Effects of HIV infection and cocaine dependence on brain activity during risky and ambiguous decision making
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HIV infection can be characterized as a brain disease with 47 percent of infected patients experiencing neurocognitive disorders. MRI studies of HIV patients reveal alterations in gray and white matter. Individuals addicted to stimulant drug use like cocaine are at high risk for engaging in sexual behaviors that contribute to acquisition of HIV. Cocaine dependence and HIV infections each disrupt neural circuits that regulate executive functions involved in decision making. The present study investigated the effects of cocaine dependence and HIV infection on neural activity in response to the valuation of potential gains in the context of unknown and known risks. The study looked at 76 participants across four groups varying in HIV status and cocaine dependence. In an fMRI scanner, participants were presented with pairs of gambles and were required to choose their preference. The behavioral results show that there were no significant differences between groups in their likelihood to select uncertain choices and their reaction times. Imaging results demonstrate increased activation for ambiguous > risky decisions throughout the lingual gyrus and occipital cortex for all four groups. There is bilateral activation in the inferior (IFG) and middle frontal gyrus (MFG) for the control group, which is not seen in either cocaine-dependent or HIV-positive groups. Both cocaine-dependent groups show only left IFG and MFG activity, and the non-cocaine-using HIV-positive group shows no activation in the IFG or MFG. The control group seems overall to have broader activation than the other groups, demonstrated by increased cluster sizes. Analysis of group effects should be conducted to evaluate potential statistical differences between groups.
Hartley, Bennett (2017). Effects of HIV infection and cocaine dependence on brain activity during risky and ambiguous decision making. Honors thesis, Duke University. Retrieved from https://hdl.handle.net/10161/14927.
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