Multiple-microelectrode arrays are being developed as engineering tools for sampling the physiological activity of large numbers of nerve cells at once, in the brain or in nerves. Such arrays present technological challenges involving fabrication, interfaces to electrical connections, multiplexing by electronics, and computational data capture. They promise new levels of understanding of how whole groups of cells in the nervous system coordinate their activity for appropriate sensory processing or motor behavior. For example, the neural mechanisms underlying walking in tetrapod vertebrates are highly complex, involving sensory input and control of motor output for several different muscle groups rotating foot, ankle, knee and hip. Control of walking provides an excellent system to simultaneously test the engineering capability of this electrode system, and to discover principles of how sensory input is used for multi-joint coordination. This project uses a novel ceramic 100-electrode array chronically implanted in the sciatic nerve of the leg to study how sensory information is used for motor regulation of the walking gait under different walking speeds and loads. Results from this work will be important not only for understanding sensorimotor integration, but for further development of a device that will be extremely useful in analyzing brain activity in general, as well as having great potential for prosthetic engineering devices to assist walking recovery, for example, after spinal cord injury. The project also will have an impact on cross-disciplinary training between neurobiologists and engineers.
