Postnatal Development of Central Feeding Circuits

There may be a genetically predetermined, inherent drive to eat that is only periodically neutralized by satiety, sleep, or other competing drives (Berthoud, 2002). In infants, and perhaps also in adults, disinhibition of feeding motor outputs by factors that remove, compete with, or otherwise neutralize inhibitory controls of feeding could be enough to initiate and maintain food intake without the need for special “hunger” stimuli (Stricker, 1984). Research reviewed in this chapter supports the view that behavioral responses to such direct and indirect controls of feeding might generally be effected through DVC neural circuits. The intrinsic components and output pathways of these circuits are accessed by numerous afferent inputs in mature rats, but by a more limited set of inputs in neonatal rats. Our understanding of these central neural systems will be enhanced by continued examination of behavioral and physiological responses to treatments that affect food intake differently in developing and mature animals. The presence or absence of responses to a given stimulus or control presumably reflects the functional integrity of neural circuits that receive and process the signal, and those that organize and execute the response. As new behavioral responses emerge during postnatal development, one may infer maturation of the neural systems and, importantly, the functional interactions among neural systems that support these responses.