Responses to wind recorded from the cercal nerve of the cockroachPeriplaneta americana

Summary

• 1. To understand better the basis for responses to wind recorded from giant interneurons of the cockroachPeriplaneta americana (Westin et al., 1977), responses to wind puffs from different directions were recorded from single sensory neurons in the cercal nerve of this animal.

• 2. When polar plots of number of action potentials vs. wind angle were constructed, all were single-lobed indicating that only one direction of displacement of the associated filiform hair excited the cell. Most responses spanned approximately a 180° range (Fig. 2) which is similar to the range of the most directional giant interneurons (No's 3, 5, and 6; Westin et al., 1977).

• 3. Approximately seven different categories of sensory response could be distinguished based on the angular range of response (Fig. 3). (Two of these could be further subdivided based on sensitivity to differences in wind velocity or acceleration.) Thus considerable directional information is available at the level of the sensory neurons and could account for the directional responses seen in some of the giant interneurons (Westin et al., 1977).

• 4. No significant differences in latency could be found among the different categories of sensory response, so that differences in latency of response in different giant interneurons (Westin et al., 1977) must be due to differences in integration time.

• 5. Though there were differences in time course of response among the different categories of sensory cells, no category was purely phasic (Fig. 4). Thus phasic responses of some of the giant interneurons (No's 2 and 3; Westin et al., 1977) are not due to an early termination of sensory input.