Sensory responses of dorsal cells in the lamprey brain

Summary Sensory responses were evoked in 17/33 dorsal cells in the brain of the lampreyIchthyomyzon unicuspis by mechanical stimulation of the dorsolateral skin of the sucker and head. Fifteen of the responsive cells tested were classified as pressuresensitive and two as nociceptive. Thus, some of the dorsal cells which are situated in the medulla of the lamprey and which project into the branches of the trigeminal nerves have sensory functions similar to those of dorsal cells in the spinal cord.