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Biomedical subjects

P Bach-y-Rita

Publications and source records attributed to P Bach-y-Rita.

At least 19 recordsLinked to original sources
PubMed1992

Evaluation of stroke rehabilitation by randomized controlled studies: a review.

In all, 22 reports of 20 randomized, controlled rehabilitation studies were evaluated. In 18 of these, the design of the trial was parallel, with a cross-over format being employed in the remaining 2 instances. Seven studies related to intensive rehabilitation during the early post-acute period. In six others, specific techniques--sometimes associated with traditional physiotherapy procedures--were compared: biofeedback, perceptual retraining, and amphetamine treatment. Eight experiments evaluated speech therapy in aphasia. Frequently, methodological considerations limited the interpretation of the results. The review showed that: 1) as regards activities of daily life and motor function, differences as between rehabilitation in stroke units on the one hand and non-rehabilitation or rehabilitation in medical wards on the other, were detected in relatively few quality studies and remained particularly inconclusive insofar as life in the home environment was concerned; 2) rehabilitation for aphasia and perceptual dysfunction proved effective for at least several months after acute stroke; 3) in general, examination of the reports cited revealed no differences in the effects of biofeedback and perceptual retraining vs conventional physiotherapy; 4) rehabilitation, whether administered by specialists or amateur caregivers purpose-trained by specialists, proved equally effective for aphasia. These conclusions constitute a valuable basis for the development and evaluation of modern rehabilitation programs for stroke patients.

Activities of Daily Living↗
PubMed1991

Electrotactile and vibrotactile displays for sensory substitution systems.

Sensory substitution systems provide their users with environmental information through a human sensory channel (eye, ear, or skin) different from that normally used, or with the information processed in some useful way. We review the methods used to present visual, auditory, and modified tactile information to the skin. First, we discuss present and potential future applications of sensory substitution, including tactile vision substitution (TVS), tactile auditory substitution, and remote tactile sensing or feedback (teletouch). Next, we review the relevant sensory physiology of the skin, including both the mechanisms of normal touch and the mechanisms and sensations associated with electrical stimulation of the skin using surface electrodes (electrotactile (also called electrocutaneous) stimulation). We briefly summarize the information-processing ability of the tactile sense and its relevance to sensory substitution. Finally, we discuss the limitations of current tactile display technologies and suggest areas requiring further research for sensory substitution systems to become more practical.

Artificial Intelligence↗
PubMed1990

Brain plasticity as a basis for recovery of function in humans.

One of the factors leading to the virtual neglect of the long-term potential for functional recovery following brain damage was the eclipse of plasticity concepts during the 100 years following Broca's 1861 publication on location of function. However, in the last 30 years evidence has been accumulating that demonstrates the plasticity of the brain and thus recovery potential is a subject of practical as well as theoretical interest. "Unmasking" of relatively inactive pathways, the taking over of functional representation by undamaged brain tissue, and neuronal group selection are among the mechanisms that are being explored. Human models of recovery of function include hemispherectomy patients that have regained bilateral function, facial paralysis patients who recover function (with appropriate rehabilitation) after VII-XII cranial nerve anastomosis, and patients with muscle transpositions to re-establish lost motor functions. The role of early and late rehabilitation, with attention to psychosocial and environmental factors, appears to be critical for recovery.

Anomia↗
PubMed1990

Biological and psychosocial factors in recovery from brain damage in humans.

In this paper we will explore some of the biological and psychosocial factors that appear to be relevant to recovery of function following brain damage, especially in regard to neurorehabilitation programmes. We will also comment on promising areas of research that relate to recovery of function. Our goal is to aid in establishing a conceptual framework for the development of theory- and experiment-based neurorehabilitation.

Brain↗
PubMed1990

An umbilical data-acquisition system for measuring pressures between the foot and shoe.

We have developed an umbilical data-acquisition system for measuring pressures between the foot and shoe during walking. It consists of pressure sensors in the insoles of shoes, amplifier circuits, umbilical cables, an analog-to-digital converter, and a graphics display card in an IBM PC for real-time data collection and display. The applied pressure on a sensor decreases its resistance, which causes the output voltage of the amplifier circuit to increase. We attach seven sensors to the surface of each insole of a pair of extra-depth shoes and calibrate all the sensors in the insole before and after each test using a load cell as a reference. The IBM PC samples the outputs from the sensor and the load cell and stores a piecewise linear lookup table for use in compensation for the nonlinearity of the sensor. On the PC's graphics display, two programs provide displays of foot pressures as real-time bar graphs or as analog pressure versus time curves.

Analog-Digital Conversion↗
PubMed1989

Perceptual learning of spatiotemporal events: evidence from an unfamiliar modality.

Perceptual learning was examined in two experiments in which subjects, originally unfamiliar with vibrotactile stimulation, were required to identify dynamic vibrotactile patterns with static visual patterns of the same two-dimensional shapes. In Experiment 1 we examined changes in performance with practice under a variety of vibrotactile spatial and temporal conditions. In Experiment 2 we investigated transfer of learning from one set of vibrotactile patterns to another different set. In neither experiment were subjects supplied with knowledge of results. Substantial perceptual learning (improvement in identification with practice) was observed in Experiment 1, although a minority of subjects did not exhibit improvement. Experiment 2 confirmed the general findings of Experiment 1 and also provided evidence of substantial positive transfer. In both experiments, multidimensional scaling of pattern confusion data revealed that practice (and improvement in identification) did not qualitatively change the relative confusability of patterns, suggesting that the (informative) structure of the patterns, irrespective of familiarity with a specific set of patterns, determined confusability. The findings are interpreted in terms of learning constructs offered by E. J. and J. J. Gibson. We conclude by considering the prospects that a connectionist mechanism can account for the observed perceptual learning.

Attention↗
PubMed1988

Clinical observations on recovery from stroke.

Recovery from stroke occurs in a similar pattern in most patients, but the final functional status is difficult to predict. This recovery is most rapid in the first few months, but it may continue for years. The factors facilitating prolonged and more complete recovery are unclear and multiple. The neurophysiologic mechanisms of synaptic sprouting, unmasking, and redevelopment of inhibition may underlie recovery and provide the basis for developing therapeutic interventions in an attempt to promote return of function. Although the impact of current rehabilitation strategies on stroke recovery is uncertain, review suggests that it is beneficial in selected groups of patients. Further research is needed to answer the many questions surrounding recovery from stroke (a) to address the mechanisms of stroke recovery in human subjects with imaging or pathologic correlation, (b) to design therapeutic techniques based on neurophysiology and assess their effectiveness in groups of patients, (c) to determine if intensive rehabilitation reduces functional dependency resulting in decreased long-term social and economic costs, (d) to determine when rehabilitation should begin, where rehabilitation should take place, and how rehabilitation programs should be organized, and (e) to enable selection of patients most likely to succeed in rehabilitation programs. Although difficult to design, studies addressing these areas will provide much useful information that will further the development and delivery of rehabilitation services, resulting in improved patient care and reduced costs.

Central Nervous System↗
PubMed1986

Is there anything out there? A study of distal attribution in response to vibrotactile stimulation.

Patterns of vibrotactile stimulation were delivered to the index fingertips of naive blindfolded subjects. The attributions made by these subjects when they were allowed to experience transformations of vibrotactile stimulation correlated with self-movement were assessed. Although the subjects became aware of the relationship between self-movement and stimulation transformation, they never developed the hypothesis of distal attribution, ie the hypothesis that the ultimate cause of their vibrotactile experience was an encounter with an object in the environment. It is proposed that further investigations of the course of acquisition of distal attribution in the situation described may be instructive in the study of externalization in other modalities.

Fingers↗
PubMed1985

Visual field rehabilitation in the cortically blind?

Investigators have recently reported that specific practice facilitates the restitution of visual fields in partially blinded humans with lesions to the striate cortex. In order to further evaluate this work, attempts were made to retrain twelve homonymous hemianopic or quadrantanopic patients with similar methods, but under conditions in which possible contaminating experimental variables were controlled, including: reliance on gross subjective impressions, large visual stimuli response variability, changes in detection strategies with practice and compensatory eccentric fixation. The results indicate that visual field increases are not trainable. It is concluded that previous studies should be regarded with caution and the restitution of visual fields after damage to the striate cortex in humans is probably not possible with existing methods.

Aged↗
PubMed1983

Tactile vision substitution: past and future.

Tactile sensory substitution for blind persons has been studied primarily in a laboratory setting. Although the studies demonstrated the feasibility of the approach, to date no practical systems are in use. In this paper, previous tactile vision substitution studies are described, and the reasons why practical systems have not yet been developed are discussed. The theoretical basis for sensory substitution is examined primarily in regard to the capacity of the somatosensory system to mediate high resolution "visual" information. Future developments that may lead to practical systems for blind persons are considered.

Biomechanical Phenomena↗