Meeting Abstract

17.6  Friday, Jan. 4  Unit responses from antenna in cockroaches generate control input predicted from control-theoretic model of wall following MONGEAU, J.-M.*; SPONBERG, S.N.; FULL, R.J.; Univ. of California, Berkeley; Univ. of California, Berkeley; Univ. of California, Berkeley

Connecting neural responses to task-level control during high-bandwidth tasks is critical to understanding the neuromechanics of high-speed locomotion. We studied high-speed wall following in the cockroach Periplaneta americana where neural delays impose severe constraints on sensorimotor control. A simple neuromechanical model of wall following developed within a control theoretic framework suggested that proportional (P) and derivative (D) information from antenna bending in response to a wall projection is sufficient for control. Population recordings of mechanoreceptive neurons in the antenna during a simulated turning experiment revealed a neural response with a phasic and tonic component consistent with P & D signaling thus suggesting that a temporally-filtered control input is generated at the level of the antenna. How the population response arises from individual mechanoreceptors remained elusive. Multi-unit extracellular recordings at the base of the antennal nerve revealed that individual units are tuned to both wall position and velocity. We hypothesized that the antenna could act as a delay line by the spatial arrangement of sensors to generate a filtered population response. We determined that afferents have different latencies and direct summation of the variable-latency responses generates a temporally-elongated phasic response supporting predictions from the model and whole-nerve recordings. Variable-latency afferent signals may provide a sufficient and low-delay preconditioned control input to the neuromechanical system of the cockroaches as demonstrated from the correspondence between the time course of the population response and the turning kinematics.