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1
Zim, Bret E. "Improved Fabrication and Quality Control of Substrate Integrated Microelectrode Arrays." Thesis, University of North Texas, 2000. https://digital.library.unt.edu/ark:/67531/metadc2484/.
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Spontaneously active monolayer neuronal networks cultured on photoetched multimicroelectrode plates (MMEPs) offer great potential for use in studying neuronal networks. However, there are many problems associated with frequent, long-term use of MMEPs. The major problems include (1) polysiloxane insulation deterioration and breakdown, (2) and loss of gold at the gold electroplated indium-tin oxide (ITO) electrodes. The objective of this investigation was to correct these major problems. Quality control measures were employed to monitor MMEP fabrication variables. The phenotypes of polysiloxane degradation were identified and classified. Factors that were found to contribute most to insulation deterioration were (1) moisture contamination during MMEP insulation, (2) loss of the quartz barrier layer from excessive exposure to basic solutions, and (3) repetitive use in culture. As a result, the insulation equipment and methods were modified to control moisture-dependent insulation deterioration, and the KOH reprocessing solution was replaced with tetramethylguanidine to prevent damage to the quartz. The problems associated with gold electroplating were solved via the addition of a pulsed-DC application of gold in a new citrate buffered electroplating solution.
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Marcos, Sanmartín Encarni. "Embodied decision making and its neural substrate." Doctoral thesis, Universitat Pompeu Fabra, 2014. http://hdl.handle.net/10803/285379.
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Decisions are the result of a deliberative process that evaluates the suitability of specific options. Studies about decision making have been mainly conducted by using restricted tasks in which humans or animals are requested to discriminate between options. However, the influence that factors related to embodiment, such as motor cost, might have on this process has frequently been ignored. In this thesis, we adopt a combined experimental and theoretical approach to examine the effect that such factors have on decision making. Our results confirm an important bias of behavior and neural activity resulting from factors related to embodiment that are external to the goal of the task itself. We use computational models to account for this bias and to shed some light on the neural mechanisms producing it. Our results translate into significant progress in the understanding of embodied decision making, providing new insights into neural mechanisms and theoretical models.Las decisiones son el resultado de un proceso de deliberación que evalúa la idoneidad de opciones específicas. Los estudios acerca de la toma de decisiones han estado principalmente dirigidos usando tareas restringidas en las que a los humanos o animales se les pide escoger entre opciones. Sin embargo, la influencia que factores relacionados con la corporificación de la toma de decisiones podrían tener en este proceso se ha ignorado frecuentemente. En esta tesis, adoptamos un enfoque experimental y teórico combinado para examinar la influencia que estos factores tienen en la toma de decisiones. Nuestros resultados confirman un importante sesgado del comportamiento y de la actividad neuronal causados por factores que son externos al objetivo de la tarea en sí. Utilizamos modelos computacionales para interpretar este sesgado que, a su vez, nos da una intuición del mecanismo neuronal que los está produciendo. Nuestros resultados se traducen en un significante progreso en la comprensión de la toma de decisiones corporificada, aportando nuevos conocimientos sobre los mecanismos neuronales y modelos teóricos.
Les decisions són el resultat d'un procés de deliberació que avalua la idoneïtat d'opcions específiques. Els estudis sobre la presa de decisions han estat principalment dirigits fent servir tasques restringides a les quals, als humans o animals, se'ls demana escollir entre opcions. No obstant, la influència que factors relacionats amb la corporificació de la presa de decisions podrien tenir en aquest procés s'ha ignorat freqüentment. En aquesta tesi, adoptem un enfocament experimental i teòric combinat per tal d'examinar la influència que aquests factors tenen en la presa de decisions. Els nostres resultats confirmen un important esbiaixat del comportament i de l'activitat neuronal degut a factors externs a l'objectiu de la tasca en sí. Fem servir models computacionals per tal d'interpretar aquest esbiaixat que, a la vegada, ens dóna una intuïció del mecanisme que l'està produint. La tesi conclou amb la presentació d'un únic model que integra tots els descobriments presentats i que podria utilitzar-se com a nou marc teòric per a recerques futures. En general, els resultats inclosos aquí es tradueixen en un significant progrés a la comprensió de la presa de decisions corporificada, aportant nous coneixements sobre els mecanismes neuronals i models teòrics.
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Cho, Hyesuk. "Exploring a Common Neural Substrate of Reading and Spelling." Diss., The University of Arizona, 2010. http://hdl.handle.net/10150/195488.
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Whether reading and spelling rely on the same orthographic representations has been a controversial issue in the neuropsychology literature. In general, associations between patterns of alexia and agraphia in neurological patients have been interpreted to support the view that reading and spelling share the same orthographic lexicon. By contrast, dissociations between reading and spelling profiles are considered as evidence for the existence of separate orthographic input and output lexicons subserving written word recognition and production. Neuroimaging research relevant to the neural substrates of orthographic processing has shown consistent association between reading and activation in the mid-lateral portions of the left fusiform gyrus (BA 37), a region that has come to be known as the "visual word form area" (VWFA). Critically, it has been shown that spelling words also activates the VWFA. These findings seem to confirm the central role of the VWFA in orthographic processing and support the view that the same orthographic representations mediate reading and spelling. Unfortunately, the available neuroimaging evidence on the relationship between reading and spelling is limited in that the relevant studies typically have involved different subject groups. The purpose of this study was to investigate whether the cortical region responsible for orthographic processing during reading is also activated during spelling in the same individuals using fMRI (functional magnetic resonance imaging). Fifteen native English speakers participated in the study and were administered reading and writing tasks designed to isolate cortical regions involved in orthographic processing during reading and writing. Results showed that the left mid fusiform gyrus corresponding to the VWFA is associated not only with orthographic processing in reading but is also recruited during the retrieval of orthographic information in spelling, suggesting that this cortical region is the common neural substrate of orthographic processing for both written language tasks. These findings are consistent with shared components cognitive models that postulate a single orthographic lexicon mediating both reading and spelling.
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Weddell, Rodger Anthony. "The neural substrate of emotion in man : a study in methodology." Thesis, University of Edinburgh, 1986. http://hdl.handle.net/1842/19402.
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Jones, Erin Boote. "Effects of substrate and co-culture on neural progenitor cell differentiation." [Ames, Iowa : Iowa State University], 2008.
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Veen, Daniel Rutger van der. "Neural substrate and the timing of behaviour in a multiple clock system." [S.l. : Groningen : s.n. ; University Library of Groningen] [Host], 2007. http://irs.ub.rug.nl/ppn/305367048.
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Lado, Wudu E. "The Neural Substrate of Sex Pheromone Signalling in Male Goldfish (Carassius auratus)." Thèse, Université d'Ottawa / University of Ottawa, 2012. http://hdl.handle.net/10393/23460.
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The transmission of sex pheromone-mediated signals is essential for goldfish reproduction. However, the neural pathways underlying this reproductive signalling pathway in the goldfish brain is not well described. Lesioning experiments have shown previously that two brain areas, the preoptic area (POA) and the ventral telencephali pars ventralis (Vv) in particular, are important for reproduction. We used patch clamp electrophysiology to study the electrical activities of POA and Vv neurons. Based on the intrinsic properties of these neurons, we suggest there are five different functional classes of POA neurons and a single class of Vv neurons. In addition, by electrically stimulating the olfactory bulb (OB), we were able to show that this primary sensory structure makes monosynaptic glutamatergic connections with both POA and Vv neurons. While electrophysiology measures signalling events occurring at short time scales on the order of milliseconds to minutes, we were also interested in studying sex pheromone signalling in the goldfish brain over a long time scale. Thus, we describe changes in gene expression in male goldfish exposed to waterborne sex pheromones (17alpha,20beta dihydroxy-4-pregene-3-one and Prostaglandin-F2alpha) over 6 hours. We perform cDNA microarrays on Prostaglandin-F2alpha-treated fish to study the rapid modulation of transcription and define the signalling pathways affected. Our microarrays showed that 71 genes were differentially regulated (67 up and 4 down). Through gene ontology enrichment analysis, we found that these genes were involved in various biological processes such as RNA processing, neurotransmission, neuronal development, apoptosis, cellular metabolism and sexual reproduction. RT-PCRs were performed to validate our microarrays and to facilitate direct comparisons of the effects of the two sex pheromones, 17alpha,20beta dihydroxy-4-pregene-3-one and Prostaglandin-F2alpha. By combining electrophysiology and gene expression analyses, we were able to study sex-pheromone signalling on two different time scales. One short, occurring on the order of milliseconds to minutes, that involves electrical activities in the brain through the glutamatergic amino-3-hydroxy-5-methylisoxazole-4-propionate and N-methyl-D-aspartate receptors; and the other long occurring several hours later that involves changes in the gene expression levels of calmodulin and ependymin among other genes underlying neuroplasticity. Reproductive neuroplasticity in the goldfish may therefore require the activation of glutamatergic receptors which then activate downstream signals like calmodulin and ependymin to transform the sex pheromones-mediate signal into gene expression.
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Lu, Yiqing [Verfasser], Ralf [Akademischer Betreuer] Galuske, Bodo [Akademischer Betreuer] Laube, and Wolf [Akademischer Betreuer] Singer. "The Neural Substrate of the Eureka Effect / Yiqing Lu ; Ralf Galuske, Bodo Laube, Wolf Singer." Darmstadt : Universitäts- und Landesbibliothek Darmstadt, 2018. http://d-nb.info/1172880298/34.
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Howk, Cory Lee. "A mathematical model for IL6-induced differentiation of neural progenitor cells on a micropatterned polymer substrate." [Ames, Iowa : Iowa State University], 2010. http://gateway.proquest.com/openurl?url_ver=Z39.88-2004&rft_val_fmt=info:ofi/fmt:kev:mtx:dissertation&res_dat=xri:pqdiss&rft_dat=xri:pqdiss:3403078.
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Mouterde, Solveig. "Long-range discrimination of individual vocal signatures by a songbird : from propagation constraints to neural substrate." Thesis, Saint-Etienne, 2014. http://www.theses.fr/2014STET4012/document.
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L'un des plus grands défis posés par la communication est que l'information codée par l'émetteur est toujours modifiée avant d'atteindre le récepteur, et que celui-ci doit traiter cette information altérée afin de recouvrer le message. Ceci est particulièrement vrai pour la communication acoustique, où la transmission du son dans l'environnement est une source majeure de dégradation du signal, ce qui diminue l'intensité du signal relatif au bruit. La question de savoir comment les animaux transmettent l'information malgré ces conditions contraignantes a été l'objet de nombreuses études, portant soit sur l'émetteur soit sur le récepteur. Cependant, une recherche plus intégrée sur l'analyse de scènes auditives est nécessaire pour aborder cette tâche dans toute sa complexité. Le but de ma recherche était d'utiliser une approche transversale afin d'étudier comment les oiseaux s'adaptent aux contraintes de la communication à longue distance, en examinant le codage de l'information au niveau de l'émetteur, les dégradations du signal acoustiques dues à la propagation, et la discrimination de cette information dégradée par le récepteur, au niveau comportemental comme au niveau neuronal. J'ai basé mon travail sur l'idée de prendre en compte les problèmes réellement rencontrés par les animaux dans leur environnement naturel, et d'utiliser des stimuli reflétant la pertinence biologique des problèmes posés à ces animaux. J'ai choisi de me focaliser sur l'information d'identité individuelle contenue dans le cri de distance des diamants mandarins (Taeniopygia guttata) et d'examiner comment la signature vocale individuelle est codée, dégradée, puis discriminée et décodée, depuis l'émetteur jusqu'au récepteur. Cette étude montre que la signature individuelle des diamants mandarins est très résistante à la propagation, et que les paramètres acoustiques les plus individualisés varient selon la distance considérée. En testant des femelles dans les expériences de conditionnement opérant, j'ai pu montrer que celles-ci sont expertes pour discriminer entre les signature vocales dégradées de deux mâles, et qu'elles peuvent s'améliorer en s'entraînant. Enfin, j'ai montré que cette capacité de discrimination impressionnante existe aussi au niveau neuronal : nous avons montré l'existence d'une population de neurones pouvant discriminer des voix individuelles à différent degrés de dégradation, sans entrainement préalable. Ce niveau de traitement évolué, dans le cortex auditif primaire, ouvre la voie à de nouvelles recherches, à l'interface entre le traitement neuronal de l'information et le comportementIn communication systems, one of the biggest challenges is that the information encoded by the emitter is always modified before reaching the receiver, who has to process this altered information in order to recover the intended message. In acoustic communication particularly, the transmission of sound through the environment is a major source of signal degradation, caused by attenuation, absorption and reflections, all of which lead to decreases in the signal relative to the background noise. How animals deal with the need for exchanging information in spite of constraining conditions has been the subject of many studies either at the emitter or at the receiver's levels. However, a more integrated research about auditory scene analysis has seldom been used, and is needed to address the complexity of this process. The goal of my research was to use a transversal approach to study how birds adapt to the constraints of long distance communication by investigating the information coding at the emitter's level, the propagation-induced degradation of the acoustic signal, and the discrimination of this degraded information by the receiver at both the behavioral and neural levels. Taking into account the everyday issues faced by animals in their natural environment, and using stimuli and paradigms that reflected the behavioral relevance of these challenges, has been the cornerstone of my approach. Focusing on the information about individual identity in the distance calls of zebra finches Taeniopygia guttata, I investigated how the individual vocal signature is encoded, degraded, and finally discriminated, from the emitter to the receiver. This study shows that the individual signature of zebra finches is very resistant to propagation-induced degradation, and that the most individualized acoustic parameters vary depending on distance. Testing female birds in operant conditioning experiments, I showed that they are experts at discriminating between the degraded vocal signatures of two males, and that they can improve their ability substantially when they can train over increasing distances. Finally, I showed that this impressive discrimination ability also occurs at the neural level: we found a population of neurons in the avian auditory forebrain that discriminate individual voices with various degrees of propagation-induced degradation without prior familiarization or training. The finding of such a high-level auditory processing, in the primary auditory cortex, opens a new range of investigations, at the interface of neural processing and behavior
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Baek, Rena C. "Therapeutic strategies for the ganglioside storage diseases." Thesis, Boston College, 2008. http://hdl.handle.net/2345/18.
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The Gangliosidoses, to include GM1 gangliosidosis and Sandhoff disease are a class of incurable lysosomal storage disorders characterized by an abnormal accumulation of gangliosides leading to progressive neurodegeneration and eventually death. GM1 gangliosidosis is caused by a genetic defect in the lysosomal-specific acid β-galactosidase, which results in the massive accumulation of ganglioside GM1 primarily in the central nervous system (CNS). Sandhoff disease (SD) results from a defect in the β-subunit of β- Hexosaminidase A and leads to the accumulation of ganglioside GM2 and its asialo derivative (GA2). As there are no effective therapies for these glycosphingolipid (GSL) storage disorders, I studied substrate reduction therapy (SRT), stem cell therapy, and adeno-associated viral (AAV) gene therapy in neonatal mice as early intervention therapies and were effective in reducing CNS GSL storage. In addition, AAV gene therapy was also evaluated in the adult GM1 gangliosidosis mice. Furthermore, analysis of the brain lipids in mice, cats, and humans with Sandhoff disease revealed that the SD cat model is intermediate between the SD mouse and the SD patient with respect to GM2 and GA2 accumulation. These findings are the first to compare the different therapies and provide valuable information for the translation of mouse studies to clinical trials in patientsThesis (PhD) — Boston College, 2008
Submitted to: Boston College. Graduate School of Arts and Sciences
Discipline: Biology
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Sonnenschein, Bonnie. "Temporal integration in the neural substrate for brain stimulation reward, duration neglect and the peak-and-end model." Thesis, National Library of Canada = Bibliothèque nationale du Canada, 1999. http://www.collectionscanada.ca/obj/s4/f2/dsk1/tape10/PQDD_0003/MQ43623.pdf.
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Wernecke, Kerstin [Verfasser], and Markus [Akademischer Betreuer] Fendt. "Predator odor-induced fear in rats : a behavioral characterization and neural substrate analysis / Kerstin Wernecke ; Betreuer: Markus Fendt." Magdeburg : Universitätsbibliothek, 2016. http://d-nb.info/1115795295/34.
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ORENA, ELEONORA FRANCESCA. "Lemons and Trust: the Contribution of Anesthesia to the Study of the Neural Substrates of Concrete and Abstract Word Processing." Doctoral thesis, Università degli Studi di Milano-Bicocca, 2017. http://hdl.handle.net/10281/142471.
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There is evidence that abstract and concrete words are represented and processed differently in the brain. Numerous studies suggest the activation of a bilateral network for both abstract and concrete words, with a greater involvement of posterior, sensory areas in concrete word processing, and a more focal activation of anterior regions, involved in verbal processing, for abstract words. This Ph.D. thesis aimed at investigating the different neural substrates of concrete and abstract words by studying memory priming during general anesthesia. Implicit memory tasks, in fact, seem to be immune to the concreteness effect and recent neurophysiological studies suggest that conscious and unconscious semantic activation involve similar brain areas. Experiment 1 focused on the priming effect for intraoperatively primed abstract and concrete words in patients under general intravenous (propofol) anesthesia. Considering the specific brain targets of propofol, I hypothesized a stronger priming effect for concrete than for abstract words. Implicit memory for primed words was tested with a three-letter word stem completion test, in which half of the stems referred to primes, and half were foils. Both stimulation and testing were auditory, to avoid cross-modality interference. A control group of patients, who did not receive any intraoperative stimulation, but completed both concrete and abstract word stem completion test, was also recruited. As expected, a priming effect was found for concrete words, since the number of target hits was significantly higher than the number of non target hits. This difference did not apply to abstract words. The abstract experimental group performed comparably to controls. These results support the thesis that abstract word processing relies on the activity of anterior brain areas, as for example the inferior frontal cortex, which are suppressed by propofol. The results would also confirm that priming, investigated through word stem completion, is not a simple perceptual, pre-semantic task, but engages multiple processes, including semantic access. As suggested by electrophysiological studies, semantic access might occur at very early stages of verbal processing, thus explaining a selective intraoperative priming effect for concrete words only. To further investigate these hypotheses, a second experiment was conducted. In experiment 2 the same methodology of experiment 1 was applied, but the volatile anesthetic sevoflurane was used, which is known to lower activity in brain regions located more posteriorly than those suppressed by propofol. The most interesting finding was the presence of a priming effect also for abstract words, which would confirm data from neuroimaging studies of a greater engagement of anterior brain regions in abstract word processing. To better define the involvement of the frontal cortex in the processing of abstract words, a series of patients undergoing awake surgery for brain tumor removal was studied in experiment 3. Patients performed a lexical and a semantic decision task, together with a standard intraoperative cognitive monitoring, during direct cortical stimulation. The fundamental role of the left inferior frontal gyrus in abstract word processing was confirmed.
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Harris, James Patrick. "The Glia-Neuronal Response to Cortical Electrodes: Interactions with Substrate Stiffness and Electrophysiology." Case Western Reserve University School of Graduate Studies / OhioLINK, 2011. http://rave.ohiolink.edu/etdc/view?acc_num=case1320950439.
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Wolf, Sébastien. "The neural substrate of goal-directed locomotion in zebrafish and whole-brain functional imaging with two-photon light-sheet microscopy." Thesis, Paris 6, 2017. http://www.theses.fr/2017PA066468/document.
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La première partie de cette thèse présente une revue historique sur les méthodes d'enregistrements d'activité neuronale, suivie par une étude sur une nouvelle technique d'imagerie pour le poisson zèbre : la microscopie par nappe laser 2 photon. En combinant, les avantages de la microscopie 2 photon et l'imagerie par nappe de lumière, le microscope par nappe laser 2 photon garantie des enregistrements à haute vitesse avec un faible taux de lésions photoniques et permet d'éviter l'une des principales limitations du microscope à nappe laser 1 photon: la perturbation du système visuel. La deuxième partie de cette thèse traite de la navigation dirigée. Après une revue exhaustive sur la chemotaxis, la phototaxis et la thermotaxis, nous présentons des résultats qui révèlent les bases neuronales de la phototaxis chez le poisson zèbre. Grace à des expériences de comportement en réalité-virtuelle, des enregistrements d'activité neuronale, des méthodes optogénétiques et des approches théoriques, ce travail montre qu'une population auto-oscillante située dans le rhombencéphale appelée l'oscillateur du cerveau postérieur (HBO) fonctionne comme un pacemaker des saccades oculaires et contrôle l'orientation des mouvements de nage du poisson zèbre. Ce HBO répond à la lumière en fonction du contexte moteur, biaisant ainsi la trajectoire du poisson zèbre vers les zones les plus lumineuses de son environnement (phototaxis). La troisième partie propose une discussion sur les bases neuronales des saccades oculaires chez les vertébrés. Nous concluons ce manuscrit avec des résultats préliminaires suggérant que chez le poisson zèbre, le même HBO est impliqué dans les processus de thermotaxisThe first part of this thesis presents an historical overview of neural recording techniques, followed by a study on the development of a new imaging method for zebrafish neural recording: two-photon light sheet microscopy. Combining the advantages of two-photon point scanning microscopy and light sheet techniques, the two-photon light sheet microscope warrants a high acquisition speed with low photodamage and allows to circumvent the main limitation of one-photon light sheet microscopy: the disturbance of the visual system. The second part of the thesis is focused on goal-directed navigation in zebrafish larvae. After an exhaustive review on chemotaxis, phototaxis and thermotaxis in various animal models, we report a study that reveals the neural computation underlying phototaxis in zebrafish. Combining virtual-reality behavioral assays, volumetric calcium recordings, optogenetic stimulation, and circuit modeling, this work shows that a self-oscillating hindbrain population called the hindbrain oscillator (HBO) acts as a pacemaker for ocular saccades, controls the orientation of successive swim-bouts during zebrafish larva navigation, and is responsive to light in a state-dependent manner such that its response to visual inputs varies with the motor context. This peculiar response to visual inputs biases the fish trajectory towards brighter regions (phototaxis). The third part provides a discussion on the neural basis of ocular saccades in vertebrates. We conclude with some recent preliminary results on heat perception in zebrafish suggesting that the same hindbrain circuit may be at play in thermotaxis as well
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Lee, Sylvia Elaine. "An Investigation of the Hippocampus as a Possible Neural Substrate of Short-term and Working Memory in ADHD and Dyslexia." OpenSIUC, 2011. https://opensiuc.lib.siu.edu/theses/750.
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The current study explored the relationship between hippocampal volume and short-term/working memory (STM/WM) in children with Attention-Deficit/Hyperactivity Disorder (ADHD) and dyslexia (RD). It was hypothesized that there would be group differences in hippocampal volume and STM/WM performance, and that there would be a relationship between hippocampal volume and STM/WM performance. Results indicated that there were not significant differences in hippocampal volume across the groups. However, a trend of smaller bilateral posterior volumes was found in the RD groups compared to the non-RD groups, while a trend of smaller right anterior hippocampal volumes was found in the ADHD groups compared to the non-ADHD groups. The RD groups had significantly poorer performance on the verbal STM/WM factor than non-RD groups, while the ADHD groups were not found to differ in STM/WM performance from the non-ADHD groups. Finally, hippocampal volume was not a significant predictor of performance on the STM/WM factor scores for any of the groups; however, bivariate correlations indicated significant volume-performance relations that should be explored further.
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Richmond, Mark Andrew. "Neural substrates of conditioned behaviour." Thesis, University of Oxford, 1998. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.301735.
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Zwan, Rick van der. "Possible neural substrates for binocular rivalry." Thesis, The University of Sydney, 1994. https://hdl.handle.net/2123/28543.
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Binocular rivalry is the perceptual consequence of dichoptic input which is not
congruent between both visual inputs. There is some evidence, both theoretical and
empirical, that the perception of binocular rivalry is mediated by interactions between
binocular neurones, rather than by interactions between monocular neurones. This
evidence suggests also a model of perception which predicts binocular rivalry as a
consequence of normal interactions between binocular neurones in a retinotopic array.
This model accounts for rivalry without postulating any additional interconnections
beyond those already thought to exist between binocular neurones simply assumes an
orderly mapping of tuning characteristics across groups of cells, as is typically observed
in visual cortex. On the basis of this model, and findings already reported, it was
hypothesised that binocular rivalry reflects extrastriate rather than area V1 processing
(no process so far attributed to area V1 has yet been reported to be affected by
binocular rivalry). It was hypothesised also that area V2 was the most likely area in
which such processing first arises.
Area V2 has been associated with the perception of 'purely subjective contours'. It has
been shown that some cells in area V2 are tuned for such contours, which are
characterised by the absence of Fourier components at the orientation of the perceived
contour, while no cells in area V1 have been found to be similarly sensitive (von der
Heydt and Peterhans 1989). This characteristic of area V2 neurones enables purely
subjective contours to be used to test the two hypotheses described above. Real contour
tilt aftereffects, which are thought to arise in area V1, are not affected by rivalry during
their induction. If purely subjective contour tilt aftereffects (Paradiso, Shimojo and
Nakayama 1989) are subject to the same types of processing as their real contour
counterparts, as suggested by the rationale and model of von der Heydt and Peterhans
(1989), interactions between subjective contour tilt aftereffects and binocular rivalry
should indicate the role, if any, of area V2 in rivalry.
It was found that purely subjective contour tilt aftereffects (Experiment One) and tilt
illusions (Experiment Four) exhibit angular functions like those observed for real
contour tilt aftereffects and illusions. Just as for real contour effects, these functions can
be described in terms of direct effects (Experiment Two) and indirect effects
(Experiment Three), suggesting purely subjective contours are processed as if they were
real contours. Unlike real contour direct effects, purely subjective contour direct and
indirect effects are reduced in magnitude by periods of rivalry during their induction
(Experiment Five). In keeping with their suggested extrastriate locus (eg. Wenderoth,
van der Zwan and Williams 1993), the magnitude of a real contour indirect effect is
also reduced by periods of rivalry occurring during its induction (Experiment Six).
These results suggest that rivalry does arise first in area V2. If this is true then complete
interocular transfer of the purely subjective aftereffect, induced with or without rivalry,
should occur because area V2 is almost exclusively binocular. This proved not to be the
case, however, suggesting the ocular dominance observed in most binocular cells has to
be taken into account in any explanation of rivalry (Experiment Seven). This was tested
using real contours and found to be the case. These last results suggested also that
rivalrous interactions occur between groups of binocular neurones only in extrastriate
cortex (Experiment Eight). This hypothesis was tested by examining the effect of
binocular rivalry on the duration of the plaid motion aftereffect, which is thought to
arise no earlier than area MT, a visual cortical area which is also thought to be almost
exclusively binocular. It was found that rivalry did reduce the duration of plaid motion
aftereffects but not linear motion aftereffects, and that the impact of rivalry might be
linked to plaid sensitive cells in area MT, although this last conclusion is tenuous
(Experiments Nine and Ten). Finally, it was shown also that the magnitude of the
reduction in duration of the aftereffect was proportional to the predominance of the
plaid stimulus during rivalry, a finding which supports the mechanism of rivalry
suggested by the binocular model.
The results together suggest that binocular rivalry does arise through binocular
interactions, but that such interactions cannot be attributed to a single cortical area. All
groups of binocular neurones may be subject to the processes that ultimately give rise to
the perception of rivalry, a conclusion which does not invalidate the binocular model of
rivalry. This has some consequences for binocular vision, particularly stereopsis, which
might occur qualitatively during binocular rivalry.
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Swett, Bruce A. "The neural substrates of graphomotor sequence learning." College Park, Md. : University of Maryland, 2007. http://hdl.handle.net/1903/6687.
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Thesis (Ph. D.) -- University of Maryland, College Park, 2007.Thesis research directed by: Neuroscience and Cognitive Science. Title from t.p. of PDF. Includes bibliographical references. Published by UMI Dissertation Services, Ann Arbor, Mich. Also available in paper.
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Kohl, C. "Neural substrates of human perceptual decision-making." Thesis, City, University of London, 2017. http://openaccess.city.ac.uk/18904/.
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Perceptual decision-making describes the process of choosing one of at least two response alternatives based on sensory evidence. This sensorimotor process underlies a range of human behaviours and has been studied extensively by both psychologists and neuroscientists. There is now a consensus, that perceptual decision-making can be explained by sequential sampling models, which assume that we make decisions by accumulating sensory evidence over time until a decision threshold is reached and the response is executed. Although these models are designed to explain behavioural data, the accumulation-to-bound processes they predict have recently been shown to occur in the brain. In this project, we set out to explore these neural correlates of decision-making in the human brain by combining mathematical modelling with neuroimaging. We fitted sequential sampling models to human decision-making data collected in a number of paradigms and directly compared the associated accumulation profiles with neural signals, which were generated either by using electroencephalographic (EEG) recordings or through transcranial magnetic stimulation (TMS). We found that decision-related accumulation profiles can be observed using a parietal EEG signal, namely the event-related potential centroparietal positivity (CPP). Additionally, we showed that accumulation is fed forward to the motor system, where it can be measured using TMS-induced motor evoked potentials. We demonstrated that, under a number of manipulations, namely difficulty, response speed instructions, non-stationary evidence, decision biases, and number of alternatives, these signals display profiles similar to those predicted by sequential sampling models. Our findings support the notion that sequential sampling occurs in the human brain and demonstrate that a model-based approach in which sequential sampling models and neuroimaging are combined and inform each other, can shed light on the underlying mechanisms of human perceptual decision-making.
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DeMarco, Andrew T., Stephen M. Wilson, Kindle Rising, Steven Z. Rapcsak, and Pélagie M. Beeson. "Neural substrates of sublexical processing for spelling." ACADEMIC PRESS INC ELSEVIER SCIENCE, 2017. http://hdl.handle.net/10150/622997.
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We used fMRI to examine the neural substrates of sublexical phoneme-grapheme conversion during spelling in a group of healthy young adults. Participants performed a writing-to-dictation task involving irregular words (e.g., choir), plausible nonwords (e.g., kroid), and a control task of drawing familiar geometric shapes (e.g., squares). Written production of both irregular words and nonwords engaged a left hemisphere perisylvian network associated with reading/spelling and phonological processing skills. Effects of lexicality, manifested by increased activation during nonword relative to irregular word spelling, were noted in anterior perisylvian regions (posterior inferior frontal gyrus/operculum/precentral gyrus/insula), and in left ventral occipito-temporal cortex. In addition to enhanced neural responses within domain-specific components of the language network, the increased cognitive demands associated with spelling nonwords engaged domain-general frontoparietal cortical networks involved in selective attention and executive control. These results elucidate the neural substrates of sublexical processing during written language production and complement lesion-deficit correlation studies of phonological agraphia.
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Ramel, Wiveka. "Neural substrates of cognitive vulnerability to depression /." Diss., Connect to a 24 p. preview or request complete full text in PDF format. Access restricted to UC campuses, 2005. http://wwwlib.umi.com/cr/ucsd/fullcit?p3161971.
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Twiston-Davies, Fay. "Neural substrates of amphetamine induced impulsive behaviour." Thesis, University of Leeds, 2013. http://etheses.whiterose.ac.uk/5882/.
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Impulsivity is a pathological feature of drug addiction. Amphetamine is a highly addictive drug that is amongst the most harmful recreational drugs abused within the UK (Nutt, King, & Phillips, 2010). Interestingly, however, amphetamine has a paradoxical relationship with impulsivity and can both alleviate and induce impulsive behaviour depending on pre-baseline levels of impulsivity and the dimension of impulsivity that is being measured. The current thesis sought to investigate the relationship between different patterns of amphetamine administration and impulsivity in the form of behavioural inhibition, and the neural substrates of amphetamine induced behavioural disinhibition, using the symmetrically reinforced Go/No-go task in rats (Harrison, Everitt, & Robbins, 1999). To assess the effects of different patterns of amphetamine administration on behavioural inhibition, separate groups of rats were treated with subchronic (4-day) and chronic (11-day) amphetamine and were tested on the Go/No-go task during drug treatment and drug withdrawal. Following two weeks of drug withdrawal, sensitivity to the acute effects of amphetamine in rats was tested with acute drug challenges. To assess the role of nucleus accumbens core D2 and GABAA receptors in the mediation of behavioural inhibition and amphetamine-induced behavioural disinhibition, separate groups of rats were also treated with intra-nucleus accumbens core infusions of the D2 antagonist eticlopride and GABAA agonist muscimol. Results revealed that short duration and high frequency binge-like amphetamine administration produced longer term increases in behavioural disinhibition than longer term and less frequent but overall higher dosing of amphetamine in rats. However, neither the binge-like (4-day) or longer term amphetamine regimes (11-day) caused any enduring changes in sensitivity to the acute disinhibitory effects of amphetamine in rats. Infusions of either eticlopride or muscimol into the NAcb core had no effect on behavioural inhibition assessed under baseline conditions, however, eticlopride infusions produced full behavioural reversal of amphetamine induced behavioural disinhibition and muscimol infusions produced partial reversal of amphetamine induced behavioural disinhibition. Taken together, these results demonstrate that different patterns of amphetamine administration produce different effects on the duration of behavioural disinhibition in rats, and further, that amphetamine induced activation of the D2 receptors within the nucleus accumbens core mediates amphetamine induced behavioural disinhibition on the symmetrically reinforced Go/No-go task. Results additionally support the possibility of dopamine-GABA interactions in the mediation of amphetamine induced behavioural disinhibition on the symmetrically reinforced Go/No-go task in rats.
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Lee, Woogul. "Neural substrates of intrinsic motivation: fMRI studies." Diss., University of Iowa, 2011. https://ir.uiowa.edu/etd/2738.
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Numerous social and educational psychologists propose that intrinsic motivation generated by personal interests and spontaneous satisfactions is qualitatively different from extrinsic types of motivation generated by external compensations and also that intrinsic motivation is more beneficial to learning than extrinsic types of motivation. However, in the field of neuroscience, intrinsic motivation has been little studied while extrinsic types of motivation (e.g., incentive motivation) have been thoroughly studied. The purpose of the present studies was to expand the neural understanding of motivation to include intrinsic motivational processes. To do so, a series of three event-related functional magnetic resonance imaging (fMRI) studies were conducted. Study 1 and Study 2 compared the neural activities when participants decided to act for intrinsic reasons (i.e., self-determined volitional and agentic behavior) versus when they decided to act for extrinsic reasons (i.e., non-self-determined volitional and agentic behavior). Both studies showed that the anterior insular cortex, known to be related to a sense of agency, was more activated during self-determined behavior associated with intrinsic reasons for acting while the posterior parietal regions (e.g., posterior cingulate cortex, angular gyrus), known to be related to a sense of a loss of agency, were more activated during non-self-determined behavior associated with extrinsic reasons for acting. These findings confirm the existence of neural-based intrinsic motivational processes, differentiate intrinsic motivation from incentive motivation, and document the important neural activities which function for generating self-determined agentic action. Study 3 examined these same neural activities as participants engaged in interesting and uninteresting versions of two experimental tasks. Results confirmed the results of the earlier two studies, as the anterior insular cortex was more recruited when participants performed the interesting, but not the uninteresting, version of the tasks. Results also extended the findings from Studies 1 and 2 in an important way in that the ventral striatum, a well-known brain region for reward processing, was more activated when participants performed the interesting, but not the uninteresting, version of the experimental tasks. These findings suggest that intrinsic motivation is generated based on the feeling of intrinsic need satisfaction (from anterior insular cortex activations) and the feeling of reward (from ventral striatum activations). Overall, the present research established three new findings: (1) the neural bases of intrinsic motivation lies largely in increased anterior insular cortical activities; (2) when people made decisions about self-determined intrinsically-motivated behavior, they show enhanced insular cortical activities and suppressed posterior parietal cortical activities; and (3) when people engaged in actual self-determined intrinsically-motivated behavior, they show enhanced insular cortical and ventral striatal activities. In establishing these new findings, the paper introduces a new area of study for motivational neuroscience--namely, intrinsic motivation.
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Pardo-Figuerez, Maria M. "Designing neuronal networks with chemically modified substrates : an improved approach to conventional in vitro neural systems." Thesis, Loughborough University, 2018. https://dspace.lboro.ac.uk/2134/27941.
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Highly organised structures have been well-known to be part of the complex neuronal network presented in the nervous system, where thousands of neuronal connections are arranged to give rise to critical physiological functions. Conventional in vitro culture methods are useful to represent simplistic neuronal behaviour, however, the lack of such organisation results in random and uncontrolled neurite spreading, leading to a lack of cell directionality and in turn, resulting in inaccurate neuronal in vitro models. Neurons are highly specialised cells, known to be greatly dependent on interactions with their surroundings. Therefore, when surface material is modified, drastic changes in neuronal behaviour can be achieved. The use of chemically modified surfaces in vitro has opened new avenues in cell culture, where the chaotic environment found in conventional culture methods can be controlled by the combination of surface modification methods with surface engineering techniques. Polymer brushes and self-assembled monolayers (SAMs) display a wide range of advantages as a surface modification tool for cell culture applications, since their properties can be finely tuned to promote or inhibit cellular adhesion, differentiation and proliferation. Therefore, when precisely combined with patterning techniques, a control over neuronal behaviour can be achieved. Neuronal patterning presents a system with instructive cues that can be used to study neuron-neuron communication by directing single neurites in specific locations to initiate synapses. Furthermore, although this area has not been much explored, the use of these patterned brushes could also be used in co-culture systems as a platform to closely monitor cell heterotypical communication. This research demonstrates the behaviour of SH-SY5Y neurons on a variety of SAMs and polymer brushes, both in isolation and combination to promote cellular spatial control. APTES and BIBB coatings promoted the highest cell viability, proliferation, metabolic activity and neuronal maturation, whilst low cell adhesion was seen on PKSPMA and PMETAC surfaces. Thereafter, PKSPMA brushes were used as a potential cell repulsive coating and its combination with micro- patterning techniques (photolithography and soft lithography) resulted in a system with instructive cues for neuronal guidance, where neuronal directionality was obtained. In the final chapter of this thesis, a chimeric co-culture system was developed where the patterned SH-SY5Y cells were co-cultured with C2C12 myoblasts in an attempt to obtain an organised neuronal-muscle co-culture system. Whilst preliminary observations showed first stages of a patterned neuronal-muscle co-culture, future work is necessary to refine and improve the patterned co-culture process.
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Wood, Richard Matthew. "Serotonin and the neural substrates of risky-choice." Thesis, University of Oxford, 2005. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.436984.
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Bergström, Fredrik. "The neural substrates of non-conscious working memory." Doctoral thesis, Umeå universitet, Fysiologi, 2016. http://urn.kb.se/resolve?urn=urn:nbn:se:umu:diva-124808.
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Background: Despite our distinct impression to the contrary, we are only conscious of a fraction of all the neural activity underlying our thoughts and behavior. Most neural processes occur non-consciously, and in parallel with our conscious experience. However, it is still unclear what the limits of non-conscious processes are in terms of higher cognitive functions. Many recent studies have shown that increasingly more advanced functions can operate non-consciously, but non-conscious information is still thought to be fleeting and undetectable within 500 milliseconds. Here we used various techniques to render information non-conscious, together with functional magnetic resonance imaging (fMRI), to investigate if non-consciously presented information can be retained for several seconds, what the neural substrates of such retention are, and if it is consistent with working memory maintenance. Results: In Study I we used an attentional blink paradigm to render stimuli (single letters) non-conscious, and a variable delay period (5 – 15 s) prior to memory test. It was found that non-conscious memory performance was above chance after all delay durations, and showed no signs of decline over time. Univariate fMRI analysis showed that the durable retention was associated with sustained BOLD signal change in the prefrontal cortex and cerebellum during the delay period. In Study II we used continuous flash suppression (CFS) to render stimuli (faces and tools) non-conscious, and a variable delay period (5 or 15 s) prior to memory test. The durable retention of up to 15 s was replicated, and it was found that stimuli identity and spatial position was retained until prospective use. In Study III we used CFS to render tools non-conscious, and a variable delay period (5 – 15 s) prior to memory test. It was found that memory performance was not better than chance. However, by using multi-voxel pattern analysis it was nonetheless possible to detect the presence vs. absence of non-conscious stimuli in the frontal cortex,and their spatial position (left vs. right) in the occipital cortex during the delay. Conclusions: Overall these findings suggest that non-consciously presented information (identity and/or position) can be retained for several seconds,and is associated with BOLD signal in frontal and posterior regions. These findings are consistent with working memory maintenance of non-consciously presented information, and thereby constrain models of working memory and theories of consciousness.
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Aldhafeeri, Faten. "An investigation into the neural substrates of tinnitus." Thesis, University of Liverpool, 2012. http://livrepository.liverpool.ac.uk/8293/.
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Aims and Objectives: The overall aim of this thesis was to investigate the neural correlates of tinnitus perception using different magnetic resonance imaging (MRI) techniques. The first objective was to investigate the neuro-functional reorganisation that may be associated with tinnitus-related emotional disturbances using functional MRI (fMRI). The second objective was to investigate the structural brain changes that are hypothesised to be associated with tinnitus perception. This investigation included an analysis of both grey and white matter using diffusion tensor imaging (DTI), a cortical thickness analysis (CTA) and voxel-based morphometry (VBM). The third objective was to investigate any correlations between the neuro-functional and the neuro-structural reorganisation that are associated with tinnitus and behavioural data, such as hearing thresholds, the Newman Handicap Inventory score and age. These analyses were performed for both the experimental and control groups. Methods: A total of 18 tinnitus sufferers and 15 age- and sex-matched healthy volunteers participated in the work that is presented in this thesis. The functional MRI study in this thesis utilised internationally standardised emotionally evocative pleasant and unpleasant visual and auditory stimuli. The fMRI paradigm consisted of a block design, during which the participants from the two groups (tinnitus and controls) viewed blocks of images and listened to sounds. The structural investigations in this thesis included DTI, CTA and VBM. Results: In the fMRI study, tinnitus sufferers exhibited significant hyperactivation in the limbic system, the prefrontal cortex (PFC) and the temporal lobe. Correlation analyses between the mean fMRI Blood Oxygen Level-Dependent (BOLD) signal and hearing thresholds revealed a significant positive correlation in the subjects with tinnitus but not the in the controls. This correlation was observed in the following regions: the right cingulate gyrus, the right medial frontal gyrus, the right superior temporal gyrus, the left inferior frontal gyrus and the left superior temporal gyrus. Tinnitus severity as measured using the Newman Tinnitus Handicap Inventory score (Newman THI) was observed to be positively correlated with the mean fMRI BOLD signal in the left superior temporal gyrus and the right cingulate gyrus. Tinnitus-like conditions induced the healthy controls to exhibit hyperactivity in the limbic system, the PFC and the temporal lobe. The DTI study demonstrated disrupted white matter (WM) integrity in the following bundles in the subjects with tinnitus relative to the control group: the left and right inferior fronto-occipital fasciculus, the corpus callosum, the left superior and inferior longitudinal fasciculus, and the left and right thalamic radiations. CTA revealed cortical thickness reductions in the subjects with tinnitus compared to the controls in a priori hypothesised regions of interest (ROI), which included the following regions: the temporal lobe, PFC, anterior cingulate cortex (ACC), cingulate gyrus (CG) and posterior cingulate gyrus (PCG). VBM revealed reduced grey matter (GM) volume in the left medial PFC in subjects with tinnitus compared to controls. Conclusion: Tinnitus perception may involve functional and structural changes in the following specific brain regions: the PFC, the temporal lobe (including the auditory cortex) and the limbic system. These structural changes may represent antecedent structural deficits that result in subsequent functional reorganisation, causing the tinnitus signal to arise.
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Obert, Alexandre. "Traitement cognitif des métaphores et de l’ironie verbale : étude comportementale et substrats neuronaux." Thesis, Reims, 2016. http://www.theses.fr/2016REIML008.
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L’objectif de cette thèse était d’explorer les bases cognitives et cérébrales des processus de compréhension du langage figuré via l’utilisation d’outils de neuroimagerie (EEG et IRMf). Nous nous sommes particulièrement intéressés aux processus inférentiels sémantiques et pragmatiques. Afin de mieux les cerner, nous avons étudié la compréhension de la métaphore verbale nouvelle (« catapulter ses paroles ») et de l’ironie verbale (« Il est détesté de tous. Cet homme est très populaire. »). Ce choix repose sur l’hypothèse selon laquelle chacune de ces figures sollicite spécifiquement un type de processus inférentiel ; de nature sémantique pour la métaphore et pragmatique pour l’ironie. Conformément à cette hypothèse, nos résultats indiquent que la compréhension des métaphores verbales nouvelles se fonde sur des processus de recherche et d’intégration d’informations sémantiques, supportant l’hypothèse d’un traitement séquentiel. L’examen des bases cérébrales du traitement de ces expressions précédées d’un contexte a mis en évidence des régions cérébrales postérieures, suggérant la mise en œuvre d’un processus de manipulation conceptuelle. Concernant le traitement de l’ironie, nous avons observé un processus tardif d’intégration d’informations plus important pour les énoncés ironiques comparés aux énoncés littéraux, suggérant un traitement pragmatique plus difficile. Enfin, nous avons mis en évidence un réseau fronto-temporal bilatéral lors du traitement de l’ironie, dont une part serait sensible au contraste entre le contexte et l’énoncé et à l’humour des énoncés. Nos résultats sont confrontés aux théories psycholinguistiques et cognitives du traitement du langage figuréOur main aim was to assess the cognitive and neural basis of the figurative language processing using neuroimaging tools (EEG and fMRI). We were especially interested in semantic and pragmatic inferential processes. In order to better grasp these processes, we have studies the comprehension of novel verbal metaphor (“to catapult his/her words”) and verbal irony (“Everybody thinks he is foul. He is a very popular man.”). This choice was based upon the hypothesis that each of these figurative expressions specifically engages one of the two inferential processes: semantic for metaphors and pragmatic for irony. Following this hypothesis, our results point out that the comprehension of novel metaphoric expression is built on the research and the integration of a semantic congruent information, supporting a sequential processing hypothesis. The assessment of the cerebral basis of the processing of such expressions embedded in a context has revealed regions in posterior areas, suggesting a conceptual manipulation process. Concerning the irony processing, we observed a greater late integration processing for ironic sentences than literal ones, suggestion a more effortful pragmatic processing. Finally, we observed a fronto-temporal network specific to irony processing. Some part of this network could be involved in both the contrast between the utterance and the context and the humor processing of the sentences. Our results are confronted with psycholinguistic and cognitive theories about figurative language processing
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Theis, Thomas [Verfasser], and MELITTA [Akademischer Betreuer] SCHACHNER. "Functional roles of transient receptor potential canonical channels and myristoylated alanine-rich protein kinase C substrate as novel interaction partners of the neural cell adhesion molecule NCAM and polysialic acid in Mus musculus (Linnaeus, 1758) / Thomas Theis. Betreuer: Melitta Schachner." Hamburg : Staats- und Universitätsbibliothek Hamburg, 2013. http://d-nb.info/1035503840/34.
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Johnsrude, Ingrid S. "The neural substrates of the processing of speech sounds." Thesis, National Library of Canada = Bibliothèque nationale du Canada, 1997. http://www.collectionscanada.ca/obj/s4/f2/dsk2/ftp02/NQ36992.pdf.
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Qin, Yuqi Natasha. "Neural Substrates of Experience in Caenorhabditis elegans Olfactory Learning." Thesis, Harvard University, 2013. http://dissertations.umi.com/gsas.harvard:11143.
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One essential function of the nervous system is to modulate behavioral response based on experience. In the past decades, increasing amount of studies has characterized the mechanisms underlying experience-dependent modulation of neural circuits. However, it is not entirely clear how the nervous system translates experience into a modulatory signal. The over-arching goal of my thesis work is to contribute to our understanding of this important neuroscience question.
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Postle, Bradley R. (Bradley Robinson). "The cognitive mechanisms and neural substrates underlying repetition priming." Thesis, Massachusetts Institute of Technology, 1997. http://hdl.handle.net/1721.1/10305.
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Cho, Soohyun. "Component processes of analogical reasoning and their neural substrates." Diss., Restricted to subscribing institutions, 2008. http://proquest.umi.com/pqdweb?did=1619392411&sid=1&Fmt=2&clientId=1564&RQT=309&VName=PQD.
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Basora, Marimon Anna 1986. "Exploring the role of genetics and environment on the neural substrates of word and rule learning." Doctoral thesis, Universitat Pompeu Fabra, 2015. http://hdl.handle.net/10803/384711.
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L’origen ambiental i genètic de les diferències individuals en l’aprenentatge de paraules i regles gramaticals és desconegut. Per aquest motiu es van realitzar dos estudis. En el primer, dos grups de bessons, monozigòtics i dizigòtics, varen desenvolupar una tasca d’aprenentatge de paraules i regles. Es va mesurar la similitud entre bessons en l’activitat cerebral i els resultats indicaren que els factors genètics eren poc rellevants. En el segon estudi es va mesurar la diferència entre bessons monozigòtics en la integritat de la matèria blanca i en el nivell d’aprenentatge de paraules i es van correlacionar ambdues mesures. Els resultats mostraren que els factors ambientals que afecten als fascicles arcuat i front-occipital esquerres explicarien, en part, les diferències individuals en l’aprenentatge de paraules. Ambdós estudis suggereixen que les experiències juguen un paper central en el modelatge dels substrats neuronals associats a l’aprenentatge de paraules i regles.The genetic and environmental origin of individual differences in word and grammar learning is unknown. Two separate studies addressed this issue. In the first study, monozygotic and dizygotic twins were exposed to a word and rule learning task while event-related potentials were recorded. Brain signal similarity between twins was measured, and indicated a weak influence of genetics in both processes. In the second study, white matter integrity estimates were obtained for language-relevant connections in a sample of monozygotic twins that also underwent a statistical word learning task. Twin differences in both white matter integrity and word learning performance were computed and correlated. Significant results in the left arcuate and inferior fronto-occipital fasciculus revealed that the environmental pressures affecting the integrity of these two structures partially explain individual differences in word learning. Taken together, both studies suggest that life experiences play a pivotal role in shaping the neural substrates of word and rule learning.
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Åberg, Emma. "Investigating the Neural Substrates and Neural Markers of Optimism and Optimism Bias : A Systematic Review." Thesis, Högskolan i Skövde, Institutionen för biovetenskap, 2021. http://urn.kb.se/resolve?urn=urn:nbn:se:his:diva-20609.
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Optimism refers to peoples’ general tendency to anticipate good outcomes in areas that are important to them. Numerous studies have shown that optimism is significantly correlated with improved physical and mental health. Optimism can come to an overly optimistic degree, called optimism bias. People generally expect better outcomes and fewer negative events to happen for themselves in the future compared to the average person. There are two sides to this: being optimistically biased might lead to risky behavior, but it might also ease people's worries about the future. To have a consistently negative view is suggested to correlate with depressive symptoms and worsened health. The aim of this thesis is to investigate the neural correlates and functional markers of optimism and optimism bias. Optimism is suggested to correlate with gray-matter volume in the thalamus, orbitofrontal cortex (OFC), and bilateral putamen. The inferior frontal gyrus (IFG) and the rostral anterior cingulate cortex (rACC) have a crucial role in dismissing undesirable information and self referential processing. Research regarding this issue might be beneficial for further understanding of the connection between optimism and well-being.
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Levine, Alexandra Toba. "Investigating neural substrates of visual motion sensitivity in deaf individuals." Thesis, University of York, 2017. http://etheses.whiterose.ac.uk/18901/.
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The aim of this thesis has been to explore neural substrates of enhanced far-peripheral visual motion processing in congenitally deaf adults. To do this, psychophysical measures were used as well as novel fMRI stimulus delivery methods to record responses to stimu- lation in the far-peripheral visual field. For the first time, far-peripheral visual field mapping measured an extended representa- tion of the visual field (72 ◦) in early visual cortex in deaf and hearing individuals. Using this method, unique evidence of plasticity within the cortical surface area distribution of visual field representations in the primary visual cortex was found in congenitally deaf adults, biased towards the far-peripheral visual field. Furthermore, neural responses to far-peripheral stimuli were measured in visual motion processing areas V5/MT+ and V6, and in auditory regions. Results show novel and dis- tinctive differences in response profiles in auditory, but not visual regions between deaf and hearing participants, indicating crossmodal plasticity in deaf participants, specific to coherent but not incoherent global optic flow field motion stimuli. Most importantly, the aim of the thesis was to relate neural measures to behavioural per- formance of motion perception. The results show evidence that unimodal plasticity in V1 and activation in visual motion areas V5/MT+ and V6 are not related to performance in two visual motion tasks (local motion detection and global motion direction discrimina- tion), but that response inhibition and excitation levels in auditory regions are related to motion processing performance in deaf and hearing individuals. In summary, the findings described in this thesis show for the first time that congenital deafness leads to plastic changes within primary visual cortex. In addition, auditory but not visual motion regions are recruited differentially between deaf and hearing individu- als, depending on the motion type, and this activation shows a trending relationship with visual motion performance in both groups.
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Forwood, Suzanna Elizabeth. "The neural substrates of visual recognition memory in the rat." Thesis, University of Cambridge, 2005. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.614703.
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Jiang, Dan. "Imagery : effects on motor performance and exploration of neural substrates." Thesis, Bangor University, 2014. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.664524.
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This thesis is written as a collection of research papers detailing four studies through which imagery perspectives, modality, ability and their neural substrates were investigated. Study 1 explored the effects of internal visual imagery and external visual imagery on the performance of a slalom-based motor task, with the results demonstrating beneficial performnance effects for internal visual imagery over external visual imagery. Study 2 followed the design of study 1, and further examined the effects of imagery modality (visual and kinaesthetic) on the performance of the slalom-based task. The results revealed that kinaesthetic imagery provided beneficial effects over internal visual imagery. Study 3 applied the Vividness of Movement Imagery Questionnaire-2 (VMIQ-2) and fMRI to study the brain activation underpinning internal visual imagery, external visual imagery and kinaesthetic imagery. Results showed internal visual imagery, external visual imagery and kinaesthetic imagery elicited both common areas of activation (in the right supplementary motor area, BA6) and dissociated areas of activation. Specifically, internal visual imagery compared to both external visual imagery and kinaesthetic imagery activated occipital and parietal and frontal brain areas (i.e., the dorsal stream) while external visual imagery activated the occipital ventral stream areas and kinaesthetic imagery activated caudate and cerebellum areas. Study 4 investigated the neural substrates of high and low imagers for different visual imagery perspectives and modality using fMRI. More brain activations were detected in the low imagers than the high imagers during all imagery conditions. Specifically, the medial temporal lobe and the superior temporal gyrus showed more activation in the low imagers. From these results it can be suggested that individuals with lower imagery ability are less efficient in recruiting relevant brain areas to generate vivid images than those with higher imagery ability.
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Lack, Barbara Anne. "Metal interactions with neural substrates and their role in neurodegeneration." Thesis, Rhodes University, 2003. http://hdl.handle.net/10962/d1005709.
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"Life" may be characterized as a controlled stationary flow equilibrium, maintained by energy consuming chemical reactions. The physiological functioning of these life systems include at least 28 of the elements isolated on the periodic table thus far, most of which are metals. However, as with Paracelsus Principle: "The dose makes the poison", there exists a definite link between metal levels, essential and toxic, and the onset of neurodegenerative diseases. The economic costs of brain dysfunction are enormous, but this pales in comparison to the staggering emotional toll on the victims themselves and their families. In an attempt to improve the understanding of the causes of neurodegeneration, this study focuses on one potential aspect: the possible link between metals and neurotransmitter homeostasis utilising a variety of electronanalytical techniques. Adsorptive cathodic stripping voltammetry was employed to investigate the binding affinities and complex formation of melatonin and its precursor serotonin with calcium, potassium, sodium, lithium and aluminium. The results showed that all the metals studied formed complexes with both pineal indoleamines. However, the stability and affmity of the ligands toward the various metals varied greatly. The study suggests a further role for melatonin, that of metalloregulator and possible metal detoxifier in the brain, the in vivo studies which followed will further substantiate this notion. This research additionally focused on the cholinergic system, in particular acetylcholine complex formation studies with mercury, lead, cadmium, copper and zinc using the adsorptive cathodic stripping voltammetry method. The formation and characterisation of a solid mercury-acetylcholine complex lent further strength to the in situ electrochemical complex formation observed. The results showed the preference of acetylcholine for environmentally toxic heavy metals (such as Cd²⁺) over those divalent cations that occur naturally in the body. The possible metalloregulatory role melatonin played in the three brain regIOns: cerebellum, cortex and corpus striatum of male Wistar rats was studied as an in vivo extension of the earlier in vitro studies. Anodic stripping voltammetry was employed to detect metal levels present. The results showed that daily injections of melatonin was responsible for significantly decreasing copper(I), cadmium(II) and lead(II) levels in various regions of the rat brain of those animals that had undergone a pinealectomy in comparison to the saline injected group having undergone the same treatment. Histological and electrochemical stripping techniques were applied to investigate the implications of high A1³⁺ levels in the brain regions, particularly the hippocampus. Melatonin showed signs of promise in indirect symptom alleviation and by significantly decreasing A1³⁺ levels in rats that had been dosed with melatonin prior to A1³⁺ treatments in comparison with the control groups. Finally a preliminary study outlining a method for the production of a calcium selective microelectrode was undertaken. Further work is still needed to optimise the microelectrode production as well as its possible applications. However, whilst the overall conclusions of this entire multidisciplinary study may indeed only be in effect one piece of a very large puzzle on neurodegenerative diseases, this piece will no doubt serve as a building block for further ideas and work in this field.
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DeMarco, Andrew Tesla, and Andrew Tesla DeMarco. "Neural Substrates of Phonological Processing in Chronic Aphasia from Stroke." Diss., The University of Arizona, 2016. http://hdl.handle.net/10150/622976.
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Deficits in phonology are among the most common and persistent impairments in aphasia after left hemisphere stroke, and can have significant functional consequences for spoken and written language. While many individuals make considerable gains through physiological restitution and in response to treatment, the neural substrates supporting phonological performance in the face of damage to critical language regions is poorly understood. To address this issue, we used BOLD fMRI to measure regional brain activation in a case series of individuals with aphasia after left MCA stroke during a phonological task. The results of this study support the idea that damage to even a portion of the phonological network results in impaired phonological processing. We found that individuals with left perisylvian damage tend to rely on the residual left-hemisphere language network, and typically recruit regions associated with domain-general cognitive processing which fall outside of the left-hemisphere language network. However, recruitment of these regions did not necessarily enhance phonological processing. Rather, more successful phonological processing outside the scanner was associated with recruitment of a language region in right posterior middle temporal gyrus and a region in left occipital pole. More successful phonological processing inside the scanner was associated with additional recruitment of the left supramarginal gyrus within the healthy control network, engagement of bilateral intraparietal sulcus from the multi-demand network, and up-regulation of the right-hemisphere network of regions homotopic to the left-hemisphere language network seen in the healthy control group. These findings emphasize the contributions of residual components of the left-hemisphere language network, engagement of a non-linguistic domain-general multi-demand network, and the participation of the non-dominant right-hemisphere language network in successful phonological processing in chronic aphasia after stroke.
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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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Szalay, Jonathan J. "Neural substrates of cocaine-cue extinction learning and consolidation in rats." Thesis, Boston University, 2012. https://hdl.handle.net/2144/31614.
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Thesis (Ph.D.)--Boston UniversityPLEASE NOTE: Boston University Libraries did not receive an Authorization To Manage form for this thesis or dissertation. It is therefore not openly accessible, though it may be available by request. If you are the author or principal advisor of this work and would like to request open access for it, please contact us at open-help@bu.edu. Thank you.
Memory system circuitry may regulate how cues associated with cocaine are extinguished. One goal of this dissertation was to investigate whether the dorsal subiculum (dSUB) region of the hippocampus and the rostral aspect of the basolateral amygdala (rBLA) were involved in acquisition of cocaine-cue extinction learning in rats (Experiment 1). Using lidocaine, rats underwent bilateral or asymmetric inactivation of the dSUB and rBLA. Following intravenous cocaine self-administration training with light and sound cues present, behavior was assessed during cue extinction tests (cues present, no cocaine available). Results demonstrated that pre-test inactivation of dSUB and rBLA, bilaterally or asymmetrically, deterred extinction. Rats maintained elevated levels of cocaine-seeking behavior, despite the absence of cocaine. Control studies in Experiment 1 showed that unilateral or ipsilateral inactivation of dSUB and rBLA prior to extinction tests were unable to deter extinction. Rats reduced cocaine-seeking behavior in the absence of cocaine. Thus, acquisition of cocaine-cue extinction learning required the dSUB and rBLA to be functionally active simultaneously in at least one brain hemisphere. These results suggest that a serial circuit within each hemisphere mediates acquisition of cocaine-cue extinction learning. A second goal was to investigate whether the dSUB, rBLA and infralimbic prefrontal cortex (IL) were involved in the consolidation of cocaine-cue extinction learning in rats (Experiment 2). The protein-synthesis inhibitor anisomycin was infused bilaterally into the dSUB, rBLA or IL. Post-test inhibition of protein synthesis in dSUB deterred extinction following a single session, whereas inhibition in rBLA disrupted extinction only following multiple sessions. Post-test manipulation of IL did not modify responding. Studies in Experiment 2 to control for the time-dependency of consolidation processes showed that bilateral protein-synthesis inhibition in dSUB and rBLA six hours after extinction sessions was unable to deter extinction. Thus, consolidation processes regulated by dSUB and rBLA occur within a critical window of time immediately following extinction sessions. Collectively, these findings suggest that neural substrates for cocaine-cue extinction interact serially during acquisition of learning but have temporally distinct roles during consolidation. Understanding the contribution of individual substrates may help guide therapeutic treatment strategies when implementing cue exposure therapy for drug relapse prevention.
2031-01-01
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Wu, Xiao wu. "Investigate the Neural Substrates of Phonological Access by Using an ArtificialLanguage." The Ohio State University, 2016. http://rave.ohiolink.edu/etdc/view?acc_num=osu1476193873215659.
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Morita, Tomoyo. "Neural substrates of human color perception revealed by the McCollough effect." Kyoto University, 2003. http://hdl.handle.net/2433/148953.
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Kyoto University (京都大学)0048
新制・課程博士
博士(人間・環境学)
甲第10318号
人博第205号
14||169(吉田南総合図書館)
新制||人||50(附属図書館)
UT51-2003-H739
京都大学大学院人間・環境学研究科人間・環境学専攻
(主査)教授 松村 道一, 教授 江島 義道, 教授 前川 覚, 教授 定藤 規弘
学位規則第4条第1項該当
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Loh, Elliot A. (Elliot Alfred) Carleton University Dissertation Psychology. "Investigations of the neural substrates and behavioural correlates of reinforcing substances." Ottawa, 1996.
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Dulawa, Stephanie C. "The neural substrates of sensorimotor gating in serotonin receptor mutant mice /." Diss., Connect to a 24 p. preview or request complete full text in PDF format. Access restricted to UC campuses, 2000. http://wwwlib.umi.com/cr/ucsd/fullcit?p9963658.
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Konagaya, Shuhei. "Design of cell culture substrates for large-scale preparation of neural cells." 京都大学 (Kyoto University), 2013. http://hdl.handle.net/2433/174963.
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de, Bourbon Teles José Miguel Pinto Cardoso. "Neural substrates supporting the influence of working memory contents on visual attention." Thesis, Imperial College London, 2013. http://hdl.handle.net/10044/1/29852.
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The present thesis investigates the neural mechanisms supporting working memory (WM) guidance of visual attention, focusing on the role of the thalamus. Chapter 1 is a review of the relevant literature and sets-up the specific research aims. Chapters 2 and 3 explore the role of the thalamus on guidance of attention by WM contents. Stroke patients with focal-brain lesions performed a WM-guided search task. In valid conditions, the colour of the search target was pre-cued by the WM cue while on neutral conditions there was no cue prior to search. In invalid conditions, the WM cue specified the colour of a search distracter and the target appeared elsewhere. First, it was hypothesized that lesions to the thalamus could lead to deficits in attentional control (e.g. failing to separate irrelevant memory contents with relevant target information and leading to increased capture from WM-like distracters during invalid search conditions). An alternative hypothesis was that the thalamus may support the capture of attention by WM contents, hence thalamic patients would display little bias of attention from the WM contents, despite those contents are being maintained in memory. It was found that patients with focal-thalamic lesions especially in the ventrolateral nucleus, showed no search benefit from the valid cues on search as opposed to a control group of patients with lesions outside the thalamus and non-stroke patients. In the invalid condition, thalamic patients showed no capture by the irrelevant search item that matched the WM cue, whereas a group of healthy age-match controls exhibited the normal effect of capture by irrelevant contents held in WM. These observations suggest that lesions to the ventrolateral nucleus of the thalamus impair the capture of attention from WM contents. In Chapter 4, I aimed to establish the role of cortical structures that are known to be structurally connected with the ventrolateral nucleus of the thalamus (i.e. superior frontal gyrus) in WM guidance of attention. To do this, I investigated the effects of transcranial direct current stimulation (tDCS) of the dorsal frontal cortex in WM guidance of attention under distinct WM loads. I found that despite the effect of WM guidance of attention decreasing as WM load increased, frontal-tDCS modulated WM guidance in these conditions. We suggest that the dorsal frontal cortex forms part of a network alongside the thalamus in supporting WM guidance of attention. Finally, I conducted a functional Magnetic Resonance Imaging (fMRI) experiment (Chapter 5) with healthy volunteers to test the hypothesis that the thalamus plays a role in WM guidance when learning of abstract cue-target feature associations needs to take place for guidance of behaviour to emerge. I used four Japanese ideograms as WM cues, each associated with the colour surrounding the sought after target in the subsequent search display (valid trials). In the neutral condition, four different Japanese ideograms were presented that did not predict the colour of the target. Hence, for WM to guide attention the association between the abstract cue and the colour that surrounded the search target needed to be learned. I found that responses in the thalamus and the frontoparietal cortex displayed sensitivity to the predictiveness of the ideogram cues as WM guidance of attention emerged during learning. The findings reported in this thesis demonstrate the pivotal role of the thalamus in WM guidance of attention.