Luis E. Cortina1, Richard G. Spencer1, and Mustapha Bouhrara1
1NIA, Baltimore, MD, United States
1NIA, Baltimore, MD, United States
Myelin content and axonal density follow an inverted U-shaped association with age in the brainstem, with myelin following a roughly symmetric time-course while axons appear to degenerate significantly more rapidly than they mature.
Figure 1: Representative region plots for structural parameters MWF, R1, and R2, and DTI indices. MWF, R1, R2, MD, RD, and AxD conform to a nonlinear trajectory along the lifespan of the adult in the human brainstem. For each ROI, the coefficient of determination, R2, and the significance of the linear regression model, p, are reported.
Figure 2: MWF, relaxation times, and DTI indices standardized and plotted as a function of age for six structures to show similarities and differences in the brainstem across the adult lifespan. Three WM regions and three GM nuclei were chosen specifically since they demonstrated significant quadratic associations with age across all parameters. Diffusivity indices were inverted for easier comparisons.