et al. (2008) examined the integrity of the fronto-striatal circuitry that underlies executive functioning in HIV. Participants in the study were diagnosed with HIV three months to sixteen years before the study. Ten out of eleven patients were on antiretroviral medication and none scored within the demented range on the HIV Dementia Scale. It was found that HIV+ patients showed less activity within the ventral prefrontal cortex (PFC) and left dorsolateral PFC. There was reduced connectivity between the left caudate and ventral PFC and between the left caudate and dorsolateral PFC compared to healthy controls. Additionally, there was hypoactivation of the left caudate in the HIV+ patients. In the control group, there was correlation between caudate activity and executive functioning as shown by performance on neuropsychological testing. Further analysis of the pathways in the HIV+ group involving left caudate showed reduced functional connectivity between the left caudate and globus pallidus (basal ganglia output nucleus). This dysfunction with the basal ganglia and PFC may explain the executive function and semantic event sequencing task impairments noted in HIV+ patients included in this study. The study by Melrose et al. (2008) also investigated parietal activation. It was found that anterior parietal activation in HIV+ patients was slightly anterior to that in control participants, which follows the idea that HIV causes a reorganization of the attention network leading to cognitive impairments. Additionally, the anterior parietal activity showed a relationship with caudate functioning, which implicates a compensatory mechanism set forth when damage to the fronto-striatal system occurs. Overall, the study by Melrose et al. (2008) showed that HIV in the brain is associated with cognitive impairments. Damage to the fronto-striatal system may underlie cognitive problems including executive function and sequencing tasks. Another area of impairment due to fronto-striatal dysfunction is in the area of emotion recognition. In a study of HIV+ patients and control adults by Clark et al. (2010), it was shown that HIV patients demonstrate impairments in the recognition of fearful facial expressions. The authors suggested that fronto-striatal abnormalities related to HIV may underlie these impairments. In identification tasks, administered by Clark et al. (2010), HIV+ patients and control participants were asked to identify different facial emotions and landscapes, with these picture categories matched for image complexity. HIV+ patients did worse than the control group on the facial recognition task but not on landscape identification. In the facial emotion task, fear recognition was