Convergence of sensory input from tooth pulp, optic chiasm and sciatic nerve onto locus coeruleus neurons in the rat

Electrophysiological studies using rats were performed to determine whether or not neurons in the locus coeruleus (LC), subcoeruleus and parabrachial areas receive convergence of sensory input from tooth pulp (TP), optic chiasm (OC) and sciatic nerve (SN). Convergence of input from these nerves was observed in 23% and 33% of LC and subcoeruleus neurons, respectively, and from two nerves in 31% and 20% of LC and subcoeruleus neurons, respectively, while convergence was rarely detected in parabrachial neurons. These results suggest that there is a convergence of peripheral sensory input onto more than half the noradrenergic coerulear neurons.