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Dissertations / Theses on the topic 'Event related potentials'
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Ahmadi, Maryam. "Single-trials analysis of event-related potentials." Thesis, University of Leicester, 2013. http://hdl.handle.net/2381/28224.
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It is a common practice to study the dynamics of sensory and cognitive processes using event-related potentials (ERPs) measured by placing electrodes on the scalp. These ERPs are very small in comparison with the on-going electroencephalogram (EEG) and are barely visible in the individual trials. Therefore, most ERP research relies on the identification of different waves after averaging several presentations of the same stimulus pattern. Although ensemble averaging improves the signal-to-noise-ratio, it implies a loss of information related to variations between the single-trials. In this thesis, I present an automatic denoising method based on the wavelet transform to obtain single-trial evoked potentials. The method is based on the inter- and intra-scale variability of the wavelet coefficients and their deviations from baseline values. The performance of the method is tested with simulated ERPs and with real visual and auditory ERPs. For the simulated data the method gives a significant improvement in the visualisation of single-trial ERPs as well as in the estimation of their amplitudes and latencies in comparison with the standard denoising technique (Donoho’s thresholding) and in comparison with the noisy single-trials. For the real data, the proposed method helps the identification of single-trial ERPs, providing a simple, automatic and fast tool that allows the study of single-trial responses and their correlations with behaviour. We used our proposed denoising algorithm to study the amplitude modulation of the ERP responses to the flashes of faces and to investigate whether the ERP responses in a visual and an auditory oddball paradigm were due to phase-resetting of on-going EEG (phase-resetting model) or due to additive neural responses adding to the background EEG in response to the stimulus presentation (additive model).
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Mark, Ruth Elaine. "Worry, information processing and event-related potentials." Thesis, Queen's University Belfast, 1992. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.333845.
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Ebmeier, Klaus Peter. "Auditory event related potentials in schizophrenic patients." Thesis, University of Aberdeen, 1991. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.317385.
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The use of P3 as a diagnostic marker for schizophrenia was examined in a qualitative and quantitative review of the literature, as well as with an auditory discrimination task involving 21 schizophrenics, 16 patients with idiopathic Parkinson's disease and 50 matched controls. Although some studies have reported a lack of significant group differences between schizophrenics (or Parkinson's disease) and controls, both the quantitative reviews and the experimental studies suggest that this is probably due to a type 2 error. The band pass employed in experimental studies modifies results in that high pass filters with high frequency cut-off are usually associated with a greater effect size. This hypothesis was confirmed by meta-analytic techniques, by filtering of wave forms with analogue and digital filters, and can be modelled by simple compound sine-wave forms. Such a simple model for wave forms observed in schizophrenics involves the reduction of a low frequency (slow) wave, super-imposed with a higher frequency sine wave. Neither the putative genetic marker impaired smooth eye pursuit, nor a positive family history of psychiatric illness were associated with abnormal P3 in schizophrenics. In controls, abnormal P3 was associated with a positive family history. In Parkinsonian patients P3 latency was correlated with clinical markers of dopaminergic hypofunction like rigidity and bradykinesia. This is in agreement with more recent studies suggesting that delayed P3 in Parkinson's disease normalises with treatment with L-DOPE. In the absence of accurate clinical markers of dopaminergic activity in schizophrenics, no direct comparisons have been made. The role of dopaminergic alterations in the generation of P3 changes in schizophrenics can be examined with in-vivo imaging of receptor binding.
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Mitchell, D. A. "Schizophrenia, electrodermal activity and event related potentials." Thesis, University of York, 1988. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.381318.
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Rogers, Dave Edward. "Event-related potentials in obsessive-compulsive disorder." Thesis, Queen's University Belfast, 2015. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.696168.
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A meta-analysis of event-related potential (ERP) studies between controls and high-OCD groups was conducted to examine whether there is a consistent relationship between differences in P300 amplitude and latency following exposure to OCD-related stimuli.After applying exclusion and inclusion criteria, 10 studies remained. The overall effect size for amplitudinal P300 differences was non-significant and results were heterogeneous, while the overall findings for latency were significant. There is therefore tentative evidence from this meta-analysis that reduced P300 latency is a neural correlate for late onset attentional bias in OCD. In the large scale study, a control group of low OCS participants ,was compared to nonclinical high OCS participants on dependent variables of event-related potential amplitude and response time. EEG differences in P100 and ipsilateral invalid negativity (IIN) were investigated as neural correlates of the facilitated attention and disengagement biases respectively. Significant differences were found between groups across IIN amplitude only, suggesting effortful disengagement only occurred in the high OCD groups under selected conditions. The implication is that delayed disengagement is the main attentional bias associated with OCD symptomatology.
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Morgan, Charlie David. "Olfactory event-related potentials in Alzheimer's disease /." 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?p9974114.
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Ting, Kin-hung. "Fast tracking and analysis of event-related potentials /." View the Table of Contents & Abstract, 2005. http://sunzi.lib.hku.hk/hkuto/record/B30268096.
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Ting, Kin-hung, and 丁建鴻. "Fast tracking and analysis of event-related potentials." Thesis, The University of Hong Kong (Pokfulam, Hong Kong), 2005. http://hub.hku.hk/bib/B45015016.
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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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Young, Malcolm Philip. "Exploratory accross-stimulus studies in event-related potentials." Thesis, University of St Andrews, 1990. http://hdl.handle.net/10023/14740.
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Event-related potentials (ERPs) were evoked by visually presented words in a number of experimental paradigms. The question of which linguistic factors, if any, underlie differences between visual word ERPs was addressed. These studies identified 3 factors as predictors of ERF variance. Studies of ERPs in language processing tasks are selectively reviewed, and methodological problems associated with ERPs evoked by non-identical stimuli are discussed. The importance of an understanding of the linguistic factors which underlie ERP differences is outlined, and a methodology for approaching this issue is set out. The statistical procedure necessary to address the question is developed and described in Chapter Two. This procedure was a quantitative modelling strategy, based on multidimensional scaling and PROCRUSTES rotation. Five quantitative modelling studies were undertaken. These experiments involved two experimental tasks, a passive exposure task in which the subjects attended but did not respond to the stimuli (experiment 1) and a category membership decision task (experiments 2 to 5). Words drawn from two semantic categories were employed. ERPs were evoked by individual members of the category of colour names (experiments 1 to 3) and by members of the category of furniture terms (experiments 4 and 5). The results of these studies suggested that word length was the important factor in the early part of the post-stimulus epoch and that this factor was followed by semantic similarity. A late positivity was present in the decision task ERPs whose modulation was related to word frequency. These results were validated by two conventionally analysed experiments which examined the relation between word length and repetition and that between word frequency and repetition. It is concluded that three factors underlie ERP variance in the experimental paradigms employed. These factors are word length (physical extent was not dissociated from length in letters), word frequency and semantic similarity. These results may inform issues of experimental control in future studies of ERPs and language processing, may suggest some reassessment of existing studies in which control was not effected for these factors and may have provided a method of wider utility in cognitive neuroscience. The results suggest that systematic information can be derived about the linguistic characteristics of individual words from single word ERPs.
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Lee, Wee Lih. "Multi-channel extraction methods for event-related potentials." Thesis, Curtin University, 2014. http://hdl.handle.net/20.500.11937/2044.
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Event-related potentials (ERPs) are neural activities that are generated in response to an event. In recent decades, multi-channel EEG recordings have been increasingly adopted in ERP studies. In this thesis, to extract an ERP-of-interest, single-trial multi-channel extraction methods have been developed. The developed methods are data-driven and thus avoid human intervention during ERP analyses. For this reason, they are also practical for real-time applications such as brain-computer interface (BCI).
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Schiano, Lomoriello Arianna. "Reading others' emotions: Evidence from event-related potentials." Doctoral thesis, Università degli studi di Padova, 2018. http://hdl.handle.net/11577/3426338.
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This Thesis aimed at investigating, by using the event-related potentials (ERPs) technique, some relevant aspects involved in human ability to read others’ emotions and in empathizing with others’ affective states. Social and affective neuroscience has largely studied faces and facial expressions since they represent relevant “pieces of information” in guiding individuals during interaction. Their importance is strictly related to the fact that they provide unique information about identity, gender, age, trustworthiness, and attractiveness, but they also convey emotions.
In Chapter 1, I have introduced the reader to the contents of this Thesis, in particular the ability to “read” others’ facial expressions and to empathize with others’ affective states.
In Chapter 2, I have offered an overview of knowledge available today on how humans process faces in general and facial expressions in particular. I have proposed a theoretical excursus starting from Bruce and Young’s cognitive model (1986) to a recent simulative model of recognition of emotional facial expressions by Wood and colleagues (2016), which considers facial mimicry helpful in discriminating between subtle emotions.
In Chapter 3 and 4, I have presented two different studies (Experiments 1 and 2, respectively) strongly related to each other, since they aimed both at testing a functional link between the visual system and facial mimicry/sensorimotor simulation during the processing of facial expressions of emotions. I have described two different studies in which ERPs, by virtue of its high temporal resolution, allowed to track the time-course of the hypothesized influence of mimicry/simulation on the stages of visual analysis of facial expressions. The aim of Experiment 1 was to explore the potential connection between facial mimicry and the early stage of the construction of visual percepts of facial expressions; while the Experiment 2 investigated whether and how facial mimicry could
interact with later stages of visual processing focusing on the construction of visual working memory representations of facial expressions of emotions, by also monitoring whether this process could depend on the degree of the observers’ empathy. For both studies, the results strongly suggest that mimicry may influence early and later stages of visual processing of faces and facial expressions.
In the second part of my Thesis, I introduced the reader to the construct of empathy, dealing with its multifaceted nature and the role of different factors in the modulation of an empathic response, especially to others’ pain (Chapter 5).
In Chapter 6 and 7, I have discussed two ERP studies (Experiments 3 and 4a) with one behavioral study included as a control study (Experiment 4b) to investigate the empathic reaction to others’ pain as a function of different variables that could play a role in daily life. Experiment 3 investigated the role of prosodic information in neural empathic responses to others’ pain. Results from this study demonstrated that prosodic information can enhance human ability to share others’ pain by acting transversely on the two main empathy components, the experience sharing and the mentalizing. The aim of Experiment 4a was to study whether the physical distance between an observer and an individual in a particular affective state, induced by a painful stimulation, is a critical factor in modulating the magnitude of an empathic neural reaction in the observer. Thus, by manipulating the perceived physical distance of face stimuli, I observed a moderating effect on empathic ERP reactions as a function of the perceived physical distance of faces. Results of Experiment 4b clarified that the critical factor triggering differential empathic reactions in the two groups in Experiment 4a was not related to the likelihood of identifying the faces of the two sizes but to the perceived physical distance.
Finally, in Chapter 8, a general discussion highlights the main findings presented in this Thesis, by also providing future suggestions to extend the research on this topics debated in the previous Chapters.<br>Questo elaborato ha l’obiettivo di indagare, tramite l’utilizzo della tecnica dei potenziali evento-relati (ERPs, Event-Related Potentials), alcuni aspetti che caratterizzano e guidano l’interazione sociale umana, come l’abilità di leggere e comprendere le emozioni altrui. Le neuroscienze sociali hanno studiato nel dettaglio volti ed espressioni facciali, in quanto stimoli che, oltre a fornire informazioni uniche circa l’identità, il genere, l’età, l’affidabilità, l’attrattività e la direzione dello sguardo, tramettono indicazioni circa gli stati emotivi dell’altro.
Il Capitolo 1 fornisce una panoramica teorica, primum, rispetto al processamento dei volti e delle espressioni facciali, deinde, sull’empatia, in particolare al dolore, intesa come capacità umana di comprendere l’altrui stato affettivo.
Nel Capitolo 2 è proposto un excursus teorico sul processamento dei volti e delle emozioni da essi veicolate, partendo dal modello cognitivo di Bruce e Young (1986) ai recenti modelli simulativi, fino a quello più attuale di Wood e colleghi (2016), che considera il ruolo della mimica facciale nella discriminazione di emozioni sottili.
Nei Capitoli 3 e 4, sono presentati due studi strettamente interconnessi (rispettivamente, Esperimento 1 e 2). Entrambi hanno come obiettivo lo studio di un collegamento funzionale tra il sistema visivo e la mimica facciale/simulazione senso-motoria, nel processamento di emozioni tramite l’osservazione di espressioni facciali. Nei due studi è stata utilizzata la tecnica degli ERPs che, data la sua alta risoluzione temporale, ha permesso di tracciare una dinamica temporale chiarendo il ruolo della mimica/simulazione sugli stadi di analisi visiva coinvolti nell’elaborazione di espressioni facciali.
L’obiettivo dell’Esperimento 1 era di indagare una possibile connessione tra la mimica facciale e uno dei primi stadi di costruzione del percetto visivo del volto; mentre l’Esperimento 2, indagava se e come la mimica facciale interagisse con uno stadio più tardivo legato alla costruzione di una rappresentazione in memoria di lavoro visiva e se questo processo dipendesse dal grado di empatia dell’osservatore. I risultati dei due Esperimenti suggeriscono come la mimica facciale influenzi sia gli stadi precoci che tardivi del processamento di emozioni tramite l’osservazione di espressioni facciali.
Nella seconda parte della Tesi, viene affrontato il tema dell’empatia, con particolare riferimento alla sua natura sfaccettata e al come variabili diverse possano modulare la risposta empatica stessa, specialmente al dolore altrui (Capitolo 5).
All’interno dei Capitoli 6 e 7 sono presentati due studi ERPs (Esperimento 3 e 4a) e un’indagine comportamentale (Esperimento 4b) con l’obiettivo di indagare la risposta empatica, elicitata nell’osservatore, quando si trova di fronte a qualcuno che sta provando dolore. L’esperimento 3 vuole studiare il ruolo della prosodia nel modulare la risposta neurale empatica nell’osservatore. I risultati dimostrano che l’informazione prosodica può aumentare la risposta empatica, agendo trasversalmente sulle due grandi componenti dell’empatia, experience sharing e mentalizing. Nell’Esperimento 4a, l’obiettivo era di comprendere se la distanza fisica tra l’osservatore e un individuo in una situazione dolorosa, potesse rappresentare un fattore importante nel modulare la grandezza della risposta empatica. Questo studio, attraverso la manipolazione della distanza fisica percepita di volti, ha mostrato una riduzione della risposta empatica rilevata nell’osservatore, in funzione della distanza fisica percepita. Il risultato dell’Esperimento 4b, invece, ha chiarito che il fattore critico nella generazione della risposta empatica (studio 4a) fosse la distanza fisica percepita e non quanto fossero discriminabili i volti tra loro.
In conclusione, nel Capitolo 8, è fornita una discussione generale che integri i risultati più importanti ottenuti negli studi descritti, cercando di delineare risvolti e prospettive future.
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Li, Jiewei, and 李杰威. "Electroencephalograph feature extraction of somatosensory event related potential (ERP)." Thesis, The University of Hong Kong (Pokfulam, Hong Kong), 2014. http://hdl.handle.net/10722/206587.
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Background:
The event related potential (ERP) is an important electrophysiological response to an internal or external stimulus on human body. In some studies, the ERP-based brain computer interface (BCI) systems were created in visual or auditory modality.
However, in these type of BCIs, either the eyes or ears of the users are occupied when they are making a choice. It is not convenient to communicate with others. Thus, a somatosensory ERP based BCI can be developed to overcome this issue. According to this, the analysis of somatosensory ERP features is necessary to evaluate if somatosensory ERP is eligible for BCIs as an input.
Objective:
1. To study ERP features and design of P300 experiment.
2. To compare three types of P300 features elicited by three modalities.
3. To produce ERP response by electrical stimuli delivered to different position, and analyze ERP features.
Methods:
Two experiments were conducted. In experiment 1, three modalities, including visual, auditory and electrical modality, were used to produce P300 response. Experiment 2 only presented electrical stimuli. In experiment 1 two electrical stimuli were presented with different intensities at one location, whereas four electrical stimuli were showed at different location with the same intensity. The amplitude and latency were compared among three modalities, and the ERP topography of experiment 2 was also analyzed.
Result and conclusion:
Fourteen subjects’ data were analyzed in our study. The amplitude and latency of electrical P300 were similar to auditory ERP. But the ERP of visual modality had the largest amplitude and shortest latency. This result shows that electrical P300 can work as well as auditory P300 in BCIs, but not as good as visual P300. In experiment 2, the latency of electrical ERP occurred around 280 ms, and the amplitude and the topography showed that the largest amplitude was located around Cz electrode. This type of ERP in experiment 2 was considered as P3a, which also can be used in BCI systems.<br>published_or_final_version<br>Orthopaedics and Traumatology<br>Master<br>Master of Medical Sciences
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Norberg, Joakim. "Fearful attention : Investigating event-related potentials in spider phobia." Doctoral thesis, Stockholms universitet, Psykologiska institutionen, 2012. http://urn.kb.se/resolve?urn=urn:nbn:se:su:diva-83688.
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Previous studies showed that emotional pictures capture attention. Further, this effect was decreased by manipulating spatial attention. In contrast, studies produced mixed findings for effects of perceptual load on attention to emotional pictures. Emotional pictures can be phobic or nonphobic. Because phobia might be an evolutionary adaption, it is possible that effects of phobic pictures on attention differ from effects of nonphobic emotional pictures. The present thesis aimed at investigating attention in spider phobia. Attention to emotional pictures was operationalized as event-related potentials (ERPs) (P1, early posterior negativity [EPN,] and late positive potential [LPP]). Two research questions were formulated. First, do phobic pictures evoke larger ERPs than what can be expected from arousal and valence? Second, are effects of spatial attention and perceptual load on ERPs the same for phobic and nonphobic emotional pictures? To investigate this, phobic and nonphobic negative pictures were presented to spider phobic and nonphobic participants. To determine effects of spatial attention on ERPs, participants were instructed to divert attention to a single letter that was presented in the periphery. To determine effects of perceptual load on ERPs, participants were instructed to perform a letter discrimination task on one, two, or three letters that were presented in the periphery. Study 1 showed enhanced LPP amplitudes to phobic pictures independent of arousal and valence. Further, this effect was present in both phobic and nonphobic participants. Study 2 showed that there was no effect of perceptual load on LPP to phobic pictures. Study 3 showed that spatial attention reduced LPP amplitudes, and to a similar extent for both phobic and nonphobic pictures. Further, perceptual load did not reduce EPN or LPP amplitudes to either phobic or nonphobic pictures. To conclude, the results suggest that phobic pictures evoke larger ERP amplitudes than nonphobic pictures. Still, ERPs to phobic and nonphobic pictures are moderated similarly by spatial attention and perceptual load.<br><p>At the time of the doctoral defense, the following papers were unpublished and had a status as follows: Paper 1: Manuscript. Paper 3: Manuscript.</p>
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Lins, Otavio G. "Ocular artifacts in recording EEGs and event related potentials." Thesis, University of Ottawa (Canada), 1993. http://hdl.handle.net/10393/6889.
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The ocular artifacts derive from the potential difference between the cornea and the fundus of the eye. This can be represented by an equivalent dipole with its positive pole directed toward the cornea. The DC potential between the cornea and the forehead measures approximately +13 mV. The scalp-distribution of the ocular artifacts can be described in terms of propagation factors--the percentage of the EOG present at the EEG electrodes. These factors are significantly different for blinks and upward eye-movements. The source dipoles for blinks and saccades are different--blink dipoles point radially whereas saccade dipoles point tangentially, in the direction of the eye movement. Blink and eye movement potentials are generated by different mechanisms--blink potentials are generated by the eyelid sliding over the cornea, eye movement potentials by the rotation of the ocular dipole. A very small downward rotation of the eyes may occur during a normal blink. The "rider artifact" at the onset of upward saccade is caused by the eyelid as it lags behind the eyes at the beginning of the movement. Smaller rider artifacts, caused by the horizontal asymmetry of the eyelid, can be noted during horizontal but not downward saccades. Techniques that use scaled EOG to remove ocular artifacts from EEG recordings may remove some of the frontal EEG together with the ocular artifacts. Dipole source techniques allow the ocular generators to be distinguished from the nearby brain generators. A problem with dipole source techniques is that the head model used in the calculation is not accurate at the eyes. A new technique uses principal component analysis to estimate the ocular artifact at each electrode without using a head model. This technique is the most effective way to remove ocular artifacts from EEG recordings. (Abstract shortened by UMI.)
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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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Schulze, Katja Kristina. "Event-related potentials in bipolar disorder : a family study." Thesis, King's College London (University of London), 2006. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.437286.
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Frangou, Sophia. "Event related potentials in familial and non familial schizophrenia." Thesis, King's College London (University of London), 2002. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.252084.
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Henderson, Ross Munro. "Visual event-related potentials in normal and abnormal development." Thesis, Glasgow Caledonian University, 2000. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.311800.
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Trikha, Abhishek. "Gender and Color Specific Differences in Event Related Potentials." BYU ScholarsArchive, 2010. https://scholarsarchive.byu.edu/etd/2455.
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This project analyzed gender and color-specific differences in event-related potentials (ERPs). Previous studies have shown that males process color differently than females. In a recent study, sex differences were found in ERPs during a visual object recognition task. There were higher EEG amplitudes in females (especially P300) than males. Significant sex and color-specific differences have been found in diseases involving altered dopamine (DA) machinery. Thus, we analyzed differences between ERPs in males vs females during a color task. We also compared the color-specific differences in ERPs between males and females. Males and females participated in EEG recording sessions for 2 color studies during a color-go-no-go task, where two studies examined the gender and color-specific differences in ERPs, respectively. Data from 32 males and 24 females and 21 females and 31 males, respectively, in two color studies demonstrated significant sex-specific differences in ERPs during a color-go-no-go task. Males consistently showed higher EEG amplitudes (particularly P300) than females, which is contradictory to what we demonstrated previously in the object recognition task, indicating different color processing systems in males and females. Regarding color-specific differences, no significant differences were found in P300s between the three colors red, green and blue in males and females when each color was the relevant stimulus, suggesting that color is not a marker for inducing ERPs in normal subjects. These studies will provide the impetus to compare patients having altered DA mechanisms such as in attention-deficit hyperactivity disorder (ADHD), Parkinson's, or chemical addiction.
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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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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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Dambacher, Michael, Martin Rolfs, Kristin Göllner, Reinhold Kliegl, and Arthur M. Jacobs. "Event-related potentials reveal rapid verification of predicted visual input." Universität Potsdam, 2009. http://opus.kobv.de/ubp/volltexte/2010/4495/.
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Human information processing depends critically on continuous predictions about upcoming events, but the temporal convergence of expectancy-based top-down and input-driven bottom-up streams is poorly understood. We show that, during reading, event-related potentials differ between exposure to highly predictable and unpredictable words no later than 90 ms after visual input. This result suggests an extremely rapid comparison of expected and incoming visual
information and gives an upper temporal bound for theories of top-down and bottom-up interactions in object recognition.
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Allefeld, Carsten, and Stefan Frisch. "Phase synchronization analysis of event-related potentials in language processing." Universität Potsdam, 2004. http://opus.kobv.de/ubp/volltexte/2008/2011/.
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Phase synchronization analysis, including our recently introduced multivariate approach, is applied to event-related EEG data from an experiment on language processing, following a classic psycholinguistic paradigm. For the two types of experimental manipulation distinct effects in overall synchronization are found; for one of them they can also be localized. The synchronization effects occur earlier than those found by the conventional analysis method, indicating that the new approach provides additional information on the underlying neuronal process.
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Armilio, Maria Luisa. "Event-related potentials during learning and recognition of complex pictures." Thesis, National Library of Canada = Bibliothèque nationale du Canada, 1997. http://www.collectionscanada.ca/obj/s4/f2/dsk2/ftp03/MQ28729.pdf.
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Markazi, Seyedehmina Ayoubian. "Wavelet-based filters for the analysis of event-related potentials." Thesis, Brunel University, 2008. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.443533.
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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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Knebel, Timothy F. "Event-related potentials during auditory discrimination : attentional and intentional effects /." Diss., This resource online, 1995. http://scholar.lib.vt.edu/theses/available/etd-02132009-171704/.
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Brandeis, Daniel. "Spatial analysis of event related potentials in perception and cognition /." [S.l.] : [s.n.], 1986. http://e-collection.ethbib.ethz.ch/show?type=diss&nr=8187.
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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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Osborne, Kenneth Juston. "Investigating The Relationship between Event-Related Potentials and Response Kinematics." W&M ScholarWorks, 2016. https://scholarworks.wm.edu/etd/1477068303.
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Movement is one of the most important functions of our nervous system. Recent research has shown that cognitive and perceptual functions ranging from our perception of others’ emotions to the planning of goal-directed behaviors depends critically on brain areas once thought to be primarily motor in nature. Given the important role our motor system plays in understanding and interacting with the world around us, it is surprising that the majority of cognitive neuroscience research using electroencephalogram (EEG) has focused primarily on perception and cognition irrespective of its relationship(s) to the execution of movement. One possible explanation for this is that EEG and event-related potential (ERP) studies typically rely on simplistic motor responses and ERP averaging techniques that do not afford an analysis of these dynamic relationships. Combining a novel method for tracking dynamic cursor movement and single-trial EEG analysis, the current study addressed this limitation in the field via assessment of younger and older adults’ goal-directed movements during a task-set switching procedure. Our results demonstrate that ERPs conventionally interpreted with respect to cognition and perception are in fact related to the kinematics of motor responses.
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Lopez, Zunini Rocio Adriana. "An ERP Investigation of Semantic Richness Dynamics: Multidimensionality vs. Task Demands." Thesis, Université d'Ottawa / University of Ottawa, 2016. http://hdl.handle.net/10393/34469.
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Semantic richness is a multidimensional and dynamic construct that can be defined as the amount of semantic information a word possesses. In this thesis, the semantic richness dimensions of number of associates, number of semantic neighbours, and body-object interaction were investigated. Forty-eight young adults were randomly assigned to perform either lexical decision (LDT) or semantic categorization tasks (SCT). The goal of this thesis was to investigate behavioural and electrophysiological differences (using the Event-Related Potential technique) between semantically rich words and semantically impoverished words. Results revealed that the amplitude of the N400 ERP component was smaller for words with high number of associates
and high number of semantic neighbours compared to words with low number of associates or low number of semantic neighbours, respectively, but only during LDT. Behavioural results, however, only showed an accuracy and reaction time advantage (during item analyses) for words with many associates. In contrast, N400 amplitudes did not differ for words with high body-object interaction rating when compared to words with low body-object interaction rating in any of the tasks, although a behavioural reaction time advantage was observed in item analyses of the
LDT. These results suggest that words with many associates or semantic neighbours may be processed more efficiently and be easier to integrate within the neural semantic network than words with few associates or semantic neighbours. In addition, the N400 effect was seen in the LDT but not in the SCT, suggesting that semantic richness information may be used in a top-down manner in order to fulfill the task requirements using available neural resources in a more efficient manner.
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Harrison, Maria. "An exploration of pre-attentive visual discrimination using event-related potentials." Thesis, University of Westminster, 2013. https://westminsterresearch.westminster.ac.uk/item/8yzqq/an-exploration-of-pre-attentive-visual-discrimination-using-event-related-potentials.
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The Mismatch Negativity (MMN) has been characterised as a ‘pre-attentive’ component of an Event-Related Potential (ERP) that is related to discriminatory processes. Although well established in the auditory domain, characteristics of the MMN are less well characterised in the visual domain. The five main studies presented in this thesis examine visual cortical processing using event-related potentials. Novel methodologies have been used to elicit visual detection and discrimination components in the absence of a behavioural task. Developing paradigms in which a behavioural task is not required may have important clinical applications for populations, such as young children, who cannot comply with the demands of an active task. The ‘pre-attentive’ nature of visual MMN has been investigated by modulating attention. Generators and hemispheric lateralisation of visual MMN have been investigated by using pertinent clinical groups. A three stimulus visual oddball paradigm was used to explore the elicitation of visual discrimination components to a change in the orientation of stimuli in the absence of a behavioural task. Monochrome stimuli based on pacman figures were employed that differed from each other only in terms of the orientation of their elements. One such stimulus formed an illusory figure in order to capture the participant’s attention, either in place of, or alongside, a behavioural task. The elicitation of a P3a to the illusory figure but not to the standard or deviant stimuli provided evidence that the illusory figure captured attention. A visual MMN response was recorded in a paradigm with no task demands. When a behavioural task was incorporated into the paradigm, a P3b component was elicited consistent with the allocation of attentional resources to the task. However, visual discrimination components were attenuated revealing that the illusory figure was unable to command all attentional resources from the standard deviant transition. The results are the first to suggest that the visual MMN is modulated by attention. Using the same three stimulus oddball paradigm, generators of visual MMN were investigated by recording potentials directly from the cortex of an adolescent undergoing pre-surgical evaluation for resection of a right anterior parietal lesion. To date no other study has explicitly recorded activity related to the visual MMN intracranially using an oddball paradigm in the absence of a behavioural task. Results indicated that visual N1 and visual MMN could be temporally and spatially separated, with visual MMN being recorded more anteriorly than N1. The characteristic abnormality in retinal projections in albinism afforded the opportunity to investigate each hemisphere in relative isolation and was used, for the first time, as a model to investigate lateralisation of visual MMN and illusory contour processing. Using the three stimulus oddball paradigm, no visual MMN was elicited in this group, and so no conclusions regarding the lateralisation of visual MMN could be made. Results suggested that both hemispheres were equally capable of processing an illusory figure. As a method of presenting visual test stimuli without conscious perception, a continuous visual stream paradigm was developed that used a briefly presented checkerboard stimulus combined with masking for exploring stimulus detection below and above subjective levels of perception. A correlate of very early cortical processing at a latency of 60-80 ms (CI) was elicited whether stimuli were reported as seen or unseen. Differences in visual processing were only evident at a latency of 90 ms (CII) implying that this component may represent a correlate of visual consciousness/awareness. Finally, an oddball sequence was introduced into the visual stream masking paradigm to investigate whether visual MMN responses could be recorded without conscious perception. The stimuli comprised of black and white checkerboard elements differing only in terms of their orientation to form an x or a +. Visual MMN was not recorded when participants were unable to report seeing the stimulus. Results therefore suggest that behavioural identification of the stimuli was required for the elicitation of visual MMN and that visual MMN may require some attentional resources. On the basis of these studies it is concluded that visual MMN is not entirely independent of attention. Further, the combination of clinical and non-clinical investigations provides a unique opportunity to study the characterisation and localisation of putative mechanisms related to conscious and non-conscious visual processing.
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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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Downey, Ryan Andrew. "Examination of lexical properties during auditory sentence processing using event-related potentials." Connect to a 24 p. preview or request complete full text in PDF format. Access restricted to UC campuses, 2006. http://wwwlib.umi.com/cr/ucsd/fullcit?p3237582.
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Thesis (Ph. D.)--University of California, San Diego and San Diego State University, 2006.<br>Title from first page of PDF file (viewed December 13, 2006). Available via ProQuest Digital Dissertations. Vita. Includes bibliographical references.
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Mallik, Peter Robert. "An Assessment of Age-Related Differences in Letter-Matching Performance using Event-Related Potentials." University of Akron / OhioLINK, 2019. http://rave.ohiolink.edu/etdc/view?acc_num=akron1562836481989997.
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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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Dumlu, Seda Nilgun. "Investigation Of Semantic Effects In Oddball Paradigm Through Event Related Potentials." Master's thesis, METU, 2012. http://etd.lib.metu.edu.tr/upload/12614613/index.pdf.
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In this study, the effect of semantic information processing was investigated by the oddball paradigm, by presenting consecutive Turkish words or word-like non-words while EEG signals are recorded. In an oddball paradigm, a series of events are presented of which one class is rarer than the other. Subjects are asked to respond to the infrequent stimuli (e.g. press a button, or count the number). The event related potential (ERP) component P300 obtained from EEG is considered as the marker of this attention capturing paradigm. P300 is obtained consistently for both visual and verbal stimulus. On the other hand, the ERP component N400 is consistently associated with semantic processing in neurolinguistics. Additionally, Late Positive Component (LPC) is a marker for the top-down attention mechanism during word comprehension. Moreover, there are other components, called early ERPs, which occur between 100-200 ms after the stimulus onset. These components orthographically and phonologically reflect low-level features of words. The target words chosen for our study are strictly limited to belong to a neutral category and not consist of any emotional content, to rule out emotional interference in semantic processing. Based on the ERP components that were obtained from this study, the LPC potential exhibited for words had higher amplitude than that of non-words consistently and statistically significantly. However, our study was confounded with the heterogeneity of non-words because some of the non-words were non-sense letter sequences while others were pseudowords. Due to this, although we observed the P300 and N400 ERPs consistently for all stimuli, we did not find significant differences for these potentials between words and non-words. To the best of our knowledge, our investigation is one of the few studies conducted with EEG recordings in a task that involved lexical decision making in Turkish.
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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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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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Heath, Jacob. "Biometric Classification of Human Subjects Using Electroencephalography Auditory Event-Related Potentials." University of Cincinnati / OhioLINK, 2015. http://rave.ohiolink.edu/etdc/view?acc_num=ucin1439300974.
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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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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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Elangovan, Saravanan. "The Role of Auditory Event Related Potentials in Understanding Speech Perception." Digital Commons @ East Tennessee State University, 2006. https://dc.etsu.edu/etsu-works/1578.
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Cameron, Allison M. "Event-related potential indices of delayed response working memory in schizophrenia /." [St. Lucia, Qld.], 2002. http://www.library.uq.edu.au/pdfserve.php?image=thesisabs/absthe17563.pdf.
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Tavakoli, Paniz. "Becoming Conscious of That Which We Are Apparently Ignoring: How the Detection of Acoustic Change Can Result in a Forced Intrusion Into Consciousness." Thesis, Université d'Ottawa / University of Ottawa, 2017. http://hdl.handle.net/10393/36601.
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We live in a busy and complex world, so the ability to focus our attention on relevant information at the expense of the irrelevant is essential in allowing us to avoid distraction. However, it is also important that our attention be captured by external stimuli that, although irrelevant to the task at hand, may nevertheless provide information about important changes to our immediate environment. This capture/orienting of attention is an involuntary, fundamental, and biological mechanism necessary for survival. The present thesis employed event-related potentials (ERPs), the minute responses of the brains electrical activity, to examine how changes in the acoustic environment can lead to the capture of attention.
Study 1 examined an ERP component, the P3a, which is associated with the processes that lead to the forced capture of attention by external stimuli. This intrusion into consciousness can be studied using an auditory sequence, the oddball paradigm, which consists of a frequently occurring and homogenous ‘standard’ stimulus. At times, a feature of the standard is changed to form a rarely occurring ‘deviant’. If the extent of change between standard and deviant is large enough, processes associated with attention capture may be activated. Study 1 of this thesis employed a more time-efficient multi-feature optimal paradigm, which allows for the presentation of numerous deviants in one auditory sequence. The standard stimulus was a pure tone. Four of the six deviants were created by changing a single feature of the standard (frequency, duration, increase and decrease in intensity), while the remaining two deviants varied on more than one feature from the standard (environmental sounds, white noise). Results revealed that only the environmental sounds (i.e. animal sounds, human voices, musical instruments) and white noise bursts, elicited the P3a, while the other four deviants did not.
Studies 2 and 3 determined whether the attention capture processes associated with the P3a could be observed during the sleep onset and sleep periods, where awareness of the external environment is diminished. For sleep to be of benefit it needs to remain as undisturbed as possible, without constant awakenings by irrelevant external input, however, the sleeping organism must still have the ability to become conscious of possibly relevant input that requires immediate action. In Study 2, a P3a was elicited again following only the environmental sound and white noise deviants across wakefulness and the sleep onset period. Surprisingly, during definitive sleep, the environmental sounds continued to elicit a P3a suggesting that attention capture processes may still remain active during sleep. Nonetheless, only the first 30 minutes of sleep were examined. Study 3 was then conducted to examine the P3a across the entire night. Results revealed that the environmental sounds did, in fact, elicited a P3a during both NREM and REM sleep. The present thesis demonstrates that attention capture mechanisms, observed during wakefulness, are also active during sleep onset and sleep when awareness of the external environment is diminished. This is especially critical because the sleeping organism may be vulnerable to external danger, requiring the immediate ability to orient attention to incoming information, leading to awaking and conscious awareness.
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Batterink, Laura, and Laura Batterink. "Implicit and Explicit Neural Mechanisms Supporting Language Processing." Thesis, University of Oregon, 2012. http://hdl.handle.net/1794/12525.
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Despite the enormous complexity inherent to language, almost all humans acquire and use their native language with apparent effortlessness, simply from being immersed in a normal social environment. It has been hypothesized that conscious processes play only a limited role in language, which may explain how language can be acquired and processed with so little effort. Using event-related potentials, this dissertation addresses this hypothesis by investigating the contributions of implicit and explicit neural mechanisms to different aspects of language.
In the first study, the neural mechanisms mediating semantic and syntactic processing of word pairs were examined, using the attentional blink (AB) to manipulate awareness of target words. In the semantic condition, correctly reported target words elicited an N400 effect, while missed target words did not elicit an N400. These results provide evidence that awareness plays a critical role in semantic processing. In the second study, the neural mechanisms that support syntactic processing of full sentences were investigated, using a cross-modal AB to manipulate awareness of syntactic violations. Syntactic violations that were not consciously detected nonetheless elicited a left anterior negativity, indicating that syntactic processing is subserved by implicit neural mechanisms. In the third study, the neural mechanisms underlying semantic acquisition were examined, using a task in which the meanings of novel pseudowords were learned through context. Novel pseudowords elicited a robust N400 effect after remarkably little exposure but only during an explicit task and only when word meanings could be explicitly recognized, indicating that vocabulary acquisition is primarily mediated by explicit neural mechanisms. In the fourth study, the neural mechanisms that support the acquisition of second language (L2) syntax were investigated, using a language-learning task in which participants were trained either implicitly or explicitly. Regardless of training condition, learners who successfully learned the novel L2 syntactic rules showed P600 effects, suggesting that explicit mechanisms play a crucial role in acquiring L2 syntax. Taken together, results from these studies suggest that awareness plays a critical yet constrained role in language processing, yielding new insight into how language is spoken and understood so effortlessly.
This dissertation includes previously published and co-authored material.<br>10000-01-01
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McLaughlin, Judith L. "Event related potentials reflect the early stages of second language lexical acquisition /." Thesis, Connect to this title online; UW restricted, 1999. http://hdl.handle.net/1773/9007.
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Sarfarazi, Mehri. "Cognitive evoked potentials during word and picture recognition." Thesis, University of Southampton, 1996. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.390673.
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