Effects of food deprivation on goal-directed behavior, spontaneous locomotion, and c-Fos immunoreactivity in the amygdala

• Published in: Behavioural brain research Vol. 197; no. 1; pp. 9 - 15
• Main Authors: Moscarello, J.M., Ben-Shahar, O., Ettenberg, A.
• Format: Journal Article
• Language: English
• Published: Shannon Elsevier B.V 30.01.2009; Elsevier
• Subjects: Amygdala - metabolism; Analysis of Variance; Animals; Basolateral amygdala; Behavioral economics; Behavioral psychophysiology; Biological and medical sciences; Central amygdala; Conditioning, Operant - physiology; Decision Making - physiology; Food Deprivation - physiology; Food motivation; Food reinforcement; Fundamental and applied biological sciences. Psychology; Male; Motivation; Motor Activity - physiology; Neural Pathways - metabolism; Proto-Oncogene Proteins c-fos - metabolism; Psychology. Psychoanalysis. Psychiatry; Psychology. Psychophysiology; Rats; Rats, Sprague-Dawley; Reinforcement Schedule; Reinforcement, Psychology; Basolateral amygdala; Central amygdala; Food reinforcement; Behavioral economics; Food motivation; Amygdala; fos Gene; Central nervous system; Basal ganglion; Feeding; Encephalon; Locomotion; Goal; Motivation; Behavior; Restricted diet; Amygdaloid nucleus; Protooncogene; Immediate early gene
• ISSN: 0166-4328; 1872-7549; 1872-7549
• DOI: 10.1016/j.bbr.2008.07.025

Previous work in our laboratory has shown that food deprivation and food presentation produce different patterns of neuronal activity (as measured by c-Fos immunoreactivity) in the medial prefrontal cortex and nucleus accumbens of rats. Since the amygdala has been implicated in both motivational and reinforcement processes and has neuronal connections to both the prefrontal cortex and nucleus accumbens, it was of interest to assess amygdaloid c-Fos immunoreactivity during similar manipulations of food deprivation and presentation. In the current study, c-Fos counts in both basolateral and central amygdalar nuclei were observed to increase in rats 12- and 36-h food deprived (relative to 0-h controls)—an effect reversed by the presentation of either a small or large meal (2.5 or 20 g of food). In another experiment, rats working on a progressive ratio schedule of reinforcement exhibited elevated break-points as a function of food deprivation, a result consistent with the view that the feeding manipulations increased the subjects’ level of motivation. In contrast, food deprivation reduced the spontaneous locomotor activity of rats, presumably as a result of an inherent energy-conservation strategy when no food is readily available. These data suggest that the state of food deprivation is associated with: (a) enhanced behavioral output only when food is attainable (increased goal-directed behavior, but decreased spontaneous activity), and (b) increased synaptic engagement in neuronal circuits involved in affective valuation and related decision-making (increased c-Fos counts in the amygdala).