| Abstract: | Experiments on giant neurons of the cerebral ganglion of the molluskPlanorbis corneus showed that heterosynaptic facilitation even if evoked by a single uncombined stimulation of the pallial nerve, is more effective than facilitation achieved by a combination of stimulations of nerves directly entering the cerebral ganglion. The intensity of facilitation does not depend on the synaptic efficiency of the heterosynaptic input for the test neuron, but on the intensity of its connection with the other neurons surrounding the giant cell (conjecturally of neurosecretory type). This fact, and also the long latent period of manifestation and achievement of the maximum of facilitation, and its nonspecificity relative to several inputs all suggest that heterosynaptic facilitation is neurosecretory in its origin. Such a mechanism of a sharp increase in the efficiency of synaptic connections in a nerve center may play an important role in the animal's nervous activity as a whole and in the formation of temporary connections in particular, although it does not reflect the specificity of the conditioned reflex.A. A. Bogomolets Institute of Physiology, Academy of Sciences of the Ukrainian SSR, Kiev. Translated from Neirofiziologiya, Vol. 12, No. 5, pp. 498–507, September–October, 1980. |
