Interaction between afferent neurones in a crab muscle receptor organ.

Two of the three mechanoreceptor neurones which innervate the crab thoracic-coxal muscle receptor organ are non-spiking. The third, the small diameter P neurone, employs graded amplitude receptor potentials with either spikes or graded amplitude active membrane responses superimposed. An excitatory synaptic connection between one of the larger non-spiking afferents and the P neurone has now been detected within the thoracic ganglion. This novel connection between two afferents innervating the same receptor strand effectively extends the dynamic sensitivity range of the P neurone.