Conditioning of the nictitating membrane response in rabbit ( Oryctolagus cuniculus) with electrical brain-stimulation as the unconditioned stimulus

Abstract

Mis, Gormezano, and Harvey [19] and Martin, Land, and Thompson [17] showed that electrical stimulation of the brain (ESB) could be used as an unconditioned stimulus (US) to establish classical (Pavlovian) conditioning of the rabbit's nictitating membrane response (NMR) to a tone conditioned stimulus (CS). Experiment 1 of the present study demonstrated classical conditioning of the rabbit's NMR to ESB with tone, lights, and back shock CSs. Conditioned responding transferred positively from acquisition training with ESB to training with a peripheral US (paraorbital eye shock). Discrimination training and tests of stimulus generalization indicated that conditioned responding to ESB was not due to nonassociative factors. Electrode placements yielding NMR elicitation were distributed widely across the pontine brainstem, whereas successful conditioning sites were located in the vicinity of the abducens nucleus. The behavioral unconditioned and conditioned responses obtained with ESB were similar in topography to those observed with paraorbital eye shock. Experiment 2 of the present study showed that an NMR conditioned with CS-eye shock pairings could be maintained with an ESB US. Electrode loci associated with successful maintenance of conditioning were located caudal and ventrolateral to the abducens nucleus in a region containing cells that are thought to comprise the accessory abducens nucleus.