Table 1.

Percent of variance explained by linear and quadratic fits

Region	${\mathit{r}}^2$ Linear	${\mathit{R}}^2$ Quadratic	Quadratic Improvement Over Linear 100$\frac{{\mathit{R}}^2-{\mathit{r}}^2}{{\mathit{r}}^2}$ %
Accumbens	0.405	0.405	0.0
Caudate	0.105	0.107	1.9
Putamen	0.251	0.254	1.2
Cerebellum	0.089	0.090	1.1
Brainstem	0.030	0.090	200.0
Amygdala	0.180	0.334	85.5
Pallidum	0.030	0.121	303.3
Thalamus	0.224	0.326	45.5
Ventral diencephalon	0.120	0.253	110.8

P < 0.001 for all regression fits; bold type indicates a better fit. See text for details.