Involvement of human amygdala and orbitofrontal cortex in hunger-enhanced memory for food stimuli

We used positron emission tomography to measure regional cerebral blood flo w (rCBF) in 10 healthy volunteers performing a recognition memory task with food and non-food items, The biological salience of the food stimuli was m anipulated by requiring subjects to fast before the experiment and eat to s atiation at fixed time points during scanning. All subjects showed enhanced recognition of food stimuli (relative to nonfood) in the fasting state. Sa tiation significantly reduced the memory advantage for food. Left amygdala rCBF covaried positively with recognition memory for food items, whereas rC BF in right anterior orbitofrontal cortex covaried with overall memory perf ormance. Right posterior orbitofrontal rCBF covaried positively with hunger ratings during presentation of food items. Regression analysis of the neur oimaging data revealed that left amygdala and right lateral orbitofrontal r CBF covaried as a function of stimulus category (i.e,, food vs non-food). T hese results indicate the involvement of amygdala and discrete regions of o rbitofrontal cortex in the integration of perceptual (food), motivational ( hunger), and cognitive (memory) processes in the human brain.