Response of medial medullary neurons to preoptic and scrotal thermal stimulation and to preoptic microinjection of capsaicin

1. 1. The neuronal discharges of medullary neurons were recorded in urethane-anaesthetized rats in response to three stimulations which produced tail vasodilation, i.e. preoptic warming, scrotal warming and preoptic microinjection of capsaicin. 2. 2. The number of neurons responding to the three stimulations in the same direction amounted to approx. 70% of the total number studied. The number of neurons responding with facilitation was about 5 times as many as those responding with inhibition. 3. 3. These medullary neurons are mostly located in the nucleus reticularis gigantocellularis.