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Tesi sul tema "Neurophysiology"
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1
Proudfoot, Malcolm. "Cortical neurophysiology of ALS". Thesis, University of Oxford, 2016. https://ora.ox.ac.uk/objects/uuid:5b8673f7-8eb2-4bf2-b3b8-d901fa134007.
Testo completoAbstract (sommario):
The experiments described in this thesis aimed to investigate the neurophysiological consequences, at the cortical level, of the neurodegenerative condition, amyotrophic lateral sclerosis (ALS). A principle tenet of this study was that ALS is, first and foremost, a disorder of the cortical motor system, the precise pathological mechanisms of which remain incompletely understood. Furthermore, the degree to which neurodegeneration can be evidenced before the onset of symptoms is thus far uncertain, and the optimal means by which to measure therapeutic response has yet to be determined. Chapter 1 introduces relevant key concepts in ALS and briefly summarises three studies completed in the early phases of pursuit for the above degree. These studies respectively considered presmyptomatic cellular ALS pathology, quantitation of disease progression and eyetracking assessment of cognitive dysfunction. Chapter 2 describes magnetoencephalography, the investigative technology utilised in the subsequent experimental chapter. In chapter 3, the effects of ALS on movement related modulation of neuronal oscillations are determined. An excessive peri-movement desynchronisation and delayed post-movement rebound was described. Functional connectivity between cortical regions at rest is appraised in chapter 4. ALS appeared to result in quite striking increases in functional connectivity, in keeping with the fMRI literature and in support of diminished intracortical inhibitory influences. The functional communication from the motor cortices is directly considered during active motor performance in chapter 5. ALS related reductions in beta-band coherence were noted in both corticospinal and inter- hemispheric communication. In conclusion, the results demonstrated considerable support for proposed excitotoxic disease mechanisms and were in alignment with reported findings in other neurodegenerative diseases. Finally, a pilot study by which the neural mechanisms for cognitive impairment in ALS are explored via antisaccade performance is described. While underpowered, the experimental design showed promise for future application.
2
Ni, Mhuircheartaigh Roisin Judith. "The neurophysiology of sedation". Thesis, University of Oxford, 2012. http://ora.ox.ac.uk/objects/uuid:5097d3ca-5f5b-4b37-b7bd-abeb10ec196d.
Testo completoAbstract (sommario):
We recognise consciousness in ourselves and in those around us. Consciousness is the essence of our existence, who and what we are, but we are willing and able to let go of it daily during sleep, which we welcome and associate with rest, recovery and well being, knowing that consciousness will return reliably, when we are ready. Yet we cannot define this thing or process which makes us "us". We do not understand how it is constructed from the activity in our brains, how it is deconstructed by sleep, drugs or disease, or how it can be reconstructed by waking or recovery. Our ignorance renders us reliant on inadequate means of measuring consciousness, dependent on movement for its detection. Propofol is an intravenous anaesthetic drug with the capacity to safely, rapidly and reliably produce sedation and anaesthesia, providing an ideal model of unconsciousness for study. Functional magnetic resonance imaging (fMRI) provides a non-invasive means of measuring activity within the brain. EEG is a convenient broad measure of neuronal activity. This thesis exploits the advantages of each of these techniques, fMRI and EEG, first separately and then together, to link highly informative, spatially specific fMRI observations to convenient, reproducible electrophysiological surface measurements. A safe and reliable model of unconsciousness suitable for fMRI interrogation is first developed and explored. Changes in the spatial extent and interregional correlation of neuronal activity when subjects become unresponsive show that the functional connectivity of the striatum is specifically impaired as perception fails. Disruption of the brain’s internal temporal frame of reference impairs the synthesis of perceptions from their fragments. The second experimental chapter specifically examines the behaviour of sleep oscillations during ultraslow increases and decreases in the depth of sedation with propofol. Functional activity shows that the brain is intensely active despite loss of consciousness and reveals measurable transitions in neuronal activity. Combined simultaneous EEG/FMRI then shows that these transitions reflect stepwise changes in the processing of experience and a shift from externally modulated thalamocortical signaling to an internal dialogue.
3
Galer, Sophie. "Impact de l'activité épileptique interictale sur le traitement cognitif: approche neurophysiologique et comportementale". Doctoral thesis, Universite Libre de Bruxelles, 2013. http://hdl.handle.net/2013/ULB-DIPOT:oai:dipot.ulb.ac.be:2013/241299.
Testo completo
4
Henrikson, Sindre. "The neurophysiology of stereoscopic vision". Thesis, University of Newcastle upon Tyne, 2018. http://hdl.handle.net/10443/4122.
Testo completoAbstract (sommario):
Many animals are able to perceive stereoscopic depth owing to the disparity information that arises from the left and right eyes' horizontal displacement on the head. The initial computation of disparity happens in primary visual cortex (V1) and is largely considered to be a correlation-based computation. In other words, the computational role of V1 as it pertains to stereoscopic vision can be seen to roughly perform a binocular cross-correlation between the images of the left and right eyes. This view is based on the unique success of a correlation-based model of disparity-selective cells { the binocular energy model (BEM). This thesis addresses two unresolved challenges to this narrative. First, recent evidence suggests that a correlation-based view of primary visual cortex is unable to account for human perception of depth in a stimulus where the binocular correlation is on average zero. Chapters 1 and 2 show how a simple extension of the BEM which better captures key properties of V1 neurons allows model cells to signal depth in such stimuli. We also build a psychophysical model which captures human performance closely, and recording from V1 in the macaque, we then show that these predicted properties are indeed observed in real V1 neurons. The second challenge relates to the long-standing inability of the BEM to capture responses to anticorrelated stimuli: stimuli where the contrast is reversed in the two eyes (e.g. black features in the left eye are matched with identical white features in the right eye). Real neurons respond less strongly to these stimuli than model cells. In Chapter 3 and 4, we make use of recent advances in optimisation routines and exhaustively test the ability of a generalised BEM to capture this property. We show that even the best- tting generalised BEM units only go some way towards describing neuronal responses. This is the rst exhaustive empirical test of this in uential modelling framework, and we speculate on what is needed to develop a more complete computational account of visual processing in primary visual cortex.
5
Atherton, Jeremy Francis. "Neurophysiology of the subthalamic nucleus". Thesis, University of Edinburgh, 2001. http://hdl.handle.net/1842/29793.
Testo completoAbstract (sommario):
Possibly as many as half the neurones in the STN have an axon collateral with branches off from the main axon and reinnervates the nucleus. This suggests that rather than working autonomously as was previously thought, the neurones of the STN can operate together as a network. Computer models of the STN showed that the level of interconnectivity within the STN would be huge, even if each axon collateral only contacted a small number of the total neurones with dendritic fields that overlapped with it. A network model showed that such a system was capable of switch-like behaviour. At low levels of activity the neurones would act autonomously. However, excitatory inputs could increase the degree of non-synchronous correlation between the activity of neurones in the STN leading them all to enter a high activity state. A single cell model was then developed in order to look at how this high activity state could be terminated. An interesting problem arose in the construction of this model; no known kinetics for the voltage-gated sodium and potassium channels could replicate the high frequency (500Hz) firing rates that are obtained by STN neurones. Intracellular recordings were made in vitro to investigate the mechanisms underlying high-frequency firing in the STN. Using a two-pulse protocol the speed of recovery from inactivation was measured giving an estimate of the inactivation characteristics of the ion channels in these neurones. These experiments showed that the neurones have very slow inactivation kinetics suggesting that STN neurones may have a much shortened refractory period, enabling high frequency firing. Such a mode of operation requires a large, fast potassium current. A potential candidate for this current is the Kv3.l potassium channel, which is strongly expressed by STN neurones.
6
Hallam, Glyn P. "The neurophysiology of emotion regulation". Thesis, University of Sheffield, 2013. http://etheses.whiterose.ac.uk/4732/.
Testo completo
7
Herrero, Jose Luis. "Neurophysiology and neuropharmacology of visual attention". Thesis, University of Newcastle Upon Tyne, 2011. http://hdl.handle.net/10443/1166.
Testo completoAbstract (sommario):
There is ample evidence that attention to stimuli can facilitate perception under different experimental tasks. For example, human observers are faster and more accurate at detecting an object in a visual scene when they know in advance its location, motion or colour. Previous electrophysiological studies on attentional modulation have characterized the effects of attention on firing rates and oscillatory activity. They have also studied how attention can change basic neuronal integration properties, such as the size of the classical receptive field or its summation area. However, the cellular mechanisms underlying this response modulation are not clear. In this thesis, I investigate which neurotransmitters and receptors contribute to attentional modulation in the primate brain. I use pharmacological manipulations on neurons in the primary visual cortex (V1) while monkeys perform a visual spatial attention task. The contribution of two main neuromodullatory systems, the cholinergic and glutamatergic system, to visual attention is examined. Findings reveal that the amount of attentional modulation in V1 is augmented when the cholinergic system is pharmacologically enhanced. This effect is mediated by the activation of muscarinic, but not nicotinic, receptors. Glutamatergic NMDA receptor activation also leads to enhanced attentional modulation in V1, although the effects are largely restricted to improved response reliability and less to increased response gain. We note that both attention and acetylcholine can alter basic neuronal coding, namely integration properties of V1 neurons. Our findings show that acetylcholine affects contextual integration through muscarinic receptors, while nicotinic receptors affect the gain with no changes in the integration. Additional investigations of the cholinergic (and gabaergic) mechanisms in extrastriate area (area MT) are conducted, as ACh may result in improved direction selectivity computations similar to those reported in the attention literature. It appears that acetylcholine does not increase neuronal sensitivities as measured by a sharpening in the motion--‐ direction tuning curve. Instead, it improves response reliability to optimal stimulus features. Taken together, these findings may have implications to neuromodulatory accounts of visual attention.
8
Watson, Alison. "The neurophysiology of human placebo analgesia". Thesis, University of Manchester, 2008. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.499914.
Testo completo
9
Baker, D. J. "The clinical neurophysiology of organophosphate poisoning". Thesis, University of Southampton, 1986. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.259652.
Testo completo
10
Bramon, Bosch Elvira. "Neurophysiology of schizophrenia : a family study". Thesis, King's College London (University of London), 2005. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.421061.
Testo completo
11
Reeve, James Edward. "Functional dyes as tools for neurophysiology". Thesis, University of Oxford, 2012. http://ora.ox.ac.uk/objects/uuid:8d8e7fa1-0f1d-4ff5-9f90-6915b15c1ad4.
Testo completoAbstract (sommario):
The aim of the project described in this thesis is to synthesise new functional molecules which interact with light for neurophysiological applications. In particular, I describe a family of amphiphilic porphyrins with large first hyperpolarisabilities which are used as SHG contrast agents and voltage-sensitive probes. In addition I detail a methodological microscopy tool and a novel caged form of a neuronal ion-channel antagonist. Chapter 1 introduces the key concepts underlying the use of dyes as SHG contrast agents. In particular it focuses on aspects of molecular design, covering both the amphiphilicity and nolinearity required by the target molecule. It covers quantification of the nonlinear properties of SHG stains, then surveys a number of examples which showcase the flexibility of SHG imaging as a biomedical technique. Chapter 2 describes a family of amphiphilic porphyrins with large first hyperpolarisabilities. Working from the structure-property relationships identified in Chapter 1, we fully characterise these dyes and demonstrate that they can be used in SHG imaging. We demonstrate that these molecules may also be tuned by complexation of a metal ion which can modulate their photophysical and solubility behaviour. Chapter 3 provides a description of how to determine the orientational distribution of dipolar dyes in a membrane by multiphoton microscopy. We measure the signal intensity of the dye in a model membrane system then find distributional moments which lead to the distribution itself. Chapter 4 explores whether off-axis contributions to the first hyperpolarisability tensor can significantly augment the dominant on-axis contribution from the main dipolar charge-transfer band. We synthesise and characterise a series of cis-donor cis-acceptor porphyrin compounds and explore their biophysical characteristics. Chapter 5 is the culmination of this project and after discussing method development, goes on to show how we measure the voltage sensitivity of an amphiphilic porphyrin SHG dye. We compare the archetypal porphyrin dye chromophore with three commercially available styryl dyes and demonstrate that our dye has greater sensitivity and a more rapid response. Chapter 6 describes a side project, the use of a photolabile cage to protect MK801, a neuronal ion-channel antagonist. By developing a water soluble photolabile cage using molecular design techniques, we are able to release MK801 in neurons with precise spatiotemporal control, allowing us to pinpoint the locus of two key neurophysiological processes.
12
Norman, Olivia Rose. "Optogenetic Tools for In-Vitro Neurophysiology". University of Toledo / OhioLINK, 2014. http://rave.ohiolink.edu/etdc/view?acc_num=toledo1408643520.
Testo completo
13
Kovanis, Panagiotis. "Neurophysiology underlying neuroimaging of cortical function". Thesis, Cardiff University, 2014. http://orca.cf.ac.uk/74565/.
Testo completoAbstract (sommario):
The aim of this study was to shed light on some of the neurophysiological mechanisms behind visual perception and specifically look into feedback processes that may be taking place during visual processing and also inhibition processes of the visual cortex. The oblique effect is a preference of the visual system for cardinal orientations rather than oblique ones. A recent MEG study (Koelewijn, et al. 2011) finds in V1 an initial inverse oblique effect (80 msec from stim onset) which however later (120msec from stimulus onset) showed a trend towards the classical oblique effect and feedback processes here are suggested taking place from the extrastriate cortex. We look into this using fMRI and interestingly we do manage to find an inverse oblique effect, which indicates that the initial MEG “inverse” effect in V1 is detectable with fMRI even though fMRI does not have the temporal resolution of MEG. Unfortunately in this fMRI study the extrastiate region was not localized. In the 3rd experimental chapter (following up on a study by Edden et al.) we look into the relation of behavioural thresholds and gamma activity in the visual cortex. Here we found in the SAM analysis) for the oblique condition, a positive correlation of the oblique main effect in a cortical location in the medial visual cortex (at a frequency range of 30--‐70 Hz) to behavioural thresholds. However here we did not detected an oblique effect when we compared oblique to cardinal condition. In the final experimental chapter we look into the relation between GABA and training effects using however two GABA scanning protocols (with and without macromolecule suppression). Here we find that training effects depend on GABA concentration (as found in unpublished findings by Edden et al.). Additionally here we find negative correlations with behavioural thresholds and GABA however these are strongest for the untrained sessions.
14
Lewi, Jeremy. "Sequential optimal design of neurophysiology experiments". Diss., Atlanta, Ga. : Georgia Institute of Technology, 2009. http://hdl.handle.net/1853/28201.
Testo completoAbstract (sommario):
Thesis (M. S.)--Biomedical Engineering, Georgia Institute of Technology, 2009.Committee Co-Chair: Butera, Robert; Committee Co-Chair: Paninski, Liam; Committee Member: Isbell, Charles; Committee Member: Rozell, Chris; Committee Member: Stanley, Garrett; Committee Member: Vidakovic, Brani.
15
Ficarella, Stefania. "The neurophysiology of internally-driven actions". Doctoral thesis, Università degli studi di Trento, 2015. https://hdl.handle.net/11572/369076.
Testo completoAbstract (sommario):
Acting in the world in a way that matches our goals, overriding impulses, is one of the first abilities that we must learn while growing up. We often change the course of our actions because of external influences or because we simply “change our mind†. As John H. Patterson said, “Only fools and dead men don't change their minds. Fools
won’t. Dead men can’t†. An important distinction must first be made between the impact of internal and external sources on action decisions, and the first part of the
introduction will be devoted to this topic. In the second part, I will discuss the topic of inhibitory control. In the scientific literature, action inhibition is often treated as a unitary phenomenon, while the distinction among different types of inhibitions might explain the diverse results and be useful for future studies. My experimental work has
been devoted to both externally-triggered and internally-driven voluntary action inhibition, in particular, in Experiment 1 I conducted a set of studies aiming at
understanding the underlying cortical circuits for internally-driven action inhibition, whereas Experiment 2 focused on proactive inhibition mechanisms. While it is beyond the scope of this manuscript to cover the entire literature on inhibitory control, I would like to propose a common view to unify the different theories concerning how the brain exerts voluntary inhibitory control and provide some suggestions for future investigations to study the way we flexibly control our actions to cope with the
constantly changing external, and internal, environment.
16
Ficarella, Stefania. "The neurophysiology of internally-driven actions". Doctoral thesis, University of Trento, 2015. http://eprints-phd.biblio.unitn.it/1450/1/TesiFicarella2015.pdf.
Testo completoAbstract (sommario):
Acting in the world in a way that matches our goals, overriding impulses, is one of the first abilities that we must learn while growing up. We often change the course of our actions because of external influences or because we simply “change our mind”. As John H. Patterson said, “Only fools and dead men don't change their minds. Fools
won’t. Dead men can’t”. An important distinction must first be made between the impact of internal and external sources on action decisions, and the first part of the
introduction will be devoted to this topic. In the second part, I will discuss the topic of inhibitory control. In the scientific literature, action inhibition is often treated as a unitary phenomenon, while the distinction among different types of inhibitions might explain the diverse results and be useful for future studies. My experimental work has
been devoted to both externally-triggered and internally-driven voluntary action inhibition, in particular, in Experiment 1 I conducted a set of studies aiming at
understanding the underlying cortical circuits for internally-driven action inhibition, whereas Experiment 2 focused on proactive inhibition mechanisms. While it is beyond the scope of this manuscript to cover the entire literature on inhibitory control, I would like to propose a common view to unify the different theories concerning how the brain exerts voluntary inhibitory control and provide some suggestions for future investigations to study the way we flexibly control our actions to cope with the
constantly changing external, and internal, environment.
17
Galley, Peter Timothy. "The development of enzyme electrodes for neurophysiology". Thesis, Imperial College London, 1991. http://hdl.handle.net/10044/1/46777.
Testo completo
18
Kwiatkowski, Jonna. "Individual Differences in the Neurophysiology of Creativity". Fogler Library, University of Maine, 2002. http://www.library.umaine.edu/theses/pdf/KwiatkowskiJ2002.pdf.
Testo completo
19
Fois, Alessandro Francesco. "Tremor classification and measurement: insights from neurophysiology". Thesis, The University of Sydney, 2022. https://hdl.handle.net/2123/29841.
Testo completoAbstract (sommario):
Tremor is a common problem, affecting perhaps 1% of the human population, and often manifests in the upper limbs where it can interfere with hand function and cause social embarrassment. The assessment and classification of human tremor into diagnostic categories remains predominantly clinical, leading to inter-observer inconsistencies that blur the diagnostic labels used in research and clinical practice and hamper both endeavours. In this thesis, I explore the use of neurophysiological techniques in a series of related studies to provide an objective method of measuring tremor and gaining insight into its biological underpinnings.
In order to explore the mechanism of Parkinsonian tremor, a cohort of participants with Parkinson's disease (PD) and tremor were studied using surface electromyography (sEMG), accelerometry, and dopamine transporter imaging (TRODAT-1 SPECT). Parkinsonian rest tremor was shown to correlate to contralateral reduction in striatal dopamine binding, a relationship that provides insight into the mechanism of rest tremor in Parkinson’s disease (PD) and was not found by previous studies that relied on clinical assessment of tremor.
In a separate cohort of participants with common tremor syndromes including Parkinson's disease, essential tremor (ET), dystonic tremor (DT), and essential tremor plus (ET plus), several neurophysiological markers were studied including sEMG and accelerometry, with the development of new metrics to quantify tremor symmetry and relative tremor power under different conditions (e.g. rest vs posture); and neurophysiological markers unrelated to tremor kinematics (but giving insight into the tremor mechanism or presence of dystonia), including the long-latency reflex (LLR), temporal discrimination threshold (TDT) and tonic vibration reflex (TVR). Several neurophysiological markers were shown to distinguish PD from other tremor types including lower tremor stability index (TSI), higher rest tremor asymmetry, higher ratio of rest to postural tremor power, and more regular EMG tremor bursts. In order to address current inter-observer inconsistencies in the classification of action upper limb tremor (DT, ET, ET plus), I performed an unsupervised cluster analysis using neurophysiological data from these participants. Using the ratio of tremor power at rest compared to posture (Rest-Posture Index; RPI) I was able to generate a DT-enriched cluster with muscle coherence characteristics typical of dystonia. Cluster analysis using all neurophysiological parameters generated an ET/ET-plus only cluster with different neurophysiological characteristics. These cluster analysis results provide objective neurophysiological evidence of a subdivision within action tremor syndromes as a whole, even though the current clinical classification system (into categories of DT, ET, and ET plus) may be inconsistent with this subdivision.
Finally, looking beyond conventional neurophysiology, data (sEMG, accelerometry, and video) from this same cohort were used to validate the measurement of tremor with automated video analysis, using the open-source pose estimation platform OpenPose. I demonstrated that OpenPose applied to videos of tremor provides an effective tool for the measurement of rest tremor and has the potential to expand access to objective tremor measurement beyond the neurophysiology laboratory.
20
Goonawardena, Anushka V. "Cannabinoid effects on hippocampal neurophysiology and mnemonic processing". Thesis, Available from the University of Aberdeen Library and Historic Collections Digital Resources. Restricted: no access until Mar. 17, 2011, 2008. http://digitool.abdn.ac.uk:80/webclient/DeliveryManager?application=DIGITOOL-3&owner=resourcediscovery&custom_att_2=simple_viewer&pid=26047.
Testo completo
21
Pacheco, Estefan Daniel. "Space, memory, action: insights from behaviour and neurophysiology". Doctoral thesis, Universitat Pompeu Fabra, 2017. http://hdl.handle.net/10803/458526.
Testo completoAbstract (sommario):
Human memory is fundamentally linked to experience. Traditionally, however, it has been studied in restricted tasks, under constrained experimental conditions. Understanding memory from a situated, embodied, spatial perspective constitutes not only a major scientific challenge but a primary issue in the design of future educational technologies. Indeed, recent developments in virtual and augmented reality (VR/AR) systems provide novel means to organize the interaction with digital content in fully spatial setups. A deeper insight into the behavioral determinants of memory is thus critical to build better Human-Computer Interaction (HCI) systems to visualize, explore and learn from data. In an interdisciplinary effort that integrates techniques from experimental psychology, HCI and neuroscience, this thesis presents a series of studies focused on the modulation of human long-term declarative memory by incidental and action-related factors. Our findings demonstrate the role of environmental information associated with items at encoding and retrieval on memory performance. In the brain, such spatial-context effect is observed in the early reinstatement of a combined spatial and stimulus-derived neural representation in the hippocampus during memory retrieval. Moreover, our data highlight the role of spatial context in shaping the underlying structure of long-term memory, which is observed in the strong statistical dependency of free recall recollection dynamics on the distance between items at encoding. Our results further underline the benefits of self-directed learning in mnemonic processing. We report enhanced item recognition when timings and materials of study are volitionally determined by the learner as compared to passive memorization. Physiologically, active learning is characterized by increased theta oscillations in the hippocampus, in line with several studies which have linked this frequency band to active information sampling in the rodent. A key question arising from these findings is how to apply this knowledge in the design of new learning paradigms. Based on the principles of experience, embodiment, agency during the exploration of large corpus of data, we introduce an ecology of technologies aimed at the optimization of human-data interaction in the field of Digital Heritage. Altogether, our results advance our understanding of the behavioral determinants of human long-term declarative memory and their underlying physiological substrate, suggesting scientifically-grounded guidelines for the design of novel educational paradigms.La memoria humana está fundamentalmente ligada a la experiencia. Tradicionalmente, sin embargo, se ha estudiado en tareas restringidas, en condiciones experimentales limitadas. La comprensión de la memoria desde una perspectiva corporal, situada, espacial, constituye no sólo un desafío científico importante, sino una cuestión primordial en el diseño de las futuras tecnologías educativas. De hecho, mejoras recientes en sistemas de realidad virtual y aumentada (VR/AR) proporcionan nuevos medios para organizar la interacción con contenido digital en configuraciones completamente espaciales. Una visión más profunda de los determinantes conductuales de la memoria es, por lo tanto, crítica para construir mejores sistemas de interacción humano-ordenador (HCI) para la exploración y visualización de datos. En un esfuerzo interdisciplinario que integra técnicas de psicología experimental, HCI y neurociencia, esta tesis presenta una serie de estudios enfocados en la modulación de la memoria humana declarativa de largo plazo por factores incidentales y relacionados con la acción. Nuestros hallazgos demuestran el papel de la información ambiental asociada a elementos durante la codificación y la recuperación en el rendimiento de la memoria. En el cerebro, este efecto de contexto espacial se observa en la repetición temprana, durante el recuerdo, de una representación neuronal conjunta de contexto y estímulos en el hipocampo. Además, nuestros datos ponen de relieve el papel del contexto espacial en la configuración de la estructura de la memoria de largo plazo, lo que se observa en la fuerte dependencia estadística entre las dinámicas del recuerdo libre y la distancia entre los elementos durante la codificación. Nuestros resultados también subrayan los beneficios del aprendizaje autodirigido en el procesamiento mnemónico. Demostramos una mejor memoria de reconocimiento cuando los tiempos y materiales de estudio son determinados voluntariamente por el estudiante en comparación con la memorización pasiva. Fisiológicamente, el aprendizaje activo se caracteriza por un aumento de las oscilaciones theta en el hipocampo, en línea con varios estudios que han vinculado la banda al muestreo activo de información en el roedor. Una cuestión clave que surge de estos hallazgos es cómo aplicar este conocimiento en el diseño de nuevos paradigmas de aprendizaje. Basado en los principios de la experiencia, la corporalidad y la acción durante la exploración de datos, introducimos una ecología de tecnologías dirigidas a la optimización de la interacción hombre-datos en el campo del patrimonio digital. En conjunto, nuestros resultados avanzan nuestra comprensión de la memoria humana declarativa de largo plazo, sus determinantes conductuales y substrato fisiológico, sugiriendo guías fundamentadas científicamente para el diseño de nuevos paradigmas educativos.
La memòria humana està fonamentalment relacionada amb l’experiència. Tradicionalment, però, s’ha estudiat en tasques restringides, sota condicions experimentals limitades. La comprensió de la memòria des d’una perspectiva espacial, corpòria i de presencia constitueix no només un repte científic important, sinó una qüestió primordial en el disseny de futures tecnologies educatives. De fet, els desenvolupaments recents en sistemes de realitat virtual i augmentada (VR/AR) proporcionen nous mitjans per organitzar la interacció amb contingut digital en configuracions totalment espacials. Una visió més profunda dels determinants conductuals de la memòria és, per tant, fonamental per construir millors sistemes d’interacció humans-computadores (HCI) per visualitzar, explorar i aprendre de dades. En un esforç interdisciplinari que integra tècniques de psicologia experimental, HCI i neurociència, aquesta tesi presenta una sèrie d’estudis centrats en la modulació de la memòria humana declarativa a llarg termini, a través de factors incidentals i relacionats amb l’acció. Les nostres troballes demostren la influència del context ambiental associada a ítems en la codificació i recuperació en el rendiment de la memòria. Al cervell, aquest efecte de context espacial s’observa en la restauració primerenca, durant el record, d’una representació neuronal conjunta de context i estímuls en l’hipocamp. A més, les nostres dades ressalten la importància del paper que té el context espacial en la configuració de l’estructura de la memòria a llarg termini, que s’observa en la forta dependència estadística entre la dinàmica de recuperació lliure i la distància entre ítems durant la codificació. Els nostres resultats també subratllen els beneficis de l’aprenentatge autodirigit en el processament mnemònic. Presentem un reconeixement millorat d’elements quan els temps i materials d’estudi són determinats voluntàriament per al estudiant en comparació amb una memorització passiva. Fisiològicament, l’aprenentatge actiu es caracteritza per l’augment de les oscil·lacions de theta en l’hipocamp, en línia amb diversos estudis que han vinculat aquesta banda de freqüències amb el mostreig d’informació activa en rosegadors. Una pregunta clau que sorgeix d’aquests resultats és com aplicar aquest coneixement en el disseny de nous paradigmes d’aprenentatge. Basant-nos en els principis d’experiència, realització i agència durant l’exploració de grans corpus de dades, introduïm una ecologia de tecnologies orientada a l’optimització de la interacció entre humans i dades en el camp del patrimoni digital. En conjunt, els nostres resultats avancen la nostra comprensió dels determinants conductuals de la memòria declarativa humana a llarg termini i el seu substrat fisiològic, suggerint pautes per al disseny de nous paradigmes educatius.
22
Norton, Jonathan Andrew. "FES-standing and muscle spasms : neurophysiology and biomechanics". Thesis, University College London (University of London), 2003. http://discovery.ucl.ac.uk/1383223/.
Testo completoAbstract (sommario):
Functional Electrical Stimulation (FES) can be used to assist patients with complete paraplegia arising from a traumatic spinal cord injury to stand. In clinical practice the take-up of this technology is poor. It was hypothesised that one potential reason was that the posture during standing was difficult to predict from non-standing biomechanical measures because of the spinal cord's motor responses to standing. In six patients biomecharrical and electrophysiological recordings were made to test whether motor activity arising as a result of standing affected their standing posture. Recordings were made using surface EMG electrodes, force plates and instrumented handles a motion analysis system. No motor activity that affected the posture of the patients was recorded during standing or when the patients changed their hip or ankle angles. The act of standing with FES assistance affected spasms in two of the six patients. In one patient his spasms became regularised to a 16s pattern when standing with FES but when standing without FES and in the second patient his spasms were stopped for periods of up to 7 hours. This prolonged cessation only occurred when standing with FES. Mechanically supported standing produced a short (5 minute) cessation in the activity. The neural activity during the sit-to-stand or steady state standing did not change with increasing experience of standing in one naive subject studied over 6 weeks. The patient used the same strategy for the sit-to-stand as other patients. He improved his performance of this strategy by shortening the phases and the intervals between the phases as well as reducing the safety margin for knee buckling. The spinal cord when removed from descending inputs is capable of generating rhythmical motor outputs in response to changes in sensory inputs. FES may interact with some of this oscillatory activity.
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Maslovskaya, Sofya. "Inverse Optimal Control : theoretical study". Thesis, Université Paris-Saclay (ComUE), 2018. http://www.theses.fr/2018SACLY013/document.
Testo completoAbstract (sommario):
Cette thèse s'insère dans un projet plus vaste, dont le but est de s'attaquer aux fondements mathématiques du problème inverse en contrôle optimal afin de dégager une méthodologie générale utilisable en neurophysiologie. Les deux questions essentielles sont : (a) l'unicité d'un coût pour une synthèse optimale donnée (injectivité); (b) la reconstruction du coût à partir de la synthèse. Pour des classes de coût générales, le problème apparaît très difficile même avec une dynamique triviale. On a donc attaqué l'injectivité pour des classes de problèmes spéciales : avec un coût quadratique, la dynamique étant soit non-holonome, soit affine en le contrôle. Les résultats obtenus ont permis de traiter la reconstruction pour le problème linéaire-quadratiqueThis PhD thesis is part of a larger project, whose aim is to address the mathematical foundations of the inverse problem in optimal control in order to reach a general methodology usable in neurophysiology. The two key questions are : (a) the uniqueness of a cost for a given optimal synthesis (injectivity) ; (b) the reconstruction of the cost from the synthesis. For general classes of costs, the problem seems very difficult even with a trivial dynamics. Therefore, the injectivity question was treated for special classes of problems, namely, the problems with quadratic cost and a dynamics, which is either non-holonomic (sub-Riemannian geometry) or control-affine. Based on the obtained results, we propose a reconstruction algorithm for the linear-quadratic problem
24
Maslovskaya, Sofya. "Inverse Optimal Control : theoretical study". Electronic Thesis or Diss., Université Paris-Saclay (ComUE), 2018. http://www.theses.fr/2018SACLY013.
Testo completoAbstract (sommario):
Cette thèse s'insère dans un projet plus vaste, dont le but est de s'attaquer aux fondements mathématiques du problème inverse en contrôle optimal afin de dégager une méthodologie générale utilisable en neurophysiologie. Les deux questions essentielles sont : (a) l'unicité d'un coût pour une synthèse optimale donnée (injectivité); (b) la reconstruction du coût à partir de la synthèse. Pour des classes de coût générales, le problème apparaît très difficile même avec une dynamique triviale. On a donc attaqué l'injectivité pour des classes de problèmes spéciales : avec un coût quadratique, la dynamique étant soit non-holonome, soit affine en le contrôle. Les résultats obtenus ont permis de traiter la reconstruction pour le problème linéaire-quadratiqueThis PhD thesis is part of a larger project, whose aim is to address the mathematical foundations of the inverse problem in optimal control in order to reach a general methodology usable in neurophysiology. The two key questions are : (a) the uniqueness of a cost for a given optimal synthesis (injectivity) ; (b) the reconstruction of the cost from the synthesis. For general classes of costs, the problem seems very difficult even with a trivial dynamics. Therefore, the injectivity question was treated for special classes of problems, namely, the problems with quadratic cost and a dynamics, which is either non-holonomic (sub-Riemannian geometry) or control-affine. Based on the obtained results, we propose a reconstruction algorithm for the linear-quadratic problem
25
Voirin, James [Verfasser]. "Ecology and Neurophysiology of Sleep in Wild Sloths / James Voirin". Konstanz : Bibliothek der Universität Konstanz, 2013. http://d-nb.info/104290054X/34.
Testo completo
26
Saftenku, Elena. "Anomalous and apparently anomalous diffusion in the area of neurophysiology". Universitätsbibliothek Leipzig, 2016. http://nbn-resolving.de/urn:nbn:de:bsz:15-qucosa-194237.
Testo completo
27
Saatchi, Mohammad Reza. "Developments in signal processing for computerised diagnosis in clinical neurophysiology". Thesis, Sheffield Hallam University, 1992. http://shura.shu.ac.uk/14384/.
Testo completoAbstract (sommario):
The aim of this study was to apply signal processing techniques to a potential known as the contingent negative variation (CNV) in order to aid detection of schizophrenia, Parkinson's disease (PO) and Huntington's Disease (lID). A data recording system was constructed and used to obtain data from 20 schizophrenic patients, 16 PO patients, 21 -at-risk- of HD patients, 11 HD patients and 43 normal control subjects. The data included the CNV, electro-oculograms (required for the preprocessing of the CNV) and the subjects reaction times to an acoustic stimulus. The CNV waveforms were initially preprocessed. This reduced the effects of background electroencephalogram and ocular artefact potentials. The CNV waveforms were then processed using a method which involved the discrete Fourier transform (OFf) and discriminant analysis. This method developed from the work of Martin Nichols and Michael Coelho. It was possible to successfully identify the majority of the patients using this method. In order to reduce the complexity of patients' Identification a different method of CNV signal processing was considered. This involved obtaining the CNV features in the time domain and using them in neural networks. This method was as effective as the method which used OFf and discriminant analysis in identifying the patients. To establish whether HO could presymptomatically be detected in the at-risk of HD group, the CNV was analysed using principal component analysis (PCA) and Ward's clustering method. This resulted in identification of 7 patients who were suggested would develop HO. The subjects' reaction times were also analysed. This indicated that the reaction times of schizophrenic, PO, HO and some at-risk of HD patients were significantly different from the reaction times of their normal control subjects.
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Mears, Ryan Phillip. "NEUROPHYSIOLOGY OF AUDITORY INHIBITORY GATING IN RAT MEDIAL PREFRONTAL CORTEX". Bowling Green State University / OhioLINK, 2006. http://rave.ohiolink.edu/etdc/view?acc_num=bgsu1151343744.
Testo completo
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Hilton, Emma. "Towards an understanding of the neurophysiology of cough in humans". Thesis, University of Manchester, 2012. https://www.research.manchester.ac.uk/portal/en/theses/towards-an-understanding-of-the-neurophysiology-of-cough-in-humans(f314ffdd-9ea0-4732-af27-afd7f34f9ffa).html.
Testo completoAbstract (sommario):
Rationale: Chronic cough (cough >8 weeks) is common, leads to an impaired quality of life, and is difficult to treat. Despite intensive investigation, ~40% of patients referred to a specialist cough clinic will remain resistant to treatment targeted at peripheral triggers such as reflux disease, rhino-sinusitis or airways inflammation. An improved understanding of underlying mechanisms in such patients would facilitate drug development. I propose that there are several important similarities between pain and cough that can be exploited better to understand underlying mechanisms. In chronic pain, a long-lasting up-regulation of afferent pain processing may be generated by changes within the central nervous system, mediated by the NMDA receptor and/or by impaired inhibitory mechanisms. A similar central neuronal up-regulation of cough may also be responsible for the pathogenesis of chronic cough (CC). Methods: A series of experimental studies were performed to address this hypothesis. Firstly, the anti-tussive and analgesic effect of ketamine, an NMDA receptor antagonist, was investigated in CC patients and healthy controls (HC). Pain thresholds were measured using electrical stimulation in the oesophagus, pharynx and chest wall. Cough sensitivity was measured using standard capsaicin cough challenges. Secondly, I designed and tested novel capsaicin cough challenges in CC patients, asthmatics (A) and HC. ED50 (dose inducing and least 50% maximal cough frequency) and Cmax (maximal cough frequency) was compared by group and gender. Finally, I investigated 2 independent mechanisms of cough inhibition. Results:(i) CC patients, but not HC, had cough induced by oesophageal electrical stimulation, whilst pain thresholds were similar. Ketamine had a significant analgesic effect but no antitussive effect in CC or HC.(ii) CC patients had both cough hypersensitivity (lower ED50) and cough hyper-responsiveness (higher Cmax) on full capsaicin dose-response curves. (iii) Both a painful cold stimulus applied to the hand and conscious cough suppression significantly inhibited capsaicin-induced cough responses in CC and HC.Conclusions:CC patients exhibited increased oesophageal sensitivity to cough, but not pain, providing evidence for a process of central sensitisation in the brainstem. Higher capsaicin-induced cough frequencies in CC may also be mediated by an increased gain within the CNS, possibly because of failed tonic inhibitory mechanisms. Furthermore, CC patients may have poorer conscious control of coughing. In conclusion, an improved understanding of mechanisms in cough will provide a strong scientific rationale for the development of novel therapeutics.
30
Weil, Jon C. (Jon Christopher). "Characterizing Spontaneous Neurophysiological Activity with Measures of Statistical Serial Dependence: a Summary Statistic and an Extension of the Joint Interval Histogram". Thesis, University of North Texas, 1994. https://digital.library.unt.edu/ark:/67531/metadc278067/.
Testo completoAbstract (sommario):
Two measures which indicate statistical serial dependence were evaluated. The n-dimensional Average Stored Information index (ndASI) is a measure of conditional information, which compares the entropies of higher order conditional distributions to estimate average statistical serial dependence. The generalized ranked joint interval histogram (RJIH-o) is a new nonparametric graphical analysis method. It extends the joint interval histogram by depicting longer interval sequences and can be interpereted precisely analagously to the joint interval histogram. The generalized ranked joint interval histogram correctly represents independence in a Poisson process model and statistical serial dependence in a directionally reinforced Markov model. The generalized ranked joint interval histogram correctly depicts the underlying periodic and strange attractors in a standard map model. Both measures can be used to effectively analyze interspike interval sequences from spontaneous neurophsyiological activity effectively.
31
Dukes, David Jefferson. "Brain Topography of Leadership: Neurophysiological Correlates of the Leadership Opinion Questionnaire". Thesis, University of North Texas, 1995. https://digital.library.unt.edu/ark:/67531/metadc332480/.
Testo completoAbstract (sommario):
Laboratory research was performed to understand leadership by attempting to link EEG baseline frequency patterns with data from the Leadership Opinion Questionnaire (LOQ) assessment survey. Research began with 293 right-handed males, 18 to 26 years-old, who completed the LOQ. Based on their scores, 61 subjects, grouped by the Ohio State Leadership Quadrants, were tested using brain-mapping technology.
32
Stratford, Kenneth James. "Quantal analysis - theory and practice : a study of chemical synaptic transmission". Thesis, University of Oxford, 1992. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.333360.
Testo completo
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Tolias, Christos. "Extracellular superoxide and nitric oxide : a real-time investigation in the role of free radicals in brain cell physiology and pathophysiology in vitro". Thesis, University of Warwick, 1999. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.484267.
Testo completo
34
曾昭雪 e Chiu-suet Margaret Tsang. "The regulation of Endothelin-1 during mouse brain development and perinatal cerebral ischemia". Thesis, The University of Hong Kong (Pokfulam, Hong Kong), 1999. http://hub.hku.hk/bib/B31221749.
Testo completo
35
McEwan, Carolyn Audrey. "Stimulation of human neuroblastoma cells using a planar microelectrode array". Thesis, University of Glasgow, 2000. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.343915.
Testo completo
36
McDonald, James Scott. "Visual processing of contrast in natural scenes". Thesis, University of Newcastle Upon Tyne, 2001. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.270824.
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37
Chen, Ying. "Study of the dorsal root reflex activity in an isolated mammalian spinal cord preparation". Thesis, University of Southampton, 1991. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.359141.
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Tsang, Chiu-suet Margaret. "The regulation of Endothelin-1 during mouse brain development and perinatal cerebral ischemia /". Hong Kong : University of Hong Kong, 1999. http://sunzi.lib.hku.hk/hkuto/record.jsp?B20622399.
Testo completo
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Fritz, Thomas. "Emotion investigated with music of variable valence : neurophysiology and cultural influence". Phd thesis, Universität Potsdam, 2008. http://opus.kobv.de/ubp/volltexte/2009/2911/.
Testo completoAbstract (sommario):
Music is a powerful and reliable means to stimulate the percept of both intense pleasantness and unpleasantness in the perceiver. However, everyone’s social experiences with music suggest that the same music piece may elicit a very different valence percept in different individuals. A comparison of music from different historical periods suggests that enculturation modulates the valence percept of intervals and harmonies, and thus possibly also of relatively basic feature extraction processes. Strikingly, it is still largely unknown how much the valence percept is dependent on physical properties of the stimulus and thus mediated by a universal perceptual mechanism, and how much it is dependent on cultural imprinting.
The current thesis investigates the neurophysiology of the valence percept, and the modulating influence of culture on several distinguishable sub-processes of music processing, so-called functional modules of music processing, engaged in the mediation of the valence percept.Musik eignet sich besonders gut, um sowohl intensive Angenehmheit/Lust und Unangenehmheit/Unlust (siehe auch Wundt, 1896), so genannte Valenzperzepte, im Zuhörer hervorzurufen. Jedoch kann derselbe musikalische Stimulus sehr unterschiedliche Valenzperzepte in verschiedenen Zuhörern hervorrufen, was nahe legt, dass das durch Musik vermittelte Valenzperzept zumindest teilweise durch kulturelle Prägung moduliert wird. Ein Vergleich von Musik verschiedener historischer Perioden legt ebenfalls nahe, dass kulturelle Prägung das Valenzperzept des Hörers bei der Wahrnehmung von Intervallen und Harmonien moduliert. Wichtigerweise ist es nach wie vor weitgehend unbekannt, inwiefern das Valenzperzept von physikalischen Eigenschaften des Stimulus (z.B. Rauhigkeit) abhängt - und daher auf einem universellen perzeptiven Mechanismus basiert - oder wie sehr es abhängt von kultureller Prägung. Die vorliegende Dissertation untersucht die Neurophysiologie des Valenzperzepts, sowie den modulierenden Einfluss von Kultur auf mehrere funktionelle Module der Musikwahrnehmung (voneinander unterscheidbare Subprozesse der Musikwahrnehmung), die bei der Entstehung des Valenzperzepts beteiligt sind.
40
Yang, In Hong. "The study of the neurophysiology of high strain rate nerve injury". Texas A&M University, 2003. http://hdl.handle.net/1969.1/416.
Testo completoAbstract (sommario):
The study of the mechanism of traumatic brain injury (TBI) processes at the cellular level is vital to obtain characterization of nerve cell damage after mechanical deformation. This understanding is needed to find feasible therapeutic targets for mechanically damaged neurons. To study the cellular level of TBI damage, development of a new in vitro cellular model of TBI might be done to simulate in vivo cellular TBI.
In this research, two studies were performed: (1) the design and construction of an in vitro cell stretching device to mechanically injure cells and (2) the characterization of the molecular and cellular level of the TBI mechanism. The cell stretching device design allows for the precise control of cell strain and duration of stretching cells such that TBI can be mimicked. Analysis of the cellular and molecular level mechanisms of TBI in the proposed in vitro model might help in the design of therapeutic strategies for the treatment of TBI. Our proposed mechanism of injury due to TBI is as follows: after the cell is stretched, a cellular signaling molecule is released to activate the cellular signaling pathway. The activated cell signal may activate kinases which phosphorylate proteins and initiate new protein synthesis. Newly phosphorylated and synthesized proteins may activate the apoptotic process.
Using a variety of pharmacological agents, one could block steps in the hypothesized mechanism and examine the effect of those agents on downstream cellular processes and cell apoptosis. For example, the inhibitions of calcium transport, protein synthesis, and caspases were performed to examine the initial activation of the signaling pathway and the role of both in the apoptosis process. Proteomics of TBI may help the understanding of the mechanism of TBI related protein expression. This work will contribute to the discovery of new therapeutic targets and better treatments for TBI.
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Brown, Katlyn Elizabeth. "The neurophysiology of sensorimotor integration in healthy aging and chronic stroke". Thesis, University of British Columbia, 2017. http://hdl.handle.net/2429/63184.
Testo completoAbstract (sommario):
Background: General decline in motor performance is often cited in healthy aging, and motor deficits persist into the chronic phase of stroke recovery. Abnormalities in sensorimotor integration may underlie these motor deficits; however, the effect of aging and chronic stroke on sensorimotor integration neurophysiology is not well understood. Further, investigation into the plasticity of sensorimotor integration is important to establish in populations experiencing sensorimotor decline.
Methods: The overall objective of this thesis was to comprehensively understand the neurophysiology of sensorimotor integration, including the influence of aging and chronic stroke on sensorimotor integration and the reliability of common neurophysiological measures. The first research chapter (Chapter 2) explores age and stroke-related differences in measures of indirect sensorimotor integration. Chapters 3 and 4 investigate baseline differences in measures of direct sensorimotor integration induced by aging and chronic stroke, respectively. Further, they use an intervention to index plasticity of sensorimotor integration in these populations. The final chapter (Chapter 5) addresses the reliability of a variety of neurophysiological methods used to examine somatosensory and motor cortical excitability, as well as sensorimotor integration.
Summary of Findings: In Chapter 2, older individuals and individuals with chronic stroke had reduced short-latency afferent inhibition, compared to younger individuals suggesting the difference is largely driven by age-related factors. Greater disinhibition post-stroke related to worse motor function and impairment. Chapter 3 showed that measures of direct sensorimotor integration are less susceptible to age-related changes than measures of indirect sensorimotor integration. Sensory training altered direct but not indirect sensorimotor integration, suggesting independent modulation of separate anatomical pathways of sensorimotor integration. Chapter 4 highlighted differences in direct sensorimotor integration between individuals with chronic stroke and older individuals such that vibration had less of an impact on baseline motor cortex excitability in individuals post-stroke and the intracortical response to sensory training was reduced. Chapter 5 showed high reliability in transcranial magnetic stimulation thresholds, the amplitudes of evoked potentials elicited at high stimulation intensities, and latency-based measures.
Conclusions: This dissertation contributes new knowledge to the impact of aging and chronic stroke on sensorimotor integration and the reliability of the measures used to quantify sensorimotor integration.Medicine, Faculty of
Graduate
42
Issa, Fadi Aziz. "Effect of Social Status on the Behavior and Neurophysiology of Crayfish". Digital Archive @ GSU, 2008. http://digitalarchive.gsu.edu/biology_diss/35.
Testo completoAbstract (sommario):
Adaptation to changing social conditions is important for many social animals. Here, the effects of social experience on the behavior and neurophysiology of the red swamp crayfish, Procambarus clarkii, were studied. Evidence is presented that shows juvenile crayfish interact and form social order, and their behavior patterns shift in accordance to social status. Dominant animals maintain a high level of aggressive behavior, while subordinates shift their behavior pattern from aggressive to submissive behavior. Adult male crayfish show similar behavior pattern during dominance formation. However, this work demonstrates that male crayfish adopt a unique strategy to signify the formation of a social order expressed in the form of pseudocopulation. Pseudocopulation between male crayfish signifies the acceptance of the social status and leads to the reduction of aggression of dominants and enhances the survival of subordinate animals. I investigated the long-term effects of social status on the behavioral and physiological responses of crayfish to unexpected sensory touch. I discovered that animals of different social experience display different orienting responses that correlate with in vivo electromyographic recordings from the legs’ depressor muscle. The status-dependent response patterns observed in vivo are retained in a reduced, in vitro, preparation that lacks descending input from the brain. The role of serotonin (5-HT) was investigated in mediating the motor output patterns of the depressor nerve. Putative serotonergic innervations of the depressor nerve were identified that originate from serotonergic neurons located in the first abdominal ganglion. Selective stimulation of the ipsilateral 5-HT neuron enhances the response of the depressor nerve to sensory stimulation. Application of 5-HT modestly increased the tonic firing activity of the depressor nerve in social isolates and subordinates but significantly decreased the activity in dominants. This work illustrates that the formation of a dominance relationship significantly and immediately alters the behavior of the participants. As the social relationship matures, the social experience that develops affects the underlying neurophysiology that mediates the behavior. It will be of great interest in future studies to identify not only the effects rather the mechanisms of how social experience induces physiological changes.
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McBride, Jennifer Ann. "Repetition or targets and distractors in visual search : Behaviour and neurophysiology". Thesis, University of Bristol, 2008. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.501505.
Testo completoAbstract (sommario):
Repetition of target properties across consecutive visual search trials affects response time: a phenomenon known as "repetition priming" in visual search. Ten visual search experiments are reported which were designed to better characterise the mechanism(s) producing this phenomenon. After replication of the effects reported in the literature with a new paradigm (Experiment 1), two further experiments (Experiments 2 and 3) were designed to identify the optimum paradigm with which to study these effects further, and revealed that repetition priming occurs only under particular circumstances. This conclusion was extended by Experiments 4-6, which showed that repetition priming effects depend on the exact stimuli and task used. These findings challenge the suggestion in the literature that repetition priming in visual search is driven by an automatic bottom-up process, and instead suggest that it is rather more flexible, and depends on the exact stimulus characteristics and task requirements.
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French, Richard L. B. "Exploring links between neurophysiology and behaviour with a behaviour-based robot". Thesis, University of Southampton, 2002. https://eprints.soton.ac.uk/256282/.
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Birge, Charles. "The Addiction of Transparency: Observations on the Emotional Neurophysiology of Whiteness". The Ohio State University, 2019. http://rave.ohiolink.edu/etdc/view?acc_num=osu1554891264402108.
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Tran, Christine. "Développement de sondes activables à deux photons pour une utilisation en neurosciences". Thesis, Sorbonne Paris Cité, 2015. http://www.theses.fr/2015USPCB165.
Testo completoAbstract (sommario):
Des sondes photoactivables (composés “cagés”) dérivées de la 2-hydroxyméthylène-diméthylaminoquinoléine, ont été préparées et testées pour une application en neurophysiologie. Ces sondes montrent une stabilité hydrolytique élevée et une faible fluorescence, avec des cinétiques de photofragmentation rapides sous irradiation UV (365 nm). Il en est également de même dans des conditions biphotoniques en IR proche (730 nm). Une optimisation de cette plateforme a été réalisée en modifiant la nature et la position des substituants du chromophore, en augmentant la conjugaison et en incorporant des éléments de symétrie C2 et S3, conduisant aux sondes dipolaires, quadrupolaires (dimériques) et octupolaires (trimériques) à haute sensibilité biphotonique ( < 2,50 GM). Les dérivés les plus efficaces ont été testés dans des expériences en neurophysiologie. Tandis que les dérivés de kaïnate sont suffisamment stables en solution aqueuse à pH 7,4 pour les expériences en conditions physiologiques, les dérivés de L-glutamate et GABA ont nécessité une connexion de type carbamate avec la plateforme photoactivable. Sans irradiation, les solutions « stock » de ces composés « cagés » (c = 200-300 µM) n’ont pas produit d’effets majeurs sur l'excitabilité des neurones à en juger par le manque d'effet sur l'activité neuronale ou de potentiels d’actions synaptiques spontanés provoqués par une dépolarisation. La photolyse en lumière blanche par pulses courts d’irradiation a permis la libération de substances actives en quantité suffisante pour produire de grands courants (jusqu’à 5 nA) dans les neurones de PurkinjePhotosensitive molecular probes (‘caged’ compounds) derived from 2-hydroxymethylenedimethylaminoquinoline were prepared and tested for applications in neurophysiology. These compounds show high hydrolytic stability and low fluorescence, with fast fragmentation kinetics upon UV irradiation (365 nm), and under two photon photolysis conditions (730 nm). This platform was optimized by modifying the substitution pattern, increasing the conjugation length and incorporating C2 or S3 symmetry elements. Dipolar, quadrupolar (dimer) and octupolar (trimer) derivatives were thus synthesized and were found exhibiting high two-photon sensitivity ( < 2,50 GM). The most efficient probes were tested in neurophysiological experiments. While kaïnate derivatives are stable in aqueous solution at pH 7.4 in physiological conditions, L-glutamate and GABA derivatives required the use of a carbamate linker. Without irradiation, any major changes were observed on neuron excitability with “stock” solutions of these caged compounds (c = 200-300 µM), according to the lack of effects on neuron activity or action potentials evoked by depolarization. White light photolysis by short pulses generated sufficient active substances to induce large inward currents (up to 5 nA) in Purkinje neurons
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Tucker, Gayle. "Mathematical modelling in neurophysiology : neuronal geometry in the construction of neuronal models". Thesis, University of Oxford, 2004. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.414405.
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Kelly, Rachel Louise. "Understanding the neurophysiology of action interpretation in right and left-handed individuals". Diss., Georgia Institute of Technology, 2015. http://hdl.handle.net/1853/53589.
Testo completoAbstract (sommario):
Investigating the neurophysiology behind our action encoding system offers a way of probing the underlying mechanisms regarding how we understand seen action. The ability to mentally simulate action (motor simulation) is a strong proposal to understand how we interpret others’ actions. The process of how we generate accurate motor simulations is proposed to be reliant on the context of the movement and sensory feedback from the limb. However, the neurophysiological mechanisms behind motor simulation are not yet understood. Known motor physiology for right-handed individuals show there is a left parietal-frontal network for the mental simulation of skilled movements; however, it remains unclear whether this is due to right limb dominance of the observer’s motor system because action simulation research has been focused primarily on right-handed individuals. The goal of this dissertation is to understand the underlying neurophysiology of the motor simulation process during action encoding. Generally, we propose different strategies of action simulation between right and left handed individuals. More specifically, we propose that right-handed individuals rely on their motor dominant left hemisphere for action encoding and motor simulation, while left-handed individuals will rely on their motor dominant right hemisphere. We will test this by evaluating neurobehavioral patterns of potential symmetry and asymmetry of motor simulation and action encoding based on patterns of limb dominance. We will also evaluate how impaired sensory feedback affects motor simulations, which can reveal how limb state affects the simulation process. The results of this series of studies will fill a void in our basic understanding of the motor simulation process and may generalize to populations with upper limb functional loss. Specifically, those with different hand dominance may require different rehabilitation programs in order to retrain an affected limb.
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Szcz??sniak, Michal Marcin Clinical School St George Hospital Faculty of Medicine UNSW. "Experimental and pathophysiological modulation of oesophageal afferent pathways: implications for oesophago-pharyngeal reflexes, regurgitation and symptom perception /". Awarded by:University of New South Wales. Clinical School - St George Hospital, 2008. http://handle.unsw.edu.au/1959.4/41094.
Testo completoAbstract (sommario):
The work presented in this thesis concerns neurophysiology and pharmacology of the oesophageal afferent pathways involved in oesophago-pharyngeal reflexes and oesophageal nociception. Disturbances of reflexes governing contractile and relaxation responses of the upper oesophageal sphincter (DOS) are likely to be implicated in the pathophysiology of conditions involving excessive oesophago-pharyngeal regurgitation, impaired oesophageal clearance, and an abnormal belch reflex. Visceral hypersensitivity, a heightened perception of gastrointestinal sensation is frequently observed in functional gastrointestinal disorders and provides compelling evidence that it plays an important role in the pathogenesis of functional heartburn and non-erosive reflux disease. The work in this thesis explores the neurophysiology, pharmacology and pathophysiology of oesophago-DOS reflexes in humans by experimentally inducing DOS relaxations in healthy controls and patients with reflux laryngitis, and by recording DOS motor responses during spontaneous oesophago-pharyngeal regurgitation. Nociception was assessed by measuring oesophageal sensitivity to electrical stimulation and oesophageal acid perfusion in healthy controls, which was then compared with several heartburn populations (functional heartburn, erosive and non-erosive reflux disease). Additional studies were performed to evaluate the potential role of intraluminal impedance in defining antegrade bolus flow through the pharyngo-oesophageal segment during swallowing as a prelude to the adaptation of the technique to find a more accurate method for the detection of oesophago-pharyngeal regurgitation. The main findings from this work are as follows. 1) Mucosal lignocaine-sensitive afferents mediate the distension-induced oesophago-DOS relaxation reflex and lignocaine insensitive, presumably muscular mechanoceptors, mediate the distension-induced oesophago-DOS contractile reflex. The latter reflex is also upregulated by oesophageal acidification indicative of a possible protective mechanism. 2) Prolonged studies in patients with proven oesophago-pharyngeal regurgitation demonstrated that the most common mechanism of oesophago-pharyngeal regurgitation is a transient, non-swallow related, relaxation of the DOS. 3) Experimental evaluation of the oesophago-DOS relaxation reflex revealed that it is upregulated in patients with reflux laryngitis, suggesting that the aberrant afferent signalling in the oesophagus may be a contributory factor mediating oesophago-pharyngeal regurgitation. 4) Measurement of oesophageal sensory thresholds in response to electrical stimulation and acid perfusion revealed that all patients, irrespective of the presence or absence of mucosal injury, exhibit acid-induced hypersensitisation. 5) The viscro-somatic referral pattern of acid- and electrically-induced chest pain is increased in patients with functional heartburn and non-erosive reflux disease. These findings support the hypothesis that central sensitisation of nociceptive pathways may contribute to symptom reporting in these heartburn populations.
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Xu, Bin. "Axonal growth, neuronal damage and epileptogenesis /". *McMaster only, 2002.
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