AUDITORY-EVOKED RESPONSES FROM THE CEREAL HEARING SYSTEM OF THE HOUSECRICKET, ACHETA-DOMESTICUS (ORTHOPTERA, GRYLLIDAE)

Action potentials (AP) N1, N2 and the excitatory postsynaptic potentia l-like response (EPSP-like) were recorded for auditory signals in Ache ta domesticus (house cricket). Recordings were made from the fifth abd ominal ganglion, the site of the first synapse of the cereal hearing s ystem. Stimulus parameters were varied to formulate an optimum set of stimulus conditions that best elicited the evoked responses. For high intensity low frequency signals, APs were clearly visible. For low int ensity signals the AP amplitude decreased leading to a broad, low-freq uency wave identified as the EPSP-like response. Pharmacologic agents tetrodotoxin and kynurenic acid were used to differentiate the potenti als. Tetrodotoxin reduced APs but had no effect on the EPSP-like respo nse. Kynurenic acid brought about complete inhibition of all auditory evoked potentials. These results indicate that the cricket cereal hear ing system can be used as a model to study auditory evoked potentials, and also suggests the possibility of the presence of excitatory amino acid receptors in the fifth abdominal ganglion of the house cricket.