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Home , Human brain, Neurostimulation

NEUROSTIMULATION TECHNOLOGIES HARNESSING ELECTRICITY TO TREAT LOST NEURAL FUNCTION

The serves as a command center, AN ELECTRICAL NERVOUS SYSTEM allowing us to perceive and respond to the world around The nervous system is made up of many types of cells, us, and it was long that any damage to it was including which link together like living wires, irreversible. Paralyzing injuries or profound conducting electrical signals throughout the body. This loss were permanent, and there was little to principle was first described in the 19th century when relieve the effects of neurodegenerative diseases like used electrical stimulation to contract Parkinson’s Disease. Now, with NIH support and years of muscles.12 Decades later, surgeons seeking to identify research, we understand the nervous system enough to and remove -inducing tissue electrically help compensate for lost function using electrical stimulated different brain areas, unlocking a wealth of stimulation to enhance neural activity. NIH, along with knowledge about how the brain is organized.13 When many other contributors, has guided and supported this the pacemaker was introduced in the 1950s, research, helping to take neurostimulation technologies researchers demonstrated for the first time that from initial discoveries in the lab and animal models to electrodes and batteries could be implanted in the innovative treatments for patients. body to simulate the action of healthy .14 NEUROSTIMULATION: THEN AND NOW

THEN (pre-1980s) The only electrical NOW FDA has approved • The electrical properties device that could • Technologies for cochlear implants for of the nervous system, be safely implanted electrically stimulating hearing loss4, deep though discovered more the nervous system allow than a hundred years ago, into was patients to compensate brain stimulators for had not been harnessed the cardiac for many types of Parkinson’s5, and a for treatments.1 damage.2 pacemaker, first device that can • Early prototypes of • Cochlear implants have were used in the 1950s.3 enabled people with restore some vision.6 very limited. The first hearing loss to hear and cochlear implants in the understand . Over 324,000 devices have been 1970s could only enhance patients’ awareness of their implanted worldwide, including 100,000 in the US and environment and aid with -reading.7 38,000 in American children.8 • Most advances in care for were • Emerging technologies have the promise of focused on limiting further damage shortly after injury, restoring vision10 and movement after paralysis rather than improving function over the longer term.9 and traumatic injury.11 Industry scientists performed clinical trials of RESEARCH-TO-PRACTICE for and Parkinson’s disease.37,38 -2010s: MILESTONES IN Mid- A RAPIDLY 1990s GROWING FIELD The FDA approved cochlear use SEEKING NEW in children, enabling hearing to be restored TARGETS For more information on the supporting evidence and research sponsors for during key developmental years.32 these milestones, see the Web .

1990

1968 1971- 1973 NIH researchers characterized the The first commercial spinal cord stimulation system normal electrical function of deep was introduced as a treatment for chronic .19 brain areas involved in movement, which are affected in A deep brain stimulation device was Parkinson’s.20,21,22 LATE 1980s/1990s: 2002- approved by the FDA to treat symptoms 2003 NEXT GENERATION of Parkinson’s disease.39 Scientists, including many DEVICES AND supported by the NIH, began The first functional APPLICATIONS 1960s experimenting with implanted 1972 prototype, using a single electrode, electrodes as a means of was implanted into a patient.23 restoring hearing loss.17,18 FDA approves a humanitarian exemption 1973 2009 for deep brain stimulation as a treatment for Obsessive-Compulsive Disorder.40 Using technology from Researchers first tested spinal cord stimulation, Studies, some funded by the NIH, the long-term safety and revealed that electrical stimulation 1960 investigators developed the effectiveness of implanting 1987- of deep brain regions could reduce first long-term, implanted 1998 electrodes in the human brain.16 device to stimulate associated with 33,34,35,36 the brain.24 Parkinson’s disease. 1970s-80s: Researchers used electrical UNLOCKING THE stimulation to help patients with Scientists first realized POTENTIAL OF spinal cord injury regain control of bodily functions, make small that electrical stimulation NEUROTECHNOLOGY 2011- The FDA approved the first two cochlear implant voluntary lower body movements, might simulate hearing. 1984- 2015 devices, which were the first neural prostheses 41,42 Attempting to repair a facial 1985 and briefly stand unaided. 1957 approved to treat hearing loss in adults.31 nerve injury, surgeons Ongoing studies have begun electrically stimulated the stimulating the spinal cord through 43 auditory nerve, causing the the skin. patient to perceive sounds.15 Researchers used a new animal model 1979- for Parkinson’s disease to identify brain 1983 regions responsible for movement and 2014 motor symptoms.28,29,30 Cochlear implants are 1950s-60s: devices that translate STIMULATING sounds into electrical The FDA approved the first visual 44 NERVES WITH Academic researchers, alone and in stimulation of the , developed with NIH nerves in the inner , support, which allows patients with ELECTRICITY partnership with technology companies, 1980s worked to upgrade cochlear implants allowing many people certain types of vision loss to perceive a using multiple electrodes.25,26,27 with hearing loss to hear small, low-resolution . indicates NIH-funded sounds and understand speech. milestones IMPACTS OF NEURAL STIMULATION TECHNOLOGIES The use of neural stimulation technologies can compensate for lost nerve function, improve quality of life, and lower the cost of education and treatment. The two examples below illustrate the value of neurotechnology and its potential application to diverse diseases and conditions.

COCHLEAR Over 80% of IMPLANTS children who SUPPORTING A FUTURE received an implant • As of December 2012, WHERE NEUROLOGICAL approximately 324,200 by 18 months of implants have been age were able to DAMAGE IS TREATABLE fitted worldwide, a nearly join and participate • Our understanding of the nervous 30-fold increase from in classes with their system will continue to grow, thanks in 1995.45 In the United hearing peers.47 States, roughly 58,000 part to major research efforts like the were implanted in adults Brain Research through Advancing and 38,000 in children.46 Innovative Neurotechnologies (BRAIN) 58 • The vast majority of cochlear implant users continue Initiative and the NIH Common Fund’s to use their implant 10 years after implantation.48 Stimulating Peripheral Activity to 59 • Implantation saves society $30,000-50,000 per person Relieve Conditions (SPARC) program. over a lifetime.49,50 These programs aim to develop and apply new tools to map the nervous DEEP BRAIN system, read its activity, and alter that activity to improve function for an STIMULATION ever-growing number of conditions. • Over 100,000 people with • These initiatives support research that Parkinson’s disease DBS patients could one day allow implanted worldwide have received experience about 51 neurotechnologies to automatically implants. 5 hours of detect and prevent epileptic ,60 • DBS reduces disease additional easy restore bladder function and reduce symptoms, and can be more moving time bladder pain,61 relieve treatment-resistant effective than therapy, per day.53 which involves unpleasant depression62, and make everyday side effects.52 activities easier for patients with • Patients continue to experience positive effects for traumatic brain injuries63, to name just a 10 or more years.54 few possibilities. • DBS can lessen Parkinson’s patients’ reliance on for symptom relief, reducing drug side effects by 44%.55 • Advances in neural stimulation • The two main pioneers of DBS as a Parkinson’s technology, in combination with a deeper treatment shared the 2013 Lasker Prize, often called understanding of the nervous system, America’s Nobel.56 offer a path to an incredible goal: a future • DBS has an FDA Humanitarian Device Exemption to in which the effects of neural diseases treat obsessive compulsive disorder, and is being tested and injuries can be reversed. in other conditions, such as treatment-resistant depression and .57 For references, supplementary information, and more on the impact of NIH, please visit http://www.nih.gov/impact