HOW THE BRAIN LEARNS TO SEE OBJECTS AND FACES IN AN IMPOVERISHED CONTEXT

A degraded image of an object or face, which appears meaningless when seen for the first time, is easily recognizable after viewing an undeg raded version of the same image(1), The neural mechanisms by which thi s form of rapid perceptual learning facilitates perception are not wel l understood. Psychological theory suggests the involvement of systems for processing stimulus attributes, spatial attention and feature bin ding(2), as well as those involved in visual imagery(3). Here we inves tigate where and how this rapid perceptual learning is expressed in th e human brain by using functional neuroimaging to measure brain activi ty during exposure to degraded images before and after exposure to the corresponding undegraded versions (Fig. 1), Perceptual learning of fa ces or objects enhanced the activity of inferior temporal regions know n to be involved in face and object recognition respectively(4-6). In addition, both face and object learning led to increased activity in m edial and lateral parietal regions that have been implicated in attent ion(7) and visual imagery(8). We observed a strong coupling between th e temporal face area and the medial parietal cortex when, and only whe n, faces were perceived, This suggests that perceptual learning involv es direct interactions between areas involved in face recognition and those involved in spatial attention, feature binding and memory recall .