Scientific Understanding of Consciousness
Consciousness as an Emergent Property of Thalamocortical Activity

Attention Top-Down Feedback



Science 15 June 2007: Vol. 316. no. 5831, pp. 1612 - 1615

Neural Mechanisms of Visual Attention: How Top-Down Feedback Highlights Relevant Locations

Yuri B. Saalmann,1 Ivan N. Pigarev,2 Trichur R. Vidyasagar1*

1 Department of Optometry and Vision Sciences, The University of Melbourne, Parkville 3010, Australia.
2 Institute for Information Transmission Problems, Russian Academy of Sciences, Bol'shoy Karetniy 19, 127994 Moscow, Russia.

Attention helps us process potentially important objects by selectively increasing the activity of sensory neurons that represent the relevant locations and features of our environment. This selection process requires top-down feedback about what is important in our environment. We investigated how parietal cortical output influences neural activity in early sensory areas. Neural recordings were made simultaneously from the posterior parietal cortex and an earlier area in the visual pathway, the medial temporal area, of macaques performing a visual matching task. When the monkey selectively attended to a location, the timing of activities in the two regions became synchronized, with the parietal cortex leading the medial temporal area. Parietal neurons may thus selectively increase activity in earlier sensory areas to enable focused spatial attention.



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