OBJECTIVE: Brain-computer interface (BCI) technology is attracting increasing 
interest as a tool for enhancing recovery of motor function after stroke, yet 
the optimal way to apply this technology is unknown. Here, we studied the 
immediate and therapeutic effects of BCI-based training to control pre-movement 
sensorimotor rhythm (SMR) amplitude on robot-assisted finger extension in people 
with stroke.
APPROACH: Eight people with moderate to severe hand impairment due to chronic 
stroke completed a four-week three-phase protocol during which they practiced 
finger extension with assistance from the FINGER robotic exoskeleton. In Phase 
1, we identified spatiospectral SMR features for each person that correlated 
with the intent to extend the index and/or middle finger(s). In Phase 2, the 
participants learned to increase or decrease SMR features given visual feedback, 
without movement. In Phase 3, the participants were cued to increase or decrease 
their SMR features, and when successful, were then cued to immediately attempt 
to extend the finger(s) with robot assistance.
MAIN RESULTS: Of the four participants that achieved SMR control in Phase 2, 
three initiated finger extensions with a reduced reaction time after decreasing 
(versus increasing) pre-movement SMR amplitude during Phase 3. Two also extended 
at least one of their fingers more forcefully after decreasing pre-movement SMR 
amplitude. Hand function, measured by the box and block test (BBT), improved by 
7.3  ±  7.5 blocks versus 3.5  ±  3.1 blocks in those with and without SMR 
control, respectively. Higher BBT scores at baseline correlated with a larger 
change in BBT score.
SIGNIFICANCE: These results suggest that learning to control person-specific 
pre-movement SMR features associated with finger extension can improve finger 
extension ability after stroke for some individuals. These results merit further 
investigation in a rehabilitation context.