Long-term changes of hippocampal sharp-waves following high frequency afferent activation.

Rats equipped with stimulating and recording electrodes in the hippocampus were trained to lap water on a variable interval schedule. High amplitude EEG sharp waves ( SPW ) were recorded from the CA1 region during drinking. High frequency stimulation of the commissural/associational system enhanced both the incidence and amplitude of the drinking associated SPWs up to 48 h. These findings indicate that strong, synchronous activation of an input pathway may induce long-term alteration of the excitability of the intra-hippocampal circuitry.