Dissertations / Theses: 'Event related potentials ERP'

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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.
published_or_final_version
Orthopaedics and Traumatology
Master
Master of Medical Sciences

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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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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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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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Folstein, Jonathan Robert. "On the Category's Edge: Event-Related Potential Correlates of Novelty and Conflicting Information in Rule-Based Categorization." Diss., The University of Arizona, 2007. http://hdl.handle.net/10150/195807.

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This dissertation consists of a review of the N2 component of the ERP and five experiments investigating the role of complex visual object categorization in modulating the N2 and two other ERP components: the P300, and a late prefrontal positivity. In the review, we focus on paradigms that elicit N2 components with an anterior scalp distribution, namely cognitive control, novelty, and sequential matching, arguing that the anterior N2 should be divided into separate control- and mismatch-related subcomponents. The experiments manipulated categorical typicality and the presence of conflicting information as participants categorized multi-featured artificial animals. In Experiments 1 and 2, rule-irrelevant features were correlated with particular categories during training. During transfer, participants applied a one- dimensional rule to stimuli with category-congruent, category-incongruent, or novel rule-irrelevant features. Category-incongruent and novel features delayed RT and P300 latency, but had no effect on the N2. Experiment 3 used a two-dimensional rule to create conflict between rule-relevant features. Conflict resulted in prolonged RTs, P300 latency, and larger amplitudes of a prefrontal positive component, but had no impact on the N2. Novel features did enhance the N2 relative to frequent features. In Experiments 4 and 5, participants categorized stimuli using a more complex three dimensional rule. Conflicting stimuli shared two features with one prototype and one feature with a second prototype while prototypes contained no conflicting information. A third category contained stimuli with either common or novel features. Again, perceptual novelty, but not conflict, increased the amplitude of the N2. Compared to prototypes, stimuli with conflicting information slowed reaction times but had no effect on P300 latency, instead enhancing a late prefrontal positive component. These results suggest limitations on the generality of the N2's sensitivity to conflicting information, while confirming its sensitivity to attended visual novelty. We suggest that, while P300 latency tracks stimulus evaluation time, application of a complex categorization rule requires a later stage of evaluation involving prefrontal cortex. In very complex rules, computations indexed by the P3 may be terminated early in favor of computations in PFC.

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Nishida, Michelle Miller. "Event Related Potentials: A Study of the Processing of Gapping Structures in Adolescents." BYU ScholarsArchive, 2005. https://scholarsarchive.byu.edu/etd/679.

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Many questions remain unanswered regarding the intricacies of the human brain, especially with regard to the complexities of language processing. One essential component of human sentence processing is the ability to detect, decipher, and recover from errors in the interpretation of both verbal and written language. This process of repair of ungrammatical sentences and revision or reinterpretation of ambiguous sentences has been studied extensively in recent years. A variety of tools have been developed, including the use of event-related potentials (ERPs) in order to assess how language is processed and developed, and to help better identify the nature of these processes. The purpose of this study was to compare event-related potential effects of speech processing of spoken and written sentences containing both incorrect and correct semantic and syntactic information. Specifically, sentences containing correct and incorrect gapping structures, each with a "missing" verb, were presented along with other grammatical and ungrammatical sentences in order to elicit and measure the P300, N400, and P600 amplitudes and latencies. The aim was to determine some of the commonalities and differences in these electrophysiological responses via the auditory and visual modalities. Two experiments were conducted with each participant, one in the auditory modality, and one within the visual using two sets of stimuli. Amplitude and topography differences were noted within and between modalities for each of the components (P300, N400, and P600), as well as between stimulus types. Significant findings suggest that in the adolescent population, incorrect gapping structures are generally processed as semantic errors, as evidenced by the N400 response, followed by the P600 response in both the auditory and visual modalities. The exact nature of the P600 component within gapping structures remains unclear. Of particular interest was the involvement of the occipital area of the brain for the processing of gapping structures. Minimal differences were noted overall between adolescents and the adult populations.

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Krupenia, Stas Simon. "An event related potential (ERP) study of symptomatic and asymptomatic adults with attention deficit hyperactivity disorder (ADHD)." University of Western Australia. School of Psychology, 2003. http://theses.library.uwa.edu.au/adt-WU2003.0035.

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This study recorded Event Related Potentials (ERPs) during completion of a Continuous Performance Task (CPT) in order to identify the contribution of response inhibition, working memory, and response monitoring to the pattern of hyperactive and impulsive and inattentive behaviour observed in patients with Attention Deficit Hyperactive Disorder (ADHD). Four ERP components, Nogo N2, Nogo P3, Go P3, and the ERN were examined and compared using a symptomatic and asymptomatic ADHD sample, and a healthy control group. The Nogo N2 had the expected frontal scalp distribution and was affected by changes to inhibitory demands. It was also suggested that this component was not wholly determined by inhibitory processing and may have been influenced by differing presentation rates of the Go stimulus, a template matching process or an in-depth response strategy. Source localisation analysis suggested a right frontal generator for this component. The Nogo P3 had the expected central distribution and had equal amplitude for those participants that were more efficient at inhibiting behaviours compared to those participants that were less efficient inhibitors. Contrary to expectations, the Nogo P3 was not affected by increasing the inhibitory demands of the task and was suggested as being a less reliable indicator of response inhibition in the present study. The Go P3 had the expected centro-parietal distribution, and appeared to provide a reliable index of working memory. Response inhibition and working memory were not impaired in the sample of symptomatic and asymptomatic ADHD adults used in this study. The symptomatic group elicited a slightly enhanced ERN compared to the asymptomatic and control groups, indicating that deficits in response monitoring may contribute to the pattern of problematic behaviour observed in people with ADHD.

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Jardin, Elliott C. "AGING AND ATTENTION TO THREAT; AN ELECTROPHYSIOLOGICAL INVESTIGATION." Cleveland State University / OhioLINK, 2015. http://rave.ohiolink.edu/etdc/view?acc_num=csu1447839343.

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Zhou, Li. "Event-Related Potentials of Visual Working Memory: Exploring Capacity Limit’s Relation with Maintenance and Proactive Interference." Miami University / OhioLINK, 2015. http://rave.ohiolink.edu/etdc/view?acc_num=miami1429790082.

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Förster, Jona. "ERP and MEG Correlates of Visual Consciousness : An Update." Thesis, Högskolan i Skövde, Institutionen för biovetenskap, 2019. http://urn.kb.se/resolve?urn=urn:nbn:se:his:diva-17375.

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Two decades of event-related potential (ERP) research have established that the most consistent correlates of the onset of visual consciousness are the early visual awareness negativity (VAN), a negative component in the N2 time range over posterior electrode sites, and the late positivity (LP), a positive component in the P3 time range over fronto-parietal electrode sites. A review by Koivisto & Revonsuo (2010) had looked at 39 studies and concluded that the VAN is the earliest and most reliable correlate of visual phenomenal consciousness, whereas the LP probably reflects later processes associated with reflective/access consciousness. However, an “early” vs. “late” debate still persists. This thesis provides an update to that earlier review. All ERP and MEG studies that have appeared since 2010 and directly compared ERPs of aware and unaware conditions are considered. The result corroborates the view that VAN is the earliest and most consistent signature of visual phenomenal consciousness, and casts further doubt on the LP as an ERP correlate of consciousness. Important new methodological, empirical, and theoretical developments in the field are described, and the empirical results are related to the theoretical background debates.

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Ottley, Mark Carlisle. "Posed and genuine smiles: an evoked response potentials study." Thesis, University of Canterbury. Psychology, 2009. http://hdl.handle.net/10092/3075.

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The ability to recognise an individual's affective state from their facial expression is crucial to human social interaction. However, understanding of facial expression recognition processes is limited because mounting evidence has revealed important differences between posed and genuine facial expressions of emotion. Most previous studies of facial expression recognition have used only posed or simulated facial expressions as stimuli, but posed expressions do not reflect underlying affective state unlike genuine expressions. The current study compared behavioural responses and Evoked Response Potentials (ERPs) to neutral expressions, posed smiles and genuine smiles, during three different tasks. In the first task, no behavioural judgment was required, whereas participants were required to judge whether the person was showing happiness in the second task or feeling happiness in the third task. Behavioural results indicated that participants exhibited a high degree of sensitivity in detecting the emotional state of expressions. Genuine smiles were usually labelled as both showing and feeling happiness, but posed smiles were far less likely to be labelled as feeling happiness than as showing happiness. Analysis of P1 and N170 components, and later orbitofrontal activity, revealed differential activity levels in response to neutral expressions as compared to posed and genuine smiles. This differential activity occurred as early as 135ms at occipital locations and from 450ms at orbitofrontal locations. There were significant interactions between participant behavioural sensitivity to emotional state and P1 and N170 amplitudes. However, no significant difference in ERP activity between posed smiles and genuine smiles was observed until 850ms at orbitofrontal locations. An additional finding was greater right temporal and left orbitofrontal activation suggesting hemispheric asymmetry of facial expression processing systems.

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Sutherland, David M. "The cognitive psychophysiology of emotion : ERP studies of emotional information processing using stimuli from the International Affective Picture System." Thesis, University of Dundee, 1998. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.324611.

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Roberts, Jenna. "Do the electrophysiological correlates of recognition memory change with time?" Thesis, University of Manchester, 2013. https://www.research.manchester.ac.uk/portal/en/theses/do-the-electrophysiological-correlates-of-recognition-memory-change-with-time(86ece727-0fbb-4a89-858e-0c9be0118cc4).html.

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The aim of this PhD thesis was to explore the way in which recognition memory changes over time. Of particular interest was how forgetting and systems level consolidation processes alter the qualitative nature of recognition judgments and the impact this has on event related potentials (ERPs) recorded during recognition. An emerging body of fMRI and animal work has started to suggest that changes to the neural basis of memory can be observed after intervals in the order of days and weeks. Although much research has examined the ERP correlates of recent recognition, there has been little attempt to compare this to remote recognition. This gap in the literature is investigated in the present PhD thesis over five ERP and two behavioural experiments. The first set of experiments investigated recognition success i.e. the subjective awareness that a stimulus has been encountered before. Previous work has associated familiarity-based recognition with an early midfrontal ERP effect whereas recollection-based recognition has been linked to a later onsetting parietal ERP effect. These effects were compared for recently studied stimuli and stimuli studied 1 week earlier. Results revealed an attenuation of the late parietal effect. This quantitative difference suggests that the neural networks underlying the ERPs for recent and remote recollection remain the same after a 1 week delay but may be less active after a period of forgetting. Behavioural work linked this to a drop in strength and episodic detail for remote recollection. Examining the midfrontal effect over time produced a more complex pattern of results. The effect was not reliable in Experiment 1 for remote familiarity judgments. In follow up experiments, however, midfrontal effects were reliable for week old memories but were not modulated by either delay or memory strength manipulations. These findings do not permit strong conclusions regarding the way familiarity memory and midfrontal ERPs vary over time, other than to say that the midfrontal effect is not a short lived correlate of recognition memory. A second set of experiments investigated how the length of the delay between study and test impacts on retrieval orientation and retrieval effort. Retrieval orientation refers to the way in which participants strategically alter how a memory cue is processed based on current task demands. Results showed ERP differences when remote memories were cued compared to when recent memories were cued. However, these differences were eliminated when recent and remote memory was matched for performance. This finding indicated that effort required at retrieval rather than memory age per se influenced differential cue processing. A follow up experiment supported this claim but found that participants may utilise delay information during recognition in a very general sense. In this experiment, ERPs indicated different cue processing when participants knew the age of the memories they were trying to retrieve compared to when they did not. Taken together, the results suggest that memory age does not influence the ERP correlates of recognition in a direct manner. More important are the indirect changes occurring over time, such as reduced memory strength, reduced episodic detail, slower reaction times and increased effort at retrieval. These variables, and possibly a range of others, should be controlled as far as possible in studies aiming to explore neural changes driven by systems consolidation. Prospective studies, where the learning phase can be controlled makes this aim feasible, as some of the experiments in this thesis have shown. Future work might benefit from focusing more on variations at encoding, rather than large differences in the length of the retention interval, as has been the traditional approach to this issue.

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Shimizu, Hideki, Hirofumi Saito, and Minoru Hoshiyama. "Characteristics of processing for trait adjectives in depressive persons : an event-related potential study." Nagoya University School of Medicine, 2006. http://hdl.handle.net/2237/6130.

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Beres, Anna M. "Translanguaging as a strategy to boost human learning : an event-related potential (ERP) investigation." Thesis, Bangor University, 2015. https://research.bangor.ac.uk/portal/en/theses/translanguaging-as-a-strategy-to-boost-human-learning--an-eventrelated-potential-erp-investigation(ef98a897-9276-486e-b422-03df63d96ba1).html.

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Bilingual education has witnessed a major shift towards mixing two languages in the classroom. However, adequate methods taking into account the needs of today’s highly multicultural world require scientific testing. Translanguaging is a method of learning in which students produce an output of their learning in a language different to that of instruction. So far, insights into the potential benefits of this method have been exclusively qualitative. The aim of this thesis was to quantify the benefits of translanguaging for new knowledge acquisition. In the main experiment (Chapter 4) I have found neuroscientific evidence for facilitated access to existing semantic representations for items used in learning mediated by translanguaging as compared to control items presented in a monolingual learning context. Participants were tested using a picture-picture priming paradigm after a learning phase involving either English or a code-switch between English and Welsh simultaneous with a switch between reading and speaking. Beyond the expected effect of semantic relatedness on the mean N400 amplitude, well known to index semantic processing effort (Kutas and Hillyard, 1980), a striking main effect of translanguaging on the same N400 was found, suggesting that relevant semantic representations had become selectively more accessible in long-term memory. Moreover, this effect could still be measured 2 to 4 weeks later without participant training. In chapters 5 and 6, I have set out to test the two components of translanguaging separately in order to determine the contribution to the overall effect of code-switching on one hand and comprehension-to-production on another. Chapter 5 focuses on the automaticity of semantic priming and the potential impact of code-switching on the N400 in Welsh-English bilinguals. Chapter 6 focuses on the effects of the comprehension-to-production switch on the N400 in Basque-Spanish bilinguals.

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Vagnini, Victoria Louise. "APPLYING REACTION TIME (RT) AND EVENT-RELATED POTENTIAL (ERPS) MEASURES TO DETECT MALINGERED NEUROCOGNITIVE DEFICIT." UKnowledge, 2007. http://uknowledge.uky.edu/gradschool_diss/528.

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This study examined the ability of reaction time (RT) and Event-Related Potentials (ERP) to detect malingered neurocognitive deficit (MNCD)in two new tasks compared to the TOMM (N = 47). Honest (HON), malingering (MAL), and traumatic brain injury (TBI) groups were compared on accuracy, RT and ERP measures. Overall, the Test of Memory Malingering (TOMM) accuracy was the most effective at classifying groups (hit rate = 100%). Several non-TOMM accuracy variables and RT variables reached hit rates in the range of 71%-88%. The TOMM RT variable had an unlimited time for participants to respond and was the most successful RT variable compared to the Old/New and Repetition Priming tasks that had a short time limit for participants to respond (approximately 1.5 seconds). The classic old/new effect RT pattern was evident for both the HON and TBI groups with significantly faster RTs for old items compared to new items. A logistic regression was employed to see if a RT and/or ERP variable added any unique prediction power in detecting malingering. The frontal-posterior ERP difference score had unique prediction power to detect malingering when classifying MAL vs. TBI (hit rate = 86%). In the Old/New task, ERP responses of HON produced greater activity in the frontal region compared to the posterior region. The opposite trend was found in TBI (posterior activity andgt; frontal) and MAL showed no significant difference.

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De, Dios Constanza. "The Influence of Motivational Salience on Attention Selection: An ERP Investigation." Scholar Commons, 2016. http://scholarcommons.usf.edu/etd/6446.

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The current study used event-related potentials (ERPs) to investigate how motivational salience in the form of expectation violation influences spatial attention. The medial frontal negativity (MFN) ERP indexes expected value, being negative to unexpected punishments and positive to unexpected rewards. The P1 and N1 ERPs index spatial attention, being larger to stimuli in attended locations. This design attached motivational value to locations by making one visual hemifield economically rewarding (greater probability of a rewarding outcome) and the other punishing (greater probability of a punishing outcome). Keypresses to a dot probe following a reward-signifying stimulus were awarded money if correct, and penalized following a punishment-signifying stimulus if incorrect. We predicted that salience would be attached to visual hemifield, thus the MFN would be most negative to punishing outcomes in the rewarding hemifield and most positive to rewarding outcomes in the punishing hemifield. We also predicted that attention would be allocated to a location where expectation was violated, thus the P1 and N1 ERPs would be larger and RTs (reaction times) faster to dot probes appearing in the same side as an outcome that violated expected value. In a sample of 36 participants, there were no significant effects on the MFN, although the means were in the predicted direction, suggesting a lack of power. Contrary to our hypothesis, keypresses were slower, P1 smaller, and N1 larger to probes opposite the location where an expectation violation occurred. This suggested that expectation violation did not direct attention to a particular location, but produced general interference.

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Smith, Hilary Anne. "The Relationship Between Briefly Induced Affect and Cognitive Control Processes: An Event-Related Potential (ERP) Study." BYU ScholarsArchive, 2017. https://scholarsarchive.byu.edu/etd/6427.

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Positive affect is generally associated with improvements in cognitive abilities; however, few studies have addressed positive affect and its relation to specific cognitive control processes. Previous research suggests positive affect conditions are more flexible/distractible states, suggesting cognitive control processes are perhaps decreased in context maintenance and increased in conflict detection/resolution. To measure the cognitive control processes, specific components of the scalp-recorded event-related potentials (ERPs) called the cue slow wave (context maintenance), the N450 (conflict detection), and conflict SP (conflict resolution) were acquired in response to an affective single-trial, cued-Stroop task. Participants were presented with pleasant, neutral, and unpleasant images prior to Stroop instruction (i.e., respond to "color" or "word") and response. Participants had greater accuracy during the pleasant condition when given a longer delay for extra time to process the high conflict task, t(36) = 3.09, p = .004, 95% CI (0.07, 0.02) compared to the unpleasant condition. Additionally, the unpleasant condition resulted in greater context maintenance than pleasant (increased cue-related slow wave amplitude; t(40) = 2.38, p = .02). Unpleasant conditions were associated with greater conflict resolution processes (as measured by the conflict SP) with high conflict trials, t(40) = 2.55, p = .015; whereas pleasant did in congruent trials, t(40) = 2.707, p = .010. Findings suggest negative affective states increase participants' focus on the task in avoidance of the distracting unpleasant picture. Our findings lay the foundation for understanding the differences between state and trait affect on cognitive control processes.

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Haig, Albert Roland. "Missing Links the role of phase synchronous gamma oscillations in normal cognition and their dysfunction in schizophrenia." University of Sydney. Psychological Medicine, 2002. http://hdl.handle.net/2123/848.

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SUMMARY Introduction: There has recently been a great deal of interest in the role of synchronous high-frequency gamma oscillations in brain function. This interest has been motivated by an increasing body of evidence, that oscillations which are synchronous in phase across separated neuronal populations, may represent an important mechanism by which the brain binds or integrates spatially distributed processing activity which is related to the same object. Many models of schizophrenia suggest an impairment in the integration of brain processing, such as a loosening of associations, disconnection, defective multiple constraint organization, or cognitive dysmetria. This has led to recent speculation that abnormalities of high-frequency gamma synchronization may reflect a core dimension of the disturbance underlying this disorder. However, examination of the phase synchronization of gamma oscillations in patients with schizophrenia has never been previously undertaken. Method: In this thesis a new method of analysis of gamma synchrony was introduced, which enables the phase relationships of oscillations in a specific frequency band to be examined across multiple scalp sites as a function of time. This enabled, for the first time, the phase synchronization of gamma oscillations across widespread regions, to be studied in electrical brain activity measured at the scalp in humans. Gamma synchrony responses were studied in electroencephalographic (EEG) data acquired during a commonly employed conventional auditory oddball paradigm. The research consisted of two sets of experiments. In the first set of experiments, data from 100 normal subjects, consisting of 10 males and 10 females in each age decade from 20 to 70, was examined. These experiments were designed to characterize the gamma synchonizations that occurred in response to target and background stimuli and their functional significance in normal brain activity, and to exclude the possibility of these findings being due to electromyogram (EMG) or volume conduction artifact. The examination of functional significance involved the development of an additional new analysis technique. In the second set of experiments, data acquired from 35 patients with schizophrenia and 35 matched normal controls was analyzed. The purpose of these experiments was to determine whether patients showed disturbances of gamma synchrony compared to controls, and to establish the relationship of any such disturbances to medication levels, symptom profiles, duration of illness, and a range of psychophysiological variables. Results: In the 100 normals, responses to target stimuli were characterized by two bursts of synchronous gamma oscillations, an early (evoked) and a late (induced) synchronization, with different topographic distributions. Only the early gamma synchronization was seen in response to background stimuli. The main variable modulating the magnitude of these gamma synchronizations from epoch to epoch was pre-stimulus EEG theta (3-7 Hz) and delta (1-3 Hz) power. Early and late gamma synchrony were also associated with N1 and P3 ERP component amplitude across epochs. Across subjects, the early gamma synchronization was associated with shorter latency of the ERP components P2, N2 and P3, smaller amplitude of N1 and P2, and smaller pre-stimulus beta power. The control analyses showed that these gamma responses were specific to a narrow frequency range (37 to 41 Hz), and were not present in adjacent frequency bands. The responses were not generated by EMG contamination or volume conduction. In the 35 patients with schizophrenia, significant abnormalities of both the early and late synchronizations were observed compared to the 35 normal controls, with distinctive topographic characteristics. In general, early gamma synchrony was increased in patients compared to controls, and late gamma synchrony was decreased. These gamma synchrony disturbances were not related to medication level or the four summed symptom profile scores (positive, negative, general and total). They were, however, associated with duration of illness, becoming less severe the longer the patient had suffered from the disorder. The disordered gamma synchrony in patients was not secondary to abnormalities in other psychophysiological variables, but appeared to represent a primary disturbance. Discussion: The early synchronization may relate to the binding of object representations in early sensory processing, or, given that a constant inter-stimulus interval was employed, may be anticipatory and related to active memory. The late response is probably involved in binding in relation to activation of the internal contextual model involved in late expectancy/contextual processing (context updating or context closure) for target stimuli. The across epochs effects may relate to whether the focus of attention immediately prior to stimulus presentation is internal or is directed at the task. The across subjects effects suggest that a larger magnitude of the early gamma synchronization might indicate that the subject maintains a more stable and less ambiguous internal representation of the environment, that reduces the complexity of input and facilitates target/background discrimination and subsequent processing. The early gamma synchronization findings in patients with schizophrenia suggest that anticipatory processing involving active memory and forward-prediction of the environment is subject to over-binding or the formation of inappropriate associations. The late synchronization disturbances may reflect a fragmentation of contextual processing, and an inability to maintain contextual models of the environment intact over time. Conclusion: This research demonstrates the potential importance of integrative network activity as indexed by gamma phase synchrony in relation to normal cognition, and the possible broad relevance of such activity in psychiatric disorders. In particular, the application in this study to patients with schizophrenia showed that an impairment of brain integrative activity (missing links) might be a key feature of this illness.

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Jaworska, Natalia. "Electrophysiological Indices in Major Depressive Disorder and their Utility in Predicting Response Outcome to Single and Dual Antidepressant Pharmacotherapies." Thèse, Université d'Ottawa / University of Ottawa, 2012. http://hdl.handle.net/10393/22873.

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Certain electrophysiological markers hold promise in distinguishing individuals with major depressive disorder (MDD) and in predicting antidepressant response, thereby assisting with assessment and optimizing treatment, respectively. This thesis examined resting brain activity via electroencephalographic (EEG) recordings, as well as EEG-derived event-related potentials (ERPs) to auditory stimuli and facial expression presentations in individuals with MDD and controls. Additionally, the utility of resting EEG as well as auditory ERPs (AEPs), and the associated loudness-dependence of AEPs (LDAEP) slope, were assessed in predicating outcome to chronic treatment with one of three antidepressant regimens [escitalopram (ESC); bupropion (BUP); ESC+BUP]. Relative to controls, depressed adults had lower pretreatment cortical activity in regions implicated in approach motives/positive processing. Increased anterior cingulate cortex (ACC)-localized theta was observed, possibly reflecting emotion/cognitive regulation disturbances in the disorder. AEPs and LDAEPs, putative indices of serotonin activity (implicated in MDD etiology), were largely unaltered in MDD. Assessment of ERPs to facial expression processing indicated slightly blunted late preconscious perceptual processing of expressions, and prolonged processing of intensely sad faces in MDD. Faces were rated as sadder overall in MDD, indicating a negative processing bias. Treatment responders (vs. non-responders) exhibited baseline cortical hypoactivity; after a week of treatment, cortical arousal emerged in responders. Increased baseline left fronto-cortical activity and early shifts towards this profile were noted in responders (vs. non-responders). Responders exhibited a steep, and non-responders shallow, baseline N1 LDAEP derived from primary auditory cortex activity. P2 LDAEP slopes (primary auditory cortex-derived) increased after a week of treatment in responders and decreased in non-responders. Consistent with overall findings, ESC responders displayed baseline cortical hypoactivity and steep LDAEP-sLORETA slopes (vs. non-responders). BUP responders also exhibited steep baseline slopes and high ACC theta. These results indicate that specific resting brain activity profiles appear to distinguish depressed from non-depressed individuals. Subtle ERP modulations to simple auditory and emotive processing also existed in MDD. Resting alpha power, ACC theta activity and LDAEP slopes predicted antidepressant response in general, but were limited in predicting outcome to a particular treatment, which may be associated with limited sample sizes.

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Mičánková, Veronika. "Kognitivní evokované potenciály a fixace očí při vizuální emoční stimulaci." Master's thesis, Vysoké učení technické v Brně. Fakulta elektrotechniky a komunikačních technologií, 2016. http://www.nusl.cz/ntk/nusl-220722.

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Cílem této diplomové práce je najít a popsat souvislost mezi fixací očí v emočně zabarveném stimulu, kterým je obrázek či video, a EEG signálu. K tomuto studiu je třeba vyvinout softwarové nástroje v prostředí Matlab k úpravě a zpracování dat získaných z eye trackeru a propojení s EEG signály pomocí nově vytvořených markerů. Na základě získaných znalostí o fixacích, jsou v prostředí BrainVision Analyzeru EEG data zpracovány a následně jsou segmentovány a průměrovány jako evokované potenciály pro jednotlivé stimuly (ERP a EfRP). Tato práce je vypracována ve spolupráci s Gipsa-lab v rámci výzkumného projektu.

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Nelson, Annie Hirt. "Effects of Reading Comprehension and Fluency Abilities on the N400 Event-Related Potential." Scholar Commons, 2010. https://scholarcommons.usf.edu/etd/1721.

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The purpose of this study is to add to the knowledge of reading development by investigating reading processes from a neurocognitive and educational perspective. This study seeks to provide some insight about reading development for the neuroscience field. The goals of this study are to attain a clearer picture of reading development by using both behavioral assessments and event-related potentials (ERPs), and to begin to bridge the gap between both fields of study. Children between the ages of 7 and 13 were placed in one of two groups depending on their reading comprehension levels for the first analyses, and reading fluency levels for the second analyses. Children were asked to read active, active violation, passive and passive violation sentences, that had been manipulated to contain primed semantic context. Brain waves were recorded during the task. Repeated measures ANOVAS were used to analyze the mean N400 like amplitudes for the groups for the sentence ending target words. The lower fluency group had the largest amplitudes for all sentence types even though the sentences were two grade levels below their actual fluency levels; decoding and reading rate were not a problem for them in the reading task. Also, the lower fluency group processed the anomalous sentences very differently than the lower comprehension group whose average age was close to the same. Other N400 like amplitudes differences among the groups were observed. Implications for reading education consist of reintroducing the sentence processing exercises back into the classroom instruction in order to improve reading comprehension skills among fluent readers with comprehension problems.

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Williams, Kimberley Clare. "Differences in visual attention processing: An event-related potential comparative analysis within psychotic disorders." University of the Western Cape, 2018. http://hdl.handle.net/11394/6746.

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>Magister Scientiae - MSc
Introduction: Sustained attention is known to be dysfunctional in psychotic disorders. Sustained attention is the ability to remain focused on a specific time-locked stimulus within a task. We aimed to determine whether there are specific group differences between CON and three psychotic disorders: SCZ, MPD and BPD, then to determine differences between these psychotic disorders. This included differences in behavioural performance and prominent electrophysiological event-related potential (ERP) wave components during cueing and target processing of a visual sustained attention task. Further we aimed to characterize ERP waveform component relationships across and within these groups for demographics, substance use, behavioural performance, and clinical variables, the last limited to the psychotic groups. Lastly, we investigated the effects of prescribed medications on ERP wave components within the psychotic groups. Methodology: 103 participants (29 schizophrenia (SCZ), 28 bipolar disorder with a history of psychosis (BPD), 21 methamphetamine-induced psychotic disorder (MPD), and 30 controls (CON)) underwent electroencephalography (EEG) record while completing a visual continuous performance task. Participants were presented with 60 trials with three consecutive S’s, the presentation of the third S required a behavioural response. Prominent ERP waveform components were extracted from cues and target stimulus. Group differences were determined by ANOVA with Bonferroni post-hoc correction or multivariate Kruskal-Wallis test dependent on data distribution. Relationships between ERP wave components were determined appropriate with Spearman’s Rank order correlation analyses.

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Houston, James R. "AGING AND CONTEXT EFFECTS IN WORKING MEMORY: AN EVENT-RELATED POTENTIAL INVESTIGATION." University of Akron / OhioLINK, 2016. http://rave.ohiolink.edu/etdc/view?acc_num=akron1470236660.

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Spokes, Tara. "Ageing and Cognitive Inhibition: An ERP analysis." Thesis, Griffith University, 2016. http://hdl.handle.net/10072/365459.

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Impaired cognitive inhibition is one of a number of changes in cognitive functioning that are associated with healthy ageing. Cognitive inhibition is the ability to suppress or withhold some cognitive process and includes the ability to block out distracting information. Successful cognitive inhibition underlies improved performance on a range of executive functions including problem solving, long-term planning and goal-directed behaviour (Darowski, Helder, Zacks, Hasher, & Hambrick, 2008). One theory posits that age-related deficits in cognitive inhibition may underlie general cognitive decline associated with older adults (Hasher & Zacks, 1988; Hasher, Zacks, & Rahhal, 1999). Previous behavioural studies have found that automatic, or unintentional cognitive inhibition is preserved with age while controlled, intentional cognitive inhibition is impaired in older adults (Collette, Germain, Hogge, & Van der Linden, 2009). In contrast, a number of neuroimaging studies suggest that older adults show less differentiation than young adults in neural processing of automatic and controlled tasks. In particular, it has been suggested that automatic tasks are processed more like controlled tasks, suggesting increased cognitive effort required to complete them (Germain & Collette, 2008).
Thesis (PhD Doctorate)
Doctor of Philosophy (PhD)
School of Applied Psychology
Griffith Health
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Rego, José. "Temporal Distancing and Emotion Regulation : An ERP Study." Thesis, Högskolan i Skövde, Institutionen för biovetenskap, 2018. http://urn.kb.se/resolve?urn=urn:nbn:se:his:diva-16062.

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Reappraisal is a cognitive emotion regulation strategy that induces a reduction in the arousal response elicited by both unpleasant and pleasant stimuli.One form of reappraisal is that of temporal distancing. Temporal distancing is the cognitive tool that allows the individual to perceive the stimuli in a broader temporal perspective.Reappraisal’s impact on the arousal response can be measured by assessing the amplitude of the event-related potential (ERP) component the late positive potential(LPP), a centro-parietal slow-wave ERP beginning around 350 ms post-stimulus and sustaining for up to several seconds. The aim of this study was to test various temporal-related perspectives in order to see their effect on the LPP. The analysis of the data suggests that a decrease in the amplitude of the LPP in response to emotionally unpleasant facial stimuli corresponds to adopting a temporal distancing strategy, regardless of the exact temporal distance chosen.

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Hansen, Tara. "Auditory and Visual Correlates of the Processing of Gapping Structures in Adults." Diss., CLICK HERE for online access, 2005. http://contentdm.lib.byu.edu/ETD/image/etd847.pdf.

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Deguchi, Chizuru. "Segmental and supra-segmental aspects of speech perception in familiar and unfamiliar languages: Influence of the listener's native language as revealed by Event-related potentials (ERPs)." Doctoral thesis, Università degli studi di Padova, 2011. http://hdl.handle.net/11577/3421599.

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The phonological structure differs between languages. Human brain structure subserving speech perception is shaped through early exposure to and long-term experience with one’s native language, so that the sensitivity to specific acoustic cues that are relevant in that language develops. Such adaptive process of brain plasticity facilitates to recognize phonemes and capture prosodic signals correctly in the native language, whereas it augments difficulty to perceive some linguistic cues in foreign languages. Speech phonology consists of segmental and suprasegmental components. Segmental components are expressed by formants defining phonemes, and suprasegmental components are defined by pitch (fundamental frequency: F0), intensity and temporal parameters (duration of phonemes and of pauses). The present studies are aimed at investigating cortical auditory processing of segmental and suprasegmental components of speech using the techniques of event-related brain potentials (ERPs). In Study I, two experiments were conducted to explore the auditory perception of vowels that belong or not to the phonemic inventory of listeners’ native language. The mismatch negativity (MMN) is an ERP component reflecting pre-attentive detection of auditory deviance compared with the integrated representation of standard features in the sensory memory (Näätänen et al., 2007; Kujala et al., 2007 for reviews). In the present study, this component was used to tap language-specific long-term memory traces for vowels (Näätänen et al., 1997; Cheour et al., 1998; Winkler et al., 1999a). An auditory sequence including four vowels (one standard and three deviants), each pronounced by three speakers, was presented in passive and active listening conditions. When all the vowels were distinctive in the native inventory (Experiment 1), the MMN was elicited by each deviant vowel category independently of speaker variability, demonstrating pre-attentive categorization based on long-term memory traces. By contrast, when a part of vowels did not belong to the native phonemic inventory (Experiment 2), deviant vowels did not elicit MMNs, indicating the lack of automatic categorization. Moreover, speaker’s variability interacted with vowel category only in the active listening condition, as reflected by behavioral data and cognitive ERP components, suggesting that listeners depended more on conscious acoustic analysis of each stimulus than on pre-attentive categorization, when the deviant to discriminate is physically similar to the standard or is not supported by the inventory in the native language. In Study II, another experiment (Experiment 3) was conducted to investigate the perception of small and large pitch changes embedded in sentences spoken in listeners’ native language, jabberwocky or a foreign language. Behavioral performance in a pitch change detection task and the ERP components elicited by pitch changes (an early centro-temporal negativity and a later positivity) were analyzed. Results showed that subjects processed phrasal pitch better in their native language than in the foreign language, while the results for jabberwocky sentences were intermediate, suggesting that both familiar prosodic patterns and natural and meaningful context in the native language help listeners to detect subtle changes in phrasal pitch contour. Overall results confirmed that long-term experience with one’s native language has effects from early stages of cortical auditory processing involved in speech perception, modulating conscious perception of speech stimuli in different languages.
La struttura fonologica varia tra le lingue. I sistemi neurali nel cervello umano che sottostanno la percezione del linguaggio parlato vengono strutturati mediante l’esposizione precoce e la lunga esperienza con la lingua nativa, in modo che la sensibilità a specifici segnali acustici che sono pertinenti in quella lingua si sviluppi in modo ottimale ed estremamente efficiente. Tale processo adattivo di plasticità cerebrale facilita il riconoscimento dei fonemi e l’acquisizione degli indizi prosodici nella lingua nativa. D’altro canto, lo stesso processo aumenta la difficoltà di percepire alcuni segnali linguistici in lingue straniere. La presente tesi presenta degli studi effettuati per indagare l’elaborazione corticale delle componenti segmentali e soprasegmentali del linguaggio parlato utilizzando le tecniche di potenziali evento-relati (ERP). Nello Studio I, sono stati condotti due esperimenti sulla percezione uditiva delle vocali che appartengono o non appartengono all'inventario fonemico della lingua nativa dei soggetti. La Mismatch Negativity (MMN) è una componente di ERP che riflette la rilevazione pre-attentiva della devianza acustica dello stimolo attuale rispetto alla rappresentazione integrata dello stimolo standard nella memoria sensoriale (Näätänen, 2007; Kujala et al., 2007) ed è stata utilizzata anche per sondare le rappresentazioni lingua-specifiche nella memoria a lungo termine (Näätänen, 1997; Cheour et al., 1998; Winkler et al., 1999a). Una sequenza uditiva è stata costruita con quattro vocali (una standard e tre devianti), ciascuna pronunciata da tre parlanti diverse, ed è stata presentata ai soggetti nelle condizioni di ascolto attivo e passivo. Quando tutte le vocali erano distintive nell'inventario della lingua nativa, la MMN è stata generata da ciascuna vocale deviante indipendentemente dalla variabilità delle parlanti, dimostrando la categorizzazione pre-attentiva basata sulle rappresentazioni nella memoria a lungo termine (Esperimento 1). Al contrario, quando una parte delle vocali non apparteneva all'inventario fonemico nativo, la MMN è stata generata da nessuna delle vocali devianti, che indica la mancanza di categorizzazione automatica (Esperimento 2). Inoltre, la variabilità dovuta alle parlanti ha interagito con la categoria vocale nella condizione di ascolto attivo, come risulta dai dati comportamentali e dalle componenti cognitive di ERP, quando il deviante per discriminare è fisicamente simile allo standard (Esperimento 1) oppure non è supportato dall'inventario nella lingua nativa (Esperimento 2), suggerendo che l’analisi acustica consapevole ed altre strategie cognitive sono impiegate per categorizzare i devianti acusticamente difficili o ambigui. Nello Studio II (Esperimento 3), è stata indagata la percezione dei cambiamenti piccoli e grandi di altezza tonale (pitch) immessi nelle frasi parlate nella lingua nativa degli ascoltatori, jabberwocky o in una lingua straniera. Sono state analizzate le prestazioni in un compito di rilevazione delle incongruenze prosodiche e gli ERP generati dai cambiamenti di altezza tonale (una componente negativa precoce e una positività più tardiva). I risultati hanno dimostrato che i soggetti sono più efficienti ad elaborare l’altezza tonale nel contesto frasale della loro lingua nativa che della lingua straniera, mentre i risultati per le frasi in jabberwocky erano intermedi, suggerendo che sia la prosodia familiare che il contesto naturale e semanticamente interpretabile della lingua nativa aiutano gli ascoltatori a rilevare i cambiamenti sottili di altezza tonale. I risultati globali di questi studi hanno confermato che la lunga esperienza con la lingua nativa ha un impatto sull’elaborazione uditiva nella corteccia fin dagli stadi precoci della percezione del linguaggio parlato, di conseguenza modulando la percezione cosciente degli stimoli parlati in lingue diverse.

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Williams, Kimberley Clare. "Differences in visual attention processing: An event-related potential comparative analysis within psychotic disorders." University of the Western Cape, 2019. http://hdl.handle.net/11394/6706.

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>Magister Scientiae - MSc
INTRODUCTION: Sustained attention is known to be dysfunctional in psychotic disorders. Sustained attention is the ability to remain focused on a specific time-locked stimulus within a task. We aimed to determine whether there are specific group differences between CON and three psychotic disorders: SCZ, MPD and BPD, then to determine differences between these psychotic disorders. This included differences in behavioural performance and prominent electrophysiological event-related potential (ERP) wave components during cueing and target processing of a visual sustained attention task. Further we aimed to characterize ERP waveform component relationships across and within these groups for demographics, substance use, behavioural performance, and clinical variables, the last limited to the psychotic groups. Lastly, we investigated the effects of prescribed medications on ERP wave components within the psychotic groups. METHODOLOGY: 103 participants (29 schizophrenia (SCZ), 28 bipolar disorder with a history of psychosis (BPD), 21 methamphetamine-induced psychotic disorder (MPD), and 30 controls (CON)) underwent electroencephalography (EEG) record while completing a visual continuous performance task. Participants were presented with 60 trials with three consecutive S’s, the presentation of the third S required a behavioural response. Prominent ERP waveform components were extracted from cues and target stimulus. Group differences were determined by ANOVA with Bonferroni post-hoc correction or multivariate Kruskal-Wallis test dependent on data distribution. Relationships between ERP wave components were determined appropriate with Spearman’s Rank order correlation analyses. RESULTS: (1) MPD reported higher use of substances compared to CON, SCZ and BPD. SCZ behavioural performance was poorer compared to CON which was shown by their longer response times, reduced accuracy and increased errors of omission. Clinically, MPD was found to have a shorter duration of illness compared to SCZ. Then SCZ was found to have more positive symptoms compared to BPD whereas BPD had more negative symptoms compared to SCZ. For the first cue, wave component differences were found only over the left hemisphere, for P100 amplitude over the frontal cortex, P300 amplitude over the central cortex, and N170 amplitude over the parietal cortex. For the presentation of the second cue, differences noted for all groups were localised to the frontal and central brain regions, for P100 and N170 ERP waveforms. For the target stimulus wave component differences were found over the prefrontal, frontal and parietal brain regions, within CON, SCZ, BPD and MPD. (2) For the first cue, education positively correlated with the N170 left parietal amplitude in CON and P300 right parietal amplitude in MPD. During the second cue, the left parietal N170 latency in SCZ correlated positively with education and the left central P300 latency correlated negatively with education in MPD. The age on the day of testing correlated positively with the target left frontal P300 latency in MPD. For the first cue, substance use positively correlated with the left and right parietal P300 latency and negatively for the right parietal P100 amplitude in SCZ. In MPD, a negative correlation was noted across left and right prefrontal N170 and P300 amplitudes, and positive correlation for the left prefrontal P300 latency in MPD. For the target stimulus, correlations were evident for the left and right parietal N70, N170 amplitudes, P300 latency, the right parietal P100 amplitude and left central P300 latency in SCZ. For the first cue, in SCZ PANSS total score correlated positively with left and right central P300 amplitudes and the left parietal P300 amplitude. For the second cue; in MPD, the PANSS negative symptom score, positively correlated with the P100 and N170 left parietal amplitude, left and right parietal P150 amplitude, left central and right parietal P300 amplitude. For the target, the Hamilton depression rating scale correlated positively with the left and right frontal P300 amplitude in MPD and then negatively with the right parietal P300 amplitude in SCZ. Behavioural performance in CON, positively correlated with the left parietal N70, P100, P150 and N170 amplitude the number of correct responses, and left central N170 amplitude. While the number of impulsive responses correlated negatively with the left parietal N70, P100, P150 and N170 and the left central N170 amplitude of CON. For the second cue, behavioural performance was related to the fronto-parietal relationship across all groups. For the target stimulus, impulsive responses positively correlated with the left parietal N70 latency in SCZ. Overall response time negatively correlated with the right parietal P300 latency for SCZ. (3) Medication was found to affect ERP wave components during the sustained visual attention task. For the first cue FGA’s increased the left central P100 amplitude in both SCZ and BPD and decreased the left parietal P100 amplitude in SCZ only. The use of antipsychotics increased the right parietal N70 and left central P100 amplitudes in BPD, specifically the right prefrontal N170 amplitude was increased with the use of SGA’s. Then clozapine use increased the left frontal P100 amplitude in SCZ. For the second cue, SGA’s decreased the right parietal P150 amplitude in SCZ but in MPD the right parietal P150 amplitude was increased with haloperidol use, and FGA. SGA’s increased the left parietal P300 latency in BPD and sodium valproate decreased the left prefrontal P300 latency. For the target stimulus, SGA’s decreased the right parietal P100, P150 and left parietal P150 amplitudes and increased the left central P300 latency in BPD. CONCLUSION: (1) sustained attentional performance is poorer in SCZ. Our study adds to previous studies showing attention processing deficits in SCZ, are evident during cueing of a sustained attention tasks; (2) substance use was found to slow cognitive processing, education improved executive function and information processing, and symptom severity was associated with dysfunction of prefrontal and frontal cortices; (3) antipsychotic medication was related to improved processing of salient information. These data support the current literature and provide novel insights to the attentional processing deficits during cueing in the psychotic disorders.

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Kingery, Kathleen M. B. A. "Brain Activity During Periods of Longer Reaction Times: Event-Related Potential Comparisons of Children With and Without ADHD." University of Cincinnati / OhioLINK, 2017. http://rave.ohiolink.edu/etdc/view?acc_num=ucin1504869304401252.

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Perna, Patrick. "Event Related Potential (ERP) correlates of verbal and spatial cognitive performance related to the effects of gender, handedness and maturation on laterality." Thesis, Queen's University Belfast, 1996. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.318825.

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Raldiris, Tarah L. "Focused Attention vs. Open Monitoring: An Event-Related Potential Study of Emotion Regulation by Two Distinct Forms of Mindfulness Meditation." VCU Scholars Compass, 2017. http://scholarscompass.vcu.edu/etd/4863.

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This study investigated the effects of two novel forms of 8-week mindfulness meditation training, focused attention (FA) and open monitoring (OM), relative to an established training, mindfulness-based cognitive therapy (MBCT), on early emotional reactivity to negative emotional images as assessed by electroencephalography (EEG). Data on the late-positive potential (LPP) were analyzed to address whether the three mindfulness interventions attenuated the LPP from pre- to post-intervention, and if significant differences existed between groups in LPP at post-intervention. Rather than an attenuation, results indicated an average increase in LPP amplitude from pre- to post-intervention. No significant differences were found in the LPP between the training conditions at post-intervention. These results provide preliminary evidence that mindfulness training in novice practitioners may heighten initial emotional reactivity. Further, well-designed research is needed to examine a wider range of neural responses to better understand emotion regulation process effects of different forms of mindfulness training.

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Abu, Qouta Nedal. "Auditiv mismatch negativity (MMN) : under hög och låg visuell belastning." Thesis, Stockholms universitet, Psykologiska institutionen, 2018. http://urn.kb.se/resolve?urn=urn:nbn:se:su:diva-157556.

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Auditiv mismatch negativity (MMN) är en neurologisk hjärnrespons som visar hur känslig hjärnan är för auditiva förändringar. Perceptuell load teorin argumenterar att krävande visuella sökuppgifter eliminerar auditiva distraktorer från att bearbetas i arbetsminnet. Syftet är att observera event-related potential (ERP) händelser för att se om avvikande ljud exkluderas under hög visuell belastning. Ett korsmodalt uppmärksamhetstest utfördes där deltagarna (N = 26) fick utföra en visuell sökuppgift med två svårighetsgrader samtidigt som de skulle ignorera tonfrekvenser som spelades upp i bakgrunden. Resultatet visade auditiv MMN-respons under både låg och hög visuell belastning. Det fanns ingen tydlig skillnad på MMN mellan låg och hög belastning. Hörselcortex registrerade en avvikande ton i oddball och att samma ton fanns i kontroll-upplägget. Argument för att distraktorer bearbetas under kontrollerad uppmärksamhet. Ytterligare studier med större stickprov och olika ljudfrekvenser, naturliga och icke naturliga, krävs för att se hur ljuden påverkar bearbetningsprocessen.

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Kastrati, Granit. "Event-related potential correlates of visual consciousness : a review of theories and empirical studies." Thesis, Högskolan i Skövde, Institutionen för kommunikation och information, 2012. http://urn.kb.se/resolve?urn=urn:nbn:se:his:diva-6124.

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Two influential theories of consciousness disagree about if consciousness initially arises along the occipitotemporal cortex to later engage frontoparietal regions and attentional mechanisms, or if it necessarily requires the latter. Consequently, different predictions are made about the temporal emergence of consciousness. The event-related potential (ERP) technique can be used to resolve the issue. It can temporally track neural activity of consciously perceived stimuli relative to stimuli bypassing consciousness. This essay describes the two theories and reviews ERP studies on visual consciousness and its relationship to attention. Three ERP correlates of consciousness have been proposed. The question is if they should be interpreted as supporting the one or the other theory. Most plausibly, visual consciousness arises along occipitotemporal regions and later incorporates frontal areas engaging higher cognitive functions. Importantly it seems that consciousness cannot arise without spatial attention/parietal regions.

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Hitziger, Sebastian. "Modélisation de la variabilité de l'activité électrique dans le cerveau." Thesis, Nice, 2015. http://www.theses.fr/2015NICE4015/document.

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Cette thèse explore l'analyse de l'activité électrique du cerveau. Un défi important de ces signaux est leur grande variabilité à travers différents essais et/ou différents sujets. Nous proposons une nouvelle méthode appelée "adaptive waveform learning" (AWL). Cette méthode est suffisamment générale pour permettre la prise en compte de la variabilité empiriquement rencontrée dans les signaux neuroélectriques, mais peut être spécialisée afin de prévenir l'overfitting du bruit. La première partie de ce travail donne une introduction sur l'électrophysiologie du cerveau, présente les modalités d'enregistrement fréquemment utilisées et décrit l'état de l'art du traitement de signal neuroélectrique. La principale contribution de cette thèse consiste en 3 chapitres introduisant et évaluant la méthode AWL. Nous proposons d'abord un modèle de décomposition de signal général qui inclut explicitement différentes formes de variabilité entre les composantes de signal. Ce modèle est ensuite spécialisé pour deux applications concrètes: le traitement d'une série d'essais expérimentaux segmentés et l'apprentissage de structures répétées dans un seul signal. Deux algorithmes sont développés pour résoudre ces problèmes de décomposition. Leur implémentation efficace basée sur des techniques de minimisation alternée et de codage parcimonieux permet le traitement de grands jeux de données.Les algorithmes proposés sont évalués sur des données synthétiques et réelles contenant des pointes épileptiformes. Leurs performances sont comparées à celles de la PCA, l'ICA, et du template-matching pour la détection de pointe
This thesis investigates the analysis of brain electrical activity. An important challenge is the presence of large variability in neuroelectrical recordings, both across different subjects and within a single subject, for example, across experimental trials. We propose a new method called adaptive waveform learning (AWL). It is general enough to include all types of relevant variability empirically found in neuroelectric recordings, but can be specialized for different concrete settings to prevent from overfitting irrelevant structures in the data. The first part of this work gives an introduction into the electrophysiology of the brain, presents frequently used recording modalities, and describes state-of-the-art methods for neuroelectrical signal processing. The main contribution of this thesis consists in three chapters introducing and evaluating the AWL method. We first provide a general signal decomposition model that explicitly includes different forms of variability across signal components. This model is then specialized for two concrete applications: processing a set of segmented experimental trials and learning repeating structures across a single recorded signal. Two algorithms are developed to solve these models. Their efficient implementation based on alternate minimization and sparse coding techniques allows the processing of large datasets. The proposed algorithms are evaluated on both synthetic data and real data containing epileptiform spikes. Their performances are compared to those of PCA, ICA, and template matching for spike detection

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Acunzo, David Jean Pascal. "Interaction between visual attention and the processing of visual emotional stimuli in humans : eye-tracking, behavioural and event-related potential experiments." Thesis, University of Edinburgh, 2013. http://hdl.handle.net/1842/8016.

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Past research has shown that the processing of emotional visual stimuli and visual attention are tightly linked together. In particular, emotional stimuli processing can modulate attention, and, reciprocally, the processing of emotional stimuli can be facilitated or inhibited by attentional processes. However, our understanding of these interactions is still limited, with much work remaining to be done to understand the characteristics of this reciprocal interaction and the different mechanisms that are at play. This thesis presents a series of experiments which use eye-tracking, behavioural and event-related potential (ERP) methods in order to better understand these interactions from a cognitive and neuroscientific point of view. First, the influence of emotional stimuli on eye movements, reflecting overt attention, was investigated. While it is known that the emotional gist of images attracts the eye (Calvo and Lang, 2004), little is known about the influence of emotional content on eye movements in more complex visual environments. Using eye-tracking methods, and by adapting a paradigm originally used to study the influence of semantic inconsistencies in scenes (Loftus and Mackworth, 1978), we found that participants spend more time fixating emotional than neutral targets embedded in visual scenes, but do not fixate them earlier. Emotional targets in scenes were therefore found to hold, but not to attract, the eye. This suggests that due to the complexity of the scenes and the limited processing resources available, the emotional information projected extra-foveally is not processed in such a way that it drives eye movements. Next, in order to better characterise the exogenous deployment of covert attention toward emotional stimuli, a sample of sub-clinically anxious individuals was studied. Anxiety is characterised by a reflexive attentional bias toward threatening stimuli. A dot-probe task (MacLeod et al., 1986) was designed to replicate and extend past findings of this attentional bias. In particular, the experiment was designed to test whether the bias was caused by faster reaction times to fear-congruent probes or slower reaction times to neutral-congruent probes. No attentional bias could be measured. A further analysis of the literature suggests that subliminal cue stimulus presentation, as used in our case, may not generate reliable attentional biases, unlike longer cue presentations. This would suggest that while emotional stimuli can be processed without awareness, further processing may be necessary to trigger reflexive attentional shifts in anxiety. Then the time-course of emotional stimulus processes and its modulation by attention was investigated. Modulations of the very early visual ERP C1 component by emotional stimuli (e.g. Pourtois et al., 2004; Stolarova et al., 2006), but also by visual attention (Kelly et al., 2008), were reported in the literature. A series of three experiments were performed, investigating the interactions between endogenous covert spatial attention and object-based attention with emotional stimuli processing in the C1 time window (50–100 ms). It was found that emotional stimuli modulated the C1 only when they were spatially attended and task-irrelevant. This suggests that whilst spatial attention gates emotional facial processing from the earliest stages, only incidental processing triggers a specific response before 100 ms. Additionally, the results suggest a very early modulation by feature-based attention which is independent from spatial attention. Finally, simulated and actual electroencephalographic data were used to show that modulations of early ERP and event-related field (ERF) components are highly dependent on the high-pass filter used in the pre-processing stage. A survey of the literature found that a large part of ERP/ERF reports (about 40%) use high-pass filters that may bias the results. More particularly, a large proportion of papers reporting very early modulations also use such filters. Consequently, a large part of the literature may need to be re-assessed. The work described in this thesis contributes to a better understanding of the links between emotional stimulus processing and attention at different levels. Using various experimental paradigms, this work confirms that emotional stimuli processing is not ‘automated’, but highly dependent on the focus of attention, even at the earlier stages of visual processing. Furthermore, the uncovered potential bias generated by filtering will help to improve the reliability and precision of research in the ERP/ERF field, and more particularly in studies looking at early effects.

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Skavhaug, Ida-Maria. "Metamemory or just memory? : searching for the neural correlates of judgments of learning." Thesis, University of Stirling, 2010. http://hdl.handle.net/1893/2410.

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Judgments of Learning (JOLs) are judgments of the likelihood of remembering recently studied material on a future test. Although JOLs have been extensively studied, particularly due to their important applications in education, relatively little is known about the cognitive and neural processes supporting JOLs and how these processes relate to actual memory processing. Direct access theories describe JOLs as outputs following direct readings of memory traces and hence predict that JOLs cannot be distinguished from objective memory encoding operations. Inferential theories, by contrast, claim JOLs are products of the evaluation of a number of cues, perceived by learners to carry predictive value. This alternative account argues that JOLs are made on the basis of multiple underlying processes, which do not necessarily overlap with memory encoding. In this thesis, the neural and cognitive bases of JOLs were examined in a series of four ERP experiments. Across experiments the study phase ERP data showed that JOLs produce neural activity that is partly overlapping with, but also partly distinct from, the activity that predicts successful memory encoding. Furthermore, the neural correlates of successful memory encoding appear sensitive to the requirements to make a JOL, emphasising the close interaction between subjective and objective measures of memory encoding. Finally, the neural correlates of both JOLs and successful memory encoding were found to vary depending on the nature of the stimulus materials, suggesting that both phenomena are supported by multiple cognitive and neural systems. Although the primary focus was on the study phase ERP data, the thesis also contains two additional chapters reporting the ERP data acquired during the test phases of three of the original experiments. These data, which examined the relative engagements of retrieval processes for low and high JOL items, suggest that encoding processes specifically resulting in later recollection (as opposed to familiarity) form one reliable basis for making JOLs. Overall, the evidence collected in this series of ERP experiments suggests that JOLs are not pure products of objective memory processes, as suggested by direct access theories, but are supported by neural systems that are at least partly distinct from those supporting successful memory encoding. These observations are compatible with inferential theories claiming that JOLs are supported by multiple processes that can be differentially engaged across stimulus contents.

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Kamp, Siri-Maria. "The Effects of Physical Distinctiveness and Word Commonness on Brain Waves and Subsequent Memory: An ERP Study." Scholar Commons, 2010. https://scholarcommons.usf.edu/etd/1675.

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Words that deviate in their physical characteristics from their surrounding lead to enhanced recall memory, a pattern known as the Von Restorff effect. Furthermore, common (high frequency; HF) words are more likely to be recalled than uncommon (low frequency; LF) words when they occur in pure lists, while this pattern is reversed in mixed lists of both HF and LF words. This study investigated whether the Von Restorff effect and the reversal of word frequency effects in mixed lists, which may both be explained by enhanced perceived distinctiveness, are associated with common underlying brain processes. Event-related potentials (ERPs) were recorded while participants studied and subsequently recalled 70 word lists using rote memorization strategies. The three list types included (1) 14 regular-sized and one larger word, (2) 14 HF words and one LF word, or (3) 14 LF words and one HF word. The behavioral data showed a typical Von Restorff effect, a word frequency effect, as well as a reversal of the word frequency effect for LF words isolated in HF word lists ("LF isolates"). Larger words and LF isolates elicited a P300, an ERP component associated with subjective distinctiveness, whose amplitude was correlated with subsequent recall for both word types. This indicates that LF isolates were perceived as distinctive, and that this perceived distinctiveness aided subsequent recall in a similar way as for physically deviant words. Both larger words and LF isolates also elicited a left-lateralized slow wave which was larger for subsequently recalled than for not recalled words. This ERP component supposedly reflects item-to-item elaborative processes, indicating that such elaborative processes are enhanced when LF words occur in HF word list. HF words isolated in lists of LF words did not elicit comparable ERP subsequent memory effects. Rather, for these "HF isolates", the N400 was negatively correlated with subsequent recall, an ERP component that reflects semantic integration processes. We conclude that the reversal of the word frequency effect in mixed lists can be explained by a combination of enhanced subjective distinctiveness and enhanced inter-item elaborative processes for LF words that occur in lists of HF words.

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Dambacher, Michael, and Reinhold Kliegl. "Synchronizing timelines: Relations between fixation durations and N400 amplitudes during sentence reading." Universität Potsdam, 2007. http://opus.kobv.de/ubp/volltexte/2011/5721/.

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We examined relations between eye movements (single-fixation durations) and RSVP-based event-related potentials (ERPs; N400’s) recorded during reading the same sentences in two independent experiments. Longer fixation durations correlated with larger N400 amplitudes. Word frequency and predictability of the fixated word as well as the predictability of the upcoming word accounted for this covariance in a path-analytic model. Moreover, larger N400 amplitudes entailed longer fixation durations on the next word, a relation accounted for by word frequency. This pattern offers a neurophysiological correlate for the lag-word frequency effect on fixation durations: Word processing is reliably expressed not only in fixation durations on currently fixated words, but also in those on subsequently fixated words.

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Siders, Craig A. "Error Related Negativity in Parkinson’s Disease: A Test of the Validity of MesencephalicDopamine Contributions to ERN." Scholar Commons, 2008. https://scholarcommons.usf.edu/etd/496.

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A model proposed by Holroyd and Coles (2002) stating that error related negativity (ERN) is caused by a decrease in mesencephalic dopamine output to the ACC was tested. A group of individuals with Parkinson's disease (N = 16) and an age and education matched group free from neurological disorder (N = 16) completed a card guessing task where the magnitude of monetary penalties and rewards for incorrect and correct answers was varied by block. Individuals with Parkinson's disease were tested after an overnight washout from dopamingeric medications. The amplitude of the mid-frontal negativity elicited by feedback was analyzed with spatial and temporal principal components analyses. Dipole source analyses were also performed. Analyses revealed no significant differences in the mid-frontal negativity amplitude between the two groups. In addition, the magnitude of consequence and the validity of response had no significant effects on fERN amplitude although there was a trend for higher magnitude consequences to be associated with larger fERN amplitude. Dipole analyses indicated the source of the mid-frontal negativity fell into the cingulate, specifically the cingulate gyrus. The results suggest that the mid-frontal negativity elicited by feedback indicating an error was made remains intact in individuals with Parkinson's disease. This does not support predictions made by Holroyd and Coles' model in regard to this group unless disruptions to the system that produces the fERN do not occur until later stages in the disease. An additional finding was a late positive potential for the error trials which began approximately 450 milliseconds after feedback and continued throughout the epoch. The ramifications of this wave are discussed.

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Hyde, Molly. "The Combined and Differential Effects of Monophasic and Biphasic Repetitive Transcranial Magnetic Stimulation on ERP-Indexed Attentional Processing in Treatment-Resistant Depression." Thesis, Université d'Ottawa / University of Ottawa, 2019. http://hdl.handle.net/10393/39932.

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In addition to low mood, major depressive disorder (MDD) is characterized by persistent cognitive deficits that impair daily functioning and resist improvement with conventional pharmacotherapies. Repetitive transcranial magnetic stimulation (rTMS) holds promise as an efficacious alternative, offering better outcomes than medication for patients with treatment-resistant depression (TRD). Yet, current rTMS protocols that administer sinusoidal biphasic pulses achieve remission in less than the majority. However, monophasic pulses may yield higher success rates based on greater cortical excitation/neuromodulation strength. MDD is associated with altered P300 event-related potentials (ERPs), indexing decreased attentional resource allocation and slower cortical processing speed. Using a cohort of 20 TRD patients who received high-frequency rTMS, this study aimed to assess the impact of monophasic and biphasic stimulation on attention-related P300 measures and their utility as correlates of clinical/cognitive response. Based on baseline and post-treatment change in P300 components, rTMS-induced increases in automatic attention/passive information processing differed by pulse type and predicted greater clinical improvement in depressed individuals. This study represents an important step towards identifying cognitive changes and underlying cortical mechanisms associated with rTMS response and targeted MDD treatment.

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Baker, Katherine Louise. "Cognitive Evoked Auditory Potentials and Neuropsychological Measures Following Concussion in College Athletes." Miami University / OhioLINK, 2008. http://rave.ohiolink.edu/etdc/view?acc_num=miami1209744334.

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Logan, Dustin Michael. "Error Awareness and Apathy in Moderate-to-Severe Traumatic Brain Injury." BYU ScholarsArchive, 2014. https://scholarsarchive.byu.edu/etd/5530.

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Moderate-to-severe traumatic brain injury (M/S TBI) is a growing public health concern with significant impact on the cognitive functioning of survivors. Cognitive control and deficits in awareness have been linked to poor recovery and rehabilitation outcomes. One way to research cognitive control is through awareness of errors using electroencephalogram and event-related potentials (ERPs). Both the error-related negativity and the post-error positivity components of the ERP are linked to error awareness and cognitive control processes. Attentional capacity and levels of apathy influence error awareness in those with M/S TBI. There are strong links between awareness, attention, and apathy. However, limited research has examined the role of attention, awareness, and apathy using electrophysiological indices of error awareness to further understand cognitive control in a M/S TBI sample. The current study sought to elucidate the role of apathy in error awareness in those with M/S TBI. Participants included 75 neurologically-healthy controls (divided randomly into two control groups) and 24 individuals with M/S TBI. All participants completed self-report measures of mood, apathy, and executive functioning, as well as a brief neuropsychological battery to measure attention and cognitive ability. To measure awareness, participants completed the error awareness task (EAT), a modified Stroop go/no-go task. Participants signaled awareness of errors committed on the previous trial. The M/S TBI group decreased accuracy while improving or maintaining error awareness compared to controls over time. There were no significant between-group differences for ERN and Pe amplitudes. Levels of apathy in the M/S TBI group were included in three multiple regression analyses predicting proportion of unaware errors, ERN amplitude, and Pe amplitude. Apathy was predictive of error awareness, although not in the predicted direction. Major analyses were replicated using two distinct control groups to determine potential sample effects. Results showed consistent results comparing both control groups to a M/S TBI group. Findings show variable levels of awareness and accuracy over time for those with M/S TBI when compared to controls. Conclusions include varying levels of attention and awareness from the M/S TBI group over time, evidenced by improving awareness of errors when they are happening, but an inability to regulate performance sufficiently to improve accuracy. Levels of apathy are playing a role in error awareness, however, not in predicted directions. The study provides support for the role of attentional impairments in error awareness and encourages future studies to look for varying levels of performance within a given task when using populations linked to elevated levels of apathy and attentional deficits.

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Carbine, Kaylie A. "Does Inhibitory Control Training Reduce Weight and Caloric Intake in Adults with Overweight and Obesity? A Pre-Registered, Randomized Controlled Event-Related Potential Study." BYU ScholarsArchive, 2020. https://scholarsarchive.byu.edu/etd/8891.

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Overweight and obesity are prevalent public health problems that impact physical, mental, and social health. Many studies have evaluated weight loss treatments, but most individuals are unsuccessful at maintaining weight loss long-term. Behavioral and cognitive interventions may be effective in promoting weight loss and weight loss maintenance. One cognitive intervention that has shown potential success in reducing weight and caloric intake is inhibitory control training (ICT). ICT involves trainings where individuals are asked to repeatedly withhold dominant responses to unhealthy or high-calorie food images in an effort to increase food-related inhibitory control abilities. Reductions in caloric intake or weight may occur after as little as one week of ICT; however, it is unclear how more frequent ICT sessions promote weight loss and reduce caloric intake. Further, studies on food-specific ICT are generally poorly powered and it is unclear how ICT affects underlying cognitive and neural mechanisms. One way to measure inhibitory control processes is through the N2 component of the scalp-recorded event-related potential (ERP). The amplitude of the N2 ERP component tends to be larger (i.e., more negative) when an individual inhibits a dominant response during go/no-go tasks compared to non-inhibition go trials. I conducted a quasi-randomized controlled trial where 100 individuals with overweight or obesity were assigned to either a generic (active control; n = 48) or food-specific ICT (experimental group; n = 52). ICTs were completed four times per week for four weeks. Weight and caloric intake were obtained at baseline, immediately after four-weeks of ICT, and at a 12-week follow-up. Participants also completed a high-calorie and a neutral go/no-go task while electroencephalogram (EEG) was recorded at each visit. Results from mixed model analyses suggest that neither weight, caloric intake, nor N2 ERP component amplitude towards high-calorie foods changed at post-testing or at the 12-week follow up for either group. Regression analyses suggest that individuals with lower baseline levels of inhibition may show greater weight loss and reductions in caloric intake after a generic ICT, while individuals with higher baseline levels of inhibition may show greater weight loss and reductions in caloric intake after a food-specific ICT. Self-report ratings indicated the appetitive drive towards food decreased over the course of the study, particularly for individuals with higher levels of baseline inhibition. Overall, generic- or food-specific ICT did not affect weight, caloric intake, or food-specific N2 ERP amplitude. Food-specific ICT may be more effective in reducing caloric intake and weight for individuals with larger inhibition responses to food stimuli, while generic ICT may be more effective in reducing caloric intake and weight for individuals with smaller inhibition responses to food stimuli. ICT may also be targeting other mediating processes, such as the appetitive value of food, as opposed to improving food-specific inhibitory control.

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Kawaguchi, Hirokazu. "Signal Extraction and Noise Removal Methods for Multichannel Electroencephalographic Data." 京都大学 (Kyoto University), 2014. http://hdl.handle.net/2433/188593.

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Compton, Sharla Elizabeth. "The Effects of Long-Term Physical Activity on Food Attention Allocation in College Freshmen Women." BYU ScholarsArchive, 2013. https://scholarsarchive.byu.edu/etd/4238.

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Purpose: The purpose of this study was to examine the effects of long-term (24 weeks) physical activity on attention allocated toward food in college freshmen women. Methods: Seventy-nine freshmen college women wore a multi-function pedometer for 24 weeks after being randomly assigned to a daily step level: 10,000; 12,500; or 15,000. After at least 16 weeks of intervention, participants were given a cognitive viewing task (pictures of food and flowers) with the neural response measured using electroencephalogram (EEG) and event-related potentials (ERPs). P300s and LPPs are components of the ERP indicating increased attention to stimuli. Results: There was a significant difference in daily step counts between groups. No interaction between step group and picture condition (food vs. flowers) was found for any of the three ERP (event-related potential) variables (P300 amplitude, P300 latency, LPP amplitude). The 12,500 group showed a significantly elevated response in comparison to the other groups for both food and flowers (F=8.84; P=0.0002). Additionally, subjective rating of hunger was significantly lower in the 15,000 step group (F=4.72; P=0.0030). Conclusion: It appears that long-term increases in physical activity are capable of reducing neural orientation toward hedonic food cues as well as subjective hunger ratings. In addition to increasing energy expenditure, increases in long-term physical activity may also influence the physiological drive to consume food.

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Simpson, Johanna. "The genetics of affective cognition : electrophysiological evidence for individual differences in affective picture processing, attention and memory." Thesis, University of Stirling, 2016. http://hdl.handle.net/1893/25203.

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Affect and cognition have traditionally been considered mutually exclusive domains and their study has evolved into two separate research fields. In recent years, however, there is increasing evidence of affective modulations of cognitive processes and interest in the study of affective cognition has grown. This thesis presents analyses of data collected in four mixed-design experiments between 2009 and 2011, which were designed to investigate affective memory and its electrophysiological correlates, individual differences in said affective memory and electrophysiological correlates, the time-course of affective memory and attentional disengagement from affective stimuli respectively. The first aim of the research presented here was to further understanding of how affective content influences picture processing and memory. Event-related potentials (ERPs) provide a valuable tool for the investigation of modulations of cognitive processes, as their excellent temporal resolution allows for the dissociation between different processes contributing to behavioural outcomes. Several important results for the study of affective cognition are reported: The late positive potential (LPP) was shown to be modulated differentially by affective content when compared to a behavioural attentional disengagement task. While the behavioural measure of attention replicated findings from participants’ self-report of arousal, LPP enhancement did not. This novel finding demonstrates that the affective modulation of the LPP cannot be used as an electrophysiological marker of slowed attentional disengagement as is common in the literature. In the domain of recognition memory, affective modulation of performance was shown to be time-sensitive, with effects developing faster for negative than for positive picture content. Affective pictures were associated with a less conservative response bias than neutral pictures but only negative pictures elicited better discrimination performance, driven by an increased in the rate of “remembered” as compared to merely familiar pictures. This was reflected in an increase of the ERP old/new effect for negative pictures in the 500 to 800ms time window, the purported correlate of recollection. The late right-frontal old/new effect between 800 and 1500 ms post stimulus onset was shown to be attenuated by affective content, supporting the interpretation of the late right-frontal effect as a correlate of relevance detection over a retrieval success interpretation. In combination, the findings add weight to the conclusion that affective content enhances memory through selective memory sparing for affective stimuli. Novel evidence for gender differences in affective cognition was found. Comparisons between female and male participants revealed that the affective modulation of the late right-frontal effect differs between the genders, underlining the importance of assessing and understanding gender differences as part of the study of affective cognition. Brain-derived neurotrophic factor (BDNF) gene val66met single nucleotide polymorphism (SNP), a small genetic change that affects the functioning of BDNF, a protein that plays an important role in neuron growth, differentiation and survival, is shown here to also affect the interaction of affect and cognition. BDNF val66met genotype modulated the early “familiarity” old/new effect selectively in response to positive pictures. The present study clearly demonstrates the value of the ERP technique in the investigation of individual differences in affective and cognitive processing and the need to take such individual differences into account as part of the endeavour to fully understand the mechanisms of affective processing, cognition and affective cognition. A better understanding of the role of gender and genetic differences in the affective modulation of affective processing and memory will have important practical implications in fields where affect and cognition interact.

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Nikjeh, Dee Adams. "Vocal and instrumental musicians : electrophysiologic and psychoacoustic analysis of pitch discrimination and production." [Tampa, Fla] : University of South Florida, 2006. http://purl.fcla.edu/usf/dc/et/SFE0001728.

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Wolf, Mary Menn. "Association Between Academic Performance and Electrocortical Processing of Cognitive Stimuli in College Students." BYU ScholarsArchive, 2011. https://scholarsarchive.byu.edu/etd/2957.

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Because event-related potentials (ERPs) can reflect individual differences in intellectual ability, individual differences in college grade-point average (GPA) may be associated with specific individual ERP waves, such as the P300. However, P300 amplitude is higher in women than in men and varies across the menstrual cycle, factors that could confound the association between GPA and ERPs. In this regard, our objective was to determine whether differences in GPA are reflected in ERPs while standardling for sex and menstrual phase. After participants provided informed consent, we obtained GPAs from 22 right-handed college students (11 male, age range 22 to 26 and 10 female, age range 17 to 24) at a university with high admission and retention standards. We assessed menstrual phase by measuring luteinizing hormone levels across the cycle. We then obtained ERPs for each male participant and ERPs during each phase of the menstrual cycle for each female participant in an object-recognition visual pop-out protocol using Net Station Software (Electrical Geodesics, Inc., Eugene, Oregon) and E-prime Software (Psychology Software Tools, Inc., Sharpsburg, Pennsylvania). Males had larger P300s than females. The male and female high GPA was significantly different from the low GPA male and female groups. High GPA in females and males were associated with a positive peak at approximately 689 ms that was not present in the low-GPA male group and was significantly diminished in low-GPA females. Electro-cortical processing of cognitive stimuli differs between college students with high and low GPAs.

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Lam, Janice Si-Man. "Second Language Semantic Retrieval in the Bilingual Mind: The Case of Korean-English Expert Bilinguals." BYU ScholarsArchive, 2018. https://scholarsarchive.byu.edu/etd/7022.

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The present study aims to explore the relationship between proficiency level and semantic retrieval in the second language. A group of Korean bilinguals who speak English with high proficiency performed semantic relatedness judgement tasks of two hundred English word pairs. Unbeknownst to the participants, half of the words in both the related and the unrelated categories contained a "hidden prime"—a common first syllable shared by the two words, if translated into Korean. Each participant's event-related potential (ERP) was recorded while reading the words. While a former study by Thierry and Wu (2007) found that Chinese-English bilinguals were affected by the hidden primes, thus causing a "N400 reduction effect" in their averaged ERP, the bilingual group of the present study was unaffected by the hidden primes. The difference between the bilingual groups' performance between Thierry and Wu's study and the present study is likely caused by the higher English proficiency of the bilingual group in the present study. This provides additional evidence supporting the Revised Hierarchical Model of semantic retrieval proposed by Kroll and Steward (1994), which suggests that increased proficiency leads to reduced reliance on the first language during second language semantic retrieval.

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Dissertations / Theses on the topic 'Event related potentials ERP'

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