WORKING IN THE LABORATORY of John B. Watson in the early 1920s, Curt P. Richter first observed the phenomenon of rats engaged in what would later be called food-anticipatory activity: “It is seen that immediately following the daily feeding period there is a period of relative inactivity lasting from four to five hours. . . . During the last two to three hours of the twenty-four the activity in...

Light signals from intrinsically photosensitive retinal ganglion cells (ipRGCs) entrain the circadian clock and regulate negative masking. Two neurotransmitters, glutamate and Pituitary Adenylate Cyclase Activating Polypeptide (PACAP), found in the ipRGCs transmit light signals to the brain via glutamate receptors and the specific PACAP type 1 (PAC1) receptor. Light entrainment occurs during th...

When fed in restricted amounts, rodents show robust activity in the hours preceding expected meal delivery. This process, termed food anticipatory activity (FAA), is independent of the light-entrained clock, the suprachiasmatic nucleus, yet beyond this basic observation there is little agreement on the neuronal underpinnings of FAA. One complication in studying FAA using a calorie restriction m...

Circadian rhythms are entrained by light and influenced non-photic stimuli, such as feeding. The activity preceding scheduled mealtimes, food anticipatory (FAA), is elicited in rodents fed a limited amount at times. FAA thought to be the output of an unidentified oscillator. Previous studies, using gene deletion receptor pharmacology, implicated dopamine type 1 (D1R) signaling dorsal striatum n...

BACKGROUND Temporal restriction of food availability entrains circadian behavioral and physiological rhythms in mammals by resetting peripheral oscillators. This entrainment underlies the activity of a timing system, different from the suprachiasmatic nuclei (SCN), known as the food entrainable oscillator (FEO). So far, the precise anatomical location of the FEO is unknown. The expression of th...

Although the impairments in cognitive performance that result from shifting or disrupting daily rhythms have been demonstrated, the neuronal mechanisms that optimize fixed-time daily performance are poorly understood. We previously demonstrated that daily practice of a sustained attention task (SAT) evokes a diurnal activity pattern in rats. Here, we report that SAT practice at a fixed time pro...

Calorie restriction (CR) delays the onset of age-related disease and extends lifespan in a number of species. When faced with reduced energy supply animals need to lower energy demands, which may be achieved in part by reducing physical activity (PA). We monitored changes in PA using implanted transmitters in male C57BL/6 mice in response to graded levels of CR (10 to 40%) or matched levels of ...

The objective of this study was to investigate whether increased dietary water content and feeding frequency increased voluntary physical activity of young, lean adult female cats. A replicated 4 × 4 Latin square design with a 2 × 2 factorial treatment arrangement (feeding frequency and water content) was used. The 4 treatments consisted of 1 meal daily dry pet food without added water (1D; 12%...

The mammalian timekeeping system generates circadian oscillations that rhythmically drive various functions in the body, including metabolic processes. In the liver, circadian clocks may respond both to actual feeding conditions and to the metabolic state. The temporal restriction of food availability to improper times of day (restricted feeding, RF) leads to the development of food anticipator...

MANY ANIMALS HAVE EVOLVED the ability to anticipate periodic food availability. In mammals, this ability is due to a circadian clock that still functions after ablation of the suprachiasmatic nucleus (SCN), although such lesions abolish (or severely disrupt) virtually all circadian rhythms in behavior and physiology when food is available ad libitum. Restriction of meals to a certain time of da...