Voxel locations (left) and corresponding representative spectra are shown for the frontal cortex (top), basal ganglia (middle), and white matter of the centrum semiovale (bottom). The major metabolites are labeled on the spectra, as well as dashed lines corresponding to pre-infection levels. Spectra are from a single representative animal, are not baseline corrected or apodized. Top: Frontal cortex MR spectra of a representative monkey before infection, at 2 and 4 wpi. Spectra are scaled to the creatine resonance because Cr levels did not change in frontal cortex during acute SIV infection. It can be seen from the spectra that NAA is decreased at 2, Cho is decreased at 4 wpi, and MI is increased at 2 and 4 wpi. (Due to the difficulty in finding spectra from a single animal that are representative of the group data in all aspects, we would like to note that the decrease in NAA at 4 wpi is not representative of the unchanged NAA concentration reflected in the group data). Middle: Basal ganglia MR spectra are scaled to the Cr peak as the Cr concentration did not change. No significant changes in NAA were observed. A decrease in Cho is evident by 4 wpi. Finally, an increase in MI can be observed from at 2 and 4 wpi. Bottom: White Matter MR spectra of a the same representative monkey before infection, at 2 and 4 wpi. Spectra are scaled to the NAA resonance because NAA levels did not change in white matter semiovale during acute SIV infection. It can be seen from the spectra that Cr is increased at 2 wpi, and Cho is increased and then decreased to baseline levels at 4 wpi. An increase in MI can also be detected.