Frequency-intensity characteristics of cricket cereal interneurons: low-frequency-sensitive units

Three identified interneurons of the cereal system were investigated electr ophysiologically; these interneurons are sensitive only to stimulation of c ereal filiform-hair sensilla by low-frequency sound. Measurement of the fre quency ranges revealed cut-off frequencies between ca. 20 and 70 Hz. Analys is of the responses near threshold and at higher intensities in the frequen cy range 5-500 Hz shows that one of them (Interneuron 9-1b) exhibits a sens itivity maximum at the frequency-intensity combination necessary for the pe rception of an intraspecific signal at 30 Hz. This band-pass behavior disap pears at higher stimulus intensities. In order to investigate the mechanism of the low-frequency selectivity of the interneurons, two-tone stimulation experiments were performed. When stimuli in the best-frequency range were superimposed by a 100-Hz tone, the spiking activity was suppressed in an in tensity-dependent manner.