Functional neuroimaging using 3T fMRI has revolutionized our ability to study of the brain's higher cognitive and affective functions in health and disease and reveal the neurobiological basis for wide-range individual differences (traits) in cognitive and affective processing, vulnerability and resilience to disease. For instance, neuroanatomical variability between individuals associated with long-standing personality traits may help explain why certain brain area or individuals are vulnerable or show decreased resilience to psychiatric or neurodegenerative diseases. Structural 3T neuroimaging can also be particularly useful for in vivo detection of pathological processes that correlate with certain behaviors, such as with alcohol consumption. We performed voxel based morphometry analyses on structural MRI scans to explore the neuroanatomical variability associated with long-standing personality traits, which may explain why certain individuals are vulnerable to psychiatric disease, dementia or show inefficient psychological response mechanisms. We discovered neuroanatomical differences related to the Five Factors of Personality (published in the journal Human Brain Mapping). Moreover, we performed a voxel based morphometry analysis in Baltimore Longitudinal Study of Aging (BLSA) participants and detected a significant volumetric decrease in the premotor portion of the frontal corpus callosum associated with alcohol consumption, controlling for dietary, demographic and cardiovascular risk factors (published in the journal European Neuropsychopharmacology). This finding suggests an increased vulnerability of this region, which may help explain why this same region develops demyelination and necrosis in alcoholism (Marchiafava-Bignami disease). Currently, we are performing two fMRI studies, one on cephalic insulin secretion and the other on food apetitiveness, as part of a broader study on the effects of endocannabinoid receptor drugs on metabolism. The goal of the first study is to demonstrate a rise in insulin levels in response to food visual stimuli (cephalic insulin response) as a result of activation of certain brain areas. Moreover, given the presence of endocannabinoid receptors in the candidate areas, we aim to demonstrate a difference in their level of activation with endocannabinoid receptor drugs. The goal of the second study is to demonstrate dissociable effects of endocannabinoid receptor drugs on food value (food choices) and salience (intensity of such choices). Development of 3T MRI methods: Over this last year, this protocol was used to develop the following applications: a tissue segmentation algorithm for fat quantification in the abdomen and thigh, which will be used in the BLSA to assess the association of subcutaneous and visceral fat with markers of inflammation; a tissue segmentation algorithms for fat quantification in the thymus gland, which is being used in the study of growth hormone supplementation; phosphorus spectroscopy to assess the energy consumption of exercising muscle, which will be used in the BLSA; fMRI paradigms to assess memory encoding and risk taking and decision making, which were incorporated in the BLSA; and development of resting state fMRI and brain spectroscopy (detailed above).
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