Enhancement of afferent fiber activity in hippocampal slices.

The potentiation of synaptic activity in the hippocampal formation is a well documented phenomenon. It has been suggested, however, that a recruitment of additional afferent fibers can contribute to such an increase in synaptic activity. The hypothesis of an enhancement in afferent fiber activity, therefore, was investigated with the in vitro hippocampal slice preparation. Isolated radiatum fiber compound action potentials were evoked with paired electrical stimuli of equal intensity and separated in time by 30-40 msec. Statistical comparisons between control and test evoked responses reveal an augmentation of the test responses in support of the hypothesis of an enhancement in afferent fiber activity.