A Novel Picture of the Organization of the Visual Brain
December 2 @ 1:30 pm - 2:45 pm
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Our current picture of the organization of the visual brain, with the primary visual cortex (area V1) providing all the feed-forward input to the other visual areas lying outside it, needs to be modified. Recent, and older, studies show that there are at least three parallel feed-forward pathways that reach the visual areas of the brain outside area V1; one is the classical pathway reaching them through area V1 while the other two by-pass V1 to reach them directly. The earliest signals reach both V1 and visual areas outside it at about 30-45 ms after stimulus onset but the precise latency depends upon characteristics of the stimulus. Moreover, stimuli belonging to some visual attributes such as colour are consciously perceived before stimuli belonging to other visual attributes such as visual motion. This temporal hierarchy in visual perception appears to depend upon differences in processing speeds, and can therefore be varied by changing the characteristics of the stimuli. Taken together, these results lead to a re-assessment of the general organization of the visual brain and to the conclusion that the visual brain consists of multiple, parallel and asynchronously organized task- and stimulus-dependent hierarchies (STDH). Which of these parallel anatomical hierarchies has temporal and perceptual precedence at any moment is related to task and stimulus and on the ability of the brain’s specialized visual areas to undertake multiple operations asynchronously.
Semir Zeki is Professor of Neuroesthetics at University College London, U.K. He specializes in studying the primate visual brain and the neural correlates of affective states, such as the experience of love, desire and beauty that are generated by sensory inputs. He has received the Golden Brain Award (1985), Award in Electronic Imaging (2002), King Faisal International Prize in Biology (2004), Erasmus Medal (Academia Europeae, 2008), Aristotle Gold Medal (2011) and Rome Prize (Atena Onlus, 2012). He has lectured widely across the world giving over 60 named lectures, published three books, and held an exhibition of his own artwork at the Pecci Museum of Contemporary Art in Milan in 2011.