Active tactile sensing for localization of objects by the cockroach antenna

Antennal movement during tactile orientation behavior was examined three-dimensionally in American cockroaches during tethered walking. When a wooden rod was presented to the tip of one antenna in an upright orientation at one of the three different horizontal positions (30°, 60°, or 90° from the center of the head), the animal touched it repeatedly with the antenna, and tried to approach it (positive thigmotaxis). Positional shifts were also observed for the contralateral unstimulated antenna. The ipsilateral antenna tended to touch the object during inward movement (adduction) at all three test angles. The cumulative turn angle made during a continuous test period of 24 s clearly depended on the object’s position; however, the contact frequencies were almost the same regardless of the position. The relationships between contact frequency and some locomotion parameters were also investigated on a shorter time scale of 3 s. The contact frequency positively correlated with the turn angle, with the accuracy of orientation at all three test angles, and with the translation velocity at test angles of 30° and 60°. It is concluded that the performance during tactile orientation can be represented effectively by the frequency with which the antennae touch the attractive objects.