International Symposium on LifeChips 2006

Sensory Substitution and Brain-Machine Interfaces
The brain is capable of major reorganization of function at all ages, and for many years following brain damage. It is also capable of adapting to substitute sensory information following sensory loss (such as blindness; tactile loss in Leprosy; damaged vestibular system due to ototoxicity, or general balance deficit as result of stroke or brain trauma), providing a suitable human-machine interface is used. One such interface is the tongue BrainPort interface. Sensory substitution allows studies of the mechanisms of late brain plasticity, in addition to offering the possibility of practical solutions for persons with major sensory loss potentially including persons with spinal cord injury. Blind persons have not necessarily lost the capacity to see, because we do not see with the eyes, but with the brain. It also offers the opportunity to study brain imaging correlates of the perceptual learning, such as PET scan studies demonstrating that the visual cortex of congenitally blind persons reveals activity after a few hours of training. The sensory substitution studies were initiated in the early 60's as models of brain plasticity. Unmasking, closing of an abnormal open loop system, volume transmission, stimulation-produced mechanisms such as those related to long-term potentiation, and nonsynaptic diffusion neurotransmission (also called volume transmission, or VT) are among the probable mechanisms of late brain plasticity. The studies discussed here support the conceptual change occurring in the neurosciences during the last few years. The recognition that the brain is highly plastic at all ages will lead to a therapeutic emphasis on late recovery of function based on highly motivating functionally oriented programs. Furthermore, the brain deals with sensory images transformed in a neural code, and can adapt to information from artificial sensory receptors also transferred to a neural code and sent to the brain via an intact sensory pathway. A minimal amount of data can produce major perceptual effect. Thus, with a 100 point array a congenitally blind person was able to perform assembly and inspection tasks on an electronic assembly line of miniature diodes, totally blind persons can catch a ball rolling across a table, and faces can be identified. Thus, with the increasing availability of miniature inexpensive technology, practical sensory substitution devices, such as for vestibular damaged, blind and deaf persons, will be commonly available.

Biography
Paul Bach-y-Rita, M.D is a neuroscientist and clinician. He is Professor of Orthopedics and Rehabilitation, and Biomedical Engineering at the University of Wisconsin, Madison and previously was Professor of Visual Sciences, and Professor of Human Physiology at the University of California, Davis. With an MD degree from the Universidad Nacional Autonoma de Mexico, he spent several Post Doctoral years at UCLA, CNRS Institute Marey in Paris, Universitat Freiburg in Germany, Istituto di Fisiologia in Pisa Italy and held a Research Career Development Award for 10 years including the last years at the Smith Kettlewell Eye Research Institute in San Francisco. He is also Chairman of the Board of Wicab, Inc, a high tech company established with the aid of the University of Wisconsin, Madison, based on concepts and experiments on late brain plasticity. The resulting brain-machine interface technology was patented by the University of Wisconsin (WARF) and assigned to Wicab, Inc. It is leading to the development of practical sensory substitution devices. He is also developing motivating late brain rehabilitation programs for persons with functional deficits (e.g., from stroke or brain trauma) for persons a year or many more after the damage.