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Dissertations / Theses on the topic 'Evoked potentials (Electrophysiology)'

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Published: 4 June 2021

Last updated: 31 July 2024

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1

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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2

Al-Nashi, Hamid Rasheed. "A maximum likelihood method to estimate EEG evoked potentials /." Thesis, McGill University, 1985. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=72016.

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A new method for the estimation of the EEG evoked potential (EP) is presented in this thesis. This method is based on a new model of the EEG response which is assumed to be the sum of the EP and independent correlated Gaussian noise representing the spontaneous EEG activity. The EP is assumed to vary in both shape and latency, with the shape variation represented by correlated Gaussian noise which is modulated by the EP. The latency of the EP is also assumed to vary over the ensemble of responses in a random manner governed by some unspecified probability density. No assumption on stationarity is needed for the noise.
With the model described in state-space form, a Kalman filter is constructed, and the variance of the innovation process of the response measurements is derived. A maximum likelihood solution to the EP estimation problem is then obtained via this innovation process.
Tests using simulated responses show that the method is effective in estimating the EP signal at signal-to-noise ratio as low as -6db. Other tests using real normal visual response data yield reasonably consistent EP estimates whose main components are narrower and larger than the ensemble average. In addition, the likelihood function obtained by our method can be used as a discriminant between normal and abnormal responses, and it requires smaller ensembles than other methods.

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3

Wetter, Spencer Ryan. "Olfactory psychophysics and electrophysiology in Huntington's Disease /." Diss., Connect to a 24 p. preview or request complete full text in PDF format. Access restricted to UC campuses, 2003. http://wwwlib.umi.com/cr/ucsd/fullcit?p3083456.

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4

Pipingas, Andrew, and apipingas@bsi swin edu au. "Steady-state visually evoked potential correlates of object recognition memory." Swinburne University of Technology, 2003. http://adt.lib.swin.edu.au./public/adt-VSWT20050322.171342.

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Object recognition memory (ORM) refers to both recognition of an object and the memory of having seen it before. In humans, ORM has been investigated using functional neuroimaging and electrophysiological techniques with tests of episodic memory retrieval involving recollection of previously studied items. Processes involved in the maintenance of a mental state adopted for the performance of a retrieval task (retrieval mode) appear to involve right frontal neural regions. More transient processes occurring at the time of item recollection (retrieval success) have shown scalp activity over parietal and right frontal regions. This activity is thought to originate in the medial temporal lobes and the underlying right frontal cortex respectively. The aforementioned findings have been derived mainly from studies using verbal stimuli. It is uncertain whether the same neural regions are involved in object recollection. It is also uncertain whether sustained modal and transient item-related activity involve the same or different right frontal regions. In this study, steady-state probe topography (SSPT) was used to investigate both sustained and transient processes involved in the retrieval of abstract pictorial objects from memory. The ability to vary the evaluation period of the steady-state visually evoked potential (SSVEP) allows investigation of cognitive processes occurring over different time scales. Neural regions involved in sustained modal processes were identified by examining the SSVEP values averaged over the duration of a memory retrieval task. Sustained SSVEP effects were observed over right fronto-temporal regions. Neural regions involved in transient retrieval success processes were identified by comparing the transient SSVEP responses to tasks with different memory loads. Comparison of a higher with a lower memory load condition showed SSVEP effects over parieto-temporal and right inferior frontal regions. Larger differences between memory loads gave effects that were larger and more right lateralized. Retrieval mode and retrieval success processes showed SSVEP effects over different right frontal regions. It was also found that, in contrast to the left lateralized parietal ERP response to recollected verbal stimuli, the SSVEP effects produced with abstract pictorial shapes showed a more bilateral pattern. This was considered to reflect the relatively non-verbalizable pictorial nature of the stimuli.

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5

Hamilton-Bruce, Monica Anne. "Conventional and topographic electroencephalography and somatosensory evoked potential studies in ischaemic stroke." Adelaide, 1998. http://web4.library.adelaide.edu.au/theses/09PH/09phh222.pdf.

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Copies of author's previously published articles inserted. Bibliography: leaves I-LXIV. Assesses the diagnostic and prognostic value of early electroencephalography (EEG) and somatosensory evoked potential studies in cortical and non-cortical ischaemic stroke. Both conventional and topographic/quantitative studies were performed. A parallel study was carried out on healthy volunteers to provide an effective control. Equipment and quantitative EEG (qEEG) variability was also assessed.

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6

Downey, Ryan Andrew. "Examination of lexical properties during auditory sentence processing using event-related potentials." Connect to a 24 p. preview or request complete full text in PDF format. Access restricted to UC campuses, 2006. http://wwwlib.umi.com/cr/ucsd/fullcit?p3237582.

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Thesis (Ph. D.)--University of California, San Diego and San Diego State University, 2006.
Title from first page of PDF file (viewed December 13, 2006). Available via ProQuest Digital Dissertations. Vita. Includes bibliographical references.

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7

Hocking, Christopher Anthony, and Christopher Hocking@med monash edu au. "Brain electrical activity and automization." Swinburne University of Technology, 1999. http://adt.lib.swin.edu.au./public/adt-VSWT20051021.110535.

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Novices and experts show distinct differences in the performance of many tasks. Experts may perform a task quickly and accurately with seemingly little attention or effort, whilst novices will perform the same task more slowly and with great effort. The transition from novice to expert performance occurs only after extended practice and has been conceptualized as a transition from controlled to automatic processing, and has been modeled as a reduction in attention or cognitive resources. Alternatively, based on findings relating to learning in the domain of number arithmetic, it has also been modeled as a transition from an algorithmic, or computationally-based process, to the use of memory retrieval. However, relatively few studies have investigated the changes in brain activity associated with such a transition. In this study, the Steady-State Probe Topography technique was used to investigate differences in the topography of the Steady-State Visual Evoked Potential (SSVEP) between an unpracticed and a well-practiced analogue of number arithmetic, Alphabet arithmetic. Subjects showed decreases in response time with practice that followed a power law and were suggestive of automatization. During initial, unpracticed performance of the task, processing of the Alphabet Arithmetic equations was characterised by increased SSVEP amplitude and decreased latency in frontal regions, whilst after extended practice, performance was characterised by reduced SSVEP amplitude and increased latency. It is suggested that the frontal activity during the initial, unpracticed stage of the task implicates a role for working memory, whilst the amplitude decrease and latency increase observed in the well-practiced task may reflect a reduction in excitation, consistent with ideas of an improvement in brain efficiency, and possibly an increase in inhibitory processes.

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Hu, Li, and 胡理. "Chasing evoked potentials: novel approaches to identify brain EEG responses at single-trial level." Thesis, The University of Hong Kong (Pokfulam, Hong Kong), 2010. http://hub.hku.hk/bib/B45589203.

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Lam, Shing-chun Benny, and 林成俊. "Fast signal processing techniques for surface somatosensory evoked potentials measurement." Thesis, The University of Hong Kong (Pokfulam, Hong Kong), 2003. http://hub.hku.hk/bib/B29246404.

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10

Carey, Marc Brandon. "Brainstem auditory evoked potentials in anuran amphibians." PDXScholar, 1992. https://pdxscholar.library.pdx.edu/open_access_etds/4267.

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In this study, I looked at the effects of sound level, temperature and dehydration/hypernatremia on the brainstem auditory evoked potential (BAEP) of four species of anuran amphibians (Rana pipiens, Rana catesbeiana, Bufo americanus and Bufo terrestris). The BAEP was used because it allowed me to monitor both the peripheral and central aspects of auditory nervous function simultaneously and over a long period of time.

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11

Line, Per, and pline@swin edu au. "Cognition and the steady state visually evoked potential." Swinburne University of Technology, 1993. http://adt.lib.swin.edu.au./public/adt-VSWT20060118.170228.

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This masters thesis examines the hemispheric activation pattern of the cognitive processes involved in a complex mental rotations test (MRT) (Vandenberg and Kuse, 1978) using Steady-State Probe Topography (SSPT) (Silberstein et al, 1990) as a method to index brain activity. The Steady State Visually Evoked Potential (SSVEP) was recorded from 64 electrode sites using a multichannel electrode helmet, and elicited by a 13 Hz sinusoidal visual flicker, whilst the subjects were performing a visual vigilance Baseline task and the MRT. Forty-one right handed subjects (twenty male and twenty-one female) were used. In the MRT the subjects were required to choose the two figures which correctly matched the criterion figure in the centre. The figures were three-dimensional objects represented in two-dimensions on a computer screen. A significant finding of this study was that when all the subjects were considered as one group, no noticeable lateralization in cerebral activation associated with mental rotation was evident. When analyzing the results for the subjects, partitioned into two groups according to gender, evidence was found suggesting that the cortical processing associated with mental rotation may be more localized bilaterally in the males than the females. However, no noticeable lateralization effects for mental rotation were found in the males or females, and hence no gender differences in hemispheric lateralization was evident. An important finding was the emergence of gender differences in hemispheric lateralization in subsets of subjects performing with higher spatial ability. A left hemisphere lateralization for mental rotation was associated with the Best Performance Male group. The Best Performance Female group showed the opposite effect, where a right hemisphere lateralization was associated with better performance on the task. The lateralization effect appeared to be stronger in the Best Performance Males than the Best Performance Females. An important conclusion from this study is that when examining for hemispheric lateralization effects in mental rotation, and possibly other visual-spatial tasks, not only gender effects need to be considered, but the level of spatial ability in the comparison groups needs also to be taken into account.

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Ting, Kin-hung. "Fast tracking and analysis of event-related potentials /." View the Table of Contents & Abstract, 2005. http://sunzi.lib.hku.hk/hkuto/record/B30268096.

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13

Whittle, Ian Roger. "Clinical applications of somatosensory evoked potentials in pediatric neurosurgery /." Title page, contents and summary only, 1985. http://web4.library.adelaide.edu.au/theses/09MD/09mdw627.pdf.

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14

Robinson, Rebecca Louise. "Experimental study of electrophysiology using the fEITER system." Thesis, University of Manchester, 2011. https://www.research.manchester.ac.uk/portal/en/theses/experimental-study-of-electrophysiology-using-the-feiter-system(399260d4-6c11-4227-9633-4d76f933e5af).html.

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Within neurophysiology, there is need for improvements to functional brain imaging devices. Neural processing within the brain occurs on milli-second through to second timescales. Currently there are no systems with the sufficient temporal resolution and depth sensitivity. Electrical impedance tomography (EIT) is a technique that offers milli-second imaging, depth sensitivity, portability and low cost. It is already applied routinely in other medical applications such as lung function monitoring and breast imaging. The research presented in this thesis has contributed to the design and development of a 32-electrode EIT system, known as fEITER (functional Electrical Impedance Tomography of Evoked Responses). fEITER has been designed to be a brain imaging device that has a temporal resolution of 100 fps with an overall SNR of greater than 70 dB operating at 10 kHz. In order to carry out human tests using fEITER, the system required applications to the local and national ethics (NRES) as well as safety standards regulation (MHRA). These processes were successfully completed, receiving a 'notice of no objection' for a clinical trial using fEITER at The University of Manchester and Manchester Royal Infirmary. A series of tank tests were analysed as a method of understanding the system performance. The data obtained from human tests showed unique results. The reference data showed a repeating 'saw tooth' that is time-locked to the heart beat of the volunteer, which is a novel observation in medical EIT. Furthermore, the auditory stimuli data showed topographical differences across the scalp with respect to the startle and controlled auditory stimuli. These observations are based on single-event evoked responses, which is unique within the field of evoked potential studies. From the observations reported in this thesis it is plausible that fEITER is measuring voltages changes that are due to the neural processing.

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Guille, Valérie. "Is the loudness dependence of the auditory evoked potential a valid marker of serotonin function?" Swinburne Research Bank, 2007. http://hdl.handle.net/1959.3/31100.

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Thesis (PhD) - Swinburne University of Technology, Brain Sciences Institute, 2007.
A thesis for Doctor of Neuropsychopharmacology, Brain Sciences Institute, Swinburne University of Technology - 2007. Typescript. Includes bibliographical references (p. 138-164).

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Simpson, David Gordon Giles, and dsimpson@swin edu au. "Instrumentation for high spatial resolution of steady state visual evoked potentials." Swinburne University of Technology, 1998. http://adt.lib.swin.edu.au./public/adt-VSWT20060711.123100.

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This thesis reports on several new and innovative instrumentation developments to solve some of the problems of brain activity monitoring, particularly SSVEP (Steady State Visual Evoked Potentials) studies. SSVEP systems generate suitable stimuli and record the resulting brain biopotentials from scalp electrodes. The instrumentation is configured as a 'Neuropsychiatric Workstation', supporting up to 136 scalp electrodes. Operating in the SSVEP mode, the Neuropsychiatric Workstation reported here significantly improves upon the previously reported spatial resolution and accuracy of maps related to the generated stimuli. These maps allows insights to be gained into the cognitive workings of the brain. A significant component of the work reported here covers the development of the multielectrode EEG measurement modules and the associated techniques for minimising interference and cross-talk. The techniques for synchronising recordings from all electrodes with the stimulus, interfacing to a host computer and real-time storage of the very large amounts of data generated to hard disk, are all reported. The SSVEP paradigm uses a sinusoidal-modulated visual stimuli. A novel linearised LED (light emitting diode) head-up display was developed, in addition to more conventional stimuli, such as the alternating checker-board display, all with sinusoidal modulation capability over a range of frequencies. The Neuropsychiatric Workstation described in thesis has been replicated several times and is in regular use at Brain Sciences Institute (BSI) at Swinburne University of Technology, and other collaborative research institutes.

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17

Chirwa, Sanika Samuel. "Differential effects of calcium and tetanic stimulation frequencies on hippocampal synaptic potentiation and depression." Thesis, University of British Columbia, 1985. http://hdl.handle.net/2429/24594.

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In the hippocampus, tetanic stimulation of an input results in a long lasting potentiation (LLP) of synaptic transmission involving that input. While high frequency tetanic stimulations are preferred to elicit LLP, low frequency tetanus induces homosynaptic and heterosynaptic depressions. The present investigations were conducted to (1) analyse the characteristics of pulses in orthodromic and antidromic tetanic stimulations and relate them to post-tetanic changes in evoked potentials (2) determine if potentiation and depression co-occur and (3) determine whether an established LLP in one input is subsequently modified by the initiation of LLP in another input (to the same CAlb neurons) or whether LLP can be reversed by homosynaptic and heterosynaptic depressions and lastly (4) determine how interference or enhancements of calcium and potassium fluxes with pharmacological substances related to potentiation and depression. Experiments were conducted on transversely sectioned rat hippocampal slices. Evoked potentials in subfield CAlb were elicited with stimulations of CAlb axons, commissural (Com), or Schaffer collaterals (Sch). Sch terminal excitability was tested with a stimulating electrode placed in the Sch/CAlb synaptic regions. Recordings were made with microelectrodes positioned in the CAlb cell bodies and/or dendritic regions, and in field CA3. It was found that potentiation and depressions co-occur. Presynaptic volleys accompanied all tested tetanic trains. Similarly, antidromic trains discharged CAlb neurons continuously but did not cause LLP. Low frequency tetanic trains caused facilitated synchronous discharges of CAlb neurons during significant portions of these trains. In contrast, few if any syn- chronous discharges followed high frequency tetanus. Yet high frequency tetanus elicited LLP and low frequency tetanus caused homo- and heterosynaptic depressions. An established LLP could be masked but not reversed by homo- and heterosynaptic depressions but this LLP was not interrupted by subsequently induced LLP of a separate input. Iontophoretic L-glutamate on CAlb cell bodies caused depression which was more pronounced if a tetanus was evoked during L-glutamate ejections. The depressions to low frequency tetanus and L-glutamate were counteracted by verapamil. Lastly, barium and 4-aminopyridine potentiations were reversed with washing. Applications of these drugs did not alter Sch terminal excitability. Tetanus induced during the presence of 4-aminopyridine still elicited LLP. It is concluded that homo- and heterosynaptic depressions are partly due to the accumulation of calcium into the CAlb neurons. The magnitude of calcium entry into presynaptic and postsynaptic regions is governed by the tetanic frequencies evoked. The results are consistent with a presynaptic mediated LLP.
Medicine, Faculty of
Anesthesiology, Pharmacology and Therapeutics, Department of
Graduate

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Fung, Shun-ming. "Fast evoked potential estimation by artificial neural networks /." Hong Kong : University of Hong Kong, 1999. http://sunzi.lib.hku.hk/hkuto/record.jsp?B21090002.

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Topalis, Apostolos. "Multiresolution wavelet analysis of event-related EEG potentials using ensemble of classifier data fusion techniques for early diagnosis of Alzheimer's disease /." Full text available online, 2006. http://www.lib.rowan.edu/find/theses.

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20

Ciorciari, Joseph, and jciorciari@swin edu au. "Topograhic distribution of human brain electrical activity associated with schizophrenia." Swinburne University of Technology, 1999. http://adt.lib.swin.edu.au./public/adt-VSWT20050610.152013.

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A literature review of the schizophrenia brain electrophysiology was undertaken with specific emphasis placed on the topographical distribution of evoked potentials (EPs). The outcomes of this review suggests that schizophrenia brain electrophysiology, demonstrate some differences, but with a variability reflective of the symptom heterogeneity. The literature associated with the use of attentional tasks while recording EPs, tended to demonstrate some consistency. The methodological issues associated with the EEG and EP recordings may also account for this variability. An evoked potential technique, which has been demonstrated to be sensitive to the changes in cognitive processes associated with attention, is the Steady State Probe Topography (SSPT) technique. The SSPT is a combination of both the Steady State Visual Evoked Potential (SSVEP) and the Probe-ERP paradigm. This technique allows the SSVEP to be measured continuously, is relatively insensitive to artifact, and can display the topographic distribution of the SSVEP measures during the attentional task. The technique employs the use of a sixty-four channel EEG recording system. This consists of a multichannel electrode helmet; multichannel amplifier/filter, task presentation computer and a computer controlled data acquisition system. Software was also developed to analyse the recorded brain electrical activity to produce the SSVEP magnitude and phase versus time series for each electrode site. The topographic distribution of the SSVEP measures associated with specific events during attentional tasks could also be displayed. At the time of the pilot study, this technique had not been applied previously to the study of schizophrenia and therefore warranted further study. Two separate studies are reported; an investigative pilot study and a chronic group study. The pilot SSVEP and schizophrenia study was designed to examine the changes in the SSVEP and its topography, during the performance of a number of attentional or activation tasks to examine the possibility of hypofrontality. The tasks selected for the study were those previously used for the examination of hypofrontality with metabolic imaging techniques; the Continuous Performance Task (CPT) and the Wisconsin Card Sort (WCS). The SSVEP was elicited by a superimposed 13Hz flicker on the visual field, while subjects performed computerised versions of the neuropsychological tasks. Topographical maps of the SSVEP magnitude distribution were then interpolated and displayed as an animated sequence synchronised with particular events occurring during the tasks. In comparison to the male control group, male schizophrenic patients exhibited differences in the SSVEP topography for all tasks, possibly reflecting the deficits in behavioural indices. Overall, the findings indicated that the technique demonstrated some merit for further examination of frontal SSVEP topography in schizophrenia. In a larger study of twenty chronic schizophrenia patients, the frontal topographical distribution of the SSVEP was examined. The earlier pilot study finding of reduced frontal SSVEP amplitude was replicated. The issue of hypofrontality in schizophrenia was applied as a possible interpretation.

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Rennie, Christopher. "Modeling the large-scale electrical activity of the brain." Connect to full text, 2001. http://hdl.handle.net/2123/816.

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Thesis (Ph. D.)--University of Sydney, 2001.
Includes published articles. Title from title screen (viewed Apr. 24, 2008). Submitted in fulfilment of the requirements for the degree of Doctor of Philosophy to the School of Physics, Faculty of Science. Includes bibliography. Also available in print form.

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Liu, Wenqing. "Fast tracking of evoked potentials variations by wavelet analysis /." Hong Kong : University of Hong Kong, 2002. http://sunzi.lib.hku.hk/hkuto/record.jsp?B25205523.

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Ting, Kin-hung, and 丁建鴻. "Fast tracking and analysis of event-related potentials." Thesis, The University of Hong Kong (Pokfulam, Hong Kong), 2005. http://hub.hku.hk/bib/B45015016.

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劉文慶 and Wenqing Liu. "Fast tracking of evoked potentials variations by wavelet analysis." Thesis, The University of Hong Kong (Pokfulam, Hong Kong), 2002. http://hub.hku.hk/bib/B31243411.

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馮順明 and Shun-ming Fung. "Fast evoked potential estimation by artificial neural networks." Thesis, The University of Hong Kong (Pokfulam, Hong Kong), 1999. http://hub.hku.hk/bib/B30257505.

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O'Neill, Barry Vincent. "The pharmacology of the loudness dependence of the auditory evoked potential (LDAEP)." Swinburne Research Bank, 2008. http://hdl.handle.net/1959.3/47108.

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Thesis (PhD) - Swinburne University of Technology, Brain Sciences Institute, 2008.
A thesis submitted for the degree of Doctorate of Philosophy, Brain Sciences Institute, Swinburne University of Technology - 2008. Typescript. Includes bibliographical references (p. 98-133)

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Richardson, Thomas Lewellyn. "The contribution of ephaptic interactions to recruitment and synchronization of neuronal discharge during evoked potentials in the hippocampal formation." Thesis, University of British Columbia, 1988. http://hdl.handle.net/2429/29173.

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The mechanisms underlying the generation and spread of seizure activity have remained elusive despite a considerable research effort over the last two decades. Most of this work has concentrated on the characteristics of neuronal excitability and burst discharge at the single cell level. These studies have provided some understanding of the possible abnormalities of neurons within an epileptic focus, but little direct insight into the factors responsible for the striking synchronization of action potentials during interictal discharge or in the spread of synchronous activity across apparently normal brain tissue. Although synaptic activation probably plays a role in the generation of seizure activity, recent evidence indicates that seizure-like discharge can occur during chemical blockade of synaptic transmission (Jefferys and Haas 1982; Taylor and Dudek 1982). This rather surprising result emphasizes the importance of considering non-synaptic mechanisms for both the synchronization and spread of abnormal neuronal activity in the central nervous system. One important non-synaptic mechanism to consider is ephaptic interactions. This term refers to the direct electrical influence of extracellular field potentials on neuronal excitability. It is possible that ephaptic interactions, generated during seizure activity, simultaneously depolarize an entire population of neurons leading to both recruitment and synchronization of action potential discharge. This thesis investigates ephaptic interactions during evoked potentials in the hippocampal formation. The hippocampus is one of the most seizure-prone regions of the brain and its anatomical structure is ideal for the generation of field effects. Evoked potentials were used as "models" of synchronous neuronal discharge since they are more reproducible, easier to control, and better understood than seizure activity. This initial investigation of ephaptic interactions lays the foundation for further studies involving the complexities of epileptic activity. The first phase of this project examined the spatial characteristics of field potentials evoked in the hippocampus and the dentate gyrus. Current source density (CSD) analysis and voltage gradient determinations obtained from these fields were used to characterize the pattern of current flow within the neuropil and to predict the polarity and relative intensity of ephaptic influences on neuronal excitability. The detailed characteristics of extracellular voltage gradients varied between CAl and the dentate gyrus, and also between anti- and orthodromic responses. In general, voltage gradients during the positive components of a somatic population spike predicted ephaptic hyperpolarization of the neuronal population, whereas gradients observed during the negative component predicted depolarization. They were often an order of magnitude greater than the smallest gradient known to influence granule cell activity. An exception to this rule was the minimal gradient observed during the negative component of the dentate response. In the second phase of the study, extracellular voltage gradients were experimentally applied to the dentate gyrus to determine the sensitivity of granule cells to ephaptic interactions. The magnitude of the applied gradients were in the range observed during the evoked potentials studied in the first phase. These experiments demonstrated a remarkable sensitivity of granule cells to the applied fields. The fields could alter the population spike from near minimal to near maximal. Surprisingly, even antidromic potentials were influenced by the gradients. On the other hand, the EPSP phase of the population spike was not influenced. These findings established that extracellular currents can influence the excitability within a neuronal population without altering synaptic drive. The final phase of the project investigated the transmembrane potential (TMP) of pyramidal and granule cells during applied fields and evoked potentials. The TMP was calculated by subtracting the extracellular from the intracellular response. This potential ultimately determines the voltage dependent behavior of a neuron and gives a direct measure of any ephaptic interactions. In order to measure the intracellular influences of applied fields, the TMP was monitored while the impaled cell was exposed to extracellular voltage gradients spanning the same range as used in phase two of the project. The TMP shifted by as much as plus or minus 5 mV, depending on the amplitude and polarity of the gradient. This large shift in TMP accounts for the observed influence of the applied field potentials, and suggests that the voltage gradients associated with evoked potentials should also have a marked effect on the TMP. A depolarizing wave of the TMP occurred during the negative component of anti- and orthodromic CA1 responses. This depolarization was capable of initiating action potentials, and decreased the latency to discharge during orthodromic responses. During epileptiform discharge, a similar depolarizing wave was associated with each negative component of the burst. These depolarizations recruit and synchronize neuronal discharge by simultaneously increasing the excitability within an entire population of cells. These data support the hypothesis that ephaptic interactions in the hippocampal formation influence the pattern of cell discharge during evoked potentials. It is postulated that similar ephaptic interactions may contribute to recruitment and synchronization during seizure activity.
Medicine, Faculty of
Cellular and Physiological Sciences, Department of
Graduate

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Carter, Bradley Graham. "The prediction of both short and long term outcomes follwing severe brain injury using somatosensory evoked potentials." Australasian Digital Theses Program, 2006. http://adt.lib.swin.edu.au/public/adt-VSWT20070130.153020/index.html.

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Hamilton-Bruce, Monica Anne. "Conventional and topographic electroencephalography and somatosensory evoked potential studies in ischaemic stroke / Monica Anne Hamilton-Bruce." Thesis, Adelaide, 1998. http://hdl.handle.net/2440/19249.

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Copies of author's previously published articles inserted.
Bibliography: leaves I-LXIV.
xxxviii, 239 [77], Lxiv leaves : ill. (chiefly col.) ; 30 cm.
Assesses the diagnostic and prognostic value of early electroencephalography (EEG) and somatosensory evoked potential studies in cortical and non-cortical ischaemic stroke. Both conventional and topographic/quantitative studies were performed. A parallel study was carried out on healthy volunteers to provide an effective control. Equipment and quantitative EEG (qEEG) variability was also assessed.
Thesis (Ph.D.)--University of Adelaide, Dept. of Medicine, 1998?

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Kiehl, Kent Anthony. "A neuroimaging investigation of affective, cognitive, and language functions in psychopathy." Thesis, National Library of Canada = Bibliothèque nationale du Canada, 2000. http://www.collectionscanada.ca/obj/s4/f2/dsk2/ftp03/NQ48667.pdf.

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31

Lin, Min Vargas Gray. "Oops, I did it again an ERP exploration of error-monitoring processes in depression /." Diss., Connect to the thesis, 2006. http://hdl.handle.net/10066/750.

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32

Larson, Michael James. "Dissociating components of cognitive control using high-density event-related potentials implementation of control, conflict processing, and error monitoring /." [Gainesville, Fla.] : University of Florida, 2004. http://purl.fcla.edu/fcla/etd/UFE0004801.

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Thesis (M.S.)--University of Florida, 2004.
Typescript. Title from title page of source document. Document formatted into pages; contains 60 pages. Includes Vita. Includes bibliographical references.

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33

Tardif, Hilarie P. "Electrophysiological and behavioural indices of simulated recognition memory impairment." Access electronically, 2003. http://www.library.uow.edu.au/adt-NWU/public/adt-NWU20040917.144100/index.html.

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34

Dainer-Best, Justin. "Attachment style as a predictor of positive event-related brain potentials in a social-stimulation task." Diss., Connect to the thesis, 2009. http://hdl.handle.net/10066/3585.

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35

Westerfield, Marissa Anne Navarrete. "The role of the cerebellum in visual spatial attention : an event-related potential study /." Diss., Connect to a 24 p. preview or request complete full text in PDF format. Access restricted to UC campuses, 1999. http://wwwlib.umi.com/cr/ucsd/fullcit?p9952646.

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36

Hu, Yong. "Investigation of the reliability of spinal cord monitoring during scoliosis surgery /." Hong Kong : University of Hong Kong, 1999. http://sunzi.lib.hku.hk/hkuto/record.jsp?B2145162X.

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37

Highsmith, Jennifer Rea. "Changes in chromatic pattern-onset VEP with full-body inversion." abstract and full text PDF (free order & download UNR users only), 2007. http://0-gateway.proquest.com.innopac.library.unr.edu/openurl?url_ver=Z39.88-2004&rft_val_fmt=info:ofi/fmt:kev:mtx:dissertation&res_dat=xri:pqdiss&rft_dat=xri:pqdiss:1446433.

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38

Lord-Maes, Janiece Marie. "Short latency evoked potentials and intra-individual variability in children." Diss., The University of Arizona, 1988. http://hdl.handle.net/10150/184623.

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Individual differences in learning with a focus on neuropsychologic anomalies underlying learning strategies has been receiving attention in recent years. As a result, interest has increased in quantifying and analyzing cognitive behavior more directly. One of the tools that measures brain activity directly is the evoked potential (EP). This study investigated the EP recorded from the brainstem region, often referred to as brainstem auditory evoked response (BAER). The importance of BAERs in detecting pathology in the brainstem has been well documented. BAERs have also been advocated as an important tool in the electrophysiological assessment of children's brainstem function relative to learning disorders. BAER latencies were recorded, therefore, from a small group of average children and studied in relation to the BAER stability overtime. Intra-individual differences were compared to between-subject differences. So little BAER research has been performed with children that more studies are needed just to clarify normal variability of BAER parameters. The present investigation studied intra-individual differences in the stability of BAER latencies over time in young subjects with normal hearing, for comparing with and contrasting to previous results from a study using an adult sample. BAER latencies were recorded for left, right, and binaural ear presentations. A coefficient of stability (CS) was calculated for each peak, for each ear over time. ANOVA results showed significance for peak and peak by ear interaction. Several BAER parameters were examined within-subjects that may not be revealed in studies between-subjects. Profiles for intra-aural differences over time showed individual differences in the stability of the BAER. Although there appeared to be a trend toward inter-ear differences the differences did not reach significance. The profiles indicated considerable intra-aural pattern replicability, and a trend toward increase in stability over time. The results supported a need for future research on laterality studies, more age specific normative data and correlational studies in relation to individual cognitive differences.

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39

Ueno, Mieko. "Event-related brain potentials in the processing of Japanese wh-questions /." Diss., Connect to a 24 p. preview or request complete full text in PDF format. Access restricted to UC campuses, 2003. http://wwwlib.umi.com/cr/ucsd/fullcit?p3112196.

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40

Cameron, Allison M. "Event-related potential indices of delayed response working memory in schizophrenia /." [St. Lucia, Qld.], 2002. http://www.library.uq.edu.au/pdfserve.php?image=thesisabs/absthe17563.pdf.

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41

Hollenberg, Brian Anthony. "A MEMS based electrode array for cortical surface potential recordings." Online access for everyone, 2005. http://www.dissertations.wsu.edu/Thesis/Fall2005/B%5FHollenberg%5F120905.pdf.

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42

Nishida, Michelle Miller. "Event related potential : a study of the processing of gapping structures in adolescents /." Diss., CLICK HERE for online access, 2005. http://contentdm.lib.byu.edu/ETD/image/etd1069.pdf.

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43

Groppe, David Martin. "Common independent components of the P3b, N400, and P600 ERP components to deviant linguistic events." Connect to a 24 p. preview or request complete full text in PDF format. Access restricted to UC campuses, 2007. http://wwwlib.umi.com/cr/ucsd/fullcit?p3274753.

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Thesis (Ph. D.)--University of California, San Diego, 2007.
Title from first page of PDF file (viewed October 5, 2007). Available via ProQuest Digital Dissertations. Vita. Includes bibliographical references.

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44

胡勇 and Yong Hu. "Investigation of the reliability of spinal cord monitoring during scoliosis surgery." Thesis, The University of Hong Kong (Pokfulam, Hong Kong), 1999. http://hub.hku.hk/bib/B31240343.

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45

Ouyang, Guang. "Study of the variability in brain potentials and responses : development of a new method for electroencephalography (EEG) analysis - residue iteration decomposition (RIDE)." HKBU Institutional Repository, 2013. https://repository.hkbu.edu.hk/etd_ra/1529.

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46

Aranda, George. "Functional brain electrical activity during affective facial processing in people with schizophrenia." Swinburne Research Bank, 2008. http://hdl.handle.net/1959.3/36027.

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Thesis (PhD) - Swinburne University of Technology, Brain Sciences Institute, 2008.
[Submitted for the degree of] Doctor of Philosophy, Brain Sciences Institute, Swinburne University of Technology - 2008. Typescript. Includes bibliographical references (p. 218-269).

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47

Steedman, David John. "Simultaneous measurement of human brain activity using near infra-red spectroscopy, electroencephalogram and the steady state visually evoked potential." Swinburne Research Bank, 2008. http://hdl.handle.net/1959.3/48535.

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Thesis (M.Sc.) - Swinburne University of Technology, Brain Sciences Institute, 2008.
A thesis submitted for M.Sc by Research, Brain Sciences Institute, Swinburne University of Technology - 2008. Typescript. Includes bibliographical references (p. 117-153)

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48

Doran, Matthew M. "The role of visual attention in multiple object tracking evidence from ERPS." Access to citation, abstract and download form provided by ProQuest Information and Learning Company; downloadable PDF file, 110 p, 2009. http://proquest.umi.com/pqdweb?did=1885675151&sid=5&Fmt=2&clientId=8331&RQT=309&VName=PQD.

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49

McLaughlin, Judith L. "Event related potentials reflect the early stages of second language lexical acquisition /." Thesis, Connect to this title online; UW restricted, 1999. http://hdl.handle.net/1773/9007.

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50

Burton, Pamela Ann. "Physiological evidence of interactive object-based and space-based attention mechanisms." Access to citation, abstract and download form provided by ProQuest Information and Learning Company; downloadable PDF file 50.79Mb,139 p, 2005. http://wwwlib.umi.com/dissertations/fullcit/3157279.

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