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Abstract:
Abstract: O'Keefe and Nadel posited that the foundation of an
organism's exploration of and navigation through space might lie in
a neurally-based cognitive mapping system. This system permits
organisms to (a) acquire representations of relations among
stimuli, (b) use those relations to form a cognitive map of that
environment, and (c) use that cognitive map to generate novel
search strategies within the environment. We used the
Computer-Generated Arena (C-G Arena) to test predictions that
hippocampus is: (a) necessary to learn the location of a hidden
target, but (b) is not necessary to learn to navigate to a visible
target. Data from functional magnetic resonance imaging (fMRI)
revealed hippocampal activity in 8 of 8 naive participants (6
bilateral, 1 left, 1 right), and 2 of 3 highly experienced
participants (2 right). For the visible conditions, hippocampal
activity was found in 5 of 8 naive participants (4 bilateral, 1
left), and in none of the experienced participants. Moreover,
activation from the visible condition was located more posteriorly
within the hippocampal formation than those in the invisible
condition. In addition, all participants showed strong activation
of the posterior parietal cortex, motor cortex, premotor cortex,
and cerebellum. These results support the importance of the
hippocampal formation in place learning, and its association with
other brain areas involved in spatial perception and
manipulation.
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