Neural substrates of behavioral aversion in lateral hypothalamus of rabbits

Unit electrophysiology of lateral hypothalamus (LH) in rabbits has revealed two functionally contrasting, topographically distinguishable groups of neurons that relate to hedonic properties of taste stimuli. To assess the neurobehavioral role of aversion-type cells (maximally excited by aversive stimuli and inhibited by rewarding stimuli) found in the rostral part of mid-lateral LH at the level of ventromedial nucleus (vmh), intracranial self stimulation (ICSS) and stimulation-escape were studied with moveable-type electrodes in this and an adjoining caudal region of LH dominated by a contrasting type of neuron. Hedonic properties of the brain stimulation conformed to the distribution of these cellular elements. Stimulation of the rostral area supported weaker ICSS and stronger escape behavior. Aversive reactions predominated in ventral parts of the rostral area. Aversion-type cells identified electrophysiologically in this region would appear to mediate behaviorally aversive functions. These cells may play a role in the activation of feeding (possibly also drinking) and in drive-reduction reward.