title: Estimation of the velocity and trajectory of three-dimensional reaching movements from non-invasive magnetoencephalography signals.
abstract: OBJECTIVE
  Studies on the non-invasive brain-machine interface that controls prosthetic devices via movement intentions are at their very early stages. Here, we aimed to estimate three-dimensional arm movements using magnetoencephalography (MEG) signals with high accuracy.
  
  
  METHODS
  Whole-head MEG signals were acquired during three-dimensional reaching movements (center-out paradigm). For movement decoding, we selected 68 MEG channels in motor-related areas, which were band-pass filtered using four subfrequency bands (0.5-8, 9-22, 25-40 and 57-97 Hz). After the filtering, the signals were resampled, and 11 data points preceding the current data point were used as features for estimating velocity. Multiple linear regressions were used to estimate movement velocities. Movement trajectories were calculated by integrating estimated velocities. We evaluated our results by calculating correlation coefficients (r) between real and estimated velocities.
  
  
  RESULTS
  Movement velocities could be estimated from the low-frequency MEG signals (0.5-8 Hz) with significant and considerably high accuracy (p <0.001, mean r > 0.7). We also showed that preceding (60-140 ms) MEG signals are important to estimate current movement velocities and the intervals of brain signals of 200-300 ms are sufficient for movement estimation.
  
  
  CONCLUSIONS
  These results imply that disabled people will be able to control prosthetic devices without surgery in the near future.
authors: Interdisciplinary Program in Neuroscience, Seoul National University, 151-742 Seoul, Korea.
authors: Hong Gi
authors: HG
authors: Yeom
authors: June Sic
authors: JS
authors: Kim
authors: Chun Kee
authors: CK
authors: Chung
mesh_terms: D000328:Adult; D000465:Algorithms; D062207:Brain-Computer Interfaces; D003627:Data Interpretation, Statistical; D005260:Female; D006801:Humans; D016014:Linear Models; D015225:Magnetoencephalography; D008297:Male; D009068:Movement / Q000502:physiology*; D010775:Photic Stimulation; D011474:Prosthesis Design; D011597:Psychomotor Performance / Q000502:physiology*; D015203:Reproducibility of Results; D059629:Signal-To-Noise Ratio; D055815:Young Adult