  Identification of intended movement type and movement phase of hand grasp
shaping are critical features for the control of volitional neuroprosthetics.
We demonstrate that neural dynamics during visually-guided imagined grasp
shaping can encode intended movement. We apply Procrustes analysis and LASSO
regression to achieve 72% accuracy (chance = 25%) in distinguishing between
visually-guided imagined grasp trajectories. Further, we can predict the stage
of grasp shaping in the form of elapsed time from start of trial (R2=0.4). Our
approach contributes to more accurate single-trial decoding of higher-level
movement goals and the phase of grasping movements in individuals not trained
with brain-computer interfaces. We also find that the overall time-varying
trajectory structure of imagined movements tend to be consistent within
individuals, and that transient trajectory deviations within trials return to
the task-dependent trajectory mean. These overall findings may contribute to
the further understanding of the cortical dynamics of human motor imagery.
