Datensatz

Zusammenfassung

PURPOSE: Visual attention, normally focused on the centre of the visual field, can be shifted to a location in the periphery. This process facilitates the recognition of objects in the attended region. The present experiment was designed to investigate the time course of sustained attention that is known to augment stimulus perception in normal subjects.amp;amp;amp;amp;amp;amp;lt;bramp;amp;amp;amp;amp;amp;gt; METHODS: Cortical activity of the human brain related to shifts of the attentional focus was examined using magnetoencephalography. Subjects had to identify a stimulus presented on a screen at one of two locations in the periphery of their visual field. Sustained attention was either directed towards the target by a preceding cue or not.amp;amp;amp;amp;amp;amp;lt;bramp;amp;amp;amp;amp;amp;gt; RESULTS: Results confirmed a reaction time advantage on recognizing objects in the part of the visual field where attention had been deployed. A stronger magnetic brain response was detected for non-cued targets at a latency of 260-380 ms after target onset. Source localization revealed a neuronal generator of the attention related component in parietal cortex.amp;amp;amp;amp;amp;amp;lt;bramp;amp;amp;amp;amp;amp;gt; CONCLUSIONS: Sustained attention facilitates target detection. The component which is localized in parieto-occipital cortex in the non-cued condition is thought to reflect a transient shift of attention towards the target location.