Long-term potentiation of the commissural path-CA1 pyramidal cell synapse in the hippocampus of the freely moving rat.

The potentiation effect of short tetani (5 sec, 50 Hz) of commissural fibers having dendritic synapses on CA1 pyramidal cells of the hippocampus was studied in freely behaving rats. High frequency stimulation produced a large increase in amplitude of the population spike and, to a lesser extent, of the extracellular synaptic responses. This increase was maintained for 4 days after a single train. The results imply that the efficiency of the synaptic transmission in the commissural path--CA1 pyramidal synapse can be modified.