[Functional maturation of the mossy synapses of hippocampal fibers during rabbit ontogeny]

The time course of functional maturation of the mossy fibre synapses in the pyramidal cells of the dorsal hippocampus CA3-CA4 areas was investigated in intact, drug-free 1-14-day old rabbits by the method of extracellular recording of focal potentials and unit responses to electrical stimulation of the fascia dentata. Focal potentials as a biphasic short latency wave, spike discharges with latency from 3 to 10 ms and inhibitory reactions of the hippocampal units appeared in response to a single shock on the 4th postnatal day. During the following ten days the amplitude of the focal potentials increased from several hundred microvolts to several millivolts. The most dramatic increase occurred between the 4th and the 7th days. Posttetanic potentiation of the responses was observed already from the 4th postnatal day.