DynamicNeuralCorrelatesofMotorErrorMonitoringand AdaptationduringTrial-to-TrialLearning

HuilingTan,NedJenkinson,andPeterBrown NuffieldDepartmentofClinicalNeurosciences,JohnRadcliffeHospital,UniversityofOxford,OX39DU,UnitedKingdom A basic EEG feature upon voluntary movements in healthy human subjects is a (13‐30 Hz) band desynchronization followed by a postmovement event-related synchronization (ERS) over contralateral sensorimotor cortex. The functional implications of these changesremainunclear.Wehypothesizedthat,becauseERSfollowsmovement,itmayreflectthedegreeoferrorinthatmovement,and the salience of that error to the task at hand. As such, the signal might underpin trial-to-trial modifications of the internal model that informsfuturemovements.Totestthishypothesis,EEGwasrecordedinhealthysubjectswhiletheymovedajoystick-controlledcursor to visual targets on a computer screen, with different rotational perturbations applied between the joystick and cursor. We observed consistentlylowerERSintrialswithlargeerror,evenwhenotherpossiblemotorconfounds,suchasreactiontime,movementduration, and path length, were controlled, regardless of whether the perturbation was random or constant. There was a negative trial-to-trial correlation between the size of the absolute initial angular error and the amplitude of the ERS, and this negative correlation was enhancedwhenothercontextualinformationaboutthebehavioralsalienceoftheangularerror,namely,thebiasandvarianceoferrors in previous trials, was additionally considered. These same features also had an impact on the behavioral performance. The findings suggestthattheERSreflectsneuralprocessesthatevaluatemotorerroranddosointhecontextofthepriorhistoryoferrors.