A cortical circuit for abrupt visual learning in the primate brain

Summary

Visual cortical plasticity declines sharply after the critical period, and yet we easily learn to recognize new faces and places throughout our lives. Such learning is often characterized by a “moment of insight”, an abrupt and dramatic improvement in recognition. We studied the brain mechanisms that support this kind of learning, using a behavioral task in which non-human primates rapidly learned to recognize visual images and to associate them with particular responses. Simultaneous recordings from the inferotemporal and prefrontal cortices revealed a transient synchronization of neural activity between these two areas that peaked around the moment of insight. This synchronization was strongest between inferotemporal sites that encoded images and prefrontal sites that encoded rewards. Moreover, its magnitude built up gradually with successive image exposures, suggesting that abrupt learning is the culmination of a search for informative visual signals within a circuit that links sensory information to task demands.