李武 教授

时间： 2012-03-16 12:30 - 14:30

地点： 哲学楼103房间

The traditional point of view of image processing in the brain emphasizes a hierarchical order of the processing stream: information about local simple image components such as line segments is first extracted in early visual cortex, whereas more complex stimulus features such as global shapes are processed subsequently in higher-order cortical areas by integrating primitive features. In the primary visual cortex (area V1) response properties of neurons are generally thought to be rather simple and stereotyped, mainly dependent on hardwired neural circuitry. In contrast to this point of view, our recent studies in awake behaving monkeys have shown that V1 neurons dynamically change their response properties according to the perceptual task being performed, suggesting that the analyses of visual images in V1 depend on a complex interaction between stimulus-driven and goal-directed processes. Moreover, repeated performing of the same perceptual task, and therefore, repetitive invoking of top-down influences specific to the task can potentiate the adaptive changes in V1 useful for solving the task, suggesting that the changes induced by perceptual learning take place in V1 under task-dependent top-down control. Our findings indicate that even V1, the earliest cortical stage along the hierarchically organized visual pathway, is capable of running different computation “programs” tailored to different perceptual tasks. This could reflect a general adaptive processing mechanism in sensory cortex.

2012-03-16

2012-03-16