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At least 739 records · Page 41Linked to original sources
PubMed2004

Neonatal loss of motor function in human spina bifida aperta.

OBJECTIVE: In neonates with spina bifida aperta (SBA), leg movements innervated by spinal segments located caudal to the meningomyelocele are transiently present. This study in neonates with SBA aimed to determine whether the presence of leg movements indicates functional integrity of neuronal innervation and whether these leg movements disappear as a result of dysfunction of upper motor neurons (axons originating cranial to the meningomyelocele) and/or of lower motor neurons (located caudal to the meningomyelocele). METHODS: Leg movements were investigated in neonates with SBA at postnatal day 1 (n = 18) and day 7 (n = 10). Upper and lower motor neuron dysfunction was assessed by neurologic examination (n = 18; disinhibition or inhibition of reflexes, respectively) and by electromyography (n = 12; absence or presence of denervation potentials, respectively). RESULTS: Movements, related to spinal segments caudal to the meningomyelocele, were present in all neonates at postnatal day 1. At day 1, leg movements were associated with signs of both upper (10 of 18) and lower (17 of 18) motor neuron dysfunction caudal to the meningomyelocele. In 7 of 10 neonates restudied after the first postnatal week, leg movements had disappeared. The absence of leg movements coincided with loss of relevant reflexes, which had been present at day 1, indicating progression of lower motor neuron dysfunction. CONCLUSIONS: We conclude that the presence of neonatal leg movements does not indicate integrity of functional lower motor neuron innervation by spinal segments caudal to the meningomyelocele. Present observations could explain why fetal surgery at the level of the meningomyelocele does not prevent loss of leg movements.

Electromyography↗
PubMed1998

Representation of cortical motor function as revealed by stereotactic transcranial magnetic stimulation.

Cortical motor representation of 12 muscles of the trunk and the upper and lower extremity was investigated in 18 healthy subjects using focal transcranial magnetic stimulation (TMS) in conjunction with a frameless stereotactic system (FSS). This combination allowed us to orientate stimulation sites to the individual central sulcus rather than to bony landmarks. Distinct but overlapping areas of muscle representation were identified and the 3-dimensional representation of those 12 muscles along the course of the central sulcus was obtained. With increasing stimulus intensity, the cortical output maps changed in that more muscles became excitable, motor evoked potential (MEP) amplitude and size of the responsive area increased and latency of the MEP decreased. These effects were more pronounced for proximal than for distal muscles, indicating a more widespread organization of corticospinal motor projection related to proximal muscles. The combination of TMS and FSS represents a method with which functional information can be directly related to underlying cortical anatomy. This correlation will be useful in the assessment of higher brain functions with TMS.

Adult↗
PubMed2005

Functional motor compensation in amyotrophic lateral sclerosis.

The present study investigated the fMRI correlates of functional compensation/neural reorganization of the motor system in patients with amyotrophic lateral sclerosis (ALS). The hypothesis was that ALS patients would recruit additional brain regions compared with controls in a motor task and that activity in these regions would vary as a function of task difficulty. Patients and controls executed a motor task with two sequences (a simple and a more difficult one) of consecutive button presses. Patients and controls both activated brain regions known to be involved in motor execution and control. Activity in ipsilateral motor areas as well as difficulty-related activity in the left cerebellum could only be observed in patients. The behavioral data indicated that the motor task was much more difficult for patients than for controls. At nearly equal difficulty the observed patterns of hemodynamic activity in controls were very similar to those observed in ALS. The findings suggest that functional compensation in ALS relies on existing resources and mechanisms that are not primarily developed as a consequence of the lesion.

Adult↗
PubMed1999

N-ethylmaleimide inhibits Ncd motor function by modification of a cysteine in the stalk domain.

N-Ethylmaleimide (NEM), which reacts readily with exposed sulfhydryl groups, has been shown to inhibit the activity of the microtubule (MT) motors kinesin, Ncd, and dynein. Currently, the mechanism of inhibition is not known for any of these proteins. To investigate the mechanism by which NEM inhibits Ncd, the recombinant Ncd motor-stalk protein MC1 (modified claret 1) was treated with varying concentrations of NEM (0-10 mM) and cosedimentation and ATPase assays were used to assess the effects of modification on MC1 interactions with MTs. In the cosedimentation assay, treatment with </=0.1 mM NEM enhanced MC1 binding to MTs in the presence of MgATP but had no effect on MC1 binding to MTs in the presence of MgAMP-PNP. In comparison, treatment with >/=0.5 mM NEM induced aggregation of MC1 and resulted in sedimentation of the motor in the absence of MTs. NEM modification had no effect on the basal ATPase rate but produced a decrease in the MT-stimulated ATPase rate. Labeling of MC1 with [3H]NEM indicated that enhanced MT binding was associated with an average labeling of 1 Cys residue per MC1 polypeptide, while aggregation was associated with an average labeling of 2 Cys residues per MC1 polypeptide. Protein digestion, structural analysis, and mass spectrometry indicate that modification of Cys313 or Cys324 in the stalk domain is correlated with enhanced binding of MC1 to MTs. These results suggest that NEM enhances Ncd binding to MTs by disruption of neck and/or stalk function and demonstrate the importance of this region in motor function.

Adenosine Triphosphatases↗
PubMed2007

Indorenate improves motor function in rats with chronic spinal cord injury.

The effect of indorenate (5-methoxytryptamine, beta-methyl carboxylate hydrochloride), a 5-HT1A agonist, was investigated on the motor performance of rats with chronic spinal cord injury. Four months after a ninth thoracic vertebrae spinal cord contusion, 29 rats were randomly allocated into two groups: saline solution and indorenate-treated animals with daily doses incremented at weekly intervals. The locomotor performance of all rats was measured by the Basso, Beattie, and Bresnahan (BBB) rating scale. The results showed that at the end of the treatment, the motor activity of indorenate group was significantly better than that presented by saline solution group. The 80% of indorenate, (against 15% of saline solution) did not show detriment on motor activity. When we analysed the motor activity of rats with basal BBB lower than 10, a significant improvement of motor recovery in indorenate-treated animals was observed. The benefits observed in locomotor function at low doses followed by increasing doses could be associated with pharmacological treatment by indorenate, a well-known 5-HT1A receptor agonist. Our results suggest a potential mechanism by which serotonergic agents may improve motor function in rats with chronic spinal cord injury.

5-Methoxytryptamine↗
PubMed2004

Influence of interhemispheric interactions on motor function in chronic stroke.

In patients with chronic stroke, the primary motor cortex of the intact hemisphere (M1(intact hemisphere)) may influence functional recovery, possibly through transcallosal effects exerted over M1 in the lesioned hemisphere (M1(lesioned hemisphere)). Here, we studied interhemispheric inhibition (IHI) between M1(intact hemisphere) and M1(lesioned hemisphere) in the process of generation of a voluntary movement by the paretic hand in patients with chronic subcortical stroke and in healthy volunteers. IHI was evaluated in both hands preceding the onset of unilateral voluntary index finger movements (paretic hand in patients, right hand in controls) in a simple reaction time paradigm. IHI at rest and shortly after the Go signal were comparable in patients and controls. Closer to movement onset, IHI targeting the moving index finger turned into facilitation in controls but remained deep in patients, a finding that correlated with poor motor performance. These results document an abnormally high interhemispheric inhibitory drive from M1(intact hemisphere) to M1(lesioned hemisphere) in the process of generation of a voluntary movement by the paretic hand. It is conceivable that this abnormality could adversely influence motor recovery in some patients with subcortical stroke, an interpretation consistent with models of interhemispheric competition in motor and sensory systems.

Adult↗
PubMed1997

Functional magnetic resonance imaging and transcranial magnetic stimulation: complementary approaches in the evaluation of cortical motor function.

Functional magnetic resonance imaging (fMRI) and transcranial magnetic stimulation (TMS) represent different approaches to mapping the motor cortex. fMRI identifies areas of hemodynamic changes during task performance while TMS provides electrophysiologic data concerning the localization and density of cortical motoneurons. Here we define the spatial correlation between fMRI and TMS maps and compared them with direct electrical cortical stimulation (ECS). We performed fMRI at 1.5 T on 3 normal subjects and 2 patients with mass lesions near the central sulcus using a multislice, asymmetric, spin-echo, echo-planar pulse sequence during the performance of a motor task. We also performed focal TMS with surface EMG recordings from the muscles primarily involved in the fMRI task. We coregistered the stimulation sites in real time with the fMRI maps using a frameless stereotactic system. In both patients we also performed ECS of the cortex during surgery under local anesthesia. fMRI maps were validated by the electrophysiologic data both pre- and intraoperatively. Our results suggest that regions of fMRI activation correspond spatially to areas of highest motoneuron density as demonstrated by electrophysiologic techniques.

Adult↗
PubMed1989

Dorsal pallidum as a functional motor output of the corpus striatum.

A major function of the dopamine in the striatum is to control the activity of its efferent systems which contain primarily GABAergic neurons. Direct intracerebral injections of haloperidol into the corpus striatum impaired the performance of rats trained to depress a lever in a sensitive reaction time task. Rats were trained to depress a lever until the presentation of a visual conditioned stimulus and then to release the lever within a time limit of 500 ms to obtain a food reward. The increase in reaction time produced by dopamine blockade of the corpus striatum was mimicked by injection of a GABA agonist muscimol in nanogram quantities into the region of the dorsal pallidum, but not into the substantia nigra reticulata. Injections of a GABA agonist into the substantia nigra impaired performance by increasing the number of anticipatory responses (increased number of lever releases before the conditioned stimulus). These results suggest that the dorsal pallidum may play an important role in the response initiation associated with activation of the corpus striatum, and that the dorsal pallidum may form a significant part of parallel striatal outputs that have different functional significance.

Animals↗
PubMed2003

Direct evidence for a binding between cognitive and motor functions in humans: a TMS study.

During voluntary motor actions, the cortico-spinal (CS) excitability is known to be modulated, on the one hand by cognitive (intention-related) processes and, on the other hand, by motor (performance-related) processes. Here, we studied the way these processes interact in the tuning of CS excitability during voluntary wrist movement. We used transcranial magnetic stimulation (TMS) both as a reliable tool for quantifying the CS excitability, through the motor-evoked potentials (MEPs), and as a central perturbation evoking a movement (because the stimulation intensity was above threshold) with subjects instructed to prepare (without changing their muscle activation) either to "let go" or to "resist" to this evoked movement. We studied the simultaneous evolution of both the motor performance and the MEPs in the wrist flexor and extensor, separately for the successful trials (on average, 66% of the trials whatever the condition) and the unsuccessful trials; this allowed us to dissociate the intention- and performance-related processes. To their great surprise, subjects were found able to cognitively prepare themselves to resist a TMS-induced central perturbation; they all reported an important cognitive effort on the evoked movement. Moreover, because TMS only evoked short-latency MEPs (and no long-latency components), the amplitude of these short-latency MEPs was found to be related in a continuous way to the actual movement whatever the prior intention. These results demonstrate that prior intention allows an anticipatory modulation of the CS excitability, which is not only selective (as already known) but also efficient, giving the intended motor behavior a real chance to be realized. This constitutes a direct evidence of the role of the CS excitability in the binding between cognitive and motor processes in humans.

Adult↗
PubMed1987

Abnormal ocular motor function predicts clinical diagnosis of familial ataxia.

Ocular motor performance was significantly impaired in familial ataxia patients as compared with normal controls. Ataxic patients showed prolonged saccadic latencies, longer saccadic refixation times, reduced visual tracking performance, and increased hypermetria. Cutoff values were derived and applied to 15 subjects at risk for developing familial ataxia. Three of 15 showed abnormal values in three or more of four categories of ocular motor performance. Within 3 years, all three subjects were diagnosed on clinical grounds as having familial ataxia. We conclude that ocular motor performance is impaired in familial ataxia and may prove useful for earlier diagnosis.

Eye Movements↗
PubMed2001

Impaired motor function in patients with psychogenic pseudoseizures.

PURPOSE: To evaluate motor speed and grip strength in patients with well-documented psychogenic pseudoseizures. METHODS: We analyzed manual motor speed and grip strength in a group of 40 patients with confirmed psychogenic pseudoseizures (without evidence of concomitant epilepsy) and a group of 40 normal controls matched for handedness and gender, and of comparable age. The two groups were compared with respect to manual motor performance with the dominant hand, nondominant hand, and asymmetry between the dominant and nondominant hands. For the patient sample, we reviewed the neurologic history. RESULTS: Patients with pseudoseizures performed more poorly than controls with both dominant and nondominant hands. In addition, pseudoseizure patients failed to demonstrate the dominant-hand advantage observed in the normal control subjects on both tasks. The patient group had a high incidence of head trauma and other antecedent neurologic risk factors, and the proportion of left-handers was 3 times higher than expected. CONCLUSIONS: Bilaterally reduced motor speed and grip strength, reduced intermanual performance asymmetry, the high percentage of left-handers, and historical evidence of antecedent insults to the brain indicate that frontal lobe impairment may be common in patients with psychogenic pseudoseizures.

Adult↗
PubMed2006

Repetitive transcranial magnetic stimulation to improve mood and motor function in Parkinson's disease.

Repetitive transcranial magnetic stimulation (rTMS) is a non-invasive brain stimulation technique that can produce lasting changes in excitability and activity in cortical regions underneath the stimulation coil (local effect), but also within functionally connected cortical or subcortical regions (remote effects). Since the clinical presentation of Parkinson's disease (PD) is related to abnormal neuronal activity within the basal ganglia and cortical regions, including the primary motor cortex, the premotor cortex and the prefrontal cortex, several studies have used rTMS to improve brain function in PD. Here, we review the studies that have investigated the possible therapeutic effects of rTMS on mood and motor function in PD patients. We highlight some methodological inconsistencies and problems, including the difficulty to define the most effective protocol for rTMS or to establish an appropriate placebo condition. We finally propose future directions of research that may help to improve the therapeutic efficacy of rTMS in PD.

Affect↗
PubMed1986

[Differential approach to restoring motor function of the intestines in peritonitis].

The authors have made a comparative estimation of the effectiveness of different methods of treatment of 330 patients with peritonitis with special reference to subdivision of motor disorders into 4 stages (compensated, subcompensated, decompensated stages and enteroplegia). It was established that sympatholytic drugs and continuous peridural anesthesia were effective in the compensated stage. Continuous intubation of the gastro-intestinal tract with the help of a rigid probe ensuring decompression in the postoperative period was the operation of choice in decompensated disturbances of the motor-evacuatory function.

Anesthesia, Epidural↗
PubMed2002

Exogenous motilin affects postprandial proximal gastric motor function and visceral sensation.

Our aim was to investigate the effect of motilin on postprandial proximal gastric motor and sensory function in healthy volunteers. Ten fasted, healthy volunteers were infused intravenously with synthetic motilin or placebo over 90 min. A liquid meal (200 ml) was ingested within 2 min at the start of the infusion. Proximal gastric volume was measured with a barostat device. Abdominal symptoms were scored by visual analog scales. Plasma motilin concentrations were measured using RIA. Endogenous motilin levels were not affected by meal ingestion. After meal intake, gastric relaxation was similar for motilin and placebo. After postprandial relaxation, motilin resulted in a faster return of gastric volume to baseline (P = 0.007). Motilin significantly increased postprandial feelings of nausea (P = 0.03) and tended to increase abdominal pain and abdominal tension. In conclusion, after normal postprandial gastric relaxation, motilin accelerated the return of gastric volume to baseline. In addition, motilin increased postprandial feelings of nausea.

Abdominal Pain↗