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At least 1,711 records · Page 95Linked to original sources
PubMed1991

Forced-choice preferential looking acuity of children with cortical visual impairment.

Forced-choice preferential-looking acuity estimates from cortically visually impaired (CVI) infants and children were compared with three measures of visual function. Mean acuity deficit varied with fixation, tracking and visual impairment. Acuity deficit correlated with centile score for sensorimotor skills, but not for gross motor skills. The results suggest that these estimates provide information about the CVI child's ability to use vision in everyday life. Correlations were found between initial acuity deficits and acuity deficits measured from three months to six years later. Forced-choice preferential-looking acuity estimates may be useful for evaluating treatment response and establishing guidelines for educational materials for these infants and children.

Blindness↗
PubMed1993

Observations of improvement of reaching in five subjects with left hemiparesis.

Kinematic analysis and surface electromyography were used to study reaching by five subjects with left hemiparesis as they attempted to touch each of three targets. The targets were placed to require movement within and out of extensor synergy. Each subject was tested five times over a nine week period. Over this time, amplitude of peak velocity and sense of limb position significantly improved in the paretic arms. The increase of amplitude of peak velocity was more strongly related to a decrease in the discontinuity of movement (r = -0.48) than to maximal level of contraction of the prime movers (anterior deltoid: r = 0.25; biceps: r = 0.39). This finding may be a sign of learning or increased maturity of reach. These results, if replicated in a larger sample, would support therapy designed to improve learning of new sensorimotor relationships in the hemiparetic limb.

Electromyography↗
PubMed1989

Long-lasting reduction of excitability by a sodium-dependent potassium current in cat neocortical neurons.

1. The function and ionic mechanism of a slow outward current were studied in large layer V neurons of cat sensorimotor cortex using an in vitro slice preparation and single microelectrode voltage clamp. 2. With Ca2+ influx blocked, a slow relaxation ("tail") of outward current followed either (1) repetitive firing evoked for 1 s or (2) a small 1-s depolarizing voltage clamp step that activated the persistent Na+ current of neocortical neurons, INaP. When a depolarization that activated INaP was maintained, an outward current gradually developed and increased in amplitude over a period of tens of seconds to several minutes. An outward tail current of similar duration followed repolarization. The slow outward current was abolished by TTX, indicating it depended on Na+ influx. 3. With Ca2+ influx blocked, the onset of the slow Na+-dependent outward current caused spike frequency adaptation during current-evoked repetitive firing. Following the firing, the decay of the Na+-dependent current caused a slow afterhyperpolarization (sAHP) and a long-lasting reduction of excitability. It also was responsible for habituation of the response to repeated identical current pulses. 4. The Na+-dependent tail current had properties expected of a K+ current. Membrane chord conductance increased during the tail, and tail amplitude was reduced or reversed by membrane potential hyperpolarization and raised extracellular K+ concentration [( K+]0). 5. The current tail was reduced reversibly by the K+ channel blockers TEA (5-10 mM), muscarine (5-20 microM), and norepinephrine (100 microM). These agents also resulted in a larger, more sustained inward current during the preceding step depolarization. Comparison of current time course before and after the application of blocking agents suggested that, in spite of its capability for slow buildup and decay, the onset of the Na+-dependent outward current occurs within 100 ms of an adequate step depolarization. 6. With Ca2+ influx blocked, extracellular application of dantrolene sodium (30 microM) had no clear effect on the current tail or the corresponding sAHP.(ABSTRACT TRUNCATED AT 400 WORDS)

Animals↗
PubMed2002

Multiple movement representations in the human brain: an event-related fMRI study.

Neurovascular correlates of response preparation have been investigated in human neuroimaging studies. However, conventional neuroimaging cannot distinguish, within the same trial, between areas involved in response selection and/or response execution and areas specifically involved in response preparation. The specific contribution of parietal and frontal areas to motor preparation has been explored in electrophysiological studies in monkey. However, the associative nature of sensorimotor tasks calls for the additional contributions of other cortical regions. In this article, we have investigated the functional anatomy of movement representations in the context of an associative visuomotor task with instructed delays. Neural correlates of movement representations have been assessed by isolating preparatory activity that is independent from the performance of an actual motor act, or from the presence of a response's target. Movement instruction (specified by visual cues) and motor performance (specified by an auditory cue) were separated by a variable delay period. We have used whole-brain event-related fMRI to measure human brain activity during the performance of such a task. We have focused our analysis on specific preparatory activity, defined as a sustained response over variable delay periods between a transient visual instruction cue and a brief motor response, temporally independent from the transient events. Behavioral and electrophysiological controls ensured that preparatory activity was not contaminated by overt motor responses or working memory processes. We report suggestive evidence for multiple movement representations in the human brain. Specific sustained activity in preparation for an action was found not only in parieto-frontal regions but also in extrastriate areas and in the posterior portion of the superior temporal sulcus. We suggest that goal-directed preparatory activity relies on both visuomotor and visuoperceptual areas. These findings point to a functional-anatomical basis for the integration of perceptual and executive processes.

Adult↗
PubMed1994

Selection of electrode positions for an EEG-based brain computer interface (BCI).

One major question in designing an EEG-based Brain Computer Interface to bypass the normal motor pathways is the selection of proper electrode positions. This study investigates electrode selection with a Distinction Sensitive Learning Vector Quantizer (DSLVQ). DSLVQ is an extended Learning Vector Quantizer (LVQ) which employs a weighted distance function for dynamical scaling and feature selection. The data analysed and classified were 56-channel EEG recordings over sensorimotor areas during preparation for discrete left or right index finger flexions. Data from 3 subjects are reported. It was found by DSLVQ that the most important electrode positions for differentiation between planning of left and right finger movement overlie cortical finger/hand areas over both hemispheres.

Adult↗
PubMed1995

Functional repair of striatal systems by neural transplants: evidence for circuit reconstruction.

Intrastriatal grafts of nigral and adrenal tissues have been found to be effective in alleviating many of the simple motor and sensorimotor deficits associated with lesions of the nigrostriatal dopamine system. However, the mechanisms by which such grafts exert their effects may be less specific than originally conceived, and both pharmacological and trophic actions play an essential role. Damage to intrinsic cortico-striatal circuits are unlikely to prove similarly amenable to such diffuse mechanisms of repair. Nevertheless, striatal grafts have been found to alleviate cognitive and motor deficits after excitotoxic lesions of the neostriatum. Accumulating evidence suggests that in this particular case many aspects of functional recovery may indeed be attributable to the striatal grafts providing an effective functional reconstruction of damaged neuronal circuits within the host brain.

Adrenal Glands↗
PubMed1993

Involvement of transmitter systems in neuropsychiatric diseases.

Normal function of the central nervous system (CNS) requires intact morphology as well as neurotransmission. Diseases of the CNS can become manifest as a sensorimotor deficit or psychic alteration, or both. When observing neuropsychiatric diseases, interaction of different transmitter systems is obvious. Thus, an increase or a decrease of transmitter systems affect each other. Mechanisms of compensation can also lead to alterations in transmitter systems not involved in the pathological process. Parkinson's disease, hyperkinetic movement disorders like ballism and Huntington's chorea, epilepsy and anxiety will be used in this paper as examples of the synergistic action of dopaminergic, peptidergic, glutamatergic, GABAergic and cholinergic neurotransmission. With our knowledge of the functional balance of transmitter systems in the CNS, various pharmacological strategies have been available to intervene in the pathophysiological process. The excitatory or inhibitory quality of the transmitter systems must be considered if such strategies are to be employed. On the other hand, a functional balance between two or more transmitter systems may cause a contrary therapeutic intervention on the opposite side of the balance.

Anxiety Disorders↗
PubMed2006

Dose-response characteristics of ketamine effect on locomotion, cognitive function and central neuronal activity.

The present dose-response study sought to determine the effects of subanesthetic dosages (4-16 mg/kg) of ketamine on locomotion, sensorimotor gating (PPI), working memory, as well as c-fos expression in various limbic regions implicated in the pathogenesis of schizophrenia. In addition, we examined whether ketamine-induced locomotion was influenced by the dark/light cycle. We found that ketamine increased locomotor activity in a dose dependent manner, but found no influence of the dark-light cycle. Additionally, ketamine dose-dependently interrupted PPI, resulting in prepulse facilitation at doses of 8 and 12 mg/kg. The dose of 12 mg/kg also induced impairments in working memory assessed by the discrete-trial delayed-alternation task. C-fos expression indicated that the dose-dependent behavioral effects of ketamine might be related to changes in the activity of limbic regions, notably hippocampus and amygdala.

Acoustic Stimulation↗
PubMed2003

Sensorimotor recovery in children after traumatic brain injury: analyses of gait, gross motor, and fine motor skills.

The recovery of gait, gross motor proficiency, and hand function was examined in 23 children (13 males, 10 females; age 4 years 7 months to 15 years 10 months) with traumatic brain injury (TBI) over five months of in patient rehabilitation. We used gait analysis, the Gross Motor Function Measure, the Developmental Hand Function Test, and the Purdue Pegboard test. Brain injury had been severe (initial Glasgow Coma Scale GCS <8) in 17 children and moderate (GCS 8-10) in six children. Compared with healthy control children of the same age and sex, repeated gait analyses in ambulatory children with brain injury showed significant reductions of velocity, stride length and cadence, and impaired balance. Spatiotemporal gait variables were correlated with Gross Motor Function Measure scores. Hand function tests revealed deficits in fine motor skills, speed, and coordination. Degree of impairment increased with trauma severity. Despite significant improvements, differences in gait velocity, stride length, and hand function of children with brain injuries and controls were still present about 8 months after TBI. Hand motor skills improved less than gait. Young age at injury was not associated with better recovery.

Adolescent↗
PubMed1994

Impact of obesity on neuropathic late complications in NIDDM.

OBJECTIVE: This cross-sectional study was aimed to investigate the isolated influence of obesity on peripheral sensorimotor and autonomic neuropathy in patients with long-term non-insulin-dependent diabetes mellitus (NIDDM). RESEARCH DESIGN AND METHODS: Ninety-one long-term NIDDM patients with a mean duration of 13.6 +/- 1.0 years and a mean age of 60.4 +/- 1.0 years were divided into two groups according to their body mass index (BMI) (lean with a BMI < 26.5: n = 41, age = 58.6 +/- 1.7 years, BMI = 23.7 +/- 0.3 kg/m2; and obese with a BMI > or = 26.5: n = 50, age = 61.9 +/- 1.2 years, BMI = 30.5 +/- 0.5 kg/m2). The two groups were not different in age, duration, gender, current parameters of glycemic control, number of smokers, cholesterol, triglycerides, and systolic and diastolic blood pressure. Neuropathic late complications were scrutinized by a standardized clinical examination that delivers a neuropathy score, pupillary autonomic neuropathy assessed by pupillometry, and cardiovascular autonomic neuropathy using a standardized test battery. RESULTS: One-way analysis of variance revealed that obese patients had poor results in the clinical neuropathy test (overall score in obese vs. lean: 71.1 +/- 2.9 vs. 80.6 +/- 3.0 points, 2P = 0.0266; 100 points were absolutely normal). This was particularly true for the discrimination perception (obese vs. lean: 67.0 +/- 4.0 vs. 81.7 +/- 3.3 points, 2P = 0.0073) and the reflex status (obese vs. lean: 57.4 +/- 4.0 vs. 71.8 +/- 4.3 points, 2P = 0.0164). Furthermore, obese patients had a poor result in the respiratory sinus arrhythmia (RSA) test, one of six autonomic function tests (RSA: obese vs. lean in average RSA percentile: 36.9 +/- 4.9 vs. 54.0 +/- 5.9%, 2P = 0.0264). CONCLUSIONS: Obesity influences sensorimotor and autonomic neuropathic late complications. The poor result in RSA in obesity may indicate an interrelation between pathogenesis of obesity and disorders of the respiratory and heart rhythm-generating control centers in the brain stem. Moreover, it could be due to intrathoracic fat deposits that alter lung mobility. Body mass control may be an important approach to reduce neuropathic complications. Beyond that, it seems necessary to control for body mass when comparing neuropathy in two groups of patients with NIDDM.

Adult↗
PubMed2001

Brain correlates of fast and slow handwriting in humans: a PET-performance correlation analysis.

The present study examined the cerebral control of velocity during handwriting. We employed H215O positron emission tomography (PET) to measure the regional cerebral blood flow (rCBF) in 10 healthy subjects. Participants were required to write the German verb 'bellen' ('to bark') either at their normal speed (i.e. fast open-loop handwriting) or to write at approximately half of their normal speed without visual feedback. The second task required a continuous modification of the motor output according to the kinaesthetic feedback from the hand (i.e. slow closed-loop handwriting). Pencil movements were recorded during PET scanning and analysed off-line using a stroke-based analysing program. The mean number of inversions in velocity (NIV) per stroke was used to quantify the mode of motor control during each PET scan. A NIV of 1 indicates fast open-loop processing, whereas an increase in NIV reflects a shift towards slow closed-loop processing of handwriting. Foci in the left primary sensorimotor cortex, the right lateral premotor cortex, the left anterior parietal cortex, the left anterior putamen, the left rostral supplementary motor area and the right precuneus showed a graded increase in functional activation with the mean NIV per stroke, suggesting that this set of brain regions is particularly involved in the processing of slow closed-loop writing movements. No area showed a negative relationship between rCBF and the mean NIV per stroke, suggesting that fast open-loop handwriting is achieved by an optimized cooperation of the manual sensorimotor network rather than by a selective activation of a distinct network component.

Adult↗
PubMed2001

Predicting long-term care institution utilization among post-rehabilitation stroke patients in Taiwan: a medical centre-based study.

PURPOSE: Early identification of predictive factors relevant to the utilization of long-term care institution for stroke patients is important and thus investigated in this study on stroke patients receiving rehabilitation therapy. METHODS: This prospective follow-up investigation carried out during patients' clinical visits, at homes or long-term care institutions, was conducted at least 6 months after stroke on 151 stroke survivors. Functional ability was evaluated with the functional independence measure (FIM) instrument at discharge of the inpatient rehabilitation programme. Balance status was measured using the seven item balance scale of the Fugl-Meyer sensorimotor assessment (FMSA). Major medical, rehabilitative and sociodemographic factors were also examined during hospitalization period as independent variables. RESULTS: Of all the patients surveyed, 23 (15.2%) had been living in long-term care institutions. Univariate statistical analysis indicated that the significant factors related to long-term care institution utilization included recurrence of attack, bilateral involvement, impaired orientation, and functional and balance status at discharge. CONCLUSIONS: Basing on the significant predictors identified, analysis using the logistic regression model correctly classified three quarters of the subjects as long-term care institution residents. The strongest predictors of long-term care institution utilization for stroke patients following rehabilitation therapy were: bilaterally affected, impaired orientation and poor standing ability at discharge.

Aged↗
PubMed2005

Wheel-running modestly promotes functional recovery after a unilateral cortical lesion in rats.

BACKGROUND: We aimed to determine whether early or delayed wheel-running (W) after a cortical lesion in rats influences functional recovery and protein expression involving synaptic plasticity. METHODS: 57 rats were arranged in 4 groups: (1) Sham, (2) NMDA, (3) W-24 h or (4) W-72 h (W-24 h and W-72 h means wheel-running for 14 days starting day 1 or day 3 after NMDA lesion). NMDA produced a standardized lesion in the unilateral sensorimotor cortex and detectable behavioral deficits. Synaptogenesis was measured by immunohistochemistry. RESULTS: Wheel-running starting after 24 h had no detectable effect, but it significantly speeded functional recovery when delayed to after 72 h. These results were in accordance with a marker linked to synaptogenesis. CONCLUSION: Wheel-running starting 3 days, but not 1 day, after an NMDA lesion is associated with improved functional recovery.

Animals↗
PubMed1997

Serial recording of somatosensory and myoelectric motor evoked potentials: role in assessing functional recovery after graded spinal cord injury in the rat.

Accurate functional outcome measures are essential in assessing therapeutic interventions after experimental spinal cord injury (SCI). We examined the hypothesis that serial recording of somatosensory (SSEP) and myoelectric motor evoked potentials (mMEPs) would provide complementary information to standard methods of behavioral analysis in a rat model of SCI and would allow objective discrimination of functional recovery in sensory and motor tracts. Clip compression injury of varying severity (sham, 23 g, 34 g, 56 g) and transections were performed at T1 in adult rats. SSEPs were recorded from the right sensorimotor cortex (SMC) after stimulation of the contralateral hind paw; mMEPs were recorded from the paraspinal, quadriceps, and the tibialis anterior muscles after anodal stimulation of the SMC. The inclined plane and Tarlov techniques were used to assess clinical neurological function. All outcome measures were assessed weekly prior to and up to 6 weeks following injury. Changes in clinical neurological function as assessed by the inclined plane and Tarlov methods varied with increasing injury severity (R = -0.72 and R = -0.73, respectively). SSEP latency was strongly correlated with injury severity (R = 0.92) and with clinical behavioral scores (R = -0.93 for inclined plane). The tibialis anterior mMEP correlated significantly, though weakly, with changes in inclined plane (R = 0.49) and Tarlov scores (R = 0.41). Although the mMEPs were sensitive to the presence of SCI, these recordings did not discriminate between severities of injury. We conclude that serial recording of SSEPs but not myoelectric MEPs correlates closely with the extent and temporal course of clinical neurological recovery after graded SCI in the rat.

Animals↗
PubMed1986

Maturational changes in cerebral function in infants determined by 18FDG positron emission tomography.

2-Deoxy-2[18F]fluoro-D-glucose positron emission tomography performed in human infants during development revealed progressive changes in local cerebral glucose utilization. In infants 5 weeks of age and younger, glucose utilization was highest in the sensorimotor cortex, thalamus, midbrain-brainstem, and cerebellar vermis. By 3 months, glucose metabolic activity had increased in the parietal, temporal, and occipital cortices and the basal ganglia, with subsequent increases in frontal and various association regions occurring by 8 months. These functional changes measured with positron emission tomography are in agreement with behavioral, neurophysiological, and anatomical alterations known to occur during infant development.

Adult↗
PubMed2004

Motor inhibition in patients with Gilles de la Tourette syndrome: functional activation patterns as revealed by EEG coherence.

There is considerable evidence that Gilles de la Tourette syndrome (TS) is due to frontal-striatal dysfunction. Here we determine whether adaptive cortical changes occur that might ameliorate the effects of this dysfunction. Specifically we test the hypothesis that increased interactions between selected cortical areas may help compensate through strengthened inhibition of inappropriate motor responses. To this end we recorded EEG in nine unmedicated patients with TS and nine age-matched healthy subjects during a variety of behavioural tasks related to motor inhibition. Functional connectivity between cortical areas was assessed by means of EEG coherence in the alpha frequency band (8-12 Hz). Elevated coherence was found between sensorimotor areas and the prefrontal and mesial frontal cortex during the acute voluntary suppression of tics. The same frontomesial network was overactive in TS patients compared with healthy subjects even when suppression of voluntary movement rather than tics was required during a Go-NoGo task. Behavioural performance in the Go-NoGo task was not different between patients and controls, confirming that the elevated frontomesial coherence in TS was likely to be adaptive rather than functionally disruptive. It is concluded that the gain in inhibitory frontomesial cortical networks is adaptively heightened in TS, and that the same network can also be engaged in the voluntary suppression of tics.

Acoustic Stimulation↗