A New Approach to Prosthetic Control: EEG Motor Signal Tracking With an Adaptively Designed Phase-Locked Loop

The feasibility of using brain waves to control an externally powered prosthetic device for amputees was investigated. Two subjects were studied; one normal and one with a right hand disarticulation. Each subject, otherwise at rest, performed the protocol of voluntarily, repetitively opening and closing his hand. The normal accomplished this, while the amputee attempted to use her missing limb as if it were present. The time between opening and the next closing, and between closing and the next opening, was approximately 2 s. Simultaneously with this procedure, electroencephglograms (EEGs) were recorded from scalp electrodes presumably overlying the motor cortex on the left side, and an electromyogram (EMG) was taken from right forearm surface electrodes. The EEG and EMG were recorded on a polygraph and on magnetic tape. The latter recording was later sampled at 128 samples/s and quantized to 210 levels.