Cortical and subcortical control of tongue movement in humans: a functional neuroimaging study using fMRI

We have used voluntary tongue contraction to test whether we can image acti vation of the hypoglossal nuclei within the human brain stem by using funct ional magnetic resonance imaging (fMRI). Functional images of the whole bra in were acquired in eight subjects by using T2-weighted echo planar imaging (blood oxygen level development) every 6.2 s. Sequences of images were acq uired during 12 periods of 31-s "isometric" rhythmic tongue contraction alt ernated with 12 periods of 31-s tongue relaxation. Noise arising from cardi ac- and respiratory-related movement was removed either by filtration (high pass; cutoff 120 s) or by inclusion in the statistical analysis as confoun ding effects of no interest. For the group, tongue contraction was associat ed with significant signal increases (P < 0.05 corrected for multiple compa risons) in the sensorimotor cortex, supplementary motor area, operculum, in sula, thalamus, and cerebellum. For the group and for six of eight individu als, significant signal increases were also seen within the medulla (P < 0. 001, predefined region of interest with no correction for multiple comparis ons); this signal is most likely to reflect neuronal activation associated with the hypoglossal motor nuclei. The data demonstrate that fMRI can be us ed to detect, simultaneously, the cerebral and brain stem control of tongue movement.