Functional MR imaging activation after finger tapping has a shorter duration in the basal ganglia than in the sensorimotor cortex

BACKGROUND AND PURPOSE: Repetitive motor tasks that produce sustained neuro nal activity in the sensorimotor cortex produce transient neuronal activity in subcortical regions. We tested the hypothesis that a reference function modeling a transient hemodynamic response would more reliably detect activ ation in the basal ganglia than would a conventional reference function, wh ich models a sustained hemodynamic response. METHODS: Functional MR imaging data were acquired in eight subjects perform ing an alternating-hand finger-tapping task. Postprocessing was performed b y cross-correlation to two types of reference functions: one that models a sustained hemodynamic response to finger tapping and one that models an ini tial transient hemodynamic response. Activation in the sensorimotor cortex, supplementary motor area, cerebellum, thalamus, and corpus striatum was ta bulated for each reference function. RESULTS With the conventional boxcar reference function, activation was det ected in the sensorimotor cortex, supplementary motor area, and cerebellum, but intermittently in the corpus striatum in all subjects, With the refere nce function for a transient response, activation in the corpus striatum wa s not detected in all subjects. CONCLUSION: In the corpus striatum, activation is detected more frequently with a reference function that models a transient response. Activated corti cal and subcortical regions can be mapped with an alternating-hand finger-t apping paradigm and a combination of reference functions.