Morphological and functional changes in sensomotor cortical synapses during the summation reflex in rabbits.

Abstract

1. Electron-microscopic study of synapses in the rabbit sensomotor cortex during the summation reflex reveals structural changes in the pre- and postsynaptic components of axodendritic synapses, possibly as a result of increased functional activity of the synaptic apparatus. 2. The strongest response to a combination of stimuli is observed in the postsynaptic matrix, and it results in marked thickening of the postsynaptic membranes in some axo-dendritic synapses. 3. The character of ultrastructural changes in synapses in the sensomotor cortex during formation of simple forms of temporary connection makes it appear likely that the postsynaptic membrane of axo-dendritic synapses is one of the earliest sites of structural consolidation of traces of incoming information.