Optimal motor synergy extraction for novel actions and virtual environments.

Dimensionality reduction techniques such as factor analysis can be used to identify the smallest number of components (motor synergies) that explain motion. Lambert-Shirzad and Van der Loos (J Neurophysiol 117: 290-302, 2017) compared dimensionality reduction techniques in bimanual hand movements, concluding that nonnegative matrix factorization was the optimal technique for extracting meaningful synergies. Their results provide a useful measure for examining how the motor system deals with novel motor tasks that allow the actor to engage with a virtual environment.