Component III

A Neurogenetic Basis for Risk Taking Behavior

Brain ScanWe are conducting brain imaging studies to explore a neural basis for risky behaviors in disinhibited individuals. Component 3 will use samples identified in Component 2, to study the differential brain activation during risky decision making associated with individual differences in behavioral disinhibition. This component utilizes a novel assessment of decisions to engage in risk taking and response to the reward and loss consequences of such decisions developed for use in functional magnetic resonance imaging. In collaboration with Component 2's twin studies, the heritability of performance on this novel task and its relationship to behavioral disinhibition and HIV risk behaviors will be determined.

In addition, we will use this data to identify single nucleotide polymorphisms (SNPs)SNPs are DNA sequence variations occurring when a single nucleotide — A, T, C, or G — in the genome differs between individuals. For example, the following are 2 sequenced DNA fragments (8 nucleotides) from 2 different individuals: AAGCCTA & AAGCTTA. They contain a difference in a single nucleotide. These differences in genetic sequences are what make individuals genetically unique. There are approximately 3.3 billion nucleotides in the human genome. associated with behavioral disinhibition (BD) and will identify brain regions of interest (ROIs)A specific area of the brain that is targeted in neuroimaging and functional magnetic resonance imaging (fMRI)studies. Certain regions of the brain are responsible for certain behaviors, and ROIs thought to be associated with behavioral disinhibition include the prefrontal cortex and the ventral striatum. that differ significantly between Hi-BD (high levels of behavioral inhibition) and Av-BD (average levels of behavioral disinhibition) groups.

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