Paul Bach-y-Rita’s research while affiliated with Smith-Kettlewell Eye Research Institute and other places

An array of factors, of a type used in a video-tactile visual substitution system, was used to determine two-point thresholds for vibration on the skin of the back. In the first study simultaneous stimulus presentations using the constant stimulus method resulted in a median threshold of 17.8 mm. In the second study, both simultaneous and successive thresholds were near 11 mm. These results differ from classical studies using touch calipers which give simultaneous thresholds Of 68 mm and successive thresholds of 17 mm.

This clinical trial investigated whether a new rehabilitation therapy using the sensory substitution system was an effective treatment for severe balance disorder in subjects with bilateral vestibular loss. The device which substitutes for vestibular input by transmitting information on head position to the tongue, consists of a tilt sensor for detecting head position, a 10 × 10 electrode array for interfacing with tongue, and a controller for processing information. Subjects who placed the electrode array on the tongue were trained to maintain a centered body position by keeping the signals on the middle of tongue using the electrode array. All subjects completed 5-20 minute training sessions 2-3 times per day for 8 weeks. Dynamic stability and gait function were tested using the Sensory Organization Test (SOT) and Dynamic Gait Index (DGI), respectively, before and after all training sessions. All subjects showed pronounced improvements in their balance performance. The average of SOT score and DGI had significantly decreased after the last training. Improvements were also noted in quality of life assessments such as the Dizziness Handicap Inventory (DHI) and the Activities-specific Balance Confidence (ABC) Scale. These results suggest that alternative sensory input through the tongue could substitute for vestibular function and the vestibular substitution device is a possible new rehabilitation tool for subjects with a persistent balance disorder who have a long term history of bilateral peripheral vestibular etiologies.

Vestibular dysfunction of either central or peripheral origin can significantly affect balance, posture, and gait. We conducted a pilot study to test the effectiveness of training with the BrainPort balance device in subjects with a balance dysfunction due to peripheral or central vestibular loss. The BrainPort balance device transmits information about the patient's head position via electrotactile stimulation of the tongue. Head position data is sensed by an accelerometer and displayed on the tongue as a pattern of stimulation. This pattern of stimulation moves forward, backward, and laterally on the tongue in direct response to head movements. Users of the device were trained to use this stimulation to adjust their position in order to maintain their balance. Twenty-eight subjects with peripheral or central vestibular loss were trained with the BrainPort balance device and tested using the following standardized quantitative measurements of the treatment effects: Computerized Dynamic Posturography (CDP) using the Sensory Organization Test (SOT), Dynamic Gait Index (DGI), Activities-specific Balance Confidence Scale (ABC), and Dizziness Handicap Inventory (DHI). All subjects had chronic balance problems and all but one had previously participated in vestibular rehabilitation therapy. The scores on the clinical tests upon entry into the study were compared to their scores following training with the BrainPort balance device. Our results exhibit consistent positive and statistically significant improvements in balance, posture and gait. These results exceed what could normally be achieved in three to five days of traditional balance training alone. Since this was not a controlled study, we are unable to distinguish the degree to which these improvements are attributable to training with the BrainPort balance device versus the balance exercises performed by all subjects as a part of the BrainPort training sessions. Nonetheless, after training with the BrainPort balance device, all subjects demonstrated significant improvements in performance beyond what might be expected from conventional vestibular rehabilitation therapy.

The tongue display unit (TDU) is a practical technology for coupling machine‐generated data into the human nervous system. Through the TDU, a human user experiences what the machine captures by direct perception. It is an enabling technology through which the human literally becomes “one with the machine,” as if the machine were another appendage of the body. Unlike conventional human‐machine interface (HMI) analog and digital displays, direct coupling to the nervous system is based on unconscious integration and is far faster and more effective than conscious interpretation of data. TDU‐based human‐machine synergism enables anticipatory behavior derived from the meaning of a data stream, rather than a reactive response to individual data. It provides a means to integrate anticipatory function into manmade processes. Unlike the invasive direct‐coupling HMI strategies being investigated by many researchers, this interface requires no surgical implants. The TDU, developed at the University of Wisconsin Medical School, uses electrotactile contact with the tongue. Prototype TDU‐based sensory prosthesis have been applied to the restoration of lost senses, such as sight to blind persons and balance to victims of vestibular loss. Earlier vibro‐ and electrotactile interfaces to various skin areas (abdomen, finger, forehead, back) have also been used with artificial sensors for vision substitution and to restore the lost sense of touch in victims of leprosy. The TDU's potential goes beyond enabling the restoration of lost senses. Decades of experience in sensory substitution suggest that the brain can abstract meaning from many different forms of data passing through the TDU, implying that it can enable subjects to directly experience processes that would otherwise be outside the range of human sensibilities. For example, using this interface to monitor a large computer network, an administrator may be able to unconsciously abstract meaning from data flows, and to sense problems in the network “by feel.” In other words, the TDU provides a practical means of creating artificial senses. This development has many potential broad impacts. First, it heralds a new and highly significant type of relationship between human and machine; they become one. Second, it enables a level of process monitoring that is unavailable through any other technology, enabling dramatic improvements in the quality, safety, and reliability of practically any industrial or commercial processes. Third, it provides a novel strategy for solving many of the most perplexing problems in the information technology industry.

Patients with bilateral vestibular loss (BVL) of both central and peripheral origin experience multiple problems with balance and posture control, movement, and abnormal gait.Wicab, Inc. has developed the BrainPort balance device to transmit head position/orientation information normally provided by the vestibular system to the brain through a substitute sensory channel: electrotactile stimulation of the tongue. Head-orientation data (artificially sensed) serves as the input signal for the BrainPort balance device to control the movement of a small pattern of stimulation on the tongue that relates to head position in real-time. With training, the brain learns to appropriately interpret the information from the device and utilize it to function as it would with data from a normal-functioning natural sense. Ina total of 40 subjects trained with the BrainPort, 18 have been tested using standardized quantitative measurements of the treatment effects. A specialized set of exercises, testing, and training procedures has been developed that may serve as the course of intensive physical therapy with the BrainPort balance device. Our results demonstrate consistent positive and statistically significant balance rehabilitation effects independent of aging and etiology of balance deficit.

This paper analyzes the process of perceptual recalibration (PR) in light of two cases of technologically-mediated cognition: sensory substitution and perceptual modification. We hold that PR is a very useful concept — perhaps necessary — for explaining the adaptive capacity that natural perceptive systems display as they respond to functional demands from the environment. We also survey critically related issues, such as the role of learning, training, and nervous system plasticity in the recalibrating process. Attention is given to the interaction between technology and cognition, and the case of epistemic prostheses is presented as an illustration. Finally, we address the following theoretical issues: (1) the dynamic character of spatial perception; (2) the role of functional demands in perception; (3) the nature and interaction of sensory modalities. We aim to show that these issues may be addressed empirically and conceptually — hence, the usefulness of sensory-substitution and perceptual-modification studies in the analysis of perception, technologically-mediated cognition, and cognition in general.

For over 40 years, since I first obtained evidence for nonsynaptic diffusion neurotransmission (most scientists call it Volume Transmission), I have been convinced that we scientists were ignoring organizational dynamics other than the mechanistic synaptic organization of the brain. For many years it was an uneasy feeling, since I was aware there are so many avenues to explore in brain function. I have wondered how much we scientists have ignored, in our quest to understand how the brain really works, due to our efforts to "be scientific". In addition to the difficulty of understanding how the brain functions, how could we even begin to explore the human experience? In this paper I will first discuss some emerging concepts of brain function. I will then comment on the development of concepts that have been a part of my own research experience.