[Change in the chemical sensitivity of the visual cortical synapses in rabbit ontogeny]

In experiments on newborn rabbits under nembutal (pentobarbital) anaesthesia, studies have been made on changes of visual evoked potential in the visual cortex during application of 1% solutions of GABA and nembutal. At the age of 7--9 days, these drugs decreased the evoked response, which may be associated with their hyperpolarizing effect on cortical synapses. Between the 11th and the 13th days, no effect of GABA and nembutal upon the evoked potential was noted. Definitive reaction to application of these pharmacological drugs typical for adult animals is formed not earlier than to the 15th--17th day. Beginning from this time, application of GABA and nembutal significantly increases visual evoked potential. The postnatal evolution of chemical sensitivity of postsynaptic membrane of neurons of the visual cortex in rabbits is discussed.