A better grasp of the function of the small area of the hippocampus known as CA2 could prove useful in understanding and treating disorders characterized by altered social behaviors, such as autism, schizophrenia, and bipolar disorder, researchers at Columbia University Medical Center reported Monday.
The hippocampus -- a pair of question-mark shaped structures in the brain's temporal lobes -- has long been understood as playing a critical role in our ability to remember the who, what, where and when of our daily lives.
"However, the role of CA2, a relatively small region of the hippocampus sandwiched between CA3 and CA1, has remained largely unknown," neuroscience and pharmacology Professor Steven A. Siegelbaum said.
In an experiment, CA2 neurons in mice were inhibited, then they were given a series of behavioral tests.
"Normally, mice are naturally curious about a mouse they've never met; they spend more time investigating an unfamiliar mouse than a familiar one," said Frederick L. Hitti, a doctoral student in Siegelbaums' lab. "In our experiment, however, mice with an inactivated CA2 region showed no preference for a novel mouse versus a previously encountered mouse, indicating a lack of social memory."
A decreased number of CA2 inhibitory neurons has been detected in individuals with schizophrenia and bipolar disorder, the researchers said, suggesting CA2 may provide a new target for therapeutic approaches to the treatment of social disorders.
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