Lateral subthalamic area as mediator of classically conditioned bradycardia in rabbits.

Examined whether a central efferent pathway passing through the lateral zona incerta (LZI) of the subthalamus would selectively mediate the bradycardia conditioned response (CR) in 22 New Zealand albino rabbits. Electrodes were implanted bilaterally in LZI or in control sites just dorsal or ventral to LZI. Two days following surgery, Ss were subjected to Pavlovian conditioning or to pseudoconditioning. Subsequent bilateral electrolytic lesions did not infuence the heart rate (HR) orienting response, unconditioned response (UCR), baseline, or lack of response to pseudoconditioning. Bilateral LZI lesions alone abolished the HR CR. In a follow-up experiment, the corneoretinal potential (CP) CR and HR were recorded in 4 Ss. Bilateral LZI lesions following conditioning to a criterion of 65% CP CRs abolished the HR CR without affecting CP CRs. Findings indicate that LZI is part of an efferent pathway that selectively mediates the HR CR in rabbits. (24 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved)