Discriminating the cortical representation sites of tongue and up movement by functional MRI.

Purpose: The purpose of this study was to investigate the possibility to discriminate the representation sites of lip and tongue movement in the primary motor cortex (PMC). In contrast to preceding studies this research was particularly focused on single subject analysis.

Procedures: Six healthy right-handed volunteers underwent functional magnetic resonance imaging (fMRI) by means of a 1.5 tesla scanner. Using a block design the subjects had to perform two different motor tasks: horizontal tongue movement and symmetrical lip pursing. To ensure that only the functional selective cortical representations for each particular motor task were determined, the approach of contrasting both motor paradigms was followed during data analysis.

Principle Results: Selective cortex activations for both motor tasks were detectable in the motor strips and could be spatially discriminated for the whole group and for the majority of the single subjects in both hemispheres. Furthermore, expanded regions responsive to both motor tasks were found bilaterally.

Conclusions: The individually proven possibility to differentiate the cortical representation sites of tongue and lip movements opens the chance to monitor therapeutic cortical effects after neuro-reconstructive surgery, e. g. hypoglossal-facial nerve anastomosis (HFA).