The physiological basis of attentional modulation in extrastriate visual areas.
Selective attention to color or motion enhances activity in specialized areas of extrastriate cortex, but mechanisms of attentional modulation remain unclear. By dissociating modulation of visually evoked transient activity from the baseline for a particular attentional set, human functional neuroimaging was used to investigate the physiological basis of such effects. Baseline activity in motion- and color-sensitive areas of extrastriate cortex was enhanced by selective attention to these attributes, even without moving or colored stimuli. Further, visually evoked responses increased along with baseline activity. These results are consistent with the hypothesis that attention modulates sensitivity of neuronal populations to inputs by changing background activity.
Wellcome Department of Cognitive Neurology, Institute of Neurology, London, UK. dave@fil.ion.ucl.ac.uk
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Chawla
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Friston
D001288:Attention / Q000502:physiology*; D001931:Brain Mapping; D002540:Cerebral Cortex / Q000033:anatomy & histology / Q000502:physiology*; D003118:Color Perception / Q000502:physiology*; D005074:Evoked Potentials, Visual; D005403:Fixation, Ocular; D006801:Humans; D008279:Magnetic Resonance Imaging; D009039:Motion Perception / Q000502:physiology*; D010775:Photic Stimulation; D011930:Reaction Time; D014741:Video Recording; D014793:Visual Cortex / Q000502:physiology; D014795:Visual Pathways / Q000502:physiology*