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Biomedical subjects

E Taub

Publications and source records attributed to E Taub.

At least 19 recordsLinked to original sources
PubMed1999

The thought translation device: a neurophysiological approach to communication in total motor paralysis.

A thought translation device (TTD) for brain-computer communication is described. Three patients diagnosed with amyotrophic lateral sclerosis (ALS), with total motor paralysis, were trained for several months. In order to enable such patients to communicate without any motor activity, a technique was developed where subjects learn to control their slow cortical potentials (SCP) in a 2-s rhythm, producing either cortical negativity or positivity according to the task requirement. SCP differences between a baseline interval and an active control interval are transformed into vertical or horizontal cursor movements on a computer screen. Learning SCP self regulation followed an operant-conditioning paradigm with individualized shaping procedures. After prolonged training over more than 100 sessions, all patients achieved self-control, leading to a 70-80% accuracy for two patients. The learned cortical skill enabled the patients to select letters or words in a language-supporting program (LSP) developed for inter-personal communication. The results demonstrate that the fast and stable SCP self-control can be achieved with operant training and without mediation of any muscle activity. The acquired skill allows communication even in total locked-in states.

Adult↗
PubMed1999

Transcollicular approach to intrinsic tectal lesions.

OBJECTIVE: We used a paramedian, infratentorial-supracerebellar, transcollicular approach to resect 11 intrinsic tectal lesions, including 8 tumors and 3 hematomas, in 11 patients. The route of access to the lesions was designed to minimize the anatomic and functional damage to the surrounding structures. METHODS: Access was through one superior colliculus in each of seven patients, through one inferior colliculus in each of two patients, and through the superior and inferior colliculi of one side in each of two patients. RESULTS: Of the eight tumors, three were totally resected, four were nearly totally resected, and one was partially resected. The preoperative ocular symptoms did not change in six of these eight patients and worsened in two, and the neurological deficits, except ocular symptoms, improved in two. All three hematomas were completely removed, along with abnormal blood vessels in the wall of the hematoma cavity; all three of these patients experienced neurological improvement. CONCLUSION: We conclude that the paramedian, infratentorial-supracerebellar, transcollicular approach permits safe removal of intrinsic tectal lesions. Resection of the superior or inferior colliculus or both on one side seems to be neurologically well tolerated.

Adult↗
PubMed1998

Alteration of digital representations in somatosensory cortex in focal hand dystonia.

Focal hand dystonia involves a loss of motor control of one or more digits; it is associated with the repetitive, synchronous movements of the digits made by musicians over periods of many years. Magnetic source imaging revealed that there is a smaller distance (fusion) between the representations of the digits in somatosensory cortex for the affected hand of dystonic musicians than for the hands of non-musician control subjects. The data suggest that use-dependent susceptibility to digital representation fusion in cortex may be involved in the etiology of focal dystonia. A successful therapy for the condition has been developed based on this consideration.

Adult↗
PubMed1998

Reorganization of auditory cortex in tinnitus.

Magnetic source imaging was used to determine whether tonotopy in auditory cortex of individuals with tinnitus diverges from normative functional organization. Ten tinnitus subjects and 15 healthy controls were exposed to four sets of tones while magnetoencephalographic recordings were obtained from the two cortical hemispheres in sequence. A marked shift of the cortical representation of the tinnitus frequency into an area adjacent to the expected tonotopic location was observed. The Euclidean distance of the tinnitus frequency from the trajectory of the tonotopic map was 5.3 mm (SD = 3.1) compared with a distance of 2.5 mm (SD = 1.3) of a corresponding frequency in the healthy controls (t = 3.13, P < 0.01). In addition, a strong positive correlation was found between the subjective strength of the tinnitus and the amount of cortical reorganization (r = 0.82, P < 0.01). These results demonstrate that tinnitus is related to plastic alterations in auditory cortex. Similarities between these data and the previous demonstrations that phantom limb pain is highly correlated with cortical reorganization suggest that tinnitus may be an auditory phantom phenomenon.

Acoustic Stimulation↗
PubMed1998

Motor cortex plasticity during constraint-induced movement therapy in stroke patients.

Stroke patients in the chronic phase received constraint-induced (CI) movement therapy. The motor cortex was spatially mapped using focal transcranial magnetic stimulation (TMS) before and after 2 weeks of treatment. Motor-output areas of the abductor pollicis brevis muscle, motor evoked potential (MEP) amplitudes and location of centre of gravity (CoG) of motor cortex output were studied. After CI therapy, motor performance improved substantially in all patients. There was also an increase of motor output area size and MEP amplitudes, indicating enhanced neuronal excitability in the damaged hemisphere for the target muscles. The mean centre of gravity of the motor output maps was shifted considerably after the rehabilitation, indicating the recruitment of motor areas adjacent to the original location. Thus, even in chronic stroke patients, reduced motor cortex representations of an affected body part can be enlarged and increased in level of excitability by an effective rehabilitation procedure. The data therefore demonstrate a CNS correlate of therapy-induced recovery of function after nervous system damage in humans.

Brain Mapping↗
PubMed1998

Perceptual correlates of changes in cortical representation of fingers in blind multifinger Braille readers.

The mature mammalian nervous system alters its functional organization in a use-dependent manner. Enhanced stimulation of a body part enlarges its cortical representational zones and may change its topographic order. Little is known about the perceptual and behavioral relevance of these plastic alterations in cortical organization. We used blind Braille readers who use several fingers on each hand and who do so for many hours each day as a model to investigate this issue. Magnetic source imaging indicated that the cortical somatosensory representation of the fingers was frequently topographically disordered in these subjects; in addition, they frequently misperceived which of these fingers was being touched by a light tactile stimulus. In contrast, neither the disordered representation nor mislocalizations were observed in sighted controls. Blind non-teacher Braille readers who used only one finger for reading were not significantly different from the sighted controls. Thus, use-dependent cortical reorganization can be associated with functionally relevant changes in the perceptual and behavioral capacities of the individual.

Adult↗
PubMed1998

Cortical reorganization and phantom phenomena in congenital and traumatic upper-extremity amputees.

The relationship between phantom limb phenomena and cortical reorganization was examined in five subjects with congenital absence of an upper limb and nine traumatic amputees. Neuromagnetic source imaging revealed minimal reorganization of primary somatosensory cortex in the congenital amputees (M=0.69 cm, SD 0.24) and the traumatic amputees without phantom limb pain (M=0.27 cm, SD 0.25); the amputees with phantom limb pain showed massive cortical reorganization (M=2.22 cm, SD 0.78). Phantom limb pain and nonpainful phantom limb phenomena were absent in the congenital amputees. Whereas phantom limb pain was positively related to cortical reorganization (r=0.87), nonpainful phantom phenomena were not significantly correlated with cortical reorganization (r=0.34). Sensory discrimination was normal and mislocalization (referral of stimulation-induced sensation to a phantom limb) was absent in the congenital amputees. The role of peripheral and central factors in the understanding of phantom limb pain and phantom limb phenomena is discussed in view of these findings.

Adult↗
PubMed1998

Thermal and EMG biofeedback learning in nonhuman primates.

Four monkeys were found able to learn to raise and lower hand temperature and to reduce muscle tension to low levels using feedback from the target physiological system. The establishment of this model of biofeedback learning in monkeys enables work on mechanisms mediating the modes of biofeedback most used in clinical practice. Results suggest that biofeedback learning does not need to be mediated by the type of human-specific cognitive strategies employed by humans.

Animals↗
PubMed1998

Plasticity of plasticity? Changes in the pattern of perceptual correlates of reorganization after amputation.

We report a follow-up study on seven arm amputees in whom magnetic source imaging had originally revealed a strong correlation between the amount of cortical invasion of the deafferented cortex and the amount of pain evoked sensation mislocalized to the phantom limb. This re-examination was performed in order to corroborate the phenomenon of mislocalization. On follow-up examination for mislocalization 4 weeks later, a close correlation had remained between the original amount of cortical representational reorganization of the amputation zone (at the first examination) and the number of sites from where painful stimuli evoked sensations referred to the phantom limb, i.e. the amount of perceptual mislocalization, at the second examination. However, contrary to our expectation, the topography of referred sensation had completely changed in every patient. These results suggest that while the overall extent of reorganization is a rather stable phenomenon, the concomitant changes in the pattern of sensory processing are not. This may be due to the fact that alterations of sensory processing are not hardwired, but are rather mediated by an extensive and interconnected neural network with fluctuating synaptic strengths. This mechanism may be of importance for neurological rehabilitation.

Accidents↗
PubMed1997

Effects of regional anesthesia on phantom limb pain are mirrored in changes in cortical reorganization.

The causes underlying phantom limb pain are still unknown. Recent studies on the consequences of nervous system damage in animals and humans reported substantial reorganization of primary somatosensory cortex subsequent to amputation, and one study showed that cortical reorganization is positively correlated with phantom limb pain. This paper examined the hypothesis of a functional relationship between cortical reorganization and phantom limb pain. Neuroelectric source imaging was used to determine changes in cortical reorganization in somatosensory cortex after anesthesia of an amputation stump produced by brachial plexus blockade in six phantom limb pain patients and four pain-free amputees. Three of six phantom limb subjects experienced a virtual elimination of current phantom pain attributable to anesthesia (mean change: 3.8 on an 11-point scale; Z = -1.83; p < 0.05) that was mirrored by a very rapid elimination of cortical reorganization in somatosensory cortex (change = 19.8 mm; t(2) = 5.60; p < 0.05). Cortical reorganization remained unchanged (mean change = 1.6 mm) in three phantom limb pain amputees whose pain was not reduced by brachial plexus blockade and in the phantom pain-free amputation controls. These findings suggest that cortical reorganization and phantom limb pain might have a causal relationship. Methods designed to alter cortical reorganization should be examined for their efficacy in the treatment of phantom limb pain.

Adult↗
PubMed1997

Input-increase and input-decrease types of cortical reorganization after upper extremity amputation in humans.

A plastic remodeling of regions in somatosensory cortex has previously been observed to occur in separate experimental paradigms in response to loss of somatosensory input and to increase in input. In this study, both types of cortical reorganization have been observed to occur concurrently in the same adult human nervous system as a result of a single intervention. Following upper extremity amputation, magnetic source imaging revealed that tactile stimulation of the lip evoked responses not only in the area of the somatosensory cortex corresponding to the face, but also within the cortical region that would normally correspond to the now absent hand. This "invasion" of the cortical amputation zone was accompanied by a significant increase in the size of the representation of the digits of the intact hand, presumably as a result of an increased importance of sensory stimulation consequent to increased dependence on that hand imposed by the loss of the contralateral extremity.

Adolescent↗
PubMed1997

The Arm Motor Ability Test: reliability, validity, and sensitivity to change of an instrument for assessing disabilities in activities of daily living.

OBJECTIVE: To continue and expand determination of the reliability, validity, and sensitivity to change of the Arm Motor Ability Test (AMAT), an instrument for assessing deficits in activities of daily living (ADL). DESIGN: The AMAT was administered twice to patients, with an interest interval of either 1 or 2 weeks, by one of two examiners assigned to patients in counterbalanced order. Patients' interest intervals and scores on the arm portion of the Motricity Index was unknown to the raters. SETTING: A referral inpatient neurological rehabilitation center. PATIENTS: Thirty-three subacute stroke inpatients with moderate to mild upper extremity motor deficit: median Motricity-Index-Arm score = 89, median chronicity = 43d, median age = 66yr; 12 were women. MAIN OUTCOME MEASURE AND RESULTS: The AMAT was developed in 1987, and interrater reliabilities at that time were found to range from .95 to .99. The present values for interrater reliability (2 scales) from videotaped test performance were: kappas = .68 to .77. Spearman correlations = .97 to .99. For performance time, interscorer reliability from videotaped test performance was .99. Homogeneities for the three AMAT measures for the total sample (Cronbach's alpha and split-half reliability) were .93 to .99. The test-retest reliabilities for the total sample were .93 to .99. The correlations to the Motricity-Index-Arm score were .45 to .61. The AMAT detected the difference in change occurring as a result of the passage of 1 versus 2 weeks in these subacute inpatients, presumably as a result of intensive therapy and/or spontaneous recovery, confirming the results of an earlier intervention study. CONCLUSION: The AMAT is an instrument with high interrater reliability, internal consistency, and sensitivity to change, as well as having satisfactory concurrent validity.

Activities of Daily Living↗
PubMed1997

Nonlinear preprocessing in short-range motion.

The phenomenon of non-Fourier motion (visually perceived motion that cannot be explained simply on the basis of the autocorrelation structure of the visual stimulus) is well recognized, and is generally considered to be due to nonlinear preprocessing of the visual stimulus prior to a stage of standard motion analysis. We devised a sequence of novel visual stimuli in which the availability of a motion stimulus depends on the nature of the nonlinear preprocessing: an nth order stimulus Pn will generate a perception of motion if it is preprocessed by a nonlinearity of polynomial order n or greater, but not if preprocessed by a nonlinearity of polynomial order less than n. We found that unambiguous motion direction was perceived for P2, P3, and P4, but not for higher-order stimuli, and we measured the contrast thresholds for direction discrimination with superimposed noise. We found that an asymmetric compressive nonlinearity can, in a unified fashion, account for these results, while a purely quadratic nonlinearity or a rectification of the form T(p) = magnitude of p cannot. We compared velocity discrimination judgements for second-order non-Fourier stimuli (P2) with standard drifting gratings. Although velocity comparisons were veridical, uncertainties were greater for the non-Fourier stimuli. This could be reproduced by substituting a Fourier grating with superimposed noise for the non-Fourier grating. These findings are consistent with a single pathway which processes both Fourier and non-Fourier short-range motion, and are discussed in the context of other investigations which have been interpreted as demonstrating separate pathways.

Adult↗
PubMed1997

Moyamoya disease in Europe, past and present status.

A questionnaire was distributed in early 1996 to 160 leading European neurological, neuro-pediatric and neurosurgical centers to assess the present status of Moyamoya disease in Europe. The response rate was 43%. Information was obtained on a total of 168 patients, of whom 110 had presented before 1992, and 58 from 1993 onward. 82% of the patients were Caucasian. In all other respects, the clinical findings were similar to those observed in Japan. The present study yields an incidence of 0.3 patients per center per year, which is approximately one-tenth of the incidence in Japan. Alongside these results, the history of the recognition and treatment of this disease in Europe is briefly discussed.

Adult↗
PubMed1997

The relationship of phantom limb pain to other phantom limb phenomena in upper extremity amputees.

In thirty-two unilateral upper extremity amputees with and without phantom limb pain, various phantom limb phenomena were investigated. In general, the incidence of non-painful phantom limb sensations was higher in patients with phantom limb pain than in pain-free amputees. Kinesthetic and kinetic phantom limb sensations were reported more frequently than exteroceptive cutaneous sensations. There was a significant positive correlation between phantom limb pain and stump pain. Patients more frequently assigned sensory than affective pain qualities to their phantom limb pain, whereas no differences between pain qualities were observed for stump pain. No support was found for a relationship between the presence of telescoping (i.e., shrinkage of the phantom limb) and phantom limb pain. These findings point to central as well as to peripheral factors contributing to phantom limb pain.

Adult↗
PubMed1997

Globus pallidus stimulation activates the cortical motor system during alleviation of parkinsonian symptoms.

Studies of 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP)-induced parkinsonism in monkeys suggest that excessive inhibitory outflow from the internal segment of the globus pallidus (GPi) suppresses the motor thalamus, which reduces activation of the cerebral cortex motor system, resulting in the slowness and poverty of movement of Parkinson's disease (PD). This hypothesis is supported by reports of high rates of spontaneous neuronal discharges and hypermetabolism in GPi (ref. 4-7) and impaired activation of the supplementary motor area (SMA) and dorsolateral prefrontal regions in PD patients. Furthermore, lesion or chronic high-frequency electrical (likely inactivating) stimulation of GPi (ref. 10-14) is associated with marked improvements in akinesia and rigidity, and the impaired activation of SMA is reversed when the akinesia is treated with dopamine agonists. To test whether improvement in motor function with pallidal surgery can be attributed to increased activity in premotor cortical regions, we assessed the changes in regional cerebral blood flow (rCBF) and parkinsonian symptoms during disruption of GPi activity with high-frequency stimulation delivered through implanted brain electrodes. Positron emission tomography (PET) revealed an increase in rCBF in ipsilateral premotor cortical areas during GPi stimulation, which improved rigidity and bradykinesia. These results suggest that disrupting the excessive inhibitory output of the basal ganglia reverses parkinsonism, via a thalamic relay, by activation of brain areas involved in the initiation of movement.

Aged↗
PubMed1997

Chronic electrical stimulation of the gasserian ganglion for the relief of pain in a series of 34 patients.

The use of an implanted system for chronic electrical stimulation of the gasserian ganglion for relief of facial pain was described in 1980 by Meyerson and Håkansson. Between 1982 and 1995, the senior author (R.R.T.) performed gasserian ganglion stimulation in 34 patients for the relief of chronic medically intractable facial pain. The etiology of pain was peripheral damage to the trigeminal nerve in 22 patients (65%), central (stroke) damage in seven (21%), postherpetic neuralgia in four (12%), and unclassifiable cause in one (3%). All patients received a trial of transcutaneous stimulation (Stage 1). Successful trials in 19 patients (56%) were followed by implantation of a permanent system (Stage II). Trial and postimplantation stimulation were deemed successful when there was a reduction of pain by at least 50% whenever the stimulator was on. Success rates varied from five (71%) of seven patients for central pain to five (23%) of 22 for peripheral pain and none (0%) of four for postherpetic neuralgia. The median follow-up duration in successful cases was 22.5 months. Infections occurred in seven patients, all of whom had undergone Stage II treatment. Infections were more frequent when the stimulating electrode from Stage I was left in place for Stage II (six [43%] of 14) than when completely new hardware was used and prophylactic antibiotic drugs were administered (one [20%] of five). Other complications included iatrogenic injury to the trigeminal nerve or ganglion in three cases (9%), transient diplopia in two (6%), increased pain in two (6%), and various technical problems in 10 (29%). It is concluded that pain of central origin (stroke) is the type most likely to be relieved by this procedure. This finding is new, as the few other clinical series reported to date contain no patients with this type of pain. The risk of infection seems to be lower when completely new hardware is used for Stage II and prophylactic antibiotic drugs are administered.

Antibiotic Prophylaxis↗