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Past research has shown that largely separate memory systems are involved in learning different kinds of tasks, Packard said. For example, the hippocampus is key to cognitive learning, such as spatial mapping--useful for rats remembering where to find food in a maze when they are released from a new starting point--while the caudate nucleus mediates stimulus-response or habit learning--such as simply learning to turn left in a maze to find food, regardless of the starting point.
Damaging one of these respective brain areas wipes out an animal's ability to learn specific tasks. For example, hippocampal system lesions impair spatial learning, while caudate nucleus lesions impair habit learning--findings replicated in humans and other primates.
Moreover, Packard's research has shown that injecting memory-enhancing drugs into the hippocampus can heighten performance on tasks that require cognitive memory, while boosts to the caudate nucleus improve rats' performance on habit-learning tasks.
However, said Packard, rats with hippocampal lesions actually perform better than undamaged rats on some habit-learning tasks that use the caudate nucleus. The findings suggest that the hippocampal memory system sometimes interferes with learning in the caudate nucleus.
Friday, October 01, 2004
The new October issue of the American Psychological Association's Monitor on Psychology includes several short articles of interest to neuroscience readers. One of these articles is about one researcher's career of researching memory systems. Here is a snip from the full article, "Memory Divided" by Deborah Smith Bailey: