Assessment of intention in movement for children with severe motor and intellectual disabilities - A case study using event-related change of EEG rhythms -

This case study was performed to assess objectively intention in movement for a child with severe motor and intellectual disabilities(SMID). We recorded electroencephalogram (EEG) on the scalp when a child with SMID moved his dominant (right) hand to react to a toy presented in front of him instantaneously. Event-related change (ERC) of EEG rhythms in a frequency band 6-9.5Hz was observed in the central region on the scalp, corresponding to motor area. We recognized movement-related ERC as event-related desynchronization (ERD); that is, the power of the EEG rhythms decreased preceding the onset of movement, and as event-related synchronization (ERS); that is, their power increased following motor execution. Considering the fact that the ERD precedes voluntary movement, we confirmed that the action of reaching for a toy occurred as a result of the child's intention. The ERS was not observed in the record one year later, so it is presumed that he came to execute automatic hand movement gradually over time. Calculation of the movement-related ERC allows short EEG recordings with fewer repetitions of the same movement. We conclude that the ERC of EEG rhythms accompanying motor execution provides a simple and useful index to assess intention in movement for children with SMID