Hedonesthesia: the nervous process determining motivated ingestive behavior.

The hedonistic theory of motivated ingestive behavior is discussed against drive-reduction theories, which claim that ingestive motivated behavior is mainly determined by the urge to meet the basic needs of the organism, often ignoring the important role of sensations. Evidence is supplied that mere sensations derived by exteroceptors can play an essential part in motivated behavior. A view is put forward that the reinforcing properties of exteroceptive stimulation in motivated ingestive 'behavior should be related to their ability to generate positive emotional states experienced as pleasure. It was pointed out, however, that the same external gustatory stimulation may possess a different hedonic value, depending on the current nutritional state of the organism. Therefore, the existence of a special nervous process which makes these stimuli emotionally positive, neutral or negative, i.e., pleasant, indifferent or aversive, depending on the given state of need is postulated. We call this nervous process hedonesthesia, and claim that it plays a decisive part in motivated ingestive behavior. The possible mechanism of hedonesthesia is explained on the block model.