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1
Alagon, J. "Discriminant analysis for time series." Thesis, University of Oxford, 1986. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.375222.
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Allefeld, Carsten. "Phase synchronization analysis of event-related brain potentials in language processing." Phd thesis, [S.l. : s.n.], 2004. http://deposit.ddb.de/cgi-bin/dokserv?idn=974114480.
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Ertan, Hayri. "The Analysis Of Auditory Evoked Brain Potentials In Recurve Archery." Phd thesis, METU, 2007. http://etd.lib.metu.edu.tr/upload/12608212/index.pdf.
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Archery can be described as a static sport requiring strength and endurance of the upper body, in particular the shoulder girdle (Mann, 1984Mann &
Littke, 1989). To get a good record in an archery competition, one requires well-balanced and highly reproducible movements during the shooting (Nishizono, 1987). The bowstring is released when audible impetus is received from a device called &ldquo
clicker&rdquo
. As the fall of the clicker is an acoustic stimulus, it may evoke a sequence of potentials that can be recorded from the scalp of an archer. Auditory Evoked Potentials (AEPs) occur at different latencies and with various relations to the auditory stimuli. Therefore, the present study aims at investigating the Long-latency Auditory Evoked Potentials in Recurve Archery. Research questions can be stated briefly as follows: (1) What kind of Brain Potentials are Evoked by the Event (Fall of Clicker) during Archery Shooting? (2) Is there any significant difference between the characteristics of the potentials measured in laboratory conditions and during archery shooting? (3) Is there any significant difference between the successful and unsuccessful shots in terms of Auditory Evoked Brain Potentials? (4) Does Archery Shooting session have any effect on Auditory Evoked Brain Potentials? The subjects of the present study were 10 non-archers (N=6 males
N=4 females) for control trials and 15 archers (N=9 males
N=6 females) for archery shooting experiments. All subjects reported normal hearing, had medical histories free of significant neurological problems, and were not taking medication known to affect brain activity. Six different control paradigms have been created. Archery shootings were performed from 18 m that is official competition distance with target face.AEBPs were recorded 200 ms before and 800 ms after the trigger (fall of the clicker) over the vertex during the shots of each subject. Paradigm 1 and 5 was conducted just before and after the archery shooting to test the effect of archery shooting on AEBPs. The hit-area is defined as the rectangle between (x1, y1), (x1, y2), (x2, y1), (x2, y2) and the miss-area is the outer part of the hit-area on the target face. The preliminary analysis has shown that fall of the clicker evokes long latency auditory brain potentials with the latency of 100 msec and 200 msec. These responses are called as N1-P2 components. The means and standard deviations of both N100 and P200 amplitudes were as follows: N100 = 27,73 ±
16,82, P200 = -21,89 ±
20,46. The latencies of given brain responses were also summarized as: N100 = 141,93 ±
41,46
P200 = 211,8 ±
43,97. N1 amplitude was significantly different in archery shooting than that of control conditions (p<
0.05) except for trial 3, N1 latency was significantly different than that of trial 2 &ndash
5 (p<
0.05). P2 amplitude is significantly different in archery shooting than that of trial 6 (p<
0.05). However, there was no significant difference in terms of P2 latency between archery shooting and control conditions (p>
0.05). There was no significant difference between successful and unsuccessful shots in terms of N1-P2 components (p>
0.05). An archery shooting session did not create any difference between these components recorded before and after the shot (p>
0.05). Having higher N1 amplitudes during archery shooting can be explained by the known multi-component structure of this wave. Different lobes and regions of the brain can be active during the time of the scalp-recorded N1 and simultaneous involvement of several of these areas may be contributing to the electrical field recorded at scalp in the archery shooting paradigm.
4
Reeve, Edward M. "Brain electrical activity assessment of concurrent music and event-related potential cognitive tasks /." The Ohio State University, 1986. http://rave.ohiolink.edu/etdc/view?acc_num=osu1487323583620978.
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Rüsseler, Jascha. "Implicit and explicit learning of event sequences an analysis with event-related brain potentials /." [S.l. : s.n.], 1999. http://deposit.ddb.de/cgi-bin/dokserv?idn=962401986.
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Turner, Ray William. "Action potential discharge in somata and dendrites of CA1 pyramidal neurons of mammalian hippocampus : an electrophysiological analysis." Thesis, University of British Columbia, 1985. http://hdl.handle.net/2429/25989.
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The electrophysiological properties of somatic and dendritic membranes of CA1 pyramidal neurons were investigated using the rat in vitro hippocampal slice preparation. A comprehensive analysis of extracellular field potentials, current-source density (CSD) and intracellular activity has served to identify the site of origin of action potential (AP) discharge in CA1 pyramidal neurons.
1) Action potential discharge of CA1 pyramidal cells was evoked by suprathreshold stimulation of the alveus (antidromic) or afferent synaptic inputs in stratum oriens (SO) or stratum radiatum (SR). Laminar profiles of the "stimulus evoked" extracellular field potentials were recorded at 25µm intervals along the dendro-somatic axis of the pyramidal cell and a 1-dimensional CSD analysis applied.
2) The shortest latency population spike response and current sink was recorded in stratum pyramidale or the proximal stratum oriens, a region corresponding to somata and axon hillocks of CA1 pyramidal neurons. A biphasic positive/negative spike potential (current source/sink) was recorded in dendritic regions, with both components increasing in peak latency through the dendritic field with distance from the border of stratum pyramidale.
3) A comparative intracellular analysis of evoked activity in somatic and dendritic membranes revealed a basic similarity in the pattern of AP discharge at all levels of the dendro-somatic axis. Stimulation of the alveus, SO, or SR evoked a single spike while injection of depolarizing current evoked a repetitive train of spikes grouped for comparative purposes into three basic patterns of AP discharge.
4) Both current and stimulus evoked intracellular spikes displayed a progressive decline in amplitude and increase in halfwidth with distance from the border of stratum pyramidale.
5) The only consistent voltage threshold for intracellular spike discharge was found in the region of the cell body, with no apparent threshold for spike activation in dendritic locations.
6) Stimulus evoked intradendritic spikes were evoked beyond the peak of the population spike recorded in stratum pyramidale, and aligned with the biphasic extradendritic field potential shown through laminar profile analysis to conduct with increasing latency from the cell body layer.
The evoked characteristics of action potential discharge in CA1 pyramidal cells are interpreted to indicate the initial generation of a spike in the region of the soma-axon hillock and a subsequent retrograde spike invasion of dendritic arborizations.Medicine, Faculty of
Cellular and Physiological Sciences, Department of
Graduate
7
Kemmer, Laura. "Event-related brain potential investigations of left and right hemisphere contributions to syntactic processing." Diss., [La Jolla] : University of California, San Diego, 2009. http://wwwlib.umi.com/cr/ucsd/fullcit?p3369000.
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Thesis (Ph. D.)--University of California, San Diego, 2009.Title from first page of PDF file (viewed September 16, 2009). Available via ProQuest Digital Dissertations. Vita. Includes bibliographical references.
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Weeden, Christy Samantha Star. "Neuroprotective Potential of Methamphetamine: Behavioral and Histological Analysis." Thesis, Montana State University, 2007. http://etd.lib.montana.edu/etd/2007/weeden/WeedenC0507.pdf.
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Stroke is a leading cause of death and ischemic stroke is the most common form. The deficits that follow ischemic stroke include memory and learning impairment. There are presently no treatments that can combat the effects of ischemia after the attack has occurred. Immediately following insult, locomotor activity increases in rodent models. The goal of the current research is to determine if methamphetamine administration following ischemic attack will have neuroprotective effects and prevent changes in locomotor behavior that are observed following insult. Ischemic insult was induced in gerbils by clamping the carotid arteries for 5 mins. Subjects in the sham surgical condition underwent similar surgical procedures, but the carotids were not clamped. Then, subjects were assigned randomly to saline or methamphetamine (5 mg/kg) injection groups. Drug treatment was administered within 2 mins of surgery. Measures of distance traveled, average speed, and number of line crossings were evaluated. Differences in levels of locomotion during the first and second halves of testing were also evaluated. Finally, sections containing the hippocampal CA1 region were rated on a 4-point scale for level of damage. Results show that subjects in the ischemic and saline condition traveled significantly further than those in the sham conditions and ischemic and methamphetamine condition. The speed of ischemic subjects treated with saline was significantly higher than ischemic subjects that received methamphetamine and sham conditions. Also, subjects in the ischemic and saline treatment group crossed more lines than sham and ischemic animals treated with methamphetamine. Analysis of cresyl violet-stained brain sections of ischemic animals treated with saline were rated as having less neuronal cell bodies in the CA 1 region. Ischemic and methamphetamine treated subjects' sections were similar to sham and saline treatment sections. These results suggest that methamphetamine, when injected after transient ischemic attack, may provide neuroprotection from damage that occurs to the CA1 region and prevent the impairments in locomotor behavior.
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Ouyang, Guang. "Study of the variability in brain potentials and responses : development of a new method for electroencephalography (EEG) analysis - residue iteration decomposition (RIDE)." HKBU Institutional Repository, 2013. https://repository.hkbu.edu.hk/etd_ra/1529.
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Ibáñez, Soria David 1983. "Analysis of brain dynamics using echo-state networks." Doctoral thesis, Universitat Pompeu Fabra, 2018. http://hdl.handle.net/10803/663491.
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In the last decade recurrent neural networks have revolutionized the field of artificial intelligence. Their cyclic connections provide them with memory and thus with the capability of modeling processes with temporal context. Echo-state networks are a framework for recurrent neural networks that enormously simplifies their design and training. In this thesis we explore the capabilities of echo-state networks and their application in EEG feature extraction and classification problems. In a first study, we proved that such networks are capable of detecting generalized synchronization changes between two chaotic time-series. In a second study, we used echo-state networks to characterize the non-stationary nature of what has been considered so far to be a stationary brain response, namely steady-state visual evoked potentials (SSVEPs). Finally, in a third study, we successfully proposed a novel biomarker for attention deficit hyperactivity disorder (ADHD), which is capable of quantifying EEG dynamical changes between low and normal attention-arousal conditions. The results presented here demonstrate the excellent non-stationary detection capabilities of these networks, and their applicability to electrophysiological data analysis.En la última decada las redes neuronales recurrentes han revolucionado el campo de la inteligencia artificial. Sus conexiones cíclicas les proporcionan memoria y por tanto la capacidad de modelar problemas con contexto temporal. Las redes echo-state simplifican enormemente el diseño y entrenamiento de las redes recurrentes. En esta tesis exploramos el uso de redes echo-state y su aplicación en problemas de clasificación y detección de patrones en señales EEG. En un primer estudio demostramos que son capaces de detectar cambios de sincronización generalizada entre dos series temporales caóticas. En un segundo utilizamos redes echo-state para caracterizar la no estacionaridad de un fenómeno considerado de estado estable, potenciales visuales evocados steady-sate (SSVEP). Finalmente en un tercer estudio proponemos un nuevo biomarcardor para TDAH capaz de cuantificar cambios en la dinámica de la señal EEG entre condiciones bajas y normales de excitación. Los resultados aquí presentados demuestran la excelente capacidad de detección de patrones no estacionarios de estas redes, así como su aplicabilidad en el análisis de datos electrofisiológicos.
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Holland, Peter James. "Frequency-domain and nonlinear analysis of local field potentials and clinical efficacy of deep brain stimulation for complex tremors." Thesis, University of Oxford, 2011. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.558309.
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Recent years have seen increasing interest in the application of ideas and techniques from the field of dynamical systems theory to neurological signals. However, the applicability of these potentially powerful methods to basal ganglia local field potentials is yet to be established. This thesis attempts to prove the merit of employment ofthese methods in the analysis of signals which represent one of the few chances to record subcortical electropbysiological activity in the awake human. Tbe nonlinear analysis technique of Recurrence Quantification Analysis was employed due to its robustness to noise and nonstationarity. The presence of non linear dynamics in local field potentials recorded from the subtbalamic nucleus, globus pallidus and motor thalamus of movement disorders patients is established for the first time using surrogate data testing, validating the suitability of this technique. Indicating its potential capability, Recurrence Quantification Analysis proves effective in discriminating local field potentials recorded from the globus pallidus and the subthalamic nucleus where spectral measures do not. Alterations in linear and nonlinear aspects of subthalamic nucleus local field potentials due to the effects of dopaminergic medication are also demonstrated. Evidence for differences in the pattern of coherence between simultaneously recorded globus pallidus and thalamic local field potentials between dystonic and tremulous patients is provided and related to bivariate nonlinear statistics. The clinical efficacy of Deep Brain Stimulation is investigated in a group of patients suffering from complex tremor resulting from acquired brain injury, with significant postoperative improvement demonstrated. However, the inability of Deep Brain Stimulation to treat ataxia, which is also a common problem in the treatment of tremor associated with multiple sclerosis, is noted in this group. In order to improve multiple sclerosis patient selection a method is developed based on the power spectrum of the electromyogram and shown to correlate significantly with clinical outcome.
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Bobrowski, Christoph. "Quellenlokalisation laserevozierter zerebraler Potentiale durch die Brain-electric-source-Analysis (BESA)." [S.l.] : [s.n.], 1998. http://www.sub.uni-hamburg.de/disse/177/index.htm.
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Wong, Ka-wai Teresa. "Event-related potential analysis of facial emotion processing." Click to view the E-thesis via HKUTO, 2007. http://sunzi.lib.hku.hk/HKUTO/record/B3955773X.
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Wong, Ka-wai Teresa, and 黃嘉慧. "Event-related potential analysis of facial emotion processing." Thesis, The University of Hong Kong (Pokfulam, Hong Kong), 2007. http://hub.hku.hk/bib/B3955773X.
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Heneidy, Hamdy Soliman. "The investigation of signal processing techniques when applied to visually evoked potential propagation path analysis." Thesis, Cranfield University, 1991. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.333546.
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Sambrook, Thomas. "An electrophysiological investigation of reward prediction errors in the human brain." Thesis, University of Plymouth, 2015. http://hdl.handle.net/10026.1/3462.
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Reward prediction errors are quantitative signed terms that express the difference between the value of an obtained outcome and the expected value that was placed on it prior to its receipt. Positive reward prediction errors constitute reward, negative reward prediction errors constitute punishment. Reward prediction errors have been shown to be powerful drivers of reinforcement learning in formal models and there is thus a strong reason to believe they are used in the brain. Isolating such neural signals stands to help elucidate how reinforcement learning is implemented in the brain, and may ultimately shed light on individual differences, psychopathologies of reward such as addiction and depression, and the apparently non-normative behaviour under risk described by behavioural economics. In the present thesis, I used the event related potential technique to isolate and study electrophysiological components whose behaviour resembled reward prediction errors. I demonstrated that a candidate component, “feedback related negativity”, occurring 250 to 350 ms after receipt of reward or punishment, showed such behaviour. A meta-analysis of the existing literature on this component, using a novel technique of “great grand averaging”, supported this view. The component showed marked asymmetries however, being more responsive to reward than punishment and more responsive to appetitive rather than aversive outcomes. I also used novel data-driven techniques to examine activity outside the temporal interval associated with the feedback related negativity. This revealed a later component responding solely to punishments incurred in a Pavlovian learning task. It also revealed numerous salience-encoding components which were sensitive to a prediction error’s size but not its sign.
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Brogin, João Angelo Ferres. "Generalização da técnica de correlação canônica para aplicações em interface cérebro-máquina /." Ilha Solteira, 2018. http://hdl.handle.net/11449/180763.
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Orientador: Douglas Domingues BuenoResumo: A busca por uma melhor compreensão das regiões do cérebro e suas funções nas ações humanas tem sido uma tarefa árdua, porém muito útil, principalmente para aplicações da engenharia de interface cérebro-máquina (ICM), bem como para o auxílio a diagnósticos médicos a partir de sinais obtidos dos pacientes em avaliação. No contexto do presente trabalho, destacam-se os trabalhos de interface cérebro-máquina (ICM) pela abrangência no envolvimento de técnicas, métodos e ferramentas comumente estudadas nos cursos de engenharia. Em particular, análises envolvendo técnicas de processamento de sinais de eletroencefalograma (EEG) têm se mostrado de significativa importância para o desenvolvimento dessa área. Uma abordagem amplamente utilizada nesse contexto é a ICM usando Potenciais Visuais Evocados de Estados Estacionários (SSVEP, do inglês Steady-State Visual Evoked Potentials), que, de forma geral, são sinais caracterizados pela resposta evocada do cérebro a estímulos visuais modulados em uma frequência específica. Assim, este trabalho tem o objetivo de propor uma generalização do coeficiente de correlação, conceito-base da análise de correlação canônica (CCA), técnica que tem se mostrado robusta e eficiente no reconhecimento de padrões, especialmente no caso dos SSVEP, e detalhar seu comportamento em função dos parâmetros relevantes para se estabelecer melhores práticas de uso em aplicações de ICM, incluindo fatores fisiológicos, técnicos e operacionais.
Abstract: The search for a better understanding of the brain's anatomy and its functions on human actions has been a harsh yet very useful task, especially for brain-computer interface engineering applications, as well as for medical diagnosis using signals from patients. In the context of this work, brain-computer interface (BCI) applications are highlighted due to their compreehensiveness related to techniques, methods and tools commonly studied in engineering. In particular, analyses involving eletroencephalogram (EEG) signals processing have proven to be of great significance for developing this field of study. A widely used approach is Steady State Visual Evoked Potentials (SSVEP) based BCI, which, in general, are signals characterized by the brain’s evoked response to visual stimuli modulated at a certain frequency. This work aims thus to propose a generalization of the correlation coefficient, which entails Canonical Correlation Analysis (CCA), a technique that has presented robustness and efficiency for pattern recognition, especially in SSVEP-based BCIs, and describe its behavior under relevant varying parameters to stablish better use practices in BCI applications, comprising physiological, technical and operational factors.
Mestre
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Saavedra, Ruiz Carolina Verónica. "Méthodes d'analyse et de débruitage multicanaux à partir d'ondelettes pour améliorer la détection de potentiels évoqués sans moyennage : application aux interfaces cerveau-ordinateur." Thesis, Université de Lorraine, 2013. http://www.theses.fr/2013LORR0138/document.
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Une interface cerveau-ordinateur permet d'interagir avec un système, comme un système d'écriture, uniquement par l'activité cérébrale. Un des phénomènes neurophysiologiques permettant cette interaction est le potentiel évoqué cognitif P300, lequel correspond à une modification du signal 300 ms après la présentation d'une information attendue. Cette petite réaction cérébrale est difficile à observer par électroencéphalographie car le signal est bruité. Dans cette thèse, de nouvelles techniques basées sur la théorie des ondelettes sont développées pour améliorer la détection des P300 en utilisant des mesures de similarité entre les canaux électroencéphalographiques. Une technique présentée dans cette thèse débruite les signaux en considérant simultanément la phase des signaux. Nous avons également étendu cette approche pour étudier la localisation du P300 dans le but de sélectionner automatiquement la fenêtre temporelle à étudier et faciliter la détectionBrain-Computer Interfaces (BCI) are control and communication systems which were initially developed for people with disabilities. The idea behind BCI is to translate the brain activity into commands for a computer application or other devices, such as a spelling system. The most popular technique to record brain signals is the electroencephalography (EEG), from which Event-Related Potentials (ERPs) can be detected and used in BCI systems. Despite the BCI popularity, it is generally difficult to work with brain signals, because the recordings contains also noise and artifacts, and because the brain components amplitudes are very small compared to the whole ongoing EEG activity. This thesis presents new techniques based on wavelet theory to improve BCI systems using signals' similarity. The first one denoises the signals in the wavelet domain simultaneously. The second one combines the information provided by the signals to localize the ERP in time by removing useless information
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Adam, Tugdual. "Investigation of the effects of Cannabidiol on sleep-like states and memory-associated brain events." Thesis, KTH, Skolan för kemi, bioteknologi och hälsa (CBH), 2020. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-282427.
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A growing interest for Cannabidiol (CBD), a component of Cannabis Sativa, has occurred over the past years. The medical potential of the component is yet to be better characterized, as its effects on sleep, and in particular memory, are to date not well understood or consistently characterized. This master thesis project focuses on analysing the effect of CBD on an anaesthesia-induced sleep-like state in rats, and its effects on the hippocampal sharp-wave-ripples, which have been shown to be associated with memory replay during sleep, and hence system consolidation. The hippocampus and prefrontal cortex, the two structures involved in memory consolidation, were recorded in 19 rats, split in two groups (CBD and vehicle). From these recordings, an automated sleep scorer using principal component analysis was developed to obtain the animals’ hypnograms, which were analysed to study sleep-like structure. From the recordings of the hippocampal pyramidal layer, and an additionnal layer deeper under it, respectively ripples and sharp waves were detected in all animals, and characterized for each group. We observed and demonstrated that CBD changes the sleep-like structure by shortening both REM and NREM bouts, resulting in an increase in transitions between both states. Additionally, we observed that, although ripples are not significantly different between both groups, sharp waves tend to be smaller among CBD animals. Lastly we noticed that both sharp wave and ripple activity, after increasing upon transition to NREM, decreases as the bout last. This finding suggests that vehicle animals, who have longer bouts and less transitions, would display less sharp wave and ripple activity, although we found no significant difference in the amount of both brain events. This paradox suggests that there is still more to characterize in order to understand if CBD enhances or not memory consolidation. In sum, CBD changes anaesthesia-induced sleep by shortening the duration of both NREM and REM bouts, resulting in an increase in transitions between both state. As for sleep events, sharp waves appeared shorter among CBD animals, although the same difference was not observed for ripples. Finally, sharp wave and ripple activity appear to peak upon transition from REM to NREM sleep, and decreases as the NREM bout lasts longer, however, no effect of CBD on this observation was highlighted.
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Bregadze, Nino. "On the feasibility of integrating the acquisition and analysis of event related brain potentionals and functional magnetic resonance imaging." Thesis, University of Exeter, 2008. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.489220.
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Watson, Martin John. "An explication of motor recovery patterns following severe traumatic brain injury : an analysis of evidence, with potential relevnce for physiotherapists." Thesis, University of East Anglia, 2007. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.445179.
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Kobayashi, Katsuya. "Different Mode of Afferents Determines the Frequency Range of High Frequency Activities in the Human Brain: Direct Electrocorticographic Comparison between Peripheral Nerve and Direct Cortical Stimulation." Kyoto University, 2015. http://hdl.handle.net/2433/202676.
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Kunkle, Brian W. "The Potential Role of Environmental Exposures and Genomic Signaling in Development of Central Nervous System Tumors." FIU Digital Commons, 2011. http://digitalcommons.fiu.edu/etd/524.
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The etiology of central nervous system tumors (CNSTs) is mainly unknown. Aside from extremely rare genetic conditions, such as neurofibromatosis and tuberous sclerosis, the only unequivocally identified risk factor is exposure to ionizing radiation, and this explains only a very small fraction of cases. Using meta-analysis, gene networking and bioinformatics methods, this dissertation explored the hypothesis that environmental exposures produce genetic and epigenetic alterations that may be involved in the etiology of CNSTs.
A meta-analysis of epidemiological studies of pesticides and pediatric brain tumors revealed a significantly increased risk of brain tumors among children whose mothers had farm-related exposures during pregnancy. A dose response was recognized when this risk estimate was compared to those for risk of brain tumors from maternal exposure to non-agricultural pesticides during pregnancy, and risk of brain tumors among children exposed to agricultural activities. Through meta-analysis of several microarray studies which compared normal tissue to astrocytomas, we were able to identify a list of 554 genes which were differentially expressed in the majority of astrocytomas. Many of these genes have in fact been implicated in development of astrocytoma, including EGFR, HIF-1α, c-Myc, WNT5A, and IDH3A. Reverse engineering of these 554 genes using Bayesian network analysis produced a gene network for each grade of astrocytoma (Grade I-IV), and ‘key genes’ within each grade were identified. Genes found to be most influential to development of the highest grade of astrocytoma, Glioblastoma multiforme (GBM) were: COL4A1, EGFR, BTF3, MPP2, RAB31, CDK4, CD99, ANXA2, TOP2A, and SERBP1. Lastly, bioinformatics analysis of environmental databases and curated published results on GBM was able to identify numerous potential pathways and gene-environment interactions that may play key roles in astrocytoma development.
Findings from this research have strong potential to advance our understanding of the etiology and susceptibility to CNSTs. Validation of our 'key genes' and pathways could potentially lead to useful tools for early detection and novel therapeutic options for these tumors.
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Shokouhi, Mahsa. "Assessment of the potentials and limitations of cortical-based analysis for the integration of structure and function in normal and pathological brains using MRI." Thesis, University of Glasgow, 2012. http://theses.gla.ac.uk/3210/.
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The software package Brainvisa (www.brainvisa.tnfo) offers a wide range of possibilities for cortical analysis using its automatic sulci recognition feature. Automated sulci identification is an attractive feature as the manual labelling of the cortical sulci is often challenging even for the experienced neuro-radiologists. This can also be of interest in fMRI studies of individual subjects where activated regions of the cortex can simply be identified using sulcal labels without the need for normalization to an atlas. As it will be explained later in this thesis, normalization to atlas can especially be problematic for pathologic brains. In addition, Brainvisa allows for sulcal morphometry from structural MR images by estimating a wide range of sulcal properties such as size, coordinates, direction, and pattern. Morphometry of abnormal brains has gained huge interest and has been widely used in finding the biomarkers of several neurological diseases or psychiatric disorders. However mainly because of its complexity, only a limited use of sulcal morphometry has been reported so far. With a wide range of possibilities for sulcal morphometry offered by Brainvisa, it is possible to thoroughly investigate the sulcal changes due to the abnormality. However, as any other automated method, Brainvisa can be susceptible to limitations associated with image quality. Factors such as noise, spatial resolution, and so on, can have an impact on the detection of the cortical folds and estimation of their attributes. Hence the robustness of Brainvisa needs to be assessed. This can be done by estimating the reliability and reproducibility of results as well as exploring the changes in results caused by other factors. This thesis is an attempt to investigate the possible benefits of sulci identification and sulcal morphometry for functional and structural MRI studies as well as the limitations of Brainvisa. In addition, the possibility of improvement of activation localization with functional MRI studies is further investigated. This investigation was motivated by a review of other cortical-based analysis methods, namely the cortical surface-based methods, which are discussed in the literature review chapter of this thesis. The application of these approaches in functional MRI data analysis and their potential benefits is used in this investigation.
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Pearce, Christopher William. "On the dynamic pressure response of the brain during blunt head injury : modelling and analysis of the human injury potential of short duration impact." Thesis, University of Exeter, 2013. http://hdl.handle.net/10871/14185.
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Impact induced injury to the human head is a major cause of death and disability; this has driven considerable research in this field. Despite this, the methods by which the brain is damaged following non-penetrative (blunt) impact, where the skull remains intact, are not well understood. The mechanisms which give rise to brain trauma as a result of blunt head impact are frequently explored using indirect methods, such as finite element simulation. Finite element models are often created manually, but the complex anatomy of the head and its internal structures makes the manual creation of a model with a high level of geometric accuracy intractable. Generally, approximate models are created, thereby introducing large simplifications and user subjectivity. Previous work purports that blunt head impacts of short duration give rise to large dynamic transients of both positive and negative pressure in the brain. Here, three finite element models of the human head, of increasing biofidelity, were employed to investigate this phenomenon. A novel approach to generating finite element models of arbitrary complexity directly from three-dimensional image data was exploited in the development of these models, and eventually a highly realistic model of the whole head and neck was constructed and validated against a widely used experimental benchmark. The head models were subjected to a variety of simulated impacts, ranging from comparatively long duration to very short duration collisions. The dynamic intracranial pressure response, characterised by large transients of both positive and negative pressure in the brain, was observed following short duration impacts in all three of the models used in this study. The dynamic intracranial response was also recorded following short duration impacts of high energy, involving large impact forces, which were deemed to be realistic representations of actual impact scenarios. With the aid of an approximate analytical solution, analysis of the simulations revealed that the dynamic response is caused by localised skull deflection, which induces flexural waves in the skull. The implications of these magnified pressures are discussed, with particular regard to the potential for intracranial cavitation.
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Forth, Adelle Elizabeth. "Slow cortical brain potentials in criminal psychopaths." Thesis, University of British Columbia, 1986. http://hdl.handle.net/2429/26467.
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Slow cortical potentials and electrodermal activity were recorded while criminal psychopaths performed a two-stimulus anticipation task with monetary reward and punishment. Twelve psychopathic and twelve nonpsychopathic male criminals received auditory stimuli signalling that monetary gain, monetary loss, or no reinforcement would occur at the end of a 6-second foreperiod. There were no electrodermal differences between groups across the reinforcement conditions. Slow EEG activity consisted of two components, identified as the early and late contingent negative variation (CNV). The late CNV did not vary as a function of group. Statistically significant group differences did emerge for the early CNV, with the early CNV of psychopaths being larger across all conditions that those of the nonpsychopaths. The latter result was consistent with the hypothesis that psychopaths have a heightened capacity to selectively attend to events that interest them.Arts, Faculty of
Psychology, Department of
Graduate
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Aravamuthan, Bhooma Rajagopalan. "Comparing the radiological anatomy, electrophysiology, and behavioral roles of the pedunculopontine and subthalamic nuclei in the normal and parkinsonian brain." Thesis, University of Oxford, 2008. http://ora.ox.ac.uk/objects/uuid:9a735b39-c1fe-4d5f-b05f-3385f27e6e58.
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Deep brain stimulation (DBS) of the subthalamic nucleus (STN) and DBS of the pedunculopontine nucleus (PPN) have been shown to be effective surgical therapies for Parkinson’s disease (PD). To better understand the PPN and STN as DBS targets for PD, this research compares the anatomy, electrophysiology, and motor control roles of these nuclei. PPN and STN connections were examined in vivo in human subjects and in the non-human primate using probabilistic diffusion tractography. Both the PPN and STN were connected with each other and with the motor cortex (M1) and basal ganglia. After studying these anatomical connections in primates, their functional significance was further explored in an anesthetized rat model of PD. Examination of the electrophysiological relationship between the PPN and basal ganglia in the presence of slow cortical oscillatory activity suggested that excitatory input from the STN may normally modulate PPN spike timing but that inhibitory oscillatory input from the basal ganglia output nuclei has a greater effect on PPN spike timing in the parkinsonian brain. To examine transmission and modulation of oscillatory activity between these structures at higher frequencies, LFP activity was recorded from the PPN and STN in PD patients performing simple voluntary movements. Movement-related modulation of oscillatory activity predominantly occurred in the α (8-12 Hz) and low β (12-20 Hz) frequencies in the STN but in the high β (20-35 Hz) frequencies in the PPN, supporting observations from rodent studies suggesting that oscillatory activity is not directly transmitted from the STN to the PPN in PD. Finally, to better understand the roles of the STN and PPN in large-scale movement, the effects of STN and PPN DBS on gait abnormalities in PD patients were studied. DBS of the STN appeared to improve gait by optimising executive gait control while DBS of the PPN appeared to restore autonomic gait control. These results have several implications for DBS patient selection, surgical targeting, and for understanding the mechanisms underlying DBS efficacy.
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Hocking, Christopher Anthony, and Christopher Hocking@med monash edu au. "Brain electrical activity and automization." Swinburne University of Technology, 1999. http://adt.lib.swin.edu.au./public/adt-VSWT20051021.110535.
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Novices and experts show distinct differences in the performance of many tasks. Experts may perform a task quickly and accurately with seemingly little attention or effort, whilst novices will perform the same task more slowly and with great effort. The transition from novice to expert performance occurs only after extended practice and has been conceptualized as a transition from controlled to automatic processing, and has been modeled as a reduction in attention or cognitive resources. Alternatively, based on findings relating to learning in the domain of number arithmetic, it has also been modeled as a transition from an algorithmic, or computationally-based process, to the use of memory retrieval.
However, relatively few studies have investigated the changes in brain activity associated with such a transition. In this study, the Steady-State Probe Topography technique was used to investigate differences in the topography of the Steady-State Visual Evoked Potential (SSVEP) between an unpracticed and a well-practiced analogue of number arithmetic, Alphabet arithmetic.
Subjects showed decreases in response time with practice that followed a power law and were suggestive of automatization. During initial, unpracticed performance of the task, processing of the Alphabet Arithmetic equations was characterised by increased SSVEP amplitude and decreased latency in frontal regions, whilst after extended practice, performance was characterised by reduced SSVEP amplitude and increased latency. It is suggested that the frontal activity during the initial, unpracticed stage of the task implicates a role for working memory, whilst the amplitude decrease and latency increase observed in the well-practiced task may reflect a reduction in excitation, consistent with ideas of an improvement in brain efficiency, and possibly an increase in inhibitory processes.
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Hauser, Monika. "Cognitive and emotional influences on event-related brain potentials." Diss., Connect to online resource, 2006. 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:3219009.
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Fath, El-Bab Mohamed. "Cognitive event related potentials during a learning task." Thesis, University of Southampton, 2001. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.367971.
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Bostanov, Vladimir. "Event related brain potentials in emotion perception research, individual cognitive assessment, and brain computer interfaces." [S.l.] : [s.n.], 2004. http://deposit.ddb.de/cgi-bin/dokserv?idn=971863164.
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Baker, Kenneth Boyd. "Long-latency event-related potentials after mild traumatic brain injury." Diss., The University of Arizona, 1998. http://hdl.handle.net/10150/282795.
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This study was an investigation of early changes in long latency event-related potentials with an emphasis on the N200/P300 complex in a group of adults with mild traumatic brain injury (TBI). Subjects with mild TBI and a matched group of non-injured subjects were presented three auditory oddball tasks differing in degree of difficulty. Subjects with TBI were tested within 100 hours of the injury and again at 20 days post-injury. Non-injured subjects also underwent two test sessions, with visit two occurring 18 days after visit one. Event-related potentials were recorded from three midline sites (Fz, Cz, Pz) during the three oddball tasks, two tone-frequency discrimination tasks and one tone-duration discrimination task. The amplitude and latency of both the N200 and the P300 were compared between the two groups. The amplitudes of the two components did not differ significantly between the two groups. However, the latencies of both the N200 and the P300 were prolonged in the mild TBI group. This delay interacted significantly with recording site, with the maximal between-group difference occurring at Fz for both components. The group effect did not interact significantly with the timing of the test session or the difficulty of the oddball task. Taking the latencies of the two components as indices of information processing speed, the data suggest the presence of reduced processing speed in the mild TBI group that persists for at least three weeks post-injury. Increasing task difficulty, at least to the level used in the present study, did not enhance the observed difference between the two groups. The findings related to recording site are consistent with neurobehavioral, neuroimaging, and pathophysiological data which indicate greater effects of injury on frontal regions of the brain.
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Mastria, Serena <1986>. "Emotional engagement and brain potentials: repetition in affective picture processing." Doctoral thesis, Alma Mater Studiorum - Università di Bologna, 2014. http://amsdottorato.unibo.it/6428/.
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The present thesis addresses several experimental questions regarding the nature of the processes underlying the larger centro-parietal Late Positive Potential (LPP) measured during the viewing of emotional(both pleasant and unpleasant) compared to neutral pictures. During a passive viewing condition, this modulatory difference is significantly reduced with picture repetition, but it does not completely habituate even after a massive repetition of the same picture exemplar. In order to investigate the obligatory nature of the affective modulation of the LPP, in Study 1 we introduced a competing task during repetitive exposure of affective pictures. Picture repetition occurred in a passive viewing context or during a categorization task, in which pictures depicting any mean of transportation were presented as targets, and repeated pictures (affectively engaging images) served as distractor stimuli. Results indicated that the impact of repetition on the LPP affective modulation was very similar between the passive and the task contexts, indicating that the affective processing of visual stimuli reflects an obligatory process that occurs despite participants were engaged in a categorization task.
In study 2 we assessed whether the decrease of the LPP affective modulation persists over time, by presenting in day 2 the same set of pictures that were massively repeated in day 1. Results indicated that the reduction of the emotional modulation of the LPP to repeated pictures persisted even after 1-day interval, suggesting a contribution of long-term memory processes on the affective habituation of the LPP. Taken together, the data provide new information regarding the processes underlying the affective modulation of the late positive potential.
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Matthews, David. "Dissociation of P300 brain potentials evoked by rare visual stimuli." Thesis, University of St Andrews, 1995. http://hdl.handle.net/10023/14732.
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The P300 event related potential (ERP) has consistently been dissociated into separate components on the basis of scalp amplitude distribution within the auditory modality (for instance Squires et al. 1975). A parietally maximum P300 deflection being evoked in response to target stimuli in comparison with a more frontally maximum P300 deflection evoked in response to rare nontarget stimuli. Results obtained within experiment 1 and 6 demonstrated such a dissociation employing auditory stimuli within a three stimulus oddball paradigm. It did not prove possible to obtain such a dissociation of P300 deflections on the basis of scalp amplitude distribution within the visual modality. Across a number of experimental manipulations both target and rare nontarget stimuli evoked P300 deflections with similar amplitude distributions (centro-parietal maximum along the midline). Experiment 5 demonstrated that frequent stimuli similarly evoked a centro-parietal maximum amplitude distribution. It was demonstrated that both stimulus probability (Experiment 4) and the physical characteristics of the stimuli (Experiment 5) affected the mean amplitude of the evoked P300 deflection. However, the scalp amplitude distribution of the evoked deflections remained constant. Within Experiment 6 it was demonstrated that within both auditory and visual modalities P300 deflections, evoked in response to both target and rare nontarget stimuli, demonstrated an equipotential amplitude distribution within an elderly group of subjects. In addition across both modalities amplitude evoked in response to rare nontarget stimuli demonstrated an asymmetric distribution across lateral chains of electrodes. Amplitude evoked along the right chain was significantly reduced in comparison to that evoked along the left chain. It would appear that the same, or a similar combination of, underlying neural generators are responsible for the activity that may be recorded at the scalp as the P300 deflection within the visual modality.
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Dalebout, Susan D. "Event-related brain potentials in Parkinson's disease : a preliminary study /." The Ohio State University, 1993. http://rave.ohiolink.edu/etdc/view?acc_num=osu1487841548271694.
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Marshall, David. "Brain-computer games interfacing with motion-onset visual evoked potentials." Thesis, Ulster University, 2016. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.685554.
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A brain-computer interface (BCI) measures brain activity and translates this activity into commands for a program to execute. BCls enable movement-free communication and interaction with technologies. This thesis evaluates the effectiveness and limitations of motion-onset visual evoked potentials (mVEP) based BCI as a control method for brain-computer games interaction. MVEP incorporates neural activity from the dorsal pathway of the visual system which allows more elegant visual stimuli than other types ofVEP and has yet to be used in computer games. This thesis investigates ifmVEP can be used as a control method in multiple computer games, what genre of game is best for interaction with m VEP and can we correct problems with existing VEP BCI computer games? Before conducting experiments involving games of different genres an evaluation of the present stateof- the-art BCI games was carried out in an extensive literature survey on BCI games categorised by genre. The literature survey shows that 'action' is the most popular genre in BCI games (49% of BC I games) and provides both games developers and BCI experts a set of design and development guidelines for BCI games. The conclusions of the survey led to the development of three BCI games of different genres namely action, puzzle and sports. The testing of different BCI games using a single paradigm enables thorough assessment ofmVEP as a control method. Five mVEP stimuli are presented as buttons to allow the subject to choose from five possible actions in each game. The performance was assessed based on offline and online BCI accuracy and game score. The results indicate that players could control the games with reasonable online accuracy (66% average for 5 class classification, with an average training accuracy of 74%). The next study intended on improving the initial study's results by adding the mVEP to an on screen HUD (Heads up Display), training in the same game environment as the participants are tested within and adding a questionnaire. Results indicate that the players could control the games with an average online accuracy of 71 %, a significant improvement from the previous study. After further analysis of recorded data the ideal setup for mVEP games is defined with key specifications indicating between three and four channels is most economical setup without influencing accuracy whilst averaging over three trials (minimises latency in communication). Finally, through the evaluation of a range o,fthe games related surveys, we found that players enjoyed the m VEP puzzle game most, rating it both the most enjoyable and appropriate game with m VEP control. Overall this thesis shows that m VEP can be used in multiple games genres with good accuracy and provides players with an entertaining and novel control method for computer games.
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Talevi, Luca. "Sviluppo e test di un sistema BCI SSVEP-based." Bachelor's thesis, Alma Mater Studiorum - Università di Bologna, 2016. http://amslaurea.unibo.it/11636/.
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Una Brain Computer Interface (BCI) è un dispositivo che permette la misura e l’utilizzo di segnali cerebrali al fine di comandare software e/o periferiche di vario tipo, da semplici videogiochi a complesse protesi robotizzate. Tra i segnali attualmente più utilizzati vi sono i Potenziali Evocati Visivi Steady State (SSVEP), variazioni ritmiche di potenziale elettrico registrabili sulla corteccia visiva primaria con un elettroencefalogramma (EEG) non invasivo; essi sono evocabili attraverso una stimolazione luminosa periodica, e sono caratterizzati da una frequenza di oscillazione pari a quella di stimolazione. Avendo un rapporto segnale rumore (SNR) particolarmente favorevole ed una caratteristica facilmente studiabile, gli SSVEP sono alla base delle più veloci ed immediate BCI attualmente disponibili. All’utente vengono proposte una serie di scelte ciascuna associata ad una stimolazione visiva a diversa frequenza, fra le quali la selezionata si ripresenterà nelle caratteristiche del suo tracciato EEG estratto in tempo reale. L’obiettivo della tesi svolta è stato realizzare un sistema integrato, sviluppato in LabView che implementasse il
paradigma BCI SSVEP-based appena descritto, consentendo di: 1. Configurare la generazione di due stimoli luminosi attraverso l’utilizzo di LED esterni; 2. Sincronizzare l’acquisizione del segnale EEG con tale stimolazione; 3. Estrarre features (attributi caratteristici di ciascuna classe) dal suddetto segnale ed utilizzarle per addestrare un classificatore SVM; 4. Utilizzare il classificatore per realizzare un’interfaccia BCI realtime con feedback per l’utente. Il sistema è stato progettato con alcune delle tecniche più avanzate per l’elaborazione spaziale e temporale del segnale ed il suo funzionamento è stato testato su 4 soggetti sani e comparato alle più moderne BCI SSVEP-based confrontabili rinvenute in letteratura.
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D'Arcy, Ryan C. N. "Neuropsychological assessment of receptive language comprehension with event-related brain potentials." Thesis, National Library of Canada = Bibliothèque nationale du Canada, 1998. http://www.collectionscanada.ca/obj/s4/f2/dsk2/tape15/PQDD_0022/MQ36426.pdf.
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Newman, Randy Lynn. "Defining phonology's role in silent reading with event-related brain potentials." Thesis, National Library of Canada = Bibliothèque nationale du Canada, 2000. http://www.collectionscanada.ca/obj/s4/f2/dsk2/ftp03/MQ57192.pdf.
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Kushnerenko, Elena V. "Maturation of the cotrical auditory event-related brain potentials in infancy." Helsinki : University of Helsinki, 2003. http://ethesis.helsinki.fi/julkaisut/hum/psyko/vk/kushnerenko/.
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Ueno, Mieko. "Event-related brain potentials in the processing of Japanese wh-questions /." Diss., Connect to a 24 p. preview or request complete full text in PDF format. Access restricted to UC campuses, 2003. http://wwwlib.umi.com/cr/ucsd/fullcit?p3112196.
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Benton, Hillary Ann. "Brain Imaging of Event Related Potentials in Children with Language Impairment." BYU ScholarsArchive, 2013. https://scholarsarchive.byu.edu/etd/3614.
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Event related potentials (ERPs) may provide specific information about how particular aspects of language are processed by the brain over time. This study investigated the electrophysiology of language processing in two children with language impairment (LI) when compared to five typically developing children. The N400, P600, and the early left anterior negativity (ELAN) were analyzed after participants listened to linguistically correct, syntactically incorrect, and semantically incorrect sentences. Participants were instructed to indicate whether the sentences were correct or incorrect. Latency and amplitude of the ERP components were compared between the two groups of participants and sentence types. Results from the current study concerning the typically developing children suggest that, at least by eight years of age, typically developing children may process linguistic information similarly to adults with regard to the areas of the brain that are activated during the processing of linguistic stimuli. When comparing results from participants with LI and their typically developing counterparts, results indicate that children with LI exhibit slower real-time language processing than typically developing children. Results also indicate that children with LI require more effort than typically developing children in processing linguistic information as indicated by the amplitude of the N400 and the ELAN. In analyzing the P600 in both groups of participants, results indicate that syntactic processing may be intact in children with LI as well as typical children. Results concerning the N400 and the ELAN were variable between the two participants with LI indicating that children with LI may be heterogeneous even in the presence of similar tasks. Results obtained from the ELAN may also indicate that the ELAN is not fully mature at eight years of age.
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Hughes, Jennifer Joy. "The psychological validity of collocation : evidence from event-related brain potentials." Thesis, Lancaster University, 2018. http://eprints.lancs.ac.uk/127732/.
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Previous studies have used psycholinguistic techniques such as eye-tracking and selfpaced reading in order to investigate the psychological validity of corpus-derived collocations (e.g. Conklin & Schmitt 2008; McDonald & Shillcock 2003a; 2003b; Underwood et al. 2004; Huang et al. 2012). The results of these studies reveal that sequences of words which form collocations are read more quickly and receive fewer fixations than sequences of words which do not form collocations. However, behavioural data and eye-tracking data can only ever provide an indirect measure of what is going on in the brain during language processing. In this thesis, I therefore investigate the psychological validity of corpus-derived collocations using a direct measure of neural activity, namely electroencephalography (EEG). More specifically, I use the event-related potential (ERP) technique of analysing brainwave data. Very few ERP studies focus on collocation, and those that do focus on collocation conceptualize and operationalize the notion differently from how it is conceptualized and operationalized in this thesis, or indeed in most corpus linguistics work. For example, although Molinaro and Carreiras (2010:179-180) use corpus-derived collocations for an ERP study, they explicitly state that they only extract collocations which are “idioms or clichés”. By contrast, in this thesis, collocation is conceptualized as a more fluid phenomenon, as compositional or non-compositional word pairs where the words have a high probability of occurring together. In Experiment 1, which is the first of four ERP experiments presented in this thesis, I aim to pilot a procedure for determining whether or not there is a neurophysiological difference in the way that the native speaker brain processes collocational adjective-noun bigrams compared to non-collocational adjective-noun bigrams. In Experiment 2, I aim to replicate the results of the pilot study using another group of native English speakers; while, in Experiment 3, I aim to investigate the processing of collocational adjective-noun bigrams and noncollocational adjective-noun bigrams in non-native speakers of English (specifically, native speakers of Mandarin Chinese). In Experiment 4, the final experiment of this thesis, I then aim to investigate the gradience of the ERP response as well as the psychological validity of different association measures, namely transition probability, mutual information, loglikelihood, z-score, t-score, Dice-coefficient, MI3, and raw frequency. The results of these studies reveal that there is a neurophysiological difference in the way that the brain processes corpus-derived collocational bigrams compared to matched noncollocational bigrams, suggesting that the phenomenon of collocation can be seen as having psychological validity. An important finding of this thesis is the discovery of the ‘Collocational N400’: an ERP component reflecting the increase in cognitive load associated with reading a collocational violation. This increase in cognitive load is greater for non-native speakers compared to native speakers, as non-native speakers have less flexibility than native speakers in their use of (non-)collocational patterns. Moreover, while there is a strong correlation between the amplitude of the collocational N400 and all of the measures of collocation strength that I investigate in Experiment 4, the strongest correlations exist between amplitude and the hybrid association measures, including z-score, MI3, and Dice co-efficient. This suggests that mutual information and log-likelihood, which are two of the most commonly used association measures in corpus linguistics (Gries 2014a:37), are not necessarily always the optimal choice. I discuss these results in relation to prior literature from the fields of corpus linguistics and cognitive neuroscience.
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Carter, Bradley Graham. "The prediction of both short and long term outcomes follwing severe brain injury using somatosensory evoked potentials." Australasian Digital Theses Program, 2006. http://adt.lib.swin.edu.au/public/adt-VSWT20070130.153020/index.html.
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Rennie, Christopher. "Modeling the large-scale electrical activity of the brain." Connect to full text, 2001. http://hdl.handle.net/2123/816.
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Thesis (Ph. D.)--University of Sydney, 2001.Includes published articles. Title from title screen (viewed Apr. 24, 2008). Submitted in fulfilment of the requirements for the degree of Doctor of Philosophy to the School of Physics, Faculty of Science. Includes bibliography. Also available in print form.
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Darling, Ryan Daniel. "Single Cell Analysis of Hippocampal Neural Ensembles during Theta-Triggered Eyeblink Classical Conditioning in the Rabbit." Miami University / OhioLINK, 2008. http://rave.ohiolink.edu/etdc/view?acc_num=miami1225460517.
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Ciorciari, Joseph, and jciorciari@swin edu au. "Topograhic distribution of human brain electrical activity associated with schizophrenia." Swinburne University of Technology, 1999. http://adt.lib.swin.edu.au./public/adt-VSWT20050610.152013.
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A literature review of the schizophrenia brain electrophysiology was undertaken with specific emphasis placed on the topographical distribution of evoked potentials (EPs). The outcomes of this review suggests that schizophrenia brain electrophysiology, demonstrate some differences, but with a variability reflective of the symptom heterogeneity. The literature associated with the use of attentional tasks while recording EPs, tended to demonstrate some consistency. The methodological issues associated with the EEG and EP recordings may also account for this variability. An evoked potential technique, which has been demonstrated to be sensitive to the changes in cognitive processes associated with attention, is the Steady State Probe Topography (SSPT) technique. The SSPT is a combination of both the Steady State Visual Evoked Potential (SSVEP) and the Probe-ERP paradigm. This technique allows the SSVEP to be measured continuously, is relatively insensitive to artifact, and can display the topographic distribution of the SSVEP measures during the attentional task. The technique employs the use of a sixty-four channel EEG recording system. This consists of a multichannel electrode helmet; multichannel amplifier/filter, task presentation computer and a computer controlled data acquisition system. Software was also developed to analyse the recorded brain electrical activity to produce the SSVEP magnitude and phase versus time series for each electrode site. The topographic distribution of the SSVEP measures associated with specific events during attentional tasks could also be displayed. At the time of the pilot study, this technique had not been applied previously to the study of schizophrenia and therefore warranted further study. Two separate studies are reported; an investigative pilot study and a chronic group study. The pilot SSVEP and schizophrenia study was designed to examine the changes in the SSVEP and its topography, during the performance of a number of attentional or activation tasks to examine the possibility of hypofrontality. The tasks selected for the study were those previously used for the examination of hypofrontality with metabolic imaging techniques; the Continuous Performance Task (CPT) and the Wisconsin Card Sort (WCS). The SSVEP was elicited by a superimposed 13Hz flicker on the visual field, while subjects performed computerised versions of the neuropsychological tasks. Topographical maps of the SSVEP magnitude distribution were then interpolated and displayed as an animated sequence synchronised with particular events occurring during the tasks. In comparison to the male control group, male schizophrenic patients exhibited differences in the SSVEP topography for all tasks, possibly reflecting the deficits in behavioural indices. Overall, the findings indicated that the technique demonstrated some merit for further examination of frontal SSVEP topography in schizophrenia. In a larger study of twenty chronic schizophrenia patients, the frontal topographical distribution of the SSVEP was examined. The earlier pilot study finding of reduced frontal SSVEP amplitude was replicated. The issue of hypofrontality in schizophrenia was applied as a possible interpretation.
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Costa, Faidella Jordi. "Regularity encoding in the auditory brain as revealed by human evoked potentials." Doctoral thesis, Universitat de Barcelona, 2011. http://hdl.handle.net/10803/78918.
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Acoustic regularity encoding has been associated with a decrease of the neural response to repeated stimulation underlying the representation of auditory objects in the brain. The present thesis encloses two studies that sought to assess the neural correlates of acoustic regularity encoding in the human auditory system, by means of analyzing auditory evoked potentials.
Study I was conducted at the Cognitive Neuroscience Research Group, at the Faculty of Psychology of the University of Barcelona (Barcelona, Catalonia, Spain), under the direct supervision of Dr. Carles Escera. This study aimed to explore the dynamics of adaptation of the auditory evoked potentials to probabilistic stimuli embedded in a complex sequence of sounds. The main outcome of this study was the demonstration that the amplitude of auditory evoked potentials adapts to the complex history of stimulation with different time constants concurrently: it adapts faster to local and slower to global probabilities of stimulation. This study also showed that auditory evoked potential amplitudes correlate with stimulus expectancy as defined by a combination of local and global stimulus probabilities.
Study II was conducted at the Institute of Child Health (ICH), at the University College of London (UCL; London, United Kingdom), under the direct supervision of Dr. Torsten Baldeweg. This study aimed to explore the influence of timing predictability in the neural adaptation to probabilistic stimuli. The main outcome of this study was the demonstration that timing predictability enhances the repetition-related modulation of the auditory evoked potentials amplitude, being essential for repetition effects at early stages of the auditory processing hierarchy.La codificació de regularitats acústiques està associada amb la reducció de la resposta neuronal a l’estimulació repetida, essent la base de la representació dels objectes auditius al cervell. La present tesi doctoral inclou dos estudis que exploren els correlats neuronals de la codificació de regularitats acústiques al sistema auditiu humà, mitjançant l’anàlisi dels potencials evocats auditius. L’objectiu del primer estudi, realitzat al Grup de Recerca en Neurociència Cognitiva de la Facultat de Psicologia de la Universitat de Barcelona (UB) i sota la supervisió directa del Dr. Carles Escera, va ser el d’explorar les dinàmiques d’adaptació dels potencials evocats auditius a estímuls probabilístics en una complexa seqüència de sons. El resultat principal d’aquest estudi va ser la demostració de que l’amplitud dels potencials evocats auditius s’adapta a la historia complexa d’estimulació amb diferents constants temporals simultàniament: s’adapta més ràpidament a probabilitats d’estimulació locals que globals. Aquest estudi també va mostrar que l’amplitud dels potencials evocats auditius correlaciona amb l’expectància d’un estímul definida com a una combinació de probabilitats locals i globals d’estimulació. L’objectiu del segon estudi, realitzat al Institute of Child Health (ICH), de l’University College of London (UCL), sota la supervision directa del Dr. Torsten Baldeweg, va ser el d’explorar la influència de la predictabilitat temporal en l’adaptació de l’activitat neuronal a estímuls probabilístics. El resultat principal d’aquest estudi va ser la demostració que la predictabilitat temporal intensifica la modulació de l’amplitud dels potencials evocats auditius a la repetició dels estímuls, essent esencial pels efectes que la repetició exerceix en etapes primerenques de la jerarquía de processament auditiu.
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Moser, Jason Scot. "Intentional regulation of negative emotions is reflected in event-related brain potentials." Access to citation, abstract and download form provided by ProQuest Information and Learning Company; downloadable PDF file 0.59 Mb., 38 p, 2006. http://gateway.proquest.com/openurl?url_ver=Z39.88-2004&res_dat=xri:pqdiss&rft_val_fmt=info:ofi/fmt:kev:mtx:dissertation&rft_dat=xri:pqdiss:1435829.
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Cameli, Luisa. "Age-related differences in semantic priming : evidence from event-related brain potentials." Thesis, National Library of Canada = Bibliothèque nationale du Canada, 1999. http://www.collectionscanada.ca/obj/s4/f2/dsk1/tape10/PQDD_0005/MQ43618.pdf.
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