On the Significance of Post‐ and Pre‐Synaptic Events for Facilitation and Inhibition in the Sympathetic Ganglion of the Cat.

It is concluded that following transmission of a single volley through the ganglion pre-synaptic potentiation is a facilitatory factor along with post- synaptic potentials in subliminally excited cells and the negative afterpotentials of excited cells.

Abstract

Summary. Transmission of a test reflex through the stellate ganglion of the cat was examined 1) after antidromic conditioning, 2) after Conditioning the same preganglionic nerve as the one from which the test reflex was elicited, 3) after conditioning the other preganglionic nerve. There was less depression after 2 than 1 and, if there was a high degree of occlusion also less after 2 than after 3. When in the same preganglionic nerve as the one used for testing a volley was set up to excite the cells 2 msec. before they were reached by a maximal antidromic volley the depression of the test reflex was again less than after antidromic conditioning alone. If the combination of antidromic and orthodromic conditioning was made so that a preganglionic nerve other than the one used for testing was stimulated to excite the ganglion cells 2 msec. before they were reached by antidromic volley the depression was the same as after antidromic conditioning alone despite a high degree of occlusion. It is therefore concluded that following transmission of a single volley through the ganglion pre‐synaptic potentiation is a facilitatory factor along with post‐synaptic potentials in subliminally excited cells and the negative afterpotentials of excited cells. There is nor indication of a long‐lasting excitatory action from the pre‐synaptic terminals neither of inhibitory preganglionic fibres. In the last section are described conditions under which pre‐synaptic failure may occur.