Scientists find the root of learning in the brain's hippocampus
June 10, 2003
Neuroscientists at NYU and Harvard identify cells in the hippocampus
that signal new memory formation
Neuroscientists at NYU and Harvard have identified how the brain's
hippocampus helps us learn and remember the sights, sounds and smells that
make up our long-term memory for the facts and events, termed declarative
memory. By studying the activity of neurons of the hippocampus, the
scientists have illuminated how the brain signals the formation of new
associative memories, a form of declarative memory. These results provide
some of the strongest direct evidence to date for learning-related
plasticity in the hippocampus.
The research findings are reported in the June 6 issue of the publication
Science in a paper entitled "Single Neurons in the Monkey Hippocampus and
the Learning of New Associations.”
Since the 1950s, scientists have been aware of the link between the
hippocampus and memory, but knew little of how this association manifested
itself in neural activity. The NYU research team, led by NYU post-doctoral
fellow Sylvia Wirth, NYU professor Wendy Suzuki and graduate student
Marianna Yanike, examined the neural correlates of associative memory
formation by using electrodes to monitor the electrical activity of
individual neurons in the brains of monkeys performing an associative
learning task. The neural and behavioral data was analyzed using dynamic
estimation algorithms developed by post-doctoral fellows Loren Frank, Anne
Smith and professor Emery Brown at Harvard University.
Each day, the monkeys were shown complex images superimposed with four
identical targets. As the monkeys learned through trial and error which
target location was associated with reward, the scientists observed dramatic
changes in the activity of some hippocampal neurons. They called these cells
"changing cells”. The changes in neural activity paralleled the animal's
behavioral learning curve indicating that these neurons are involved in the
initial formation of new associative memories.
”Because the activity in many changing cells continued after the animal
learned the association, this suggest that these cells may participate in
the eventual storage of the associations in long-term memory.” said Suzuki.
The team's research signifies a major breakthrough in understanding the
brain basis of memory. Understanding the memory functions of the normal
brain is a critical first step in intervening in situations where memory
function is impaired such as in Alzheimer's Disease.
New York University
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