Age effects in terms of explained variance (R2), time constant (t), absolute change, and percentage change
| TBV-corrected volumes | Raw volumes | |||||
|---|---|---|---|---|---|---|
| R2 | t | R2 | t | Absolute change | Percentage change | |
| Cerebral cortex | 0.77 | 9.47 | 0.38 | 14.88 | 129,206 | −21.5 |
| Cerebral WM | 0.73 | 11.06 | 0.21 | 5.33 | 103,314 | 26.1 |
| Hippocampus | 0.08 | 5.51 | 0.01 | 322 | 3.7 | |
| Amygdala | 0.14 | 6.42 | 0.03 | 241 | 6.8 | |
| Caudate | 0.04 | 0.05 | 682 | −8.2 | ||
| Putamen | 0.17 | 0.14 | 1703 | −13.1 | ||
| Pallidum | 0.11 | 0.10 | 434 | −11.4 | ||
| Accumbens | 0.09 | 0.09 | 195 | −13.0 | ||
| Thalamus | 0.01 | 2.16E-4 | 63 | 0.4 | ||
| Cerebellum GM | 0.07 | 0.07 | 11,047 | −8.9 | ||
| Cerebellum WM | 0.27 | 4.54 | 0.20 | 2.87 | 6347 | 27.3 |
| Brainstem | 0.35 | 7.03 | 0.19 | 3.69 | 3893 | 22.1 |
| Lateral ventricle | 0.14 | 0.11 | 8372 | 99.8 | ||
| Inferior lateral ventricle | 0.01 | 0.01 | 78 | 12.5 | ||
| Third ventricle | 0.02 | 0.01 | 72 | 7.9 | ||
| Fourth ventricle | 3.96E-4 | 9.06E-7 | 2 | 0.1 | ||
R2 is from the nonlinear regression analysis. Time constant (t) indicates the rate of development, calculated from the exponential fitting equations of the form x = b1 + b2 × e(−age/t), where b1 is the estimated value at the asymptote and b2 is the difference between the b1 value and the estimated value at age zero. Lower values indicate a faster developmental course. When no value of t is presented, a linear fit best described the data, and R2 is from the linear regression. Absolute and percentage change is calculated from the estimated mean values for 8 year olds and 30 year olds.