The volitional movement of ones limbs is commanded by electrical activity in the neurons of the motor cortex, the output part of the brain. In quadriplegia, the spinal cord is damaged, but the motor cortex is perfectly functional. This array of electrodes, implanted into motor cortex could be used to record the electrical activity of these neurons. The electrode array could then provide large numbers of signals which could control functional neuromuscular systems or external mechanical devices (wheelchairs, artificial limbs, etc.). A three dimensional electrode array could be used in this application. The array is constructed from monocrystaline silicon and contains 100 needle shaped electrodes which protrude from a 4mm x 4mm substrate. Each sharpened electrode is 1.5mm in length and is about 80 microns in diameter at its base. A modification of this silicon electrode array is used to conduct a set of experiments in cats 1) to demonstrate that such an array of electrodes is capable of recording cortical neural activity and 2) to optimize the electrical properties of the electrodes such that they can provide the greatest isolation of single unit or unit cluster neural activity.
