The coding of airborne-sound and vibration signals in bimodal ventral-cord neurons of the grasshopper Tettigonia cantans

In grasshoppers, the auditory and vibra- tional senses converge on the same ventral-cord neurons. All neurons in the ventral cord that discharge impulses in response to either airborne-sound or vi- bration stimuli also receive synaptic inputs from the other sensory system. The latter elicit either sub- threshold excitation or inhibition.

The coding of the conspecific song in the responses of most ventral-cord neurons of Tettigonia cantans is considerably improved when the stimulus consists not of simulated natural sounds alone, but of such
sounds together with either maintained vibration or vibration matched to the temporal structure of the song.

Stridulating tettigoniids produce both airborne and substrate-conducted sound. Thus the perception of airborne sound and vibration, and their simulta- neous processing in individual ventral-cord neurons, may be of fundamental importance - not only in localizing a nearby sound source, but also in facilitat- ing the recognition of conspecific signals.