["Learning" by subicular neurons and theta rhythm]

In anesthetized cats, activity of subicular neurones was studied during dorsal hippocampal stimulation with single pulses or trains of pulses. Two different populations of neurones were observed in subicular region: one with phasic discharges in response to single and repetitive stimulation, and the other with inhibitory reactions. The second group of neurones changed activity in the course of repetitive stimulation and showed tendency towards driving phenomenon: the neurones started firing preceding each stimulus in the train. The extrapolation only occurred during trains of stimuli in theta range. Significance of hippocampal theta activity in the memory processes is discussed.