Year: 2004
Type: dissertation
Abstract: This work began with a review of visual spatial selective attention, from a behavioural perspective with particular emphasis placed upon the spotlight model.To complement the behavioural review, the physiological aspects of the visual system were studied to find possible loci of the spotlight.The literature pointed to the pulvinar nucleus of the thalamus, interacting with the parietal and frontal cortices.Some experimental work examined relationships between visual spatial selective attention and event-related potentials (ERPs) recorded from the scalp.The second section of this thesis reviewed the ERP measures relating specifically to the visual modality for their possible application in a visual attentional task.This yielded two independent findings.First, the Probe-ERP paradigm comprising an attentional task being performed by the subject, with a separate stimulus to probe the unused resources within the system.Second, the steady-state evoked response, with the stimulus presented as a small sinusoidal variation around a mean level of contrast.The combination of the Probe-ERP paradigm and the steady-state visually evoked potential (SSVEP) warranted experimental evaluation.Implementation of the SSVEP required the design and construction of a complete sixty-four channel system, with provision of topographic data presentation, to display potentials across the scalp.This work involved development of computer hardware and instrumentation, software for data collection, analysis, artifact detection, interpolation and topographic display.After completion of the system, exploratory research involving the SSVEP began.An examination of the relationship between SSVEP and spontaneous EEG activity, particularly in the alpha band (8-13 Hz), indicated that the SSVEP probe activity and spontaneous alpha activity resulted from related, but independent mechanisms.Two other major experiments followed, involving the Probe-SSVEP with visual vigilance and selective attention.The results indicated that particular regions of the v brain are involved with these activities-including the prefrontal, the right temporal, and the parieto-occipital areas.As an adjunct to the major experimental work, a small pilot involving a few braininjured individuals indicated that the technique has promise in examination of clinical populations.vi Acknowledgments.I would like to acknowledge the following people for their work or assistance.Mr Rob di Pierro, Mr Joe Ciorciari, and Dr Shuangyong Ma for your assistance with the patient recording at St. Vincent's Hospital.Dr Jon Currie, for liaising with the Departments of Neurology, Neurosurgery, and finding the individuals from whom the recordings were made.The Department of Psychiatry at St. Vincent's
Author: Mark Schier
Language: English
Subfield: Cognitive Neuroscience
Field: Neuroscience
Domain: Life Sciences
Open Access status: green
OpenAlex ID: W112257652