UCI researchers have found that a single brief memory is actually processed differently in separate areas of the brain - an idea that until now scientists have only suspected to be true. The finding will influence how researchers examine the brain and could have implications for the treatment of memory disorders caused by disease or injury.
The results are published in the Proceedings of the National Academy of Sciences.
In a study using rats, researchers Emily L. Malin and James L. McGaugh of UCI's Center for the Neurobiology of Learning and Memory demonstrate that while one part of the brain, the hippocampus, is involved in processing memory for context, the anterior cingulate cortex, a part of the cerebral cortex, is responsible for retaining memories involving unpleasant stimuli. A third area, the amygdala, located in the temporal lobe, consolidates memories more broadly and influences the storage of both contextual and unpleasant information.
"These results are highly intriguing," said McGaugh, a member of the National Academy of Sciences who pioneered the study of drug and stress-hormone influences on memory. "It is the first time we have found this fragmentation in the brain of what we would think of as a single experience. For example, different aspects of an experience, such as a car accident, would be processed by different parts of the brain. The experience is fragmented in our brain, even though we think of it as one event."
According to Thomas J. Carew, Donald Bren Professor and chair of UCI's Department of Neurobiology and Behavior, understanding which parts of the brain process which types of memories gives scientists a better grasp on why particular types of memory impairment can occur and why, for example, different types of strokes might affect different memory systems. "This study is a terrific demonstration of how different components of our neural real estate can be allocated to process different aspects of memory," said Carew. "The more we know about the specialization of memories, the more we can understand how and why the processing of memory can go awry, which in turn can critically inform clinical problems involving a wide range of cognitive deficits."
McGaugh's previous work has shown the key role emotional arousal and the accompanying release of stress hormones play in creating lasting memories. The amygdala has been shown to be activated by the release of these hormones.