Neuroscience Seminar Series: Lee Miller (Northwestern University): "Development of an adaptive neural interface to restore natural hand use during paralysis"

Functional Electrical Stimulation offers the means to restore motor function to patients suffering paralysis due to spinal cord injury or other neurological disorders. Current FES devices must be controlled by the patient’s own residual movements of an unparalyzed body part, so they allow only very simple, prepropgramed hand movements. To address this limitation, we have now developed an FES prosthesis controlled by signals recorded from neurons in the hand area of the motor cortex (M1). We work with monkeys in which we perform peripheral nerve blocks to paralyze the hand and forearm temporarily. By recording signals from both M1 and muscles (EMG) while the monkey makes normal movements, we can compute a “decoder” that subsequently converts new M1 recordings into predicted EMG. During paralysis, we use these real-time predictions to control the FES commands delivered to implanted, intramuscular electrodes. The system essentially bypasses the spinal cord, allowing the monkeys to regain voluntary control of the paralyzed muscles with apparently approximately “normal” patterns of cortical activity. However, in a patient, the initial step of decoder calculation from signals collected during normal movement would not be possible. We are currently developing the methods necessary to compute adaptive versions of these decoders that will not require recording EMG activity. This will also allow us to deliver stimulation through multi-contact, peripheral nerve electrodes, through which we cannot record, but with which we can potentially activate many muscles from a single implant site. A system combining a natural, high performance control signal with the ability to control more muscles, more dexterously would greatly enhance the independence and well being of spinal cord injured patients.

 Host: Tamar Makin