Matthew Nagle

Imagine this: you are sitting at one side of a room. There’s a computer at the opposite wall. You want to open your e-mail account without moving from your seat, and you, merely by focusing your thoughts on the action, can actually do this. Does this sound like absurd science fiction? It’s not.

A company named Braingate has developed a combination of hardware and software to directly sense the neuronal signals in the brain which controls limb movement. This device, with the size of a baby aspirin, when implanted in the brain records the neuronal signals and sends those to a computer, which then converts the signal to digital instruction and performs actions like moving a cursor. In 2006 the first clinical trial was performed on a 25 year old quadriplegic paralyzed person named Matthew Nagle. The trial became a grand success when after some practice Nagle could move and click a computer cursor and even make a robotic arm pick up small things. Since then quite a number of clinical trials have been performed on paralyzed

The devices are implanted in the cerebral cortex region of brain. These implants are now developed into wireless and subcutaneous devices for ease of use and minimal invasiveness. One important issue is to select the optimal neural signals to provide control. Two major types of neural signals are received by NI systems: action potential (spike) and field potential (FP). Motor cortex is the most common source of electrical potentials read by NIs. Spike of a single cell in motor cortex can provide information for hand velocity, position, forces, and goals. Higher information levels like upcoming plans for hand motion can be decoded from parietal and frontal neuron spiking. FPs are more complex than spikes. These reflect the flow of transmembrane current of synaptic origin, summed across groups of neurons of varying size and spatial