing and activation methods, and by designing stimuli that modeled the optic flow encountered during different types of self-motion, colleagues in the Reiser lab and I showed that this cell-type - named Lobula Plate Columnar 1 (LPC1) - is required for the stopping behavior of walking flies caused by back-to-front translation motion but is not involved in the rotational optomotor response. Using calcium imaging, I found that LPC1 was selectively excited by back-to-front motion on the eye ipsilateral to the neuron population and inhibited by front-to-back motion on the contralateral eye, demonstrating a simple mechanism for its selectivity to translation over rotation. I also examined an anatomically similar cell type - named Lobula-Lobula Plate Columnar type 1 (LLPC1) - and found that its selectivity results from a similar but opposite calculation for the detection of front-to-back translational motion. The detection of back-to-front motion had previously been hypothesized to be useful for collision avoidance, and this work provides a neural mechanism for how this detection could be accomplished, as well as providing a platform from which to explore the larger network for translation optic flow.
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Suñol, Rodrigo Maria. "Brain correlates of obsessive-compulsive symptoms in healthy children." Doctoral thesis, Universitat de Barcelona, 2021. http://hdl.handle.net/10803/671026.
Full textAbstract:
Esta tesis busca contribuir al estudio de los correlatos neurobiológicos de los síntomas obsesivos-compulsivos subclínicos (SOCS) con la esperanza de que sus hallazgos puedan ser eventualmente vinculados al desarrollo del trastorno obsesivo-compulsivo (TOC) y servir para identificar individuos vulnerables a desarrollarlo. Para ello, presentamos tres estudios realizados en una muestra de niños sanos, en los que utilizamos un enfoque multidimensional de los síntomas e implementamos distintas modalidades de neuroimagen, así como la combinación de datos de neuroimagen y genética, para aportar una visión integral de los factores que subyacen los SOCS. En el primer estudio, analizamos cambios volumétricos en la sustancia gris y blanca asociados a los SOCS y, en el segundo, evaluamos alteraciones de conectividad funcional asociadas a estos síntomas. En ambos, estudiamos el efecto de la edad y el sexo en dichas asociaciones. Finalmente, en el tercer estudio, identificamos nodos cerebrales en los que la conectividad funcional dinámica tiende a reverberar (atractores) y estudiamos su relación con los SOCS y su base genética.
Nuestros resultados vinculan los SOCS totales con alteraciones en el circuito cortico-estriato- talamo-cortical (CSTC), hecho que concuerda con el modelo neurobiológico del TOC, pero también en regiones límbicas fuera de este circuito. También observamos que diferentes síntomas se asocian a alteraciones neurobiológicas distintas, lo que coincide con el modelo multidimensional del trastorno. Además, encontramos que los cambios estructurales relacionados con los síntomas de orden eran específicos de niños menores de 10 años, mientras que los cambios estructurales y funcionales asociados con los síntomas de acumulación eran específicos de sujetos de más de 10 años, especialmente en niñas, lo que sugiere que estos grupos demográficos pueden ser especialmente vulnerables a desarrollar dichos síntomas. Finalmente, identificamos polimorfismos en los genes GRM7 y GNAQ, implicados en la modulación de la neurotransmisión glutamatérgica, y PARVA, asociado a la regulación del citoesqueleto de actina, que predisponen al aumento de la capacidad atractora del hipocampo, vinculada a los SOCS totales. Del mismo modo, hallamos polimorfismos en los genes ATP1B1 y TESC, implicados en el mantenimiento de gradientes electroquímicos, que predisponen y protegen, respectivamente, al aumento de las propiedades atractoras del córtex parietal superior, relacionadas con los síntomas de orden.Obsessive-compulsive disorder (OCD) is characterized by the presence of intrusive thoughts that cause anxiety (obsessions) and lead to repetitive behaviors or mental acts aimed at reducing this anxiety (compulsions). Although OCD has been associated with alterations in the cortico-striato- thalamo-cortical (CSTC) circuits, the clinical heterogeneity of the disorder makes its neurobiology difficult to investigate. Given that the evidence suggests that different OCD symptoms could arise from distinct neurobiological alterations, the use of the multidimensional model, which allows characterizing different symptom dimensions, could help define more homogeneous subgroups of patients and identify more robust endophenotypes. However, the studies that have used this approach have given heterogeneous findings, possibly due to differences between patients in terms of medication, chronicity, or comorbidities. Notably, epidemiological studies show that obsessive-compulsive symptoms (OCSs) in childhood predispose to developing OCD in adulthood. Furthermore, the symptom profile observed in adulthood is consistent with the same symptom precursors in childhood. Therefore, OCSs could be studied in samples of healthy children from a dimensional perspective, thus avoiding the confounding factors typically observed in clinical samples. This thesis seeks to contribute to the study of the neurobiological correlates of OCSs in hopes that its findings may eventually be linked to the development of OCD and serve to characterize at-risk individuals. With that aim, we present three studies assessing a sample of healthy children, in which we use a multidimensional approach and implement different neuroimaging modalities and techniques, as well as the combination of neuroimaging and genetic data, to provide a comprehensive view of the factors underlying OCSs. In the first study, we analyzed volumetric changes in gray and white matter associated with total and dimensional OCSs whereas, in the second one, we evaluated functional connectivity alterations associated with total and dimensional OCSs. In both studies, we also assessed the effect of age and sex on these associations. In the third one, we identified brain nodes in which dynamic functional connectivity tends to reverberate (attractors) and we studied their relationship with total and dimensional OCSs. Furthermore, by combining neuroimaging and gene expression data, we identified genetic variants that moderated the relationship between OCSs and attractors. Our results link total OCSs with alterations in the CSTC circuit, which concurs with the prevailing neurobiological model of OCD, but also in limbic regions outside of this circuit. We also observed that different symptoms were associated with distinct neurobiological alterations: obsessing symptoms were related to alterations in limbic regions; doubt/checking symptoms were associated with changes in the ventral cognitive CSTC loop, the insula and regions mediating frontal processing; ordering symptoms were associated with alterations in the ventral cognitive and sensorimotor CSTC loops and the superior parietal cortex; hoarding symptoms were related to alterations in different CSTC loops, suggesting a larger CSTC alteration. Structural changes related to ordering symptoms were specific to boys under 10 years of age, whereas structural and functional changes associated with hoarding symptoms were specific to children over 10 years of age, especially to girls, which suggests that these demographic groups may be more susceptible to developing such symptoms. Finally, we identified polymorphisms in the GRM7 and GNAQ genes, involved in the modulation of glutamate neurotransmission, and in the PARVA gene, associated with the regulation of the actin cytoskeleton, that predisposed to an increase in the attractor properties of the hippocampus, linked to total OCSs. We also found polymorphisms in the ATP1B1 and TESC genes, involved in the maintenance of electrochemical gradients, that predisposed and protected, respectively, to an increase in the attractor properties of the superior parietal cortex, related to ordering symptoms.
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Laine, P. (Pekka). "Dopamine transporter in alcoholism:a SPET study." Doctoral thesis, University of Oulu, 2001. http://urn.fi/urn:isbn:9514265270.
Full textAbstract:
Abstract
A large body of animal studies indicates that reinforcement from alcohol is
associated with dopaminergic neurotransmission in the mesocorticolimbic pathway.
However, as most psychiatric phenomena cannot be studied with animals, human
studies are needed. Furthermore, because of the fluctuating nature of phenomena
regarding the status of abuse and withdrawal, repeated observations of the same
study subjects under different situations can elucidate a variety of
pathophysiological mechanisms.
In this study 42 alcoholics were monitored during withdrawal and 30
alcoholics after four weeks of abstinence.
123I-β-CIT
SPET was used as a method for the semi quantification of their striatal dopamine
transporter (DAT) densities reflecting the function and structure of the
dopaminergic system.
DAT density was markedly lower during withdrawal among alcoholics as
compared to control subjects, but it elevated during abstinence to the level of
healthy volunteers. This increases in DAT density during withdrawal and
afterwards correlated with the depression scores of alcoholics. DAT density
correlated with the Novelty Seeking (NS) personality trait, especially among
abstinent alcoholics. After four weeks of controlled abstinence alcoholics with
an A1 allele of dopamine receptor D2 were found to have higher DAT densities than
alcoholics without it.
The results indicate that striatal DAT density is associated with mood,
personality, A1 genotype and the length of the abstinence period after heavy
alcohol drinking.
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Goçalo, Cássia Gongora. "Análise do comportamento natatório de larvas de peixes marinhos com técnicas de imageamento de alta frequência." Universidade de São Paulo, 2015. http://www.teses.usp.br/teses/disponiveis/21/21134/tde-07052015-105843/.
Full textAbstract:
O comportamento natatório de larvas de peixes na fase da primeira alimentação de Rachycentron canadum e Epinephelus marginatus foi descrito usando imagens de câmeras de alta frequência (60 a 2000 quadros por segundo) pelas técnicas de imageamento: microscopia de campo claro, sistema de filtros pareados e holografia. Oito métricas comportamentais foram registradas na presença de náuplios de copépodes; rotíferos Brachionus sp. e; sem alimento: natação rotineira (1 a 2,9 vezes o comprimento do corpo por segundo, CP s-¹); natação explosiva (3 a 40 CP s-¹); recuo; distâncias percorridas; batimentos do complexo caudal na natação e manutenção da posição (40 b s-¹); contrações rápidas do corpo em formato de C (de 0,16 a 0,40 s) e S (0,009 a 0,17 s); repouso; e comportamento alimentar (visualização das presas e tentativa de captura). As larvas alteraram a velocidade de natação na presença de presas e aumentaram em função da idade. Os maiores valores alcançados do número de Reynolds foram na presença de presas, para natação rotineira foi 200. As contrações da musculatura e mudanças na velocidade de natação indicam relação com aspectos ecológicos dos organismos, como busca por alimento e interações intra e interespecíficas.The swimming behavior of first feeding fish larvae Rachycentron canadum and Epinephelus marginatus was described using images acquired with high-speed cameras (60 to 2000 frames per second) by the imaging techniques: bright field microscopy, matched filters system and holography. Eight behavioral metrics were recorded in the presence of copepod nauplii; rotifer Brachionus sp.; and unfed: routine swimming (1 to 2.9 body lengths per second, BL s-¹); burst swimming (3 to 40 BL s-¹); backward swimming; distance traveled; caudal beat frequency of swimming and maintaining of the position (about 40 b s-¹); fast C-turns (0.16 to 0.40 s) and S-turns (0.009 to 0.17 s); rest; and feeding behavior (observation of prey and attempts to capture). The larvae altered their swimming velocity in the presence of prey and incresead according to age. The highest values of the Reynolds number were reached in the presence of prey, to routine swimming was < 20, and to bust swimming > 200. Muscles contractions and changes in the swimming showed a relation to ecological aspects of organisms, like food searching and intra and interspecific interactions.
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Vogel, Karen. "Terapia de aceitação e compromisso no tratamento da fobia de espaços fechados: ensaio clínico randomizado." Universidade de São Paulo, 2015. http://www.teses.usp.br/teses/disponiveis/5/5142/tde-01042015-102601/.
Full textAbstract:
Os exames de Ressonância Magnética vêm sendo muito requisitados nas diferentes especialidades médicas como complemento diagnóstico e acompanhamento evolutivo de diversas patologias. Embora seja um método diagnóstico de excelência, os pacientes que se submetem ao exame podem apresentar muito desconforto em razão do espaço restrito do aparelho. A fobia de espaços fechados é considerada um tipo de fobia específica, segundo o Manual Diagnóstico e Estatístico de Transtornos Mentais DSM 5 (APA, 2013). OBJETIVOS: Verificar se uma sessão de Terapia de Aceitação e Compromisso é tão eficaz quanto sete sessões deste mesmo modelo terapêutico no tratamento de pacientes com medo de realizar exames de Ressonância Magnética. MÉTODO: Foi realizado um ensaio clínico randomizado com dois grupos paralelos, um grupo recebeu uma sessão e o outro grupo recebeu sete sessões de tratamento de Terapia de Aceitação e Compromisso. Os participantes foram avaliados no início e ao final do tratamento a partir dos seguintes instrumentos: Inventário de Claustrofobia de Rachman e Taylor (1993), Inventário de Depressão de Beck et al. (1961) e Inventário de Ansiedade estado-traço de Spielberger, Gorsuch e Lushene (1970). O estudo foi realizado em um hospital público na cidade de São Paulo com 30 pacientes. Desfecho principal: permanecer dentro de um simulador de Ressonância Magnética por, no mínimo, trinta minutos após o término de cada um dos tratamentos. Desfechos secundários: as diferenças nos escores dos Inventários de Claustrofobia, Inventário de Depressão de Beck e Inventário de Ansiedade Estado-traço do início e do final do tratamento. RESULTADOS: 92,9% dos participantes (N) do grupo de sete sessões conseguiram realizar exame de Ressonância Magnética no simulador após o tratamento, enquanto que 50% dos participantes do grupo de uma sessão conseguiram realizar o exame no simulador (p=0,033). Dos sujeitos que tiveram melhor resposta ao tratamento, 78% eram do sexo masculino, 80% eram casados, 78% não faziam uso de medicação psiquiátrica e em relação ao diagnóstico, 20% deles tinham diagnóstico de fobia específica de Ressonância Magnética e 80% deles tinham diagnóstico de fobia de espaços fechados. Todos os sujeitos portadores do diagnóstico Fobia específica de realizar exames de Ressonância Magnética conseguiram realizar o exame no simulador independente do número de sessões. Já os portadores de fobia de espaços fechados responderam mais ao tratamento de sete sessões (92%, p=0.009). O inventário de claustrofobia evidenciou que os indivíduos do grupo sete sessões responderam ao tratamento (p=0,002) e mostrou diferenças significativas nos escores antes e depois do tratamento e que se mantiveram três meses depois. Já no inventário de Beck, observa-se melhora dos sintomas depressivos ao final do tratamento (p=0,015), porém não há diferença após três meses. Observou-se através dos coeficientes de Regressão que quanto maior a pontuação no inventário de claustrofobia e de Depressão de Beck, menor a probabilidade de conseguir permanecer no simulador. Entretanto, fazer pelo menos sete sessões de terapia aumenta a probabilidade do desfecho positivo desejado. O estudo mostrou ainda que sete sessões de terapia foram benéficas, pois mesmo com escores elevados de sintomatologia depressiva os pacientes foram bem sucedidos na realização do exame de Ressonância Magnética no simuladorThe MRI exams have been in considerable demand in various medical specialties to diagnose diseases. Although it is an effective diagnostic method, patients who are subjected to the exam might present high levels of discomfort due to the confined space of the device. The phobia of enclosed spaces is considered a type of specific phobia, according to the Diagnostic and Statistical Manual of Mental Disorders 5 (APA, 2013). Objectives: to check if a single session of Acceptance and Commitment Therapy is as effective as seven sessions of the same therapeutic model for the treatment of patients with fear of undergoing MRI exams and enclosed spaces phobia. METHODS: A randomized clinical trial study with two parallel groups was performed, one group underwent one session and the other group underwent seven sessions of Acceptance and Commitment Therapy. Participants were assessed at the beginning and at the end of treatment with the following instruments: Claustrophobia Inventory from Rachman and Taylor (1993), Beck Depression Inventory from beck et al. (1961) and Anxiety Inventory State - Trait from Spielberger, Gorsuch and Luschene (1970). The study was performed in a public hospital in the city of Sao Paulo with 30 patients. Main outcome: to remain in a MRI simulator for at least 30 minutes after each treatment. Secondary outcomes: compare the differences in the inventories of Claustrophobia, Beck Depression Inventory and the Anxiety Inventory Trait- State scores compared at the beginning and at the end of treatments. RESULTS: 92.9% of participants (N) on the seven sessions group were able to carry out the MRI exam simulator after treatment, while 50% of participants of the one session group were able carry out the post treatment session in the simulator (p = 0.033). From the participants who had better response to treatment, 78 % were male, 80 % were married, 78 % did not use psychiatric medication and 20 % had a diagnosis of specific MRI phobia, 80% had a diagnosis of enclosed spaces phobia. All subjects with the Specific Phobia of performing MRI exams diagnosis were able to perform at the simulator test without considering the number of treatment sessions. Those with phobia of enclosed spaces responded more to the seven sessions treatment (92 %, p = 0.009). The inventory of claustrophobia showed that individuals in the seven sessions group performed the treatment (p = 0.002), showing significant differences before and after treatment and the level of performance was the same three months later. The Beck Inventory showed that there was improvement in depressive symptoms at the end of treatment (p = 0.015), but there was no difference after three months. It was observed through the regression coefficients that the higher the score on the inventory of claustrophobia and Beck Depression Inventory, the lower the probability of performing in the simulator. However, doing at least seven sessions of therapy increases the likelihood of the desired positive outcome. The study also showed that seven therapy sessions were beneficial, because even with high scores of depressive symptoms patients were successful in the test of the MRI simulator
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Loughran, Jonathan David. "Investigation of microbubble behaviour under ultrasound for molecular imaging." Thesis, Imperial College London, 2013. http://hdl.handle.net/10044/1/19004.
Full textAbstract:
Modern advances in ultrasound imaging technology have led to the development of targeted microbubble contrast agents; micrometer sized encapsulated bubbles coated with binding agents. Their gas core gives them high echogenicity, scattering incident ultrasound and allowing them to oscillate to producing a detectible sound of their own. The binding agent allows them to be used for molecular imaging. The work in this thesis aims to provide a better understanding of the behaviour of microbubble contrast agents, but with a focus on their use as molecular imaging agents. The thesis starts with an introduction to microbubble contrast agents, stating their current clinical usage both as a normal contrast agent and for molecular imaging and highlighting their strengths and limitations. In the following chapter, the theory behind the modelling of microbubble motions is introduced, discussing modelling bubble oscillations using the Rayleigh-Plesset equation, and the translation of a bubble in an acoustic field through Bjerknes forces. The first piece of novel work to be presented in this thesis is in the form of a model for non-spherical oscillations in microbubble contrast agents, with the application of modelling the destruction of microbubble contrast agents. A Boussinesq-Scriven approach was taken, to adapt a pre-existing model for shell free bubbles by taking into account the viscoelastic effect of the shell. Results calculated using the developed model showed a significant difference in destruction threshold between the shelled and shell-free bubbles. The second piece of work focuses on the effects of an ultrasound field on adherent microbubbles including their detachment and deflation. Analysis of experimental results on targeted microbubbles adherent to a micro-tube with flow shows that the effects of ultrasound are significant even at relatively low acoustic pressure. As acoustic pressure is increased, the percentage of detached and/or deflated microbubbles does also. Four forces are identified which could be responsible for detachment, namely, shear, primary and secondary Bjerknes, and oscillations and their relative significance is investigated. The results from this work are then used to make suggestions about the clinical imaging for targeted contrast agents. The final novel piece of work presented is a dual transducer arrangement as a potential method of increasing targeted microbubble binding efficiency through the creation of a simple one-dimensional acoustic manipulator, capable of being implemented in any clinical ultrasound scanner with a phased array. Simulations and experimental investigations were carried out on the system in order to demonstrate the feasibility of such an acoustic manipulator and to gain understanding of its practicalities.
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Rotgé, Jean-Yves. "Rôle des voies thalamo-corticales dans le trouble obsessionnel-compulsif : approches méta-analytique et physiopathologique chez l'homme et l'animal." Thesis, Bordeaux 2, 2010. http://www.theses.fr/2010BOR21783/document.
Full textAbstract:
Le trouble obsessionnel-compulsif (TOC) est un trouble anxieux fréquent et invalidant. Pour un grand nombre de patients, il existe une résistance aux thérapeutiques actuellement disponibles, soulignant toute l'importance de mieux préciser la physiopathologie du TOC. Le principal objectif de cette thèse est d’étudier les altérations anatomiques et fonctionnelles des voies thalamo-corticales intéressant le cortex orbitofrontal (COF) et le cortex cingulaire antérieur (CCA) dans le TOC. Pour cela, nous avons utilisé plusieurs outils complémentaires permettant d’appréhender cette problématique sous différents angles méthodologiques.Concernant les altérations anatomiques associées au TOC, nous avons rapporté les données de méta-analyses des études de neuro-imagerie volumétrique et morphométrique ainsi que les résultats d'une étude originale d'imagerie volumétrique. Une diminution du volume orbitofrontal, une augmentation du volume thalamique et une relation entre ces modifications de volumes ont été observées chez les patients avec TOC comparativement aux témoins. Les modifications de densité de matière grise concernaient le COF et le putamen dans le sens d'une augmentation et les cortex pariétal et préfrontal dorsolatéral dans le sens d'une diminution dans le TOC.Concernant les altérations fonctionnelles associées au TOC, nous avons détaillé un travail de méta-analyse des études d'imagerie fonctionnelle, un travail expérimental chez le primate basé sur des manipulations pharmacologiques intra-cérébrales, puis un travail expérimental chez l'homme reposant sur le développement d'une tâche comportementale originale couplée à l'imagerie fonctionnelle. Dans notre méta-analyse, nous avons décrit la participation fonctionnelle de régions comme le COF, le thalamus et le striatum lorsque des symptômes obsessionnels et compulsifs étaient provoqués chez des patients. Chez le primate subhumain, nous avons montré qu'une hyperactivation du noyau ventral-antérieur, par levée de l'inhibition GABAergique, entraînait l'apparition de comportements pseudo-compulsifs. Ensuite, à l'aide d'une tâche originale qui mettait les sujets en situation de vérifier, nous avons mis en évidence que les dysfonctions orbitofrontales associées au doute lors de la prise de décision n'étaient pas modulées ni par les informations contextuelles (signaux d'erreur), ni par la réponse comportementale chez les patients avec TOC comparativement à des sujets témoins.Enfin, la superposition des cartes morphométriques et fonctionnelles a trouvé une relation entre les altérations anatomiques et fonctionnelles au sein du COF. Nos résultats soulignent toute l'importance des voies thalamo-orbitofrontales dans la physiopathologie du TOCObsessive-compulsive disorder (OCD) is a frequent and disabling anxiety disorder. Available treatments are effective for most patients but impairing residual symptoms and treatment resistance are common in OCD patients. Therefore, a better understanding of OCD pathophysiology is essential for further improvement of therapeutic strategies. The main goal of my thesis was to assess the anatomical and funtional thalamocortical alterations associated with OCD. Concerning the anatomical thalamocortical alterations associated with OCD, we conducted two meta-analyses of anatomical neuroimaging studies and an original volumetric neuroimaging study. We reported a smaller thalamic volume and a greater orbitofrontal volume, but also an inverse relationship between the volume changes in OCD patients compared with healthy subjects. Furthermore, we showed that gray matter density within the orbitofrontal cortex and the putamen were enhanced in OCD. Concerning the functional thalamocortical alterations associated with OCD, we reported data coming from a meta-analysis of functional neuroimaging studies, an experimental study in subhuman primates using local brain pharmacological manipulations and an event-related neuroimaging study in OCD patients. In our meta-analysis, we showed that the orbitofrontal cortex, the thalamus and the striatum were involved in the mediation of OCD symptoms. In subhuman primates, the pharmacologically induced overactivity within the ventralanterior thalamic nucleus leaded to the emergence of compulsive-like behaviors. Then, in our neuroimaging study, we found that doubt-related orbitofrontal dysfunctions were not modulated by neither error signals nor compulsive-like behaviors in OCD patients, compared with healthy subjects. Finally, we described by using meta-analytic data that anatomical and functional brain alterations overlap with the lateral orbitofrontal cortex in OCD. In conclusion, our results suggest that the thalamo-orbitofrontal network may play a primary role in the genesis and mediation of OCD symptoms
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Lieutaud, Thomas. "Quelles potentialités thérapeutiques pour l’érythropoiétine recombinante dans le traitement des traumatismes du système nerveux central ?" Thesis, Lyon 1, 2012. http://www.theses.fr/2012LYO10010/document.
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L'érythropoiétine (Epo) est une protéine ubiquitaire dans les tissus de l'organisme. Elle est dotée d'une fonction endocrine, autocrine et paracrine. Elle favorise les activités anti-apoptotiques des tissus soumis à un stress hypoxique. Dans de nombreux modèles animaux de traumatisme ou d'agression du système nerveux central et quelques études cliniques, l'Epo recombinante humaine (Epo-rh) a révélé des propriétés neuroprotectrices. L'objectif principal de ce travail est d'améliorer les connaissances sur l'Epo afin de favoriser l'inclusion de l'Epo-rh dans l'arsenal thérapeutique chez l'homme après traumatisme du système nerveux central. Deux axes de travail ont été explorés : dans un première partie, pour expliquer l'échec de la mise en oeuvre d'une étude de la tolérance et d'efficacité biologioque de l'Epo-rh dans le Traumatisme Médullaire Déficitaire (TMD) chez l'homme, nous avons étudié l'épidémiologie des TMD sur la période 1997-2006, à partir du Registre des accidents du Rhône. Ensuite nous avons étudié l'évolution de cette incidence entre 2 périodes de 6 ans : 1995-2001 et 2003-2008. Parallèlement, compte tenu d'une incidence de traumatisme crânien (TC) 20 fois plus élevée que celle du TMD chez l'homme, nous avons entrepris de caractériser les effets d'un TC expérimental par percussion fluide latérale (LFPI) chez le rat afin de mieux comprendre la pharmacologie et les mécanismes d'action moléculaires, en particulier anti-inflammatoires et neuroprotecteurs, de l'Epo-rhErythropoietin (Epo) is an ubiquitous cytokine. It has endocrine, paracrin and autocrin functions. It improves antiapoptotic mechanisms on all tissues subjected to hypoxic stress. In many animal models of brain trauma but also in other brain injury models, and some human clinical studies, recombinant Human Epo (Epo-rh) has proven neuro-protective properties. The main goal of this work was to improve and incorporate Epo-rh in the pharmacological arsenal of treatment in brain and spinal cord traumatic injuries in human. In a first part, to explore the reasons of failure of inclusion in a Spinal Cord Injury (SCI) study to test the thrombo-embolic tolerance and efficacy of Epo-rh, we studied the epidemiology of SCI using the road crash Rhône registry in the period 1997-2006. Then we compared the epidemiological trends of the SCI incidence, associated trauma, mortality and fatality rates in two periods of 6 years: 1995-2001 and 2003-2008. In a second part, due to the 20-fold higher incidence of traumatic brian injury (TBI) in comparison to SCI, we characterized the effects of a moderate (1.6-1.8 atm) lateral fluid percussion injury (LFPI) in order to understand and characterize the pharmacological, anti-inflammatory and neuroprotective mechanisms of action of Epo-rh in such a brain injury
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Vathavooran, Arunasalam. "Applying froth imaging techniques to characterise the dewatering behaviour of fine coal." Thesis, University of Nottingham, 2006. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.440997.
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Lu, Ran. "Intravital Imaging of Dynamic Behaviors of Leukocytes in UVB-induced Skin Inflammation." University of Toledo Health Science Campus / OhioLINK, 2013. http://rave.ohiolink.edu/etdc/view?acc_num=mco1357227508.
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Nguyen, Harrison Tri Tue. "Computational Neuroscience with Deep Learning for Brain Imaging Analysis and Behaviour Classification." Thesis, The University of Sydney, 2021. https://hdl.handle.net/2123/27313.
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Recent advances of artificial neural networks and deep learning model have produced significant results in problems related to neuroscience. For example, deep learning models have demonstrated superior performance in non-linear, multivariate pattern classification problems such as Alzheimer’s disease classification, brain lesion segmentation, skull stripping and brain age prediction. Deep learning provides unique advantages for high-dimensional data such as MRI data, since it does not require extensive feature engineering. The thesis investigates three problems related to neuroscience and discuss solutions to those scenarios.
MRI has been used to analyse the structure of the brain and its pathology. However, for ex- ample, due to the heterogeneity of these scanners, MRI protocol, variation in site thermal and power stability can introduce scanning differences and artefacts for the same individual under- going different scans. Therefore combining images from different sites or even different days can introduce biases that obscure the signal of interest or can produce results that could be driven by these differences. An algorithm, the CycleGAN, will be presented and analysed which uses generative adversarial networks to transform a set of images from a given MRI site into images with characteristics of a different MRI site.
Secondly, the MRI scans of the brain can come in the form of different modalities such as T1- weighted and FLAIR which have been used to investigate a wide range of neurological disorders. The acquisition of all of these modalities are expensive, time-consuming, inconvenient and the required modalities are often not available. As a result, these datasets contain large amounts of unpaired data, where examples in the dataset do not contain all modalities. On the other hand, there is a smaller fraction of examples that contain all modalities (paired data). This thesis presents a method to address the issue of translating between two neuroimaging modalities with a dataset of unpaired and paired, in semi-supervised learning framework.
Lastly, behavioural modelling will be considered, where it is associated with an impressive range of decision-making tasks that are designed to index sub-components of psychological and neural computations that are distinct across groups of people, including people with an underlying disease. The thesis proposes a method that learns prototypical behaviours of each population in the form of readily interpretable, subsequences of choices, and classifies subjects by finding signatures of these prototypes in their behaviour.
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Ma'rof, A. Azeqa. "Imagined intergroup contact effects on prosocial attitudes and behavior." Thesis, University of Sheffield, 2018. http://etheses.whiterose.ac.uk/21270/.
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This thesis examines the effectiveness of imagined intergroup contact at promoting intergroup helping behaviour. Theoretically, it is argued that by adopting a third-person perspective in the imagined contact task prosocial action can be facilitated across intergroup boundaries. The results of eight studies provide evidence that imagining prosocial contact from the third-person perspective increased prosocial attitudes and actions. Additionally, results revealed that the imagined helping did not need to be specific to a particular group, or even an intergroup encounter: Any imagined helping scenario subsequently enhanced specific and generalised attitudes towards helping others, and increased the likelihood of observing prosocial behaviour. Importantly these effects were observed in laboratory and field studies, in the UK and Malaysia, and with majority and minority groups. Overall, this thesis contributes to a greater understanding the impact of mental simulation on enhancing prosocial attitudes and behaviours, and helps explain how and why imagined contact can encourage intergroup helping in a range of experimental and real-life contexts.
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Lee, Lucy. "Imaging the effects of 1 Hz repetitive transcranial magnetic stimulation during motor behaviour." Thesis, University College London (University of London), 2004. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.414431.
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Lee, Ria J. Heilbrun Kirk. "Imagined versus actual violence: the role of cognitions in predicting violence risk /." Philadelphia, Pa. : Drexel University, 2004. http://dspace.library.drexel.edu/handle/1860/366.
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Baba, Aïssa Hind. "Anatomie et physiologie des voies de sortie du cervelet chez le rongeur." Thesis, Université Paris sciences et lettres, 2021. http://www.theses.fr/2021UPSLE018.
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Une acquisition sensorielle et une perception précises sont des éléments clés de la survie. Bien que de nombreux paramètres sous-jacents au traitement des informations sensorielles soient connus, plusieurs aspects sont encore mal compris, comme la contribution exacte de chaque structure cérébrale. Ici, nous analysons la contribution cérébelleuse au traitement sensoriel dans le système des vibrisses de la souris. Nous identifions une projection anatomique et physiologique disynaptique des noyaux cérébelleux vers le cortex sensoriel primaire, impliquant notamment le thalamus postérieur médian (POm). La modulation de cette projection cérébelleuse et thalamique de type "driver" induit un déficit dans une tâche de discrimination sensorielle fine, et sa co-activation avec des entrées périphériques induit le recrutement accru des projections du POm dans la couche I du cortex sensoriel. Dans leur ensemble, nos résultats montrent que le cervelet cible aussi des zones corticales non motrices et peut directement moduler le traitement sensoriel par l'intermédiaire d'un noyau thalamique d'ordre élevé, le POmAccurate sensory acquisition and perception are key features to survival. Though many parameters underlying the processing of sensory information is known, several aspects are still poorly understood, such as the exact contribution of each cerebral structure. Here, we analyze the cerebellar contribution to sensory processing in the mouse whisker system. We identify an anatomical and physiological disynaptic projection from the cerebellar nuclei to the primary sensory cortex, involving notably by the posterior medial thalamus (POm). The modulation of this strong driver-like cerebello-thalamic projection induces an impairment in a fine sensory discrimination task, and its co-activation along with peripheral inputs induces the increased recruitment of POm projections to layer I of sensory cortex. Taken together, our results show that the cerebellum targets non-motor cortical areas and can directly modulate sensory processing through a higher order thalamic nucleus, the POm
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Miller, Nicola Anne. "The significance of kinaesthetic vocal sensations related to listening behaviour : an MRI study." Thesis, University of Aberdeen, 2014. http://digitool.abdn.ac.uk:80/webclient/DeliveryManager?pid=216996.
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The aim of this project was to investigate the nature and possible significance of first-person kinaesthetic vocal sensations observed in association with musical listening. Hearing and voice are known to be closely linked but the mechanisms that underlie their close relationship are not yet understood. The presence of kinaesthetic vocal sensations challenges accounts of auditory processing that are divorced from peripheral vocal input and, instead, suggests the hypothesis that auditory and vocal processing mechanisms rely on shared peripheral substrates in addition to their increasingly recognized shared (brain-based) central substrates. To investigate this hypothesis, I used MRI and developed a measurement protocol (informed by established methods in cephalometry) that would allow me to relate vocal structures to their direct and indirect bony attachments to the craniofacial skeleton, cervical spine and sternum. After establishing the method's validity in subjects at rest, I acquired midsagittal MR images (under conditions where articulatory and postural input was negligible) while subjects (1) hummed and (2) listened (in a focused way) to low and high notes at each end of their range. Geometric and shape analysis of craniocaudal, craniocervical and anteroposterior variables revealed significant differences between low- and high-note conditions and widespread correlations between variables for both humming and listening investigations. An unexpected association between pitch change and changes of cervical alignment was also found. These results were complemented and extended by using the same MR images to build an active shape model (ASM). In addition to showing how vocal structures move together, ASM showed goal-related vocal activity to consist of one or more independent modes of variation. Together, the observations, experimental results, and evidence from diverse historical and contemporary sources, support the hypothesis that mechanisms underlying auditory and vocal processing rely on shared central and peripheral substrates. Wide-ranging implications arising from this hypothesis are also discussed.
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Armstrong, Barbara. "Instructed human imagining behavior effectiveness for reducing experimentally induced learned helplessness." Thesis, University of Ottawa (Canada), 1987. http://hdl.handle.net/10393/5187.
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