Fig. 6. Negative fMRI responses can be evoked in human striatum via noxious peripheral and selective afferent stimulations.

a Human striatum anatomical mask used for subsequent panels, color-coded by striatal compartment. b Noxious forearm stimulations given to human subjects and the corresponding BOLD fMRI response maps (n = 7 subjects, 11 scans). Noxious 5 Hz, 0.5 ms pulse width, stimulation with intensity determined by subject pain rating was delivered in 20 s intervals, repeated over 6 trials flanked by 30 s rest. These findings indicate that anticipated noxious stimulation in human subjects and unanticipated footshock in awake rats (Fig. 3) may both contribute to shaping negative striatal hemodynamic responses. c–e Brain maps indicating a striatal projection stimulated in human subjects via transcranial magnetic stimulation (TMS) (green dot), and its corresponding BOLD fMRI response maps. 68 TMS pulses were presented with a variable inter-trial interval jittered with delays of 2.4, 4.2, and 7.2 s delivered over 6 min and 41 s (167 volumes) in a fast event-related design. c TMS of the right M1 (n = 79 subjects). d TMS of the right anterior middle frontal gyrus (n = 80 subjects). e TMS of the right posterior middle frontal gyrus (n = 79 subjects). Arrows indicate the voxel with most significant activation and match the striatal compartment color legend used in (a). Unmasked versions of the human fMRI response maps displayed here as well as corresponding time courses are shown for noxious forearm stimulation, M1 TMS, aMFG TMS, and pMFG TMS in Fig. S12, Fig. S13, Fig. S14, and Fig. S15, respectively.