Fig. 6.
Correlation of R2t* with myelin index and correlations between neuronal, glial, and synaptical indices. (A) Correlation between R2t* (seconds−1) and myelin index (dimensionless). Myelin index [defined as a ratio of T1 and T2 weighted images (26)] values were generated using data from the HCP averaged across 1,018 healthy subjects. Regional R2t* values were calculated by averaging results from 12 healthy volunteers, ages 34 ± 7.6 y, approximately matching HCP age group. Each point represents a FreeSurfer region. (B and C) Scatter plots of relative (to neurons) concentrations of glial cells (Yglia/Yneuron) and synapses (Ysynapse/Yneuron) vs. (Yneuron) for all six AHBA datasets. Each point represents the logarithm of gene expression in one FreeSurfer ROI in one AHBA dataset. In all panels blocks of FreeSurfer regions are marked by different colors: cingulate, red; frontal, orange; occipital, green; parietal, blue; and temporal, black. The shaded areas in the panels represent the 95% confidence bands.