March 21, 2008

Talk explores mysteries of memory

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Neal Cohen, Ph.D., delivers the Brainstorm keynote address. (photo by Neil Brake)

Talk explores mysteries of memory

Imagine you have no idea how old you are, what day it is or where you live, and, in just a few minutes, won't even remember reading this sentence.

Such has been the life for the past 55 years for patient HM, a man whose hippocampus was removed to cure his epilepsy.

Neal Cohen, Ph.D., introduced his work studying patient HM and others with memory disorders in this week's Brainstorm keynote address. Cohen defined memory using a quotation from Tennessee Williams: “Life is all memory except for the one present moment that goes by you so quick you hardly catch it going.”

Patient HM provides a unique model to study the role of the hippocampus and its role in “binding pieces of memory together.” Without this structure, each memory remains an island, and no context of how that individual memory fits into the original event is realized. In other words, memories are unable to be reconstructed.

Cohen's recent research at the University of Illinois focuses on testing various memory systems with eye movements. This design has the advantage of not requiring verbal reports or conscious awareness of the subject.

For example, when shown a picture of a face, most people's eyes focus on the internal structure (eyes, nose, mouth); however, the pattern of eye movement differs depending on the familiarity of the face. These differences are so pronounced, in fact, that eye movement can be used to predict whether that person is familiar or not.

“These eye movements are controlled by the hippocampus,” explains Cohen. “Your eyes know long before you respond and even before I ask you what the answer is.”

The Brainstorm address was sponsored by the Vanderbilt Kennedy Center for Research on Human Development, Vanderbilt Brain Institute, and the Middle Tennessee Chapter Society for Neuroscience.