Two Pet studies are proposed to elucidate the specific contributions of the orbitofrontal cortex (OFC) and amygdala to olfactory and hedonic processing in humans. Study 1 examines whether activity in the amygdala, OFC and pyriform cortex varies in a concentration dependent manner. 15 subjects will be exposed to four concentrations of butanol and four concentrations of phenylethyl alcohol while cerebral blood flow (rCBF) is measured with PET. Study I also examines whether attention modulated rCBF) is measured with PET. Study 1 also examines whether attention modulated rCBF in these regions by imaging subjects while attend to and ignoring ordorants. In study 2,25 subjects will be exposed to highly aversive, pleasant and neutral stimuli to examine if rCBF in the OFC and amygdala varies with the hedonic meaning or emotional responses induced by odorants. These studies represent the first steps in a research program aimed at elucidating the functions of the OFC and amygdala in humans, with a long-term goal of determining the role of these structures in normal and abnormal emotional behavior.
