Functional Recovery of Cricket Giant Interneurons after Cercal Ablations

In order to explore the functional recovery of the cercal sensory system of the cricket Gryllus bimaculatus, changes in response properties of four air-motion sensitive giant interneurons (GIs 8–1, 9–1, 9–2 and 9–3) were investigated after partial sensory deprivations. Velocity thresholds, response magnitudes and response latencies of each GI to a directional air current stimulus were investigated 21 days after ipsilateral or contralateral cercal ablations. The results were compared to those measured 1 day after the same treatment (Matsuura and Kanou, 1998) in order to specify the changes which occurred during the first 20 days. Each GI showed a different pattern of change in responses according to the direction of stimulus air current; i.e. the changes observed were direction dependent regardless of whether they were compensational or not. Compensational changes in response magnitudes and/or response latencies were observed in GIs 8–1, 9–1 and 9–2 when air currents were applied from particular directions. As there was no regeneration of cercal filiform hairs, those changes must be caused by the changes in synaptic strength between GIs and particular sensory afferents associated with cercal filiform hairs. Such neural compensation must underlie the basis of behavioral compensation when the insects have damaged sensory apparatus.