Recollection, as defined by memory specialists, is the ability to call up specific details about an encounter, while familiarity is simply knowing that someone or something has been encountered before. Both are elements of recognition memory and both, new research suggests, are functions of the brain's hippocampus.

Published in the Feb. 2 issue of the journal Neuron, the University of California, San Diego study contradicts a recent body of work which maintains that the hippocampus is involved only in recollection.

Led by senior researchers John Wixted, chair of the UCSD psychology department, and Larry Squire, a professor of psychiatry and neurosciences at the UCSD School of Medicine and the San Diego Veterans Affairs Health System, the study addresses one of the central debates in the neuroanatomy of memory.

A seahorse-shaped structure in the left and right medial temporal lobes of the brain, the hippocampus has long been known as a critical area for processing memory. Memory is impaired, often severely, in people whose hippocampi have been damaged by trauma or disease by Alzheimer's, for example, or oxygen deprivation following a heart attack.

The details of hippocampal function, however, are hotly contested in scientific circles.

"It is important to be able to assign a process to a specific region of the brain, but it is also intoxicating," Wixted said. "Psychologists and neuroscientists have jumped at the notion that the hippocampus is critical only for the recollection component of recognition and that the adjacent cortical areas take care of familiarity only. But our findings suggest that conclusion might have been premature."

The study compared six memory-impaired patients with discrete hippocampal damage that is, p
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Contact: Inga Kiderra
ikiderra@ucsd.edu
858-822-0661
University of California - San Diego
1-Feb-2006