What psychological process mediates feeding evoked by electrical stimulation of the lateral hypothalamus?

Because electrical stimulation of the lateral hypothalamus (ESLH) can elicit both feeding and reward, most investigators have concluded that stimulation does not evoke the aversive cues associated with hunger. It has been hypothesized, instead, that ESLH primes ingestion by evoking pleasurable taste sensations. A direct taste of this hedonic hypothesis was undertaken in rats that showed stimulus-bound feeding. Contrary to the prediction, it was found that the taste reactions (gapes, tongue protrusions, etc.) during ESLH were more aversive than hedonic. It is suggested that the stimulation influences behavior by potentiating the salience, but not the hedonic value, of external stimuli. The advantages of this incentive salience hypothesis are that it circumvents the need to postulate a hedonic sensory experience during stimulation and that it can explain how evoked feeding may switch to other behaviors when conditions are altered.