Motor cortex oscillations, motor pathways and motor control in rolandic epilepsy

Aims:- There is increasing evidence that rolandic epilepsy, chara cterised by focal motor seizures arising from rolandic cort ex and interictal spiking activity over centro-temporal cortical regions, is associated with motor coordination disorders. This was investigated using psychobehavioral measures, diffusion weighted imaging (DWI) and neuromagnetic induced motor responses. Methods:- Children aged between 8 and 14 years with a diagnosis of rolandic epilepsy were assessed using the Movement-ABC (MABC-2,Henderson et al., 2007), DWI, and cued unilateral index finger movements in MEG. For each individual, cortical locations of MEG motor responses were identified using a beamforming approach. Mean magnitude and peak frequency were extracted from time-frequency windows of interest. Mean DWI fractionalanisotropy (FA) was computed for motor tracts in the dominant hemisphere between the following ROIs: supplementary motor area (SMA), M1, thalamus, cerebellum, basal ganglia. Results:- MABC-2 scores were variable but significantly below the popu lation mean and several children scored below the 5th percen tile. Greater magnitude of post-movement beta rebound activity (PMBR) and ipsilateral movement-related beta desynchrony(MRBDi) during movements of the dominant index finger predicted better scores on the MABC-2 aiming and catching sub-test.Greater PMBR and MRBDi were predicted by higher FA of thalamus to SMA tracts. Conclusion:- Smaller MRBDi and PMBR in patients with poorer motor co-ordi nation may reflect abnormal motor network activity. The magnitude of these induced beta band responses, believed to reflect inhibitory control (Engel & Fries, 2010, Curr. Op.Neurobio.), maybe partially determined by structural characteristics of specific motor pathways, reflected in their FA. Induced cortical oscillatory responses and DWI of motor pathways may provide markers of impaired motor skills during development