Modelling active antennal movements of the American cockroach: towards biorobotic models of active sensing

Cockroach antennae are multimodal sensory appendages engaging in active olfactory and tactile sensing. They are involved in unisensory behaviours such as chemotaxis, thigmotaxis, obstacle negotiation and tactile orientation. Studies of multisensory capabilities mediated by the antennae are however lacking. Here we report on an integrated experimental and computational approach to investigate how sensory information affects antennal movements. We present a modelling approach to characterise the relationship between antennal searching movement of the American cockroach Periplaneta americana and the spatial properties of encountered odorant concentrations. Video recordings reveal that the animal’s antennae exhibit systematic movements in the presence of behaviourally relevant odorants. We hypothesise a dynamic coupling between the left and right antenna modulated by odour stimulation. To test this we designed experiments in which cockroaches were exposed to odorants arriving with different temporal patterns. We measured the spatial structure of the odorant plume encountered by the antennae at any given time and generated a spatial odorant concentration map. We then employed an adaptive frequency, coupled Hopf oscillator to model antennal movements in response to odorant concentration, using this map for sensory drive signals for the model. We present simulation results of antennal movements in response to odorant concentrations.