The Cortical Distribution of Sensory Memories

Abstract

Recent investigations are allowing precise statements to be made about where in the cortex sensory memories are stored and retrieved. After highlighting new work that has refined the long-recognized contributions of frontal and temporal association areas, this review turned to sensory cortex and suggested that its role in the storage of sensory information and in the retrieval of perceptual memories is not qualitatively different from that played by “later” association areas. In particular, we presented evidence that neuronal activity in sensory cortex contributes to remembering the sensory features of a stimulus. Studies in species as different as humans and rats show that learned recognition of elemental stimulus features can be strictly localized in a way that is best accounted for by information storage within the framework of sensory cortical maps. Finally, electrophysiological studies in monkeys have shown that learning to recognize a stimulus is based on distinct changes in the patterns of neuronal activity in sensory cortex. Thus, each functional region of cortex appears to carry out the dual functions of information processing and information storage. Storage and retrieval involve the very populations of cortical neurons that explicitly encode the relevant information, ensuring that the stored and recalled information is of comparable quality to the information present during on-line processing.