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Electrophysiological explorations of linguistic pre-activation and its consequences during online sentence processingDeLong, Katherine Ann. January 2009 (has links)
Thesis (Ph. D.)--University of California, San Diego, 2009. / Title from first page of PDF file (viewed August 25, 2009). Available via ProQuest Digital Dissertations. Vita. Includes bibliographical references.
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Event related potentials reflect the early stages of second language lexical acquisition /McLaughlin, Judith L., January 1999 (has links)
Thesis (Ph. D.)--University of Washington, 1999. / Vita. Includes bibliographical references (leaves 79-90).
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Does type of stimulus influence task-irrelevant evaluative categorization processes?Corral, Guadalupe, January 2009 (has links)
Thesis (Ph. D.)--University of Texas at El Paso, 2009. / Title from title screen. Vita. CD-ROM. Includes bibliographical references. Also available online.
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Event-related brain potential investigations of left and right hemisphere contributions to syntactic processingKemmer, Laura. January 2009 (has links)
Thesis (Ph. D.)--University of California, San Diego, 2009. / Title from first page of PDF file (viewed September 16, 2009). Available via ProQuest Digital Dissertations. Vita. Includes bibliographical references.
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Physiological evidence of interactive object-based and space-based attention mechanismsBurton, Pamela Ann. January 2005 (has links)
Thesis (Ph.D.)--University of Delaware, 2005. / Principal faculty advisor: Hoffman, James E., Dept .of Psychology. Includes bibliographical references.
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Predictability of the target stimulus for sensory-guided movement modulates somatosensory cortical potentials /Legon, Wynn. January 2005 (has links)
Thesis (M.Sc.)--York University, 2005. Graduate Programme in Kinesiology and Health Science. / Typescript. Includes bibliographical references (leaves 72-82). Also available on the Internet. MODE OF ACCESS via web browser by entering the following URL: http://gateway.proquest.com/openurl?url%5Fver=Z39.88-2004&res%5Fdat=xri:pqdiss &rft_val_fmt=info:ofi/fmt:kev:mtx:dissertation&rft_dat=xri:pqdiss:MR11836
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The pharmacology of the loudness dependence of the auditory evoked potential (LDAEP)O'Neill, Barry Vincent. January 2008 (has links)
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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Improved localization of neural sources and dynamical causal modelling of latency-corrected event related brain potentials and applications to face recognition and primingKashyap, Rajan 22 December 2015 (has links)
Event related potentials (ERPs) are obtained from noninvasive electroencephalograms (EEG) which measure neuronal activity of brain on the scalp. However, conventional ERPs derived by averaging of single EEG trials have strong latency variability and are smeared, resulting in blurred scalp topography, especially in late components of ERP. The smearing problem had been addressed by reconstructing ERPs after latency correction with a new EEG analysis method Residue Iteration Decompo¬sition (RIDE), which was demonstrated in a face priming paradigm to improve distinctness in scalp topography (Ouyang et al., 2011). This thesis aims to (1) extend the benefits of RIDE to neural source space by localizing the neural generators of ERPs, thereby developing an integrated RIDE framework for improvement in source localization and causal modeling of effective source networks, and (2) apply the framework to the face priming paradigm for famous faces, to explore the dynamics of face processing and priming. We localized sources through brain electrical source analysis for both conventional ERP and RIDE derived ERPs (RERPs). RERPs allowed localization of an additional motor execution source (Premotor Cortex, PMC), apart from 5 other common sources, of which 2 (Occipital Lobe, OL; Fusiform Gyrus, FG) were obtained from early activity (< 250 ms) and 3 (Mediotemporal lobe, MTL; Prefrontal Cortex, PFC; Anterior Temporal Lobe, ATL) from late activities (> 250 ms) of RERPs respectively. Priming effects, i.e., the difference between primed famous (PF) and unprimed famous (UF) face conditions in source waveforms (SWFs), were extended and enhanced in RERPs, especially for late sources. The priming effects revealed (1) the role of sources in each hemisphere that play in perception, memory and execution, (2) parallel processing of information in sources, (3) early processing in the right hemisphere, and (4) predominance of the right hemisphere in face recognition. Results confirmed SWFs of RERPs as better choice for the dynamic causal model (DCM). Two candidate DCM models, forward (F) and forward-backward (FB) were outlined on each hemisphere with SWFs from PF and UF conditions of RERP data. Priming has tendency to facilitate the FB model in the left hemisphere. On the other hand, independent of model preference, priming strengthened a bidirectional connection between FG and PFC in both hemispheres; this indicates a strong role of FG in structural representation and of PFCs in controlling decisions about face familiarity. Priming modulates the pathway FGMTLPFC differently in the two hemispheres, strengthening the involvement of MTL in the left hemisphere and weakening in the right hemisphere. This indicates proficiency of the left and right MTL in processing different aspects of facial information. Further, a backward connection ATLPFC in the left hemisphere was found to be functionally relevant for both conditions in speeding up response time in individual subjects, reinforcing the role of PFC in executive functioning and ATL in naming of famous faces. Thus, an integrated framework of source localization and DCM with RERPs allows a novel, comprehensive understanding of time resolved dynamics in face recognition and priming, thereby piloting prospects of its application to other experimental paradigms.
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Differential effects of calcium and tetanic stimulation frequencies on hippocampal synaptic potentiation and depressionChirwa, Sanika Samuel January 1985 (has links)
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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A neuroimaging investigation of affective, cognitive, and language functions in psychopathyKiehl, Kent Anthony 05 1900 (has links)
Psychopathy is a complex personality disorder denned by a constellation of affective
and behavioral characteristics. There is accumulating behavioral evidence suggesting that the
condition is associated with impairments in affective, cognitive, and language functions.
However, relatively little is known regarding the neural systems underlying these
abnormalities. The present thesis is comprised of five experiments designed to elucidate and
characterize the abnormal functional architecture underlying these abnormalities in
psychopathic criminals. In Experiments 1 and 2, functional magnetic resonance imaging
(fMRI) was used to elucidate the neural systems underling abnormal semantic and affective
processes in these individuals. In Experiments 3, 4 and 5, event-related potentials (ERPs)
were used to characterize the temporal features of cognitive and language functions in
psychopaths.
The results from Experiment 1 revealed that compared to control participants,
psychopaths performed more poorly and failed to showed the appropriate neural
differentiation between abstract and concrete stimuli during a lexical decision task. These
deficits were located in the right anterior superior temporal gyrus.
The results from Experiment 2 indicated that psychopaths, relative to control
participants, showed less activation for processing affective stimuli than for neutral stimuli in
several neural regions, including the right amygdala/hippocampal formation, left
parahippocampal gyrus, ventral striatum, and in the anterior and posterior cingulate.
Psychopaths did show greater activation for processing affective than for neutral stimuli in
regions located outside the limbic system, including bilateral inferior frontal gyrus. These
latter data suggesting that psychopaths used different neural systems than did controls for
performing the task.
The results from Experiments 3 and 4 indicated that psychopathy is associated with
abnormalities in the P3 ERP component elicited by target stimuli during visual and auditory
oddball tasks. In addition, the psychopaths' ERPs to visual and auditory target stimuli were
characterized by large fronto-central negativities in the 350-600 millisecond time window.
These fronto-central ERP negativities are similar to those observed for patients with temporal
lobe damage.
In Experiment 5, using a standard sentence processing paradigm, no group
differences were observed between psychopaths and nonpsychopaths in the amplitude of the
N400 potential elicited by terminal words of sentences that were either congruent or
incongruent with the previous sentence context. These results indicate that the abnormal
fronto-central ERP negativities observed in previous studies of language function in
psychopaths are not related to processes involved in the generation of the N400.
Taken together, these data suggest that one of the cardinal abnormalities in
psychopathy is abnormal semantic processing of conceptually abstract information and
affective information and that these abnormalities are related to the function of neural circuits
in the anterior temporal lobes and lateral frontal cortex. / Arts, Faculty of / Psychology, Department of / Graduate
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