Striatal functional connectivity networks are modulated by fMRI resting state conditions

Resting state fluctuations in blood oxygenation level dependent functional connectivity magnetic resonance imaging (BOLD fcMRI) time-series have been increasingly employed to study functional connectivity networks in healthy and diseased brain. FcMRI studies have been conducted under a number of different conditions, including resting eyes open, visual fixation and finger tapping. BOLD fcMRI networks are believed to reflect both anatomically constrained spontaneous fluctuations and state-dependent activity. In this study, state-dependence of functional connectivity to dorsal and ventral striatum was assessed with fcMRI during an eyes open resting state condition (REST) and during continuous 3 Hz transcutaneous electrical nerve stimulation (TENS), with the a priori hypotheses: (1) dorsal striatum connectivity with sensorimotor/attention networks will be stronger during TENS compared to REST, (2) ventral striatum connectivity with limbic system emotion-processing network will be weaker during TENS compared to REST and (3) ventral striatum connectivity with sensorimotor/attention networks will be stronger during TENS compared to REST. These hypotheses were confirmed by the results obtained, indicating that resting state BOLD fMRI networks reflect, in substantial measure, state-dependent activity.