UC Irvine

Background: Robot-assisted rehabilitation movement training is becoming increasingly popular but produces variable benefits. A recent study showed that the benefits of robotic hand training after stroke decreased if participants could not accurately sense finger movement at baseline. In that study, finger proprioception was measured with a new test called the “Crisscross” test in which participants pushed a button when they thought their index and middle fingers were overlapped as a robot exoskeleton slowly moved their fingers past each other [5]. The goal of this project was to search for a neural correlate of proprioceptive processing during the Crisscross test. Since previous work found that proprioception influences Event Related Desynchronization (ERD) measured before hand movement, we hypothesized that ERD before the button pressing response during the Crisscross test would reflect proprioceptive error. Methods: Five healthy participants (4 male, 1 female, aged 22-66) had their right index and middle fingers randomly moved in crossing patterns by a robotic exoskeleton and were asked to press a button with their left hand when they believed their right fingers were perfectly aligned. We measured ERD using EEG electrodes over the motor area contralateral to the button pressing hand. Results: The magnitude of the ERD associated with the button press during the Crisscross test was weakly correlated with the size of the proprioceptive error on each trial for four participants. Conclusions: Although more evidence is needed, these results suggest the intriguing possibility that ERD may serve as a novel neural correlate of proprioceptive processing.