Novel Neurotech Approach Uses Sensory Stimulation

by Warren Grill, senior technical editor and James Cavuoto, editor

While many first generation neurostimulation devices have endeavored to activate motor fibers in order to restore functions lost as a result of neurological diseases and disorders, a new class of devices is targeting sensory fibers in an effort to treat sensory dysfunction and eventually restore lost motor function as well.

A Providence, RI firm called Afferent Corp., founded in 2000, is currently working toward commercializing technology using low level electrical stimulation to treat sensory dysfunction resulting from disease and injury. The company has received over $1.7 million in start-up funding and grants. In an interview with Neurotech Business Report, Afferent founder and CEO Jason Harry said that the firm’s first products, which he hopes will be available for testing in 15 to 18 months, will be targeted at the market for stroke treatment.

Harry categorizes his devices, which will initially make use of surface stimulation, as a restorative approach to stroke treatment, as opposed to the assistive category of treatment, which includes everything from stents to walkers to orthoses. The foundation of Afferent’s development efforts lies in the interplay between mechanoreceptors and neuromuscular performance. Mechanoreceptors, which are found throughout muscles and joints, provide motion and force feedback that is key to all coordinated movement, the acquisition of motor skills, and development of strength. Harry’s mantra, suggestive of the environmentalist slogan, is “Think Cortically, Act Peripherally.”

Much of the technology behind Afferent was developed by James Collins, a professor of biomedical engineering at Boston University, and uses low-level electrical stimulation to enhance sensory function. The principle, called “stochastic resonance,” has been found in many non-linear physical and biological systems. It describes systems in which the ability to detect a signal in the presence of noise is actually enhanced by adding a critical amount of noise.

In this instance the “noise” is created by low-level electrical stimulation. Collins and colleagues have demonstrated that electrical stimulation, at a level too low to be perceived, improved the detection of a mechanical stimulus applied to the foot. Following this, they went on to show that electrical noise stimulation, applied to the skin around the knee, reduced postural sway and improved balance performance in healthy elderly individuals standing on one foot. These results suggest that noise-based devices, such as randomly vibrating shoe inserts, may help users overcome motor dysfunction.

Decrements in sensory performance, caused by age or disease, contribute to sensorimotor dysfunction including falls. It is possible that enhancing sensory function using low-level electrical stimulation may provide a means to rehabilitate persons with sensory loss due to age, diabetes, or stroke.

Afferent has an exclusive license to the broad U.S. patents that protect its technology. The company took advantage of Boston University’s technology transfer incubator, called the Community Technology Fund. In 2000, $1 million was received in the company’s first institutional round of financing from Pharos, LLC. Afferent also received a $225,000 award from the Slater Center for Biomedical Technology, a state of Rhode Island fund that has also assisted nearby Cyberkinetics, Inc.