[Physiological analysis of food motivation in experimentally induced water-salt imbalance].

Internal or motivational factors and external or signal factors were assessed to determine their role in motor-food response during conditioning in cats and dogs. Under experimental water-salt dysbalance visceral signalling was shown to be an essential factor involved in a goal-directed response. In addition to dominant motivation, a conditioned food signal seems to be this factor. In search for neurophysiological correlates of food motivation, we studied responses of n. tractus solitaris in rats to adequate chemical stimulation of the tongue receptors and viscerochemoreceptors. 3 groups of neurons were distinguished: those responding to the stimulation of only one receptive zone (taste and viscerochemical neurons) and neurons responding to the stimulation of both receptive areas ("convergence" units). Under salt deprivation, threshold concentrations of salt for responses from n. solitaris decreased and the response from a convergence neuron to viscerochemical stimulation diminished following application of sodium chloride on the tongue receptor.