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W. Skrandies, A. Jedynak, T. Hayakawa; Visually Evoked Brain Activity and Sustained Attention . Invest. Ophthalmol. Vis. Sci. 2003;44(13):4111.
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© ARVO (1962-2015); The Authors (2016-present)
Purpose: We studied visual information processing in healthy adults who had to discriminate grating targets of high or low spatial frequency. We analyzed how and when attention effects occurred in visual evoked brain activity. Methods: Grating stimuli were shown sequentially in a randomized order on a computer monitor in the left or right of the visual half-field. Task relevant stimuli had a random occurrence probability of 20%. Electrical brain activity was recorded in 16 adults from an array of 30 electrodes extending from the inion to Fz. For each subject mean potentials were averaged off-line over 750 ms. Results: Six different components with mean latencies between 76 and 643 ms were analyzed. At all latencies components evoked by task relevant stimuli had significantly higher field strength than those evoked by irrelevant stimuli. As expected, late components occurred with relevant stimuli displaying a significant influence of task condition. The scalp topography of these components, however, was also influenced by visual stimulus location. The amount of lateralization was modulated by task relevance. Analysis of early components revealed that at latencies of 76 ms the lateralization of activity was influenced by task relevance and attention. Conclusions: Our data demonstrate attention effects to stimuli occurring in different parts of the visual field. Neurophysiological correlates of sustained attention are seen early during primary stimulus processing, but physical stimulus characteristics like visual field location may also influence the topography of late, cognitive brain components.
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