The Neural Foundations for Memory and Social Cognition In The Human Brain

National Institute Of Mental Health

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Abstract

This past year we have continued to focus on a major part of long-term memory, termed semantic memory, that is composed of general information, such as facts, ideas, and the meaning of objects and words. We are particularly interested in characterizing the neural substrate mediating object and word meaning and its role in object perception. We are also interested in understanding how abstract knowledge, such as information about social interactions, is represented. Our studies have shown that information about salient properties of an object - such as what it looks like, how it moves, and how it is used - is stored in the sensory and motor systems active when objects are perceived and manipulated. As a result, objects belonging to different categories such as animate entities (people, animals) and manmade manipulable objects (tools, utensils) are represented in partially distinct neural circuits composed of distinct processing nodes located in multiple cortical areas. These distributed circuits also underpin our ability to understand more abstract events such as social and mechanical interactions. It is now generally accepted that long-term memories are distributed throughout cerebral cortex. Controversy exists, however, about the details of this neural system. Specifically, recent claims suggest that, in addition to the distributed networks or circuits noted above, a central processor or "hub" is necessary where information from disparate sources is combined. Moreover, this "hub" is believed to be located in the most anterior sectors of the temporal lobes. We evaluated this possibility in a series of fMRI studies. Contrary to the "hub" model, we found that the anterior temporal lobes are selectively involved in memory functions concerning other individuals, rather than memory for all types of objects as would be predicted by the hub view. Thus, consistent with clinical data from patients with damage to this region, the anterior temporal lobes should be best thought of as part of a widely distributed social processing system for representing others.