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At least 415 records · Page 23Linked to original sources
PubMed1983

Cardiovascular findings in a patient with severe tetanus.

We report a case of tetanus associated with the syndrome of sympathetic overactivity. BP changes were associated with changes in systemic vascular resistance index (SVRI). Cardiac index (CI) varied independently from changes in SVRI and was correlated with the stroke volume. Oxygen consumption during the hypotensive periods was normal. Among several pharmacologic agents, only curare was effective in decreasing the severity and number of the hypertensive episodes. Physical stimulation of the patient rapidly reversed the hypotension. The potential mechanisms involved in producing these cardiovascular abnormalities are discussed.

Antihypertensive Agents↗
PubMed1998

Transcranial magnetic stimulation in study of the visual pathway.

The authors critically reviewed experiments in which transcranial magnetic stimulation (TMS) and repetitive TMS (rTMS) of the higher visual pathway were used. Topics include basic mechanisms of neural excitation by TMS and their relevance to the visual pathway (excitatory and inhibitory effects), TMS and rTMS of calcarine cortex (suppression, unmasking, and phosphenes), TMS of V5 (suppression), TMS and rTMS of higher level temporoparietooccipital areas (perceptual errors, unmasking, and inattention), the role of frontal lobe output in visual perception, and vocalization of perceived visual stimuli (role of consciousness of linguistic symbols).

Attention↗
PubMed2004

The scanning tunnelling microscope as an operative tool: doing physics and chemistry with single atoms and molecules.

The scanning tunnelling microscope, initially invented to image surfaces down to the atomic scale, has been further developed in the last few years to an operative tool, with which atoms and molecules can be manipulated at will at low substrate temperatures in different manners to create and investigate artificial structures, whose properties can be investigated employing spectroscopic dI/dV measurements. The tunnelling current can be used to selectively break chemical bonds, but also to induce chemical association. These possibilities give rise to startling new opportunities for physical and chemical experiments on the single atom and single molecule level. Here we provide a short overview on recent results obtained with these techniques.

Microchemistry↗
PubMed2004

Robot-assisted adaptive training: custom force fields for teaching movement patterns.

Based on recent studies of neuro-adaptive control, we tested a new iterative algorithm to generate custom training forces to "trick" subjects into altering their target-directed reaching movements to a prechosen movement as an after-effect of adaptation. The prechosen movement goal, a sinusoidal-shaped path from start to end point, was never explicitly conveyed to the subject. We hypothesized that the adaptation would cause an alteration in the feedforward command that would result in the prechosen movement. Our results showed that when forces were suddenly removed after a training period of 330 movements, trajectories were significantly shifted toward the prechosen movement. However, de-adaptation occurred (i.e., the after-effect "washed out") in the 50-75 movements that followed the removal of the training forces. A second experiment suppressed vision of hand location and found a detectable reduction in the washout of after-effects, suggesting that visual feedback of error critically influences learning. A final experiment demonstrated that after-effects were also present in the neighborhood of training--44% of original directional shift was seen in adjacent, unpracticed movement directions to targets that were 60 degrees different from the targets used for training. These results demonstrate the potential for these methods for teaching motor skills and for neuro-rehabilitation of brain-injured patients. This is a form of "implicit learning," because unlike explicit training methods, subjects learn movements with minimal instructions, no knowledge of, and little attention to the trajectory.

Adaptation, Physiological↗
PubMed2006

Virtual reality in posturography.

Balance dysfunctions are common, especially among elderly people. Present methods for the diagnosis and evaluation of severity of dysfuntion have limited value. We present a system that makes it easy to implement different visual and mechanical perturbations for clinical investigations of balance and visual-vestibular interaction. The system combines virtual reality visual stimulation with force platform posturography on a moving platform. We evaluate our contruction's utility in a classification task between 33 healthy controls and 77 patients with Ménière's disease, using a series of tests with different visual and mechanical stimuli. Responses of patients and controls differ significantly in parameters computed from stabilograms. We also show that the series of tests achieves a classification accuracy slightly over 80% between controls and patients.

Artificial Intelligence↗
PubMed2005

Robot-enhanced motor learning: accelerating internal model formation during locomotion by transient dynamic amplification.

When adapting to novel dynamic environments the nervous system learns to anticipate the imposed forces by forming an internal model of the environmental dynamics in a process driven by movement error reduction. Here, we tested the hypothesis that motor learning could be accelerated by transiently amplifying the environmental dynamics. A novel dynamic environment was created during treadmill stepping by applying a perpendicular viscous force field to the leg through a robotic device. The environmental dynamics were amplified by an amount determined by a computational learning model fit on a per-subject basis. On average, subjects significantly reduced the time required to predict the applied force field by approximately 26% when the field was transiently amplified. However, this reduction was not as great as that predicted by the model, likely due to nonstationarities in the learning parameters. We conclude that motor learning of a novel dynamic environment can be accelerated by exploiting the error-based learning mechanism of internal model formation, but that nonlinearities in adaptive response may limit the feasible acceleration. These results support an approach to movement training devices that amplify rather than reduce movement errors, and provide a computational framework for both implementing the approach and understanding its limitations.

Adaptation, Physiological↗
PubMed2006

A novel mechatronic body weight support system.

A novel mechatronic body weight support (BWS) system has been developed to provide precise body weight unloading for patients with neurological or other impairments during treadmill training. The system is composed of a passive elastic spring element to take over the main unloading force and an active closed-loop controlled electric drive to generate the exact desired force. Both force generating units, the passive spring and the active electric drive, act on the patient via a polyester rope connected to a harness worn by the patient. The length of the rope can be adjusted with an electric winch to adapt the system to different patient sizes. The system is fully computer controlled. At unloading loads of up to 60 kg and walking speeds of up to 3.2 km/h, the mean unloading error and the maximum unloading error of the presented BWS system was less than 1 and 3 kg, respectively. The performance was compared with those of two purely passive BWS systems currently being used by most other rehabilitation groups. This comprised counterweight systems and static BWS systems with fixed rope lengths. Counterweight systems reached mean and maximum unloading errors of up to 5.34 and 16.22 kg, respectively. The values for the static BWS were 11.02 kg and 27.67 kg, respectively. The novel mechatronic BWS system presented in this study adjusts desired unloading changes of up to 20 kg within less than 100 ms. Thus, not only constant BWS, but also gait cycle dependent or time variant oscillations of the desired force can be realized with high accuracy. Precise and constant unloading force is believed to be an important prerequisite for BWS gait therapy, where it is important to generate physiologically correct segmental dynamics and ground reaction forces. Thus, the novel BWS system presented in this paper is an important contribution to maximize the therapeutic outcome of human gait rehabilitation.

Biomechanical Phenomena↗
PubMed2003

Attentional blink modulation during sustained and after discrete lead stimuli presented in three sensory modalities.

Previous studies found larger attentional modulation of acoustic blinks during task-relevant than during task-irrelevant acoustic or visual, but not tactile, lead stimuli. Moreover, blink modulation was larger overall during acoustic lead stimuli. The present experiment investigated whether these results reflect modality specificity of attentional blink modulation or effects of continuous stimulation. Participants performed a discrimination and counting task with acoustic, visual, or tactile lead stimuli. Stimuli were presented sustained or consisted of two short discrete stimuli. The sustained condition replicated previous results. In the discrete condition, blinks were larger during task-relevant than during task-irrelevant stimuli in all groups regardless of lead stimulus modality. Thus, previous results that seemed consistent with modality-specific accounts of attentional blink modulation reflect effects of continuous stimulus input.

Acoustic Stimulation↗
PubMed2004

The effect of stimulus modality and task difficulty on attentional modulation of blink startle.

The effects of the sensory modality of the lead stimulus and of task difficulty on attentional modulation of the electrical and acoustic blink reflex were examined. Participants performed a discrimination and counting task with either two acoustic, two visual, or two tactile lead stimuli. In Experiment 1, facilitation of the electrically elicited blink was greater during task-relevant than during task-irrelevant lead stimuli. Increasing task difficulty enhanced magnitude facilitation for acoustic lead stimuli. In Experiment 2, acoustic blink facilitation was greater during task-relevant lead stimuli, but was unaffected by task difficulty. Experiment 3 showed that a further increase in task difficulty did not affect acoustic blink facilitation during visual lead stimuli. The observation that blink reflexes are facilitated by attention in the present task domain is consistent across a range of stimulus modality and task difficulty conditions.

Acoustic Stimulation↗
PubMed1987

Propofol for intravenous sedation.

This study investigated the properties of propofol when given by subanaesthetic infusion to provide sedation as an adjunct to spinal anaesthesia for lower limb surgery in 40 patients. Sedation, defined as sleep with preservation of eyelash reflex and purposeful reaction to verbal or mild physical stimulation, was satisfactorily achieved and maintained with minimal complications. The mean duration of infusion was 98 minutes and a mean infusion rate of 3.0 mg/kg/hour was required in patients over 65. This was significantly less (p less than 0.005) than the 4.1 mg/kg/hour required in younger patients. Recovery was impressively rapid; patients regained full consciousness approximately 4 minutes after the end of infusion, and were free from minor postoperative sequelae. Conversion to general anaesthesia was achieved in three patients where surgery encroached outside the analgesic field of the regional block, simply by increasing the infusion rate to approximately 10 mg/kg/hour.

Adolescent↗
PubMed2004

A new instrument for assessing quality of life in atopic dermatitis: international development of the Quality of Life Index for Atopic Dermatitis (QoLIAD).

BACKGROUND: Atopic dermatitis (AD) is a chronic or chronically relapsing inflammatory skin condition that can have a considerable impact on those affected. There are a number of instruments available to measure outcome in dermatological conditions but none have been developed specifically for AD. In addition, most measure symptoms and/or daily functioning, which are potential influences on quality of life (QoL) rather than assessments of the construct itself. OBJECTIVES: The aim of the current study was to develop a new instrument specifically designed to measure QoL in adults with AD-the Quality of Life Index for Atopic Dermatitis (QoLIAD). METHODS: The instrument was developed based on the needs-based model of QoL and was produced in several different countries simultaneously. Its content was derived from 65 in-depth interviews with relevant patients in the U.K., Italy and the Netherlands. The initial version of the measure was produced in U.K. English and translations were produced for the Netherlands, Italy, Germany, France and the U.S.A. using a dual translation panel methodology. A Spanish version was developed using the same adaptation process after the instrument was finalized. Field-test interviews were conducted with approximately 20 patients in each country to assess face and content validity. The instrument [in addition to the Dermatology Life Quality Index (DLQI) and the Psychological General Well-Being Schedule (PGWB)] was then administered to up to 300 AD patients in each country at two time points to finalize the instrument and test its psychometric properties. RESULTS: The initial version of the QoLIAD had 56 items that reflected the areas of need fulfillment identified in the qualitative interviews as having been affected by AD: mental and emotional stimulation, physical and emotional stability, security, sharing and belonging, self-esteem, personal development and fulfillment. Comments from patients in field-test interviews resulted in the removal of 14 items, to leave a 42-item instrument that was considered relevant and acceptable. The number of patients participating in the survey were 286 in the U.K., 46 in the Netherlands, 213 in France, 187 in Germany, 178 in the U.S.A. and 83 in Spain. Application of the Rasch model to these data identified the final 25-item QoLIAD. Unidimensionality was confirmed, with deviation of the total scale from the Rasch model evident at a single time point in one country only (the U.K.). All language versions, with the exception of the Dutch measure, had test-retest reliability coefficients in excess of 0.85. The test-retest in the Netherlands was 0.80. However, this country had the smallest sample size and the corresponding reliability for the DLQI was only 0.40. The QoLIAD had adequate internal consistency and the initial indications of construct validity were good. The levels of association with the DLQI indicated that the two instruments measure related but distinct constructs. CONCLUSIONS: The QoLIAD is a practical, reliable, valid and culturally applicable instrument for measuring the impact of AD and its treatment on QoL in clinical trials or in routine clinical practice.

Adolescent↗
PubMedDate not supplied

Some conditions affecting manipulative play with objects in severely mentally handicapped children.

Four experiments investigated contact and manipulative activity with play materials in severely handicapped children functioning at the 1--2-year-old stage of normal development. Experiment 1 found that many mentally handicapped children were as quick to contact and manipulate a novel object as were comparable normal children and that auditory (or visual) feedback seemed to be effective in sustaining attentive activity with an object. A small minority of the handicapped children, however, were very slow to contact either familiar conventional toy or a novel object. Experiments 2 and 3 found that adding stimulus features such as lights, sounds or bright colours to an object had no consistent effect on the latencies of these 'slow responders' to contact the object. Experiment 4 found that the amount and kinds of manipulative play of mentally handicapped children differed from the normal children only in that they interacted less with an attendant adult and displayed less frequent representational use of toys in pretend play. The play of both normal and handicapped children was relatively unaffected by whether only a few (four) or many (15) toys were provided.

Acoustic Stimulation↗
PubMedDate not supplied

Current practices in sensory motor programming with developmentally delayed infants and young children.

This study examined the current practices of sensory motor programming with developmentally delayed infants and young children. A survey was conducted of facilities listed as serving this population group. There were 625 facilities which responded (response rate 84%). The responses of these facilities showed that each modal facility served between 21-50 children in day settings, and that 95% of the facilities offered individualized sensory motor programmes. Responses indicated that the way sensory motor programming was developed, the activities used, and the expected benefits had a high degree of similarity. Differences, however, were reported in the professional background of the programme directors, in their theoretical orientation, and in the assessment instruments used for developing and evaluating sensory motor programmes. There are implications for future study.

Child↗
PubMed1982

The effect of care programmes on the dependency status of elderly residents in an extended care setting.

This paper presents data gathered in an operational research project undertaken in a geriatric centre providing care for approximately 400 long-term residents. The centre supplies nursing, medical, paramedical, day hospital and home care services. Programmes of social and diversional activities are provided and residents are also visited by various community groups. However, the long-term residents participating in this project represent a section of the population unable to utilize or participate in the social and diversional programmes usually offered. The aim of the study was to determine whether the dependency status of residents receiving long-term care is affected by nursing and/or medical patterns of institutional management. The project was carried out in two stages: 1 a habit training toileting programme intended to improve continent status; 2 activity programmes at differing levels of intensity and specifically designed to increase mental, social and physical stimulation.

Activities of Daily Living↗
PubMed1992

A comparison of the sedative effects of three alpha 2-adrenoceptor agonists (romifidine, detomidine and xylazine) in the horse.

The sedative effects of a new alpha 2-adrenoceptor agonist, romifidine, were compared with those of xylazine and detomidine. Five horses were treated with two doses of romifidine (40 micrograms/kg body weight and 80 micrograms/kg body weight), two doses of detomidine (10 micrograms/kg body weight and 20 micrograms/kg body weight) and one dose of xylazine (1 mg/kg body weight) given by intravenous injection using a Latin-square design. The dose of 80 micrograms/kg romifidine appeared equipotent to 1 mg/kg xylazine and 20 micrograms/kg detomidine, although at these doses both xylazine and detomidine had a shorter action. Detomidine 20 micrograms/kg and xylazine both produced greater lowering of the head and a greater degree of ataxia than romifidine at either dose. Romifidine produced sedation similar to that of the other drug regimes. The effect upon imposed stimuli was similar.

Acoustic Stimulation↗
PubMed1995

Somatosensory activations of the parietal operculum of man. A PET study.

We tested the hypothesis that somatosensory discrimination of roughness (microgeometry) but not of shape (macrogeometry) would activate the parietal operculum (PO) in man. It was also investigated whether a simple square pulse indentation of the skin on the index finger would activate the PO. Regional cerebral blood flow was measured with [15O]butanol and positron emission tomography in a total of 20 normal volunteers. Ten subjects used their right hand to discriminate objects that differed in roughness and similar smooth objects that differed in length. Ten other subjects pressed a button when they felt a square pulse indentation of the skin on their right index finger in a somatosensory reaction time task. Discrimination of roughness activated one field in the PO contralaterally and two fields ipsilaterally to the stimulated hand. The discrimination of length activated one field in the PO located ipsilaterally to the stimulated hand. The somatosensory reaction time task also activated one contralateral and two ipsilateral fields in the PO, and these fields partially overlapped the activated fields in the roughness discrimination task. Based on the extension of these fields and their overlaps we conclude that there exist at least one part of the contralateral PO and at least two parts of the ipsilateral PO that can be activated by somatosensory stimulation of the right hand. We argue further that the contralateral activated part contains a region than can be activated by roughness.

Adult↗
PubMed1995

Differential formation of topographic maps on the cerebral cortex and superior colliculus of the mouse by temporally correlated tactile- tactile and tactile-visual inputs.

Coincident electrical activity of nerve fibres seems to play a fundamental role in the development of ordered connections in the CNS. To test this hypothesis on the formation of topographic maps we connected two cutaneous regions of the body of newborn mice by implanting an artificial bridge of pig hair. Through this procedure we produced the mechanical fusion of the ear with either the shoulder or the nose. In these conditions the ear not only was connected with shoulder or nose, but was also in relation with the nasal or the inferior portion of visual space. Therefore the probability of temporally correlated tactile-tactile inputs (ear-shoulder or ear-nose) as well as tactile-visual inputs (ear-inferior or ear-nasal visual space) increased. By recording from the primary somatosensory cortex and superior colliculus, we found that the formation of topographic maps was based on different principles. The somatosensory cortex developed in terms of tactile-tactile correlated inputs, showing somatosensory neurons with receptive fields extending through the fused parts of the body. Conversely, the superior colliculus processed tactile-visual correlated inputs; we found somatosensory-visual bimodal neurons with visual receptive fields extending into the portion of visual space where the artificial bridge was directed. These results suggest that the fusion of two body parts is represented in terms of cutaneous coordinates in the cortex and external world (visual) coordinates in the superior colliculus. Therefore the differential tactile-tactile and tactile-visual coincident activity seems to be correlated to the different meaning of information processing of these two brain regions.

Acoustic Stimulation↗