Imaging cortical oscillations during sustained visuomotor coordination in MEG

Cortical oscillations have been shown to play an important role in a wide range of neural activities. In particular, task-related changes in spectral power and task-related modulations of coupling both within and between neuronal assemblies in specific frequency bands have been reported. In the current study, we use magnetoencephalography (MEG) recordings to produce maps of task-related changes of spectral power in the alpha (8-15Hz), beta (15-30) and gamma (30-50Hz) range during a sustained visuomotor coordination task in which 4 subjects were asked to use a track-ball device to continuously counter the quasi-random rotations of a cube in a 3D environment. We use a wavelet-based method to compute and compare the time-frequency maps corresponding to the visuomotor task to those of the control conditions. We find that, compared to rest conditions, visuomotor coordination is associated with a sustained depression of spectral power in mu and beta bands over the sensorimotor cortex throughout the whole duration of the task (8 seconds) followed by a wide-band increase in power starting within 1 to 2 seconds after the end of the coordination task. The spatial distribution of the relative power changes in relevant frequency bands are computed and displayed as topographic images on a flattened sensor geometry.