Our aim is to understand how nutrition impacts brain function and energy use. We focus on how dietary manipulations (e.g. calorie restriction, high fat diet) affect the cortex, which we probe in vivo using two-photon imaging and electrophysiology techniques in mice. We additionally carry out dietary manipulations and fMRI work in humans in collaboration with others. We have previously demonstrated that calorie restriction reduces cortical function in mice to save energy, resulting in impaired behavioral function. These changes are triggered by reductions in the levels of leptin, a hormone that is secreted by adipose tissue in proportion to fat mass. Decreased leptin, in turn, drives energy-saving changes in neuronal and synaptic electrophysiology. Current questions of interest include: How do high fat diets impact mouse cortex? Does diet have a similar impact on human cortex? How do different metabolic hormones (e.g. leptin, insulin) affect the cortex and by which mechanisms?