Hochberg LR et al. (2006) Neuronal ensemble control of prosthetic devices by a human with tetraplegia. Nature 442: 164–171

Encouraging proof-of-concept results were recently reported in Nature from an ongoing clinical pilot trial investigating the viability of neuromotor prostheses for the restoration of damaged motor function in humans with tetraparesis.

Hochberg et al. carried out a series of experiments on a 25-year-old man who had become tetraplegic 3 years previously from a knife wound that had transected his spinal cord. The researchers implanted a 96-microelectrode sensor, which could detect multiple neuron activity, into the primary motor cortex arm area of the patient. They were able to record action potentials from the sensor, demonstrating that neuronal spiking in this area was still intact 3 years after spinal cord injury.

The patient was instructed to imagine specific limb motions, which resulted in modulations of his neuronal firing patterns consistent with those previously observed in the monkey primary motor cortex. The researchers created a decoder for the firing patterns that could translate them into real actions via a 'neural cursor'; the patient was subsequently able to operate a television, and open and close a prosthetic hand, amongst other activities.

The authors conclude that their data show that ensemble firing patterns can be used as a control signal for motor commands, thus justifying future attempts to create a human neuromotor prosthesis with a wireless, implantable system rather than the current transcutaneous connection to a bulky external system.