Grant Number: 1R01NS053603-01
Project Title: Primate model of an intracortically controlled FES prost
PI Information: ASSOCIATE PROFESSOR LEE E. MILLER, lm@northwestern.edu 

Abstract: DESCRIPTION (provided by applicant):
The goal of this project is to develop a primate model of an upper extremity neuromuscular stimulation system controlled by means of intra-cortical recording electrodes. Individuals with spinal cord injury become paralyzed because they have lost the ability to activate their muscles. These patients' muscles can still be made to contract if they are activated by means of electrical stimuli applied directly to the muscle or nerves. Likewise, the areas of the brain that normally control movement are still active, but their connection to the muscles has been lost as a result of the injury. Researchers at Case Western Reserve University (CWRU) have demonstrated that implanted functional electrical stimulation (FES) neuroprostheses can be used to restore grasp functions to individuals with tetraplegia. Although remarkable, these systems are limited to pre-programmed grasp patterns, and require considerable conscious attention. A more natural control system, with more degrees of freedom could provide greatly improved function. At Northwestern, we have developed methods to predict the activity of arm and hand muscles during grasping movements based on micro-electrode recordings from the brain of a monkey. From a single, chronically implanted array of electrodes, predictions can be made of the activity of shoulder, arm and hand muscles. This type of electrode has yielded maintained recordings for periods in excess of 3 years, and it has recently been approved for experimental use in human patients. We believe that intra-cortical recordings like these provide the potential for simultaneous control of multiple degrees of freedom through natural thought processes. By combining the strengths of the Northwestern and CWRU groups, we propose to develop a brain-computer interface adequate for controlling a neuroprosthesis. The development of a primate model of this neuroprosthetic system would be a major step toward its implementation in human patients. This application includes the following specific aims: 1) We propose to use a 100-electrode array implanted in the primary motor cortex of a mnkey to provide the input to a set of decoders designed to produce real-time predictions of the activity of particular hand muscles. 2) We propose to use the control algorithms developed in aim 1 and an implanted FES prosthesis to restore grasp following temporary muscle paralysis induced by a pharmacological nerve block. 3) We propose to develop these control algorithms without the use of initial EMG measurements, as would be necessary in order to implement the system for a patient.

Thesaurus Terms:
biological model, computer human interaction, implant, model design /development, neuromuscular stimulator, neuroregulation
brain electrical activity, limb movement, mathematical model, microelectrode, motor cortex
Macaca, electromyography, medical implant science

Institution: NORTHWESTERN UNIVERSITY
750 N. Lake Shore Drive, 7TH
CHICAGO, IL 60611
Fiscal Year: 2006
Department: PHYSIOLOGY
Project Start: 01-JAN-2006
Project End: 31-DEC-2010
ICD: NATIONAL INSTITUTE OF NEUROLOGICAL DISORDERS AND STROKE
IRG: ZRG1

J Neurophysiol (April 1, 2003). 10.1152/jn.00632.2002

Prediction of Muscle Activity by Populations of Sequentially Recorded Primary Motor Cortex Neurons
 
M. M. Morrow and L. E. Miller

Department of Physiology, Northwestern University Medical School and Northwestern University Institute for Neuroscience, Chicago, Illinois 60611

Submitted on Submitted 5 August 2002; accepted in final form 21 November 2002

Task and data collection
These data were recorded from a single monkey (Macaca nemestrina) during execution of a stereotypic precision grip task. The monkey was seated in a standard primate chair with its right hand loosely restrained. The left hand was used to reach toward a small Plexiglas device with a 13-mm-thick vertical bar instrumented with two force-sensitive resistors. The bar could only be gripped by apposition of thumb and index finger, which were inserted into 16-mm-wide slots parallel to the bar. A single trial began with the left hand on a touch pad at waist level. Following a 1-s touch pad hold time, an LED in the center of the bar was illuminated, instructing the monkey to grip the device. After a random hold time ranging from 500 to 1,500 ms, a tone indicated success and the monkey was given a juice reward and could return its hand to the touch pad to initiate the next trial following a random intertrial interval. Figure 1 shows a series of three of these trials, including several EMG signals, grip force, and several logical signals indicating the state of the devices. The monkey typically operated the precision grip device in alternate blocks with several other similar devices, each requiring different use of the hand.

Surgery
Following training, a stainless-steel chamber was implanted above the primary motor cortex, along with a halo-type head restraint. EMG leads were implanted subcutaneously on 23 arm and hand muscles, with leads routed to a connector implanted in the monkey's back (Miller et al. 1993 ). All animal-related procedures were approved by the institutional animal care and use committee at Northwestern University.