Table 1. Functional connectivity between brain regions in fMRI data acquired following placebo treatment (n = 23).

	Caudate	Thalamus	Ventral midbrain	Left dorsolateral prefrontal cortex	Right dorsolateral prefrontal cortex
Caudate	3.16	0.561	0.641	0.658	1.395
Thalamus	0.195	2.607	1.348	−0.227	1.103
Ventral midbrain	0.216	0.5	2.787	0.134	0.822
Left dorsolateral prefrontal cortex	0.221	−0.084	0.048	2.809	1.165
Right dorsolateral prefrontal cortex	0.426	0.371	0.267	0.377	3.395
Residual variances	2.726	2.312	2.45	2.466	2.894

Sample correlations are shown below the diagonal; sample variances and covariances are shown on and above the diagonal. Residual variances are estimated by principal component analysis (Honey et al., 2002) and indicate the variance in each region that is not accounted for by connectivity with other regions.