Convergence of multi-modal sensory signals at thoracic interneurons of the escape system of the cockroach, Periplaneta americana.

Research on the escape system of the cockroach has focused upon the role of giant interneurons in conveying information on wind stimulation from the cerci located on the abdomen to motor control centers in the thoracic ganglia. In the thoracic ganglia the ventral giant interneurons connect to a population of interganglionic interneurons referred to as type A thoracic interneurons. In this paper we have tested the type A interneurons for additional sensory inputs in the absence of ventral giant interneuron activity. We find that the cells that receive ventral giant interneuron activity are also influenced by a variety of additional sensory inputs; wind mediated activity in a pathway that descends from the head, tactile inputs from several loci, auditory stimuli and light responses. Moreover, behavioral observations indicate that at least some of these activities can alter the escape movements. The results suggest that these interneurons serve as a site of convergence for numerous types of sensory activity. They further suggest that the escape system is capable of responding to directional wind information encoded in the ventral giant interneurons in the context of a wealth of additional information.