The Neural Engineering Program
Established 1970, the program is multi-disciplinary with the overall goal of design, development and evaluation of implantable devices for functional electrical stimulation that can replace or augment impaired function of the nervous system.
The Neural Engineering Program consists of six investigators, specializing in neurophysiology, neuropathology, and biomedical engineering, and several highly skilled technicians in the fields of animal care, surgical assistance, cell biology, and electrode fabrication. The department has been supported by the NINDS Neural Prosthesis Program since its establishment in 1970 by Drs. F. Terry Hambrecht and Karl Frank (present director, Joseph J. Pancrazio).
The research encompasses materials biocompatibility, determination of safe and effective electrical parameters for various types of electrodes implanted into the cortex, the deep brain, the cochlear nucleus, and spinal cord. The program has an international reputation for expertise in the problems related to the electrode-tissue interface – a major factor in the success of implantable neural prostheses. We are also recognized for microelectrode technology, microwire array fabrication techniques and a method for inserting microelectrodes into targeted areas of the brain.
The Huntington Helix Electrode
Many configurations of peripheral nerve electrodes, brain surface electrodes and penetrating microelectrodes have been designed, tested and patented. The Huntington Helix electrode has been the most thoroughly evaluated nerve electrode in animals and the most frequently implanted in humans. This electrode is licensed to Cyberonics, Inc., Houston, Texas, for vagal nerve stimulation (VNS) for the treatment of epilepsy and approved by the FDA in 1996. Over 8,000 implants have been made worldwide. VNS is also being used successfully for the treatment of drug-refractory depression and obesity.
The Huntington Helix electrode is also being used by Neural Control, Inc., Cleveland, Ohio, for stimulation of the glossopharyngeal nerve in stroke patients experiencing difficulty in swallowing. Improvement of swallowing has been demonstrated in the first two patients. Finally, urologists at UCSF and the University of Colorado have used the HMRI electrode for nerve stimulation in the treatment of urinary disorders.
We have designed arrays of penetrating microelectrodes, which can be implanted permanently into the brain. With funding from the National Institutes of Health, we have been developing microelectrode technology and investigating issues related to the safe and effective use of this application. We are collaborating with the Illinois Institute of Technology, the University of Chicago and the NIH investigators to develop a visual prosthesis for the blind. Arrays of microelectrodes developed and fabricated at HMRI will be implanted into the primary visual cortex, and will activate neurons of the visual pathway, to restore at least a crude form vision.
Auditory Prosthesis Development
In collaboration with the House Ear Institute (Los Angeles), and Cochlear Corporation (Sydney, Australia), we have been developing an auditory prosthesis that utilizes an array of microelectrodes implanted directly into the cochlear nucleus of the brainstem. This device is intended to restore some hearing to people who have been deafened by destruction of their auditory nerves by bilateral acoustic tumors, as occurs in Type II Neurofibromatosis. After several years of animal studies, the first human implants were performed in 2004.
Parkinson’s Disease Program
We are also a part of the Consortium on Deep Brain Stimulation for Parkinson’s Disease. Our role in this collaborative research will be to use our microstimulation experience to develop arrays of microelectrodes that will reduce the trauma inflicted by electrodes in current use. They will be used for simultaneous stimulation and recording from the globus pallidus or the subthalamic nuclei. Initially, we envision this electrode array as a research tool, but it will be designed with the ultimate objective of application in human patients with Parkinson’s Disease.
Spinal Cord Injured Patients
Our microwire penetrating microelectrodes are implanted into spinal cord to control the parasympathetic reflex of bladder contraction and somatic reflex of external urethral sphincter relaxation in order to achieve stimulation-induced micturition. The goal of this NIH-funded project is to develop the neuroprosthetic device for artificial control of micturition in spinal cord injured patients. We also studying mechanisms of stroke-induced bladder hyperreflexia and possibility its treatment by intraspinal microstimulation.
In addition to using the well-established approach of activating the nervous system with electrical stimulation, we are also exploring the possibility of activating the neurons by light. This can be accomplished by expressing a recently discovered light-sensitive ion channel Channelrhodopsin 2 in target neurons.