See Supplementary Information for additional Methods.
Permission for these studies was granted by the US Food and Drug Administration (Investigational Device Exemption; CAUTION: Investigational Device. Limited by Federal Law to Investigational Use Only) and the Partners Healthcare/Massachusetts General Hospital Institutional Review Board. Core elements of the investigational BrainGate system have been described previously
6 (link),7 (link).
During each session, participants were seated in a wheelchair with their feet located near or underneath the edge of the table supporting the target placement system. The robotic arm was positioned to the participant’s right (
Fig. 1a). Raw neural signals for each channel were sampled at 30 kHz and fed through custom Simulink (Mathworks Inc., Natick, MA) software in 100 ms bins (S3) or 20 ms bins (T2) to extract threshold crossing rates
2 ,30 ; these threshold crossing rates were used as the neural features for real-time decoding and for filter calibration. Open and closed-loop filter calibration was performed over several blocks, which were each 3 to 6 minutes long and contained 18–24 trials. Targets were presented using a custom, automated target placement platform. On each trial, one of 7 servos placed its target (a 6 cm diameter foam ball supported by a spring-loaded wooden dowel rod attached to the servo) in the workspace by lifting it to its task-defined target location (
Fig. 1b). Between trials, the previous trial’s target was returned to the table-top while next target was raised. Due to variability in the position of the target-placing platform from session to session and changes in the angles of the spring-loaded rods used to hold the targets, visual inspection was used for scoring successful grasp and successful touch trials. Further details on session setup, signal processing, filter calibration, robot systems, and target presentations are given in Methods.
