On the Innervation of the Slowly Adapting Stretch Receptor of the Crayfish‘ Abdomen. An Electrophysiological Approach

The synaptic effects of efferent fibres innervating the slowly adapting stretch receptor have been determined by intracellular records from reflexly intact receptors. Three such efferent fibres have been functionally identified. They all have an inhibitory action on the receptor and they probably correspond to the three efferent fibres described anatomically by Alexandrowicz (1967). The three types of IPSPs have similar reversal potentials and it is suggested that their synapses are intermingled and distributed over the somadendritic complex of the receptor. The inhibitory efficiency of the three types of IPSPs are markedly different, that of the thick accessory fibre being about five times more effective than the other two.