昆虫における音の方向知覚の神経機構

抄録

The auditory T large fibre which lies in the cord between the brain and metathoracic ganglion receives at the prothoracic ganglion not only the excitatory effect from the ipsilateral tympanic nerve, but also the inhibitory and weak excitatory effects from the contralateral one. The impulses newly evoked on this fibre are conducted to the brain and the metathoracic ganglion at the same time. The large difference in the number of impulses between the responses of a pair of the auditory T large fibres is found in the responses to a sound, the frequency of which is involved most dominantly in the stridulation of the group which is also the most effective frequency to the tympanic organ. The inhibitory effect does not operate to make the difference in threshold between a pair of T large fibres larger, but does to exaggerate the difference in the number of impulses between them. By this mechanism, the central neural network may make directional sense sharp.