Distributed cortical network for visual attention

Robert T. Knight

doi:10.1162/jocn.1997.9.1.75

Distributed cortical network for visual attention

1997-01-01

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Robert T. Knight

DOI：10.1162/jocn.1997.9.1.75

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The contribution of prefrontal and posterior association cortex to voluntary and involuntary visual attention was assessed using electrophysiological techniques in patients with focal lesions in prefrontal (n = 11), temporal-parietal (n = 10), or lateral parietal cortex (n = 7). Subjects participated in a task requiring detection of designated target stimuli embedded in trains of repetitive stimuli. Infrequent and irrelevant novel visual stimuli were randomly interspersed with the target and background stimuli. Controls generated attention dependent N1 (170 msec) and N2 (243 msec) potentials maximal over extrastriate cortex. Anterior and posterior association cortex lesions reduced the amplitude of both the N1 and N2 potentials recorded over extrastriate cortex of the lesioned hemisphere. The pattern of results obtained reveals that an intrahemispheric network involving prefrontal and posterior association cortex modulates early visual processing in extrastriate regions. Voluntary target detection generated a parietal maximal P300 response (P3b) and irrelevant novel stimuli generated a more fronto-centrally distributed P300 (P3a). Cortical lesions had differential effects on P3a and P3b potentials. The P3b was not significantly reduced in any cortical lesioned group. Conversely, the P3a was reduced by both prefrontal and posterior lesions with decrements most severe throughout the lesioned hemisphere. These data provide evidence that an association cortex network involving prefrontal and posterior regions is activated during orientation to novel events. The lack of a significant effect on the visual target P3b in patients with novelty P3a reductions supports the notion that different neural systems are engaged during voluntary vs involuntary attention to visual stimuli.

Keyword:

EVENT-RELATED POTENTIALS

SUPERIOR TEMPORAL SULCUS

GO/NO-GO DISCRIMINATION

DORSOLATERAL PREFRONTAL LESIONS

AUDITORY SELECTIVE ATTENTION

HUMAN HIPPOCAMPAL-FORMATION

ASSOCIATION CORTEX LESIONS

POSITIVE EVOKED-POTENTIALS

BILATERAL STIMULUS ARRAYS

INDEX FOCUSED ATTENTION

Distributed cortical network for visual attention

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