Middle-latency responses of awake and anesthetized Japanese macaques

The middle-latency response (MLR) of two Japanese macaques were investigated. In the awake state, the configuration of the MLR components showed two positive peaks: Pa and Pb. The latency and the configuration of Pa were very similar to those of humans. In the topographic recordings, the largest Pa amplitude was found from the vertex, or R1, which is 1 cm lateral to the vertex. In the anesthetic state, Pa and Pb gradually disappeared. This study shows that the MLR in awake Japanese macaques is similar to that in humans, and differs from that in cats. Therefore these awake monkeys are suitable as animal models of human MLR.