Unit activity recorded from the globus pallidus during classical conditioning of the rabbit nictitating membrane response.

Single and multiple unit activity were recorded from the region of the globus pallidus (GP) in rabbits during classical conditioning of the nictitating membrane response. The most common response recorded in the GP was a short latency (less than 60 ms) change in firing following presentations of the pure tone conditioned stimulus (CS) and the corneal airpuff unconditioned stimulus (US). This response pattern was present in 39% of the pallidal records, and appeared to be elicited by the auditory components of the CS and US. Similar response patterns were seen in a few records from the putamen, entopeduncular nucleus, and ventral pallidum/substantia innominata. All of the single units that displayed this response pattern had a very sporadic pattern of spontaneous activity. Several other records from the GP displayed short latency responses after US presentations that appeared to be related to the tactile component of the airpuff. Responses of pallidal neurons to the CS and US were largely unaffected by the training procedures. It is concluded that this structure is most likely not directly involved in the classical conditioning of simple, striated muscle responses.