%0 Journal Article
%T An EEG-based study of discrete isometric and isotonic human lower limb muscle contractions
%A Joseph T Gwin
%A Daniel P Ferris
%J Journal of NeuroEngineering and Rehabilitation
%D 2012
%I BioMed Central
%R 10.1186/1743-0003-9-35
%X We recorded 264-channel EEG while 8 neurologically intact subjects performed isometric and isotonic, knee and ankle exercises at two different effort levels. Adaptive mixture independent component analysis (AMICA) parsed EEG into models of underlying source signals. We generated spectrograms for all electrocortical source signals and used a na£¿ve Bayesian classifier to decode exercise type from trial-by-trial time-frequency data.AMICA captured different electrocortical source distributions for ankle and knee tasks. The fit of single-trial EEG to these models distinguished knee from ankle tasks with 80% accuracy. Electrocortical spectral modulations in the supplementary motor area were significantly different for isometric and isotonic tasks (p£¿<£¿0.05). Isometric contractions elicited an event related desynchronization (ERD) in the ¦Á-band (8¨C12£¿Hz) and ¦Â-band (12¨C30£¿Hz) at joint torque onset and offset. Isotonic contractions elicited a sustained ¦Á- and ¦Â-band ERD throughout the trial. Classifiers based on supplementary motor area sources achieved a 4-way classification accuracy of 69% while classifiers based on electrocortical sources in multiple brain regions achieved a 4-way classification accuracy of 87%.Independent component analysis of EEG reveals unique spatial and spectro-temporal electrocortical properties for different lower limb motor tasks. Using a broad distribution of electrocortical signals may improve classification of human lower limb movements from single-trial EEG.
%U http://www.jneuroengrehab.com/content/9/1/35/abstract