Effects of oral experience on rewarding properties of oral stimulation

The oropharyngeal sensory and motor experiences of ingestion have long been considered to be rewarding or motivating. Recent work has suggested that the reinforcing properties of oral stimulation are modulated by experience with an ingestive bout. Two processes that result from the repeated oral experience that occurs during an ingestive bout, sensitization and oral habituation, may influence the reinforcing or rewarding properties of oral stimulation. The first process, sensitization, describes an initial increase in responsiveness following the first presentation of a stimulus: such an increase in responding has been noted in the ingestive behavior of both rats and humans. The second process, oral habituation, occurs after sensitization of responding, and results from continued repeated exposure to oral stimulation. During oral habituation, ingestive responsiveness declines; decreased ingestive responding to oral stimulation is demonstrated even in the absence of substantial post-ingestive signals. Both oral habituation and sensitization reflect process through which experience may modulate the rewarding properties of oral stimulation.