Neurophysiological studies of the response characteristics of auditory fibres in the cricket (Gryllidae orthoptera) with particular reference to Teleogryllus oceanus, (le guillou)

Single unit recordings of primary and central auditory fibers of the cricket Teleogryllus oceanicus show responses to frequencies over the range 1kHz to at least 42kHz. The characteristic frequencies, (ChFs) of units were distributed over most of the bandwidth investigated although few units were recorded with ChFs below 4kHz or in the region 7kHz to 10kHz. Some units showed more than one peak of sensitivity and others were broad-banded with no tuning to a particular frequency. Primary units whose ChFs approximated. to the carrier frequency (C.F.) of the species proclamation song were the most highly tuned. The derived threshold curves for all primary and central threshold data had major peaks of sensitivity at 4.8kHZ and 22kHz. The majority of primary units were not spontaneously active and had tonic response patterns but phasic responses were occasionally observed. Some central units have highly complex response patterns involving correlated spiking responses, silent periods and rebound activity. The response pattern of a single unit may vary with both the intensity and frequency of the stimulus. The implications of these findings are discussed