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Results for “sensorimotor function”

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PubMed1996

A neuromagnetic study of movement-related somatosensory gating in the human brain.

Neuromagnetic fields from the left cerebral hemisphere of five healthy, right-handed subjects were investigated under three different experimental conditions: (1) electrical stimulation of the right index finger (task S); (2) voluntary movement of the same finger (M); (3) M+S condition, consisting of voluntary movements of the right index finger triggering the electrical stimulus at the very beginning of the electromyogram. The three conditions were administered in random order every 5-8 s. In addition, the task somatosensory evoked fields (task SEFs) gathered during condition (1) were compared with control SEFs recorded at the beginning of the experiment during rest. In all subjects the overlay of somatosensory stimulation on movement provoked a decrement in brain responsiveness (gating) as determined by the amplitude of gated SEFs. The latter was found as the difference between the neuromagnetic fields during M+S condition (overlaying of movement and sensory stimulation) minus neuromagnetic fields under M condition (M only). The gating effect was found to begin approximately 30 ms after movement onset, and to last for the whole period of the ongoing movement. The theoretical locus of gating was estimated by dipole localisation of the difference between task SEFs and gated SEFS using a moving dipole model. The site of the "early" gating effect (< 40 ms) was found to be more anteriorly located than the "later" (> 40 ms) gating effect. The task SEFs were found to be larger (significant after 30 ms) than the control SEFs elicited under the basal condition. The results are discussed with respect to timing, mechanism (centrifugal and centripetal), locus and selectivity of gating. In addition, the results are discussed with regard to clinical application (measuring attentional deficits in patients with impairments of higher mental functions and measuring gating deficits in patients with disturbed sensorimotor integration.

Adult↗

PubMed2001

Neurophysiological classification of ulnar entrapment across the elbow.

Ulnar nerve entrapment across the elbow (UAE), a common entrapment, requires neurophysiological evaluation for a diagnosis, but a standardised neurophysiological classification is not available. The aim of our study was to evaluate the validity of a neurophysiological classification of UAE, developed by us. To this end, we examined whether sensorimotor deficits, as observed by the physician and as referred by the patients, increased with the neurophysiological severity according to the classification. We performed a multiperspective assessment of 63 consecutive arms from 52 patients with a clinical diagnosis of UAE. Neurophysiological, clinical and patient-oriented validated measurements were used. The neurophysiological classification is based on the presence or absence of evoked responses and on the normality or abnormality of conduction findings. A strict relationship was observed between the degree of neurophysiological severity and the clinical findings (sensorimotor deficits). Moreover, a significant positive correlation between hand functional deficit and neurophysiological classification was observed. Conversely, a clear correlation between neurophysiological pattern and symptoms was not found. The neurophysiological classification is easy to use and reliable, but further multicentric studies should be performed.

Adult↗

PubMed2006

Abnormalities in skilled reaching movements are improved by peripheral anesthetization of the less-affected forelimb after sensorimotor cortical infarcts in rats.

Unilateral damage to sensorimotor cortical (SMC) regions can profoundly impair skilled reaching function in the contralesional forelimb. Such damage also results in impairments and compensatory changes in the less-affected/ipsilesional forelimb, but these effects remain poorly understood. Furthermore, anesthetization of the ipsilesional hand in humans with cerebral infarcts has been reported to produce transient functional improvements in the paretic hand [Floel A, Nagorsen U, Werhahn KJ, Ravindran S, Birbaumer N, Knecht S, et al. Influence of somatosensory input on motor function in patients with chronic stroke. Ann Neurol 2004;56:206-12; Voller B, Floel A, Werhahn KJ, Ravindran S, Wu CW, Cohen LG. Contralateral hand anesthesia transiently improves poststroke sensory deficits. Ann Neurol 2006;59:385-8]. One aim of this study was to sensitively assay the bilateral effects of unilateral ischemic SMC damage on performance of a unimanual skilled reaching task (the single pellet retrieval task) that rats had acquired pre-operatively with each forelimb. The second aim was to determine whether partially recovered contralesional reaching function is influenced by anesthetization of the ipsilesional forelimb. Unilateral SMC lesions were found to result in transient ipsilesional impairments in reaching success and significant ipsilesional abnormalities in reaching movements compared with sham-operates. There were major contralesional reaching impairments which improved during a 4 week training period, but movements remained significantly abnormal. Anesthetization of the ipsilesional forelimb with lidocaine at this time attenuated the contralesional movement abnormalities. These findings indicate that unilateral ischemic SMC lesions impair skilled reaching behavior in both forelimbs. Furthermore, after partial recovery in the contralesional forelimb, additional improvements can be induced by transient anesthetization of the ipsilesional forelimb. This is consistent with the effects of unilateral anesthetization in humans which have been attributed to the modulation of competitive interhemispheric interactions. The present findings suggest that such interactions are also likely to influence skilled reaching function in rats.

Anesthesia↗

PubMed2006

Oculomotor functions of the parietal lobe: Effects of chronic lesions in humans.

This review summarises research in patients with chronic lesions of parietal oculomotor cortex and compares their oculomotor performance to patients with lesions of the frontal eye field (FEF). The observations identify the oculomotor functions for which these regions are indispensable, and explore dynamic interactions within cortical and subcortical networks for oculomotor control. The experiments examined endogenously generated saccades, saccades to visual targets, antisaccades, saccade choice and saccade remapping for inhibitory spatial tagging. The findings suggest that the key function of parietal oculomotor cortex is the computation of sensorimotor transformations, rather than the initiation of either voluntary or reflexive saccades. They also reveal the re-organisation of cortico-subcortical networks after brain injury, and provide insight into their dynamic interactions: FEF lesions result in disinhibition of reflexive saccades toward the contralesional field and an impairment of reflexive saccades toward the ipsilesional field; whereas parietal lesion result in the opposite pattern.

Chronic Disease↗

PubMed2005

Spatial navigation impairment in mice lacking cerebellar LTD: a motor adaptation deficit?

L7-PKCI transgenic mice, which lack parallel fiber-Purkinje cell long-term depression (LTD), were tested with two different mazes to dissociate the relative importance of declarative and procedural components of spatial navigation. We show that L7-PKCI mice are deficient in acquisition of an adapted goal-oriented behavior, part of the procedural component of the task. This supports the hypothesis that cerebellar LTD may subserve a general sensorimotor adaptation process shared by motor and spatial learning functions.

Adaptation, Physiological↗

PubMed1996

Tactile perception of spatial stimuli on the lip surface by young and older adults.

Although older adults are subject to both subtle changes and major disorders of the oral sensorimotor system, relatively little is known about oral sensory function in old age. Accurate assessment of oral tactile perception is needed to document disability, aid prognosis, and plan treatment for older adults with disorders affecting speech or feeding. However, normative information currently available for older adults is mainly based on two-point discrimination, a problematic measure of tactile spatial resolution. Grating orientation discrimination, a technique developed to provide a clear and reliable measure of spatial resolution, was used to test sensitivity of the upper and lower lip vermillion, on right and left sides, in a sample of 40 young adults and 40 adults age 66-85. Results indicated that spatial acuity at the lip vermilion declines significantly in old age and that women tend to have better acuity than men. No significant differences were found in acuity between the upper and lower lips or between right and left sides for either age group. Peripheral changes in receptor density and lip tissue composition are suggested as likely causes for the age-related decline.

Adolescent↗

PubMed1990

Swallowing dysfunction in nephropathic cystinosis.

BACKGROUND: Nephropathic cystinosis causes renal failure in most patients at approximately 10 years of age. This can be prevented or retarded by cystine-depleting therapy with oral cysteamine. Many patients who do not receive adequate cysteamine therapy undergo renal transplantation, but the accumulation of cystine continues in other organs, resulting in various clinical abnormalities. We report age-related swallowing dysfunction in patients with nephropathic cystinosis. METHODS: We studied 43 patients with cystinosis (24 who had received a renal transplant and 19 who had not), 3 to 31 years of age. Oral motor function was assessed by a cranial-nerve oral sensorimotor examination, and an oral motor index was calculated for each patient. The oral phase of swallowing was assessed by ultrasonography, and the pharyngeal and esophageal phases were evaluated by videofluoroscopy. RESULTS: Approximately half the patients were slow eaters. Oral motor dysfunction, reflected by a higher oral motor index, increased with age. Speech, oral structure and anatomy, and tongue and lip strength were particularly affected. Seven of nine patients 21 to 31 years old had abnormalities in all three phases of swallowing; the deficits were variable in younger patients. In 28 patients with cystinosis, the mean (+/- SD) duration of oropharyngeal swallowing for a dry swallow (3.06 +/- 1.06 seconds) was longer than in 14 normal subjects (1.89 +/- 0.57 seconds; P less than 0.001). This prolongation reflected impairment of the initiation phase of swallowing. CONCLUSIONS: Swallowing dysfunction is a late complication of nephropathic cystinosis, probably related to muscular dysfunction. Changes in the consistency of foods, swallowing exercises, and long-term cysteamine therapy should be considered for patients with cystinosis who have difficulty in swallowing.

Adolescent↗

PubMed2002

Right parieto-premotor activation related to limb-independent antiphase movement.

In both quadrupedal and bipedal walking, cyclic movements of opposite limbs are made in antiphase, with identical frequency of all four limbs. These kinematical characteristics generated the hypothesis that, in humans, the cerebral control of this stereotypic movement pattern is associated with a common circuitry involved in antiphase movement, independent from execution by either the two upper or the two lower limbs. By means of positron emission tomography (PET), we identified cerebral activations related to limb-independent antiphase movement, distributed over the right anterior parietal and the right dorsal premotor cortex. Particularly, involvement of the right parietal cortex demonstrates a lateralized brain function for higher-order somatosensory processing, enabling the sensorimotor anchoring of stereotypic multilimb movement.

Acoustic Stimulation↗

PubMed2025

Polygenic Associations between Motor Behaviour, Neuromotor Traits, and Active Music Engagement in Four Cohorts.

Phenotypic investigations have shown that actively engaging with music, i.e., playing a musical instrument or singing may be protective of motor decline in aging. For example, music training associated with enhanced sensorimotor skills accompanied by changes in brain structure and function. Although it is possible that the benefits of active music engagement "transfer" to benefits in the motor domain, it is also possible that the genetic architecture of motor behaviour and the motor system structure may influence active music engagement. This study investigated whether polygenic scores (PGS) for five behavioural motor traits, 12 neuromotor structural brain traits, and seven rates of change in brain structure traits trained from existing discovery genome-wide association studies (GWAS) predict active music engagement outcomes in four independent cohorts of unrelated individuals of European ancestry: the Canadian Longitudinal Study on Aging (CLSA; N=22,198), Wisconsin Longitudinal Study (WLS; N=4,605), Vanderbilt's BioVU Repository (BioVU; N=6,150), and Vanderbilt's Online Musicality study (OM; N=1,559). Results were meta-analyzed for each PGS main effect across outcomes and cohorts, revealing that PGS for a faster walking pace was associated with higher amounts of active music engagement. Within CLSA, a higher PGS for walking pace was associated with greater odds of engaging with music. Findings suggest a shared genetic architecture between motor function and active music engagement. Future intervention-based research should consider the genetic underpinnings of motor behavior when evaluating the effects of music engagement on motor function across the lifespan.

BioVU↗

PubMed2006

Impaired postnatal development of hippocampal dentate gyrus in Sp4 null mutant mice.

Sp4, a member of the Sp1 family of transcription factors, is expressed restrictively in the developing nervous system and abundantly in the hippocampus. Previously, we demonstrated that hypomorphic Sp4 mice display hippocampal vacuolization and concomitant deficits in memory and sensorimotor gating. Here, we report further analyses of Sp4 functions during postnatal development of the dentate gyrus in Sp4 null mutant mice. A reduced cell proliferation restrictively in hippocampus, but not cerebellum, was observed in the first week of postnatal development of Sp4 null mutant mice. The dendritic growth and arborization of dentate granule cells was decreased in hippocampal cultures in vitro from mutant neonatal mice. The adult Sp4 null mutant mice displayed decreased dentate granule cell density with reduced width of both dentate gyrus and the molecular layer. The abnormality of the molecular layer was indicated by a reduced level of synaptophysin expression in the mutant mice. The Sp4 transcription factor therefore appears to predominantly regulate the development of dentate granule cells.

Animals↗

PubMed2005

Impaired Cl- extrusion in layer V pyramidal neurons of chronically injured epileptogenic neocortex.

In the mature brain, the K(+)/Cl- cotransporter KCC2 is important in maintaining low [Cl-]i, resulting in hyperpolarizing GABA responses. Decreases in KCC2 after neuronal injuries result in increases in [Cl-]i and enhanced neuronal excitability due to depolarizing GABA responses. We used the gramicidin perforated-patch technique to measure E(Cl) ( approximately E(GABA)) in layer V pyramidal neurons in slices of partially isolated sensorimotor cortex of adult rats to explore the potential functional consequence of KCC2 downregulation in chronically injured cortex. E(GABA) was measured by recording currents evoked with brief GABA puffs at various membrane potentials. There was no significant difference in E(Cl) between neurons in control and undercut animals (-71.2 +/- 2.6 and -71.8 +/- 2.8 mV, respectively). However, when loaded with Cl- by applying muscimol puffs at 0.2 Hz for 60 s, neurons in the undercut cortex had a significantly shorter time constant for the positive shift in E(Cl) during the Cl- loading phase (4.3 +/- 0.5 s for control and 2.2 +/- 0.4 s for undercut, P < 0.01). The positive shift in E(Cl) 3 s after the beginning of Cl- loading was also significantly larger in the undercut group than in the control, indicating that neurons in undercut cortex were less effective in maintaining low [Cl-]i during repetitive activation of GABA(A) receptors. Application of furosemide eliminated the difference between the control and undercut groups for both of these measures of [Cl-]i regulation. The results suggest an impairment in Cl- extrusion resulting from decreased KCC2 expression that may reduce the strength of GABAergic inhibition and contribute to epileptogenesis.

Animals↗

PubMedDate not supplied

[Formation of a defensive conditioned reflex to an acoustic stimulus in rabbits after early visual deprivation].

The formation of a defensive conditioned reflex to sound has been studied in rabbits raised from birth up to 30 days of life in dark. It was shown that, as compared with control animals of the same age, elaboration of reflex to sound takes place in them in shorter times periods and with less pairings. This corresponds to changes in electrographic manifestations of conditioning: increased amplitude and reduced peak latency of evoked potentials to acoustic stimuli in the auditory and sensorimotor cortical zones. The data obtained testify to enahcned functional activity of the auditory cortex, apparently due to a compensatory enhancement of impulse activity coming from the intact receptors of the auditory apparatus. It has been assumed that the observed functional changes appearing in the cortical end of the signal analyser (auditory zone); in response to sound, following visual deprivation, are a consequence of an early nature training of synaptic structures with regard to perceptionof impulses of acoustic modality.

Animals↗

PubMed2005

Electroencephalographic spectral power in writer's cramp patients: evidence for motor cortex malfunctioning during the cramp.

We investigated cortical activation as reflected in task-related spectral power (TRPow) changes in 8 writer's cramp patients during writing on a digital board and during isometric contraction and compared them to those of 8 age-matched healthy subjects. Scalp EEG was recorded over the contralateral primary sensorimotor area (SM1(c)), and from the ipsilateral sensorimotor area (SM1(i)). The electromyogram (EMG) was recorded from the Extensor Digitorum Communis (Extensor), Flexor Digitorum Superficialis (Flexor), and First Dorsal Interosseous (FDI) muscles. We analyzed (1) handwriting performance, (2) changes in the TRPow confined to alpha and beta band, and (3) the EMG spectral power during both tasks, writing and isometric contraction. During writing, all patients developed writer's cramp. The handwriting in writer's cramp patients was associated with significantly less reduction of the beta-range TRPow and lower frequency of the TRPow reduction compared to controls. No significant differences between patients and controls for the alpha band TRPow reduction during handwriting were observed. During writing, the patients showed higher EMG spectral power than the controls but this difference was at the border of significance. The present results indicate disorder in the motor execution system, in writer's cramp patients, associated with impaired functional beta-network state of the contra- and ipsilateral sensorimotor cortices, most probably due to inadequate modulation of the intracortical inhibition associated with writing.

Adult↗

PubMed2004

Brain network interactions in auditory, visual and linguistic processing.

In the paper, we discuss the importance of network interactions between brain regions in mediating performance of sensorimotor and cognitive tasks, including those associated with language processing. Functional neuroimaging, especially PET and fMRI, provide data that are obtained essentially simultaneously from much of the brain, and thus are ideal for enabling one to assess interregional functional interactions. Two ways to use these types of data to assess network interactions are presented. First, using PET, we demonstrate that anterior and posterior perisylvian language areas have stronger functional connectivity during spontaneous narrative production than during other less linguistically demanding production tasks. Second, we show how one can use large-scale neural network modeling to relate neural activity to the hemodynamically-based data generated by fMRI and PET. We review two versions of a model of object processing - one for visual and one for auditory objects. The regions comprising the models include primary and secondary sensory cortex, association cortex in the temporal lobe, and prefrontal cortex. Each model incorporates specific assumptions about how neurons in each of these areas function, and how neurons in the different areas are interconnected with each other. Each model is able to perform a delayed match-to-sample task for simple objects (simple shapes for the visual model; tonal contours for the auditory model). We find that the simulated electrical activities in each region are similar to those observed in nonhuman primates performing analogous tasks, and the absolute values of the simulated integrated synaptic activity in each brain region match human fMRI/PET data. Thus, this type of modeling provides a way to understand the neural bases for the sensorimotor and cognitive tasks of interest.

Animals↗

PubMedDate not supplied

The dependance of neuronal reactions of the sensorimotor cortex to a simultaneous complex stimulus upon the level of differentiation of its components.

The change in the neuronal activity of the sensorimotor area of the cerebral cortex of the cat was investigated in awake animals as a function of the level of differentiation of the components of a simultaneous heteromodal complex stimulus. Two groups of neurons in the sensorimotor cortex were distinguished on the basis of the character of this relationship and a number of other parameters. It was shown that the parameters of the reactions of all neurons recorded to the positive conditional stimulus following the consolidation of the conditioned motoric reaction are established first. Such parameters of the responses as degree of manifestation, intensity, duration, and the length of the latent period changed in the process of development. The reactions of neurons of both groups to inhibitory signals were stabilized only after the consolidation of the differentiation skill. In the process only the pattern of the discharge changed in the neurons of the first group, while in the neurons of the second group, the degree of manifestation of the response, its sign, duration, and length of the latent period could vary. Fluctuations in the level of differentiation following the development of the inhibitory conditioned reactions had an effect only on the responses of the neurons of the second group to the components of the complex.

Acoustic Stimulation↗

PubMed1990

Relationship of sensory organization to balance function in patients with hemiplegia.

Standing balance and dynamic weight shifting were evaluated in 10 subjects with hemiplegia using a sensory organization balance test (SOT) and the Fugl-Meyer sensorimotor assessment (FMSA). The SOT is a timed balance test that evaluates somatosensory, visual, and vestibular function for maintenance of upright posture. In contrast, the FMSA is a functional status assessment that indicates the amount of assistance needed during various balance tasks and the tolerated duration of the task. The results of both clinical tests were compared to determine whether the SOT correlated with functional ability. The SOT scores were significantly correlated with the FMSA balance subscores and the FMSA total lower extremity scores. Based on the results of this preliminary study, the authors concluded that the SOT may be useful for evaluating a patient's functional status. Further implications for the evaluation and treatment of balance dysfunction in persons with hemiplegia are discussed.

Adult↗

PubMed1995

[The functional-structural characteristics of the neurons in cultured explants of the cerebral cortex of rats subjected to immobilization-cold exposure in the prenatal developmental period].

A tissue culture was obtained from the sensorimotor cortex of rat embryos after keeping pregnant animals under immobilization-cold stress. The functional state of culture was determined by RNA synthesis intensity. On analysing the tissue morphology, much attention was paid to the pattern of cytoskeleton (microtubules and microfilaments) of neuronal processes. For both periods of cultivation (7 and 14 days), the levels of RNA synthesis in culture of stressed animals were weaker than in the control one by 44 and 34%, resp. After 2 weeks of incubation the density of microtubules, i.e. the number of microtubules per process width, was reduced by 26% in profiles of dendrites. No changes in the number of microfilaments were detected. Besides, destruction of the neuron cytoplasm, redistribution of microtubules within dendrites, and reduction in the number of synaptic endings were noticed. All these alterations seem to be caused by lowering the capability of neurons to form their processes.

Animals↗

PubMed1994

[Unilateral, sensorimotor femoral nerve paralysis following abdominal gynecological operation].

Unilateral or bilateral femoral nerve functional deficiency deficit occurs as a rare iatrogenic complication of gynaecological abdominal or vaginal surgery. Self-retaining abdominal retractors, that exert a constant pressure on the femoral nerve during the operation, are the most frequent cause. This situation occurs especially, if retractors of unsuitable size are used on very slender patients with thin abdominal walls. The favourable prognosis of the femoral nerve sensory and motor deficiencies can be complicated by damage to the knee joint resulting from leg muscle paresis. A personal observation and a literary review on sensomotor paresis after gynaecological abdominal surgery are discussed.

Adult↗