Maturation of inhibitory circuits in the gustatory cortex and expression of taste preference

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Project Summary As animals transition from relying on their mother’s milk to foraging and consuming foods, they experience an abundance of new tastes. These experiences regulate taste preference later in life through a process which likely relies on plasticity in neural circuits associated with taste and feeding. The gustatory cortex (GC) is involved in processing tastes and is required for taste-motivated behaviors as well as learning about tastes. How these early experiences affect the development of taste preferences or the maturation of GC circuits has not been the subject of investigation. Maturation of inhibitory circuits in other primary sensory systems is a hallmark of postnatal development. This proposal will investigate the role of taste experience in shaping later taste preference, whether a postnatal sensitive window exists in which experience shapes taste preference, and the cellular- and circuit-level GC physiology which is sensitive to taste experience, with a focus on inhibition. The first part of the proposal will examine how taste preferences mature from juvenile to adult ages. The role of taste experience at the time of weaning versus in adulthood in modulating taste preference will also be examined. Maturation of inhibitory networks within the GC will be examined by quantifying parvalbumin-positive inhibitory neurons, their connection strength onto pyramidal neurons, and the total spontaneous GABAergic synaptic transmission onto pyramidal neurons in the GC from pre- and post-weaning ages. The role of taste experience on inhibitory maturation will also be examined. Finally, the relationship between the maturation of inhibition and the development of taste preferences will be assessed by chemical disruption of stabilizing proteins on parvalbumin-positive neurons. These studies will elucidate the necessity of a mature inhibitory circuit in GC for the behavioral expression of taste preference as well as whether a sensitive window exists in which experience shapes taste preference. While mechanisms underlying learning about the value or physical cues associated with tastes has been investigated in adulthood, the postnatal mechanisms leading to such a refined circuit have not been described. The results of these studies will indicate the role of early food experiences in determining taste-based choices throughout life.