Functional Connectivity in the Pharmacologically Activated Brain: Resolving Networks of Correlated Responses to d-Amphetamine

We investigated the functional connectivity structure underlying the widespread relative cerebral blood volume (rCBV) response to d-amphetamine in the rat brain by systematically analyzing the intersubject correlations between the response amplitudes in 48 atlas-defined brain structures. A cluster analysis resolved three distinct networks of brain regions that exhibited closely coupled responses: one corresponding to primary dopamine projections from the midbrain to the striatum, a second consisting predominantly of forebrain cortical and basal ganglia regions that share a widespread correlation pattern resembling the univariate group response, and a third including structures in the periventricular dopamine system. These results suggest that different functional networks underlie the brain’s response to d-amphetamine. This approach may provide important new insights regarding the central systems that underlie pharmacological action. Magn Reson Med 57: 704 –713, 2007. © 2007 Wiley-Liss, Inc.