Organization of Receptive Fields of Cricket Giant Interneurons Revealed by Cercal Ablations

In order to determine the contribution of each cercus and its receptors in organizing the receptive field of four air-motion sensitive giant interneurons (GIs 8–1, 9–1, 9–2 and 9–3 ) of the cricket Gryllus bimaculatus, effects of removing the ipsilateral or contralateral cercus (referred to the side of the axons) on specific parameters of the wind-evoked responses of these neurons were investigated. All 4 GIs received only excitatory inputs from a group of filiform hairs on the ipsilateral cercus. In addition to the ipsilateral excitatory inputs, GIs 8–1 and 9–1 received weak excitatory and strong inhibitory inputs from a group of filiform hairs on the contralateral cercus. GI 9–2 received only inhibitory inputs from filiform hairs on the contralateral cercus. GI 9–3 received excitatory inputs from filiform hairs on the contralateral cercus and no inhibitory input was confirmed. In addition to such simple excitatory and inhibitory connections, the rebound motion of cercal filiform hairs had some role in organizing the receptive fields of GIs 9–2 and 9–3. Furthermore, the possibility of using a rebound depolarization of the membrane potential for mediating the long latency response in GIs 8–1 and 9–2 will be discussed.