Correlations between the plasma viral load and metabolite ratios in the frontal lobe and basal ganglia. All values are changes from pre-infection measurements. 6a: Plasma viral load vs. Cho/Cr in the frontal lobe for the entire duration of the study. Regression analysis revealed a statistically significant linear correlation (P < 0.001, R = 0.8). 6b: Plasma viral load vs. NAA/Cr for the chronic phase of the study (>4 weeks) in the basal ganglia. Regression analysis revealed a statistically significant negative correlation (P < 0.02, R = -0.73) The line represents the least squares fit.