Pilot Award Recipient: Xiong Jiang, PhD

Probing Alterations of Neuronal Selectivity in Middle-age HIV+ Individuals

March 01, 2012

Due to decreases in mortality rates and increased rates of HIV infection among older adults, the prevalence of older adults (>50 years old) living with HIV has increased substantially. This poses a significant public health concern, as older adults with HIV infection are more vulnerable to cognitive dysfunction (HIV-associated neurocognitive disorders, HAND) than their younger counterparts. It has been suggested that this increased vulnerability might be due to HIV-induced premature cognitive aging. Recently, magnetic resonance imaging (MRI) has provided a non-invasive way to examine pathological changes. Diffusion tensor imaging (DTI) has provided evidence for changes in brain white matter in HIV (see Bakshi & Ketonen, 2006 for a review). However, changes in grey matter have proven to be difficult to detect using both anatomical MRI and conventional functional MRI (fMRI), especially at the early stage of HAND. Here we propose, to conduct a pilot study to use fMRI-Rapid adaptation (fMRI-RA) to probe differences in neuronal selectivity between HIV+ middle age (45-55 years) adults and age-matched HIV- controls. Neuronal selectivity in occipital and temporal cortex as well as prefrontal cortex will be estimated while subjects perform a face odd-ball task, in hope to identify the neural causes of accelerated aging by quantitatively linking decline in behavioral performance to decline in neuronal specificity, to provide a general index of broad cognitive decline in HAND that can aid HAND diagnosis, to identify neural targets for therapeutic interventions.