Directional Sensitivity of Auditory Ascending Neuron in The Bushcricket Gampsocleis gratiosa

Quantitative analyses on phonotactic behavior of the bushcricket demonstrate that the bushcricket possesses good capability to determine direction of sound source. The morphological structure, laterality and directional sensitivity of the auditory ascending neuron in the prothoracic ganglion of the bushcricket have been studied. At its best frequency of 15 kHz, the laterality threshold difference of the neuron has a large value up to about 16 dB. Its directional sensitivity depends closely on stimulus frequency. The higher the stimulus frequency, the greater the directional threshold differences. Spike count and latency shift of the ascending neuron in response to each stimulus depend on the angle of incidence of sound. Therefore, the two parameters can be used as directional cues of sound source by the ascending neuron.