Hippocampal modulation of nucleus accumbens: behavioral evidence from amphetamine-induced activity profiles.

The experiments examined amphetamine-induced locomotion and stereotyped behavior in hippocampal-ablated and control rats for 30 days following surgery. Locomotor counts, stereotypy ratings, and locomotor-time profiles showed that d-amphetamine sulfate produced a selective enhancement of locomotion (cage crosses) at the expense of stereotyped behavior in hippocampal rats relative to normal control rats. This enhancement emerged over the first 2 weeks postsurgery. To examine the role of the striatum in this amphetamine-induced effect, combined hippocampal damage and 6-hydroxydopamine-induced damage of the nucleus accumbens or caudate-putamen were used. These results suggested that amphetamine-enhanced locomotion of hippocampal rats is dependent upon the integrity of the nucleus accumbens and may reflect a change of nucleus accumbens activity relative to caudate-putamen activity. Together these findings suggest that the hippocampus may participate in the control of locomotion by projections that modulate the activity of the nucleus accumbens.