THE FUNCTIONAL-ANATOMY OF ATTENTION TO VISUAL-MOTION - A FUNCTIONAL MRI STUDY

Attention can enhance or modulate neural responses to stimuli at early and late stages of sensory processing. We were interested in the modu latory effect of attention to visual motion on cortical responses as m easured by functional MRI, Subjects were scanned during repeated prese ntations of identical stimuli (visual motion) while only the attention al component of the task was varied. Enhanced haemodynamic responses d uring attentive conditions defined an occipitoparietofrontal system, i ncluding sensory and association areas, as well as the medial thalamus and superior colliculus. Attentional modulation was not restricted to extrastriate areas (including V3a and the V5 complex) but was also ev ident, to a lesser degree, in early visual areas close to the calcarin e fissure (V1/V2 border), Attention-related enhancement of cortical re sponsiveness is discussed in terms of data that implicate modulatory s hort-term changes in synaptic efficacy and reciprocal connections betw een striate, extrastriate, parietal and frontal areas. Given the simil arity of our attentional network to that controlling eye movements, th e results of this study are in accord with theories linking oculomotor control and attention.