The purpose of this study is to test how the brain responds when individuals eat enjoyable foods such as chocolate. Eating certain foods can make one want to keep eating even when feeling full, caused by dopamine in the brain. The researchers believe this dopamine response can be measured by looking at the individual's eye.

With obesity at an all-time high, understanding eating behavior beyond physical need is a priority. Food reinforcement is driven by central dopamine activity. However, objective measurement of brain dopamine-related behavioral events is hindered by the lack of non-invasive, accessible techniques that are amenable to testing in a "naturalistic" environment. The goal of this project is to develop a non-invasive, accessible methodology to measure dopaminergic responses to food in a natural setting. This research will use a novel, hand-held electroretinograph (ERG) that does not require eye dilation and uses a skin electrode to measure retinal dopamine activity. Previous work establishes that retinal dopamine activity can be used as a proxy for central dopamine function. The ability to assess both subjective behavioral variables and central dopaminergic responses simultaneously will provide an ideal approach for innovative studies of the control of eating behavior.

Inclusion Criteria:

• body mass index 20-30 kg/m2
• free of any major illness or disease

Exclusion Criteria:

• food allergies
• participation in a weight loss diet or exercise program
• pregnancy
• lactation
• metabolic illness or disease (diabetes, renal failure, thyroid illness, hypertension)
• eye illness or disease (narrow angle glaucoma, macular degeneration, retinal detachment, cataracts)
• psychiatric, neurological or eating disorders (schizophrenia, depression, Parkinson's Disease, Huntington's Disease, cerebral palsy, stroke, epilepsy, anorexia nervosa or bulimia nervosa)
• take prescription medications except for oral contraceptives or antihyperlipidemia agents

Community sample