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Results for “sensorimotor function”

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PubMed1989

Neurodevelopmental status of infants and young children treated for brain tumors with preirradiation chemotherapy.

In an effort to reduce the severity of late neurotoxicities associated with cranial irradiation, 14 infants and young children with malignant brain tumors were given preirradiation chemotherapy for 2 to 22 months (median, 8 months). Prospective neurodevelopmental evaluations were routinely conducted and now extend from 35 to 60 months (median, 41 months) postdiagnosis, and 10 to 52 months (median, 31 months) postirradiation in the 12 surviving children. At the initiation of chemotherapy, less than one fourth of the patients displayed normal performance status or mental functioning on age-corrected tests; the majority remained stable or declined while receiving chemotherapy. Declining mental development and adaptive behavior were noted in six patients following radiation therapy with only two patients now functioning in the normal range for age. The analysis suggests that neurodevelopmental progress is a function of multiple factors, including neurologic and sensorimotor deficits associated with the tumor, surgical intervention, and chemotherapy that antedated radiation therapy. This implies that delaying irradiation will not necessarily improve the patients' functional status. Whether the interval of postponement of irradiation evidenced in this sample will translate into an ultimately better quality of life remains unknown. Given the probable interaction of multiple risk factors, well-controlled prospective clinical trials are needed to definitively analyze this issue.

Auditory Perception↗

PubMed1992

Effects of d-amphetamine on the recovery of function following cerebral ischemic injury.

Amphetamine with appropriate motor experience has been found to facilitate the recovery of motor function after several different types of brain injuries. We investigated whether amphetamine would hasten the recovery of spatial mapping ability in gerbils previously subjected to a 3-min episode of forebrain ischemia. Amphetamine did not promote behavioral recovery, nor did it attenuate ischemic cell damage of hippocampal CA1 neurons. The beneficial effects of amphetamine after brain injury may be limited to restoration of sensorimotor ability and not to cognitive functions such as memory.

Animals↗

PubMed1995

The neurological development of prehension: a developmental neurologist's view.

From the developmental neurological point of view prehension is an important function as it involves the total sensorimotor nervous system. In order to make efficient performance possible both postural activity and motility of arms and hands must be coordinated, implying an intricate interplay between tonic and phasic activities. The analysis of the development of the different contributors suggests that they are based on independently developing brain mechanisms. This independency guarantees the variability which is required for adequately adaptive and purposeful functioning. A lack of this ability to vary, i.e. monotonous and stereotyped function resulting from deficient or deficiently coupled brain mechanisms leads to maladaptive and impaired motor function. Identification of the dysfunctioning brain mechanisms may inform treatment strategies.

Arm↗

PubMedDate not supplied

[Color campimetry in the diagnosis of diseases of the retina and optic nerve].

Color campimetry was realized with the use of an IBM-compatible computer display with a program permitting the registration of brightness sensitivity thresholds and the time of sensorimotor reaction to visual stimuli offered on the display in each point of the visual field. Investigation of light and color sensitivity thresholds and of the time of sensorimotor reaction to stimuli of different spectral composition in normal subjects helped study the functional topography of the retina by the time of sensorimotor reaction and by the brightness sensitivity thresholds. The methods of equalization by the brightness of the stimulus and background by means of recording the time of sensorimotor reaction was tried in experiments with different background brightness and stimulus size and in ophthalmologic examinations of patients with color abnormalities, diseases of the retina and optic nerve, with glaucoma and albinism.

Adult↗

PubMedDate not supplied

[Correlation of electric potentials of the hippocampus, amygdala and neocortex during instrumental conditioned reflexes in the dog].

Coherence and spectral functions of biopotentials of the hippocampus, amygdala, frontal and sensorimotor cortical areas were estimated in dogs during instrumental alimentary behaviour and during self-stimulation of emotionally positive brain areas. Formation of functional systems: frontal cortex--amygdala, frontal cortex--hippocampus, and sensorimotor cortex--amygdala, synchronously acting in delta- and theta bands of electrical activity, was observed at the stage of a stabilized motor habit. THe hippocampus and amaygdala poorly co-operated, probably reflecting their different roles in the organization of behaviour.

Amygdala↗

PubMed1992

Clinical differentiation of the attention deficit disorder subtypes: do sensorimotor deficits characterize children with ADD/WO?

Previous researchers found that children with Attention Deficit Disorder Without Hyperactivity (ADD/WO) tended to perform more poorly than children with Attention Deficit Disorder With Hyperactivity (ADD/H) on measures of motor and sensory functions. In the present study, a prototype sensorimotor soft sign battery was developed which limited cognitive involvement. It was hypothesized that ADD/WO children would exhibit a greater number of soft signs than ADD/H children who in turn would show more soft signs than normal children. Participants were 31 children ranging in age from 72 to 144 months. The SNAP checklist (Pelham & Murphy, 1981) was used in arriving at an experimental diagnosis. No differences were found between the ADD/WO and normal groups. The ADD/H group exhibited more soft signs than the normal group at all ages and more than the ADD/WO group above 96 months of age.

Journal Article↗

PubMed1991

Sensorimotor performance and rotation correlate to lesion size in right but not left hemisphere brain infarcts in the spontaneously hypertensive rat.

In order to correlate behavioural deficits to lesion size and to reveal possible functional asymmetries in the rat brain, locomotor activity, rotation and sensorimotor integration to touch were studied in spontaneously hypertensive rats (SHR) subjected to right or left middle cerebral artery occlusion. Control and infarcted rats showed no difference in locomotor activity. Infarcted rats tended to rotate towards the side of the lesion. A large sensorimotor deficit was found contralateral to the infarcted hemisphere. The absolute values of the side-biases for the rotation and sensorimotor tests were of the same degree irrespective of lesion side. Whereas the left hemisphere lesion size did not correlate to the behavioural outcome, the size of the right hemisphere lesion was highly correlated to the total sensorimotor deficit. Furthermore, the sensorimotor deficit of specific body parts was found to correlate to the damage of certain brain regions in a rostrocaudal fashion, reminiscent of a somatotopical organization. The extent of ipsilateral rotation correlated to brain tissue loss at the level of the posterior caudate-putamen. The present results indicate an asymmetrical organization for brain functions involved in the performance of the rotation and sensorimotor tests.

Animals↗

PubMed2005

Subcortical lesions after transient thread occlusion in the rat: T2-weighted magnetic resonance imaging findings without corresponding sensorimotor deficits.

PURPOSE: To investigate infarct evolution and functional consequences of exclusive subcortical or cortico-subcortical strokes, transient middle cerebral artery occlusion (MCAO) was conducted in Wistar rats. MATERIALS AND METHODS: MCAO was induced in male Wistar rats (260-300 g) for 60 minutes. Lesion volumes and absolute T2 times on magnetic resonance imaging (MRI) were assessed 1 and 14 days after MCAO using a 4.7-T MRI animal scanner in conjunction with functional testing (adhesive tape removal, cylinder test, and ledged beam walking). RESULTS: Functional test scores were not distinguishable between sham-operated animals (N = 5) and those with exclusive caudoputaminal infarct (N = 8; group cp), but showed significant deficits in animals with cortico-subcortical infarction (N = 10; group cp+). The cp group had lower absolute T2 times and a more pronounced reduction in T2 lesion volume over time than the subcortical component in the cp+ group. There was no correlation of T2 lesion size or absolute T2 times and functional impairment in either group. CONCLUSION: When judged from functional tests alone, subcortical ischemic lesions may not be diagnosed reliably. Furthermore, T2-weighted (T2-w) MRI does not well anticipate functional deficits in primarily striatal lesions.

Animals↗

PubMed2003

Evidence for axonal pathology and adaptive cortical reorganization in patients at presentation with clinically isolated syndromes suggestive of multiple sclerosis.

Previous work has suggested that functional reorganization of cortical areas might have a role in limiting the clinical impact of axonal pathology in patients with established multiple sclerosis (MS). Since there is evidence for irreversible tissue damage even in patients with early MS, we assessed, using functional MRI (fMRI) and a general search method, the brain pattern of movement-associated cortical activations in patients at presentation with clinically isolated syndromes (CIS) suggestive of MS. To elucidate the role of cortical reorganization in these patients, we also investigated the extent to which the fMRI changes correlated with the extent of overall axonal injury of the brain. From 16 right-handed patients at presentation with CIS and 15 right-handed, age- and sex-matched healthy volunteers, we obtained: (1). fMRI (repetitive flexion-extension of the last four fingers of the right hand), (2). conventional MRI scans, and (3). a new, unlocalized proton MR spectroscopy ((1)HMRS) sequence to measure the concentration of N-acetylaspartate of the whole brain (WBNAA). Compared to controls, patients with CIS had more significant activations of the contralateral primary somatomotor cortex (SMC), secondary somatosensory cortex, and inferior frontal gyrus. They also had significant decreased WBNAA concentration. Relative activation of the contralateral primary SMC was strongly correlated with WBNAA levels (r = -0.78, P < 0.001). This study shows that axonal pathology and functional cortical changes over a rather distributed sensorimotor network occur in patients at presentation with CIS suggestive of MS and that these two aspects of the disease are strictly correlated. This suggests that the increased functional recruitment of the cortex in these patients might have an adaptive role in limiting the clinical impact of irreversible tissue damage.

Adaptation, Physiological↗

PubMed1988

Saccadic command signals in the superior colliculus: implications for sensorimotor transformations.

Recent findings concerning the anatomical and functional organization of the deep division of the primate superior colliculus are summarized. These data are interpreted as supporting the hypothesis that the deeper layers of the superior colliculus are organized in motor, rather than sensory, coordinates. According to this hypothesis, a dynamic remapping of sensory signals is required for interfacing with the map of motor error space contained in the superior colliculus.

Animals↗

PubMed2000

Functional MR imaging and traumatic paraplegia: preliminary report.

PURPOSE: To evaluate residual activity in the sensorimotor cortex of the lower limbs in paraplegia. METHODS: 5 patients suffering from a complete paralysis after traumatic medullar lesion (ASIA=A). Clinical evaluation of motility and sensitivity. 1. Control functional MR study of the sensorimotor cortex during simultaneous movements of hands, imaginary motor task and passive hands stimulation. 2. Concerning the lower limbs, 3 fMRI conditions: 1-patient attempts to move his toes with flexion-extension, 2-mental imagery task of the same movement, 3-peripheral passive proprio-somesthesic stimulation (squeezing) of the big toes. RESULTS: Activations were observed in the primary sensorimotor cortex (M1), premotor regions and in the supplementary motor area (SMA) during movement and mental imaginary tasks in the control study and during attempt to move and mental imaginary tasks in the study concerning the lower limbs. Passive somesthesic stimulation generated activation posterior to the central sulcus for 2 patients. CONCLUSION: Activations in the sensorimotor cortex of the lower limbs can be generated either by attempting to move or mental evocation. In spite of a clinical evaluation of complete paraplegia, fMRI can show a persistence of sensitive anatomic conduction, confirmed by Somesthesic Evoked Potentials.

Adult↗

PubMed2004

Neurometabolic functioning and neuropsychological correlates in children with ADHD-H: preliminary findings.

Proton magnetic resonance spectroscopy (MRS) and neuropsychological testing were conducted on 8 children with attention-deficit/hyperactivity disorder (ADHD-H), with no learning disabilities or comorbidities and 8 controls. Magnetic resonance spectroscopy revealed increased Glutamate/Glutamine in both frontal areas, and increased N-acetyl aspartate and Choline in the right frontal area of the ADHD-H subjects. Neuropsychological testing revealed few within- and between-group differences. Findings related to frontal lobe dysfunction in ADHD-H subjects were noted. N-acetylasparte/creatine (NAA/Creatine) in the right frontal region, and myoinositol/creatine (Myo inositol/Creatine) in the right and left frontal regions appear to be highly associated with the regulation of sensorimotor, language, and memory and learning functioning in children with ADHD-H.

Aspartic Acid↗

PubMed2003

[Rehabilitation after stroke. Imaging techniques show how the cortical reorganization is affected by training].

It is widely accepted that reorganisation of the brain occurs after a focal brain lesion such as stroke. Neuroimaging methods are used to study such reorganisation in vivo. Improvements in arm and hand motor function during recovery post-stroke have been related to reorganisation in primary and secondary sensorimotor areas by indirect measure of synaptic activity with functional MRI. Reorganisation occurs in both the affected and the unaffected hemispheres. Preliminary training studies post-stroke have shown correlations between improvements in motor function and brain activity changes. Recent research findings are reviewed herein. Further understanding of the neurobiological mechanisms of post-stroke recovery will lead to development of optimal treatment strategies during rehabilitation of stroke survivors.

Brain↗

PubMed1989

Sensorimotor disturbances in patients with lesions of the parietal cortex.

Somatosensory and motor disturbances of hand function were examined in 9 patients with parietal lobe lesions. A quantitative score was used for the elaboration of sensorimotor profiles displaying the relative degree of functional impairment. In patients with anterior parietal lobe lesions somaesthesis was clearly more disturbed than motor function. Simple aspects of somaesthesis (surface sensibility, two-point discrimination, position sense) were disturbed to about the same degree as complex somatosensory (tactile recognition) tasks. On the other hand, patients with lesions of the posterior parietal lobe showed preferential impairment of complex somatosensory and motor functions (exploratory and manipulative finger movements). In 4 patients, analysis of motor behaviour by means of an optoelectronic system showed that reaching, formation of hand aperture and target acquisition were less disturbed than manipulative behaviour. Finger movement trajectories during dynamic digital palpation of objects were grossly deranged in the patients with posterior parietal damage. The temporal characteristics of the finger movements during active touch were completely destroyed. This leads to a breakdown of the finely tuned digital scanning process required for the sequential sampling of mechanoreceptive information. Remarkably, these patients could produce the exploratory finger movements imitatively. The motor disability of the parietal hand does not lie in the loss of the kinetic memory to perform these movements, but in the loss of their evocation by appropriate sensory stimuli. This deficit is not due to a lack of somatosensory information because that may be relatively well preserved. It is concluded that the motor disturbance in posterior parietal lobe disease lies essentially in the conception and execution of the spatiotemporal movement patterns necessary to bring those receptors into action which would normally provide the information about tactile objects. This illustrates the intricate mutual dependence of the spatiotemporal organization of receptor activation by movement and of the formation of movement trajectories on the basis of adequate sensory processing.

Adult↗

PubMedDate not supplied

Motor coordination in weightless conditions revealed by long-term microgravity adaptation.

The functional approach to studying human motor systems attempts to give a better understanding of the processes behind planning movements and their coordinated performance by relying on weightlessness as a particularly enlightening experimental condition. Indeed, quantitative monitoring of sensorimotor adaptation of subjects exposed to weightlessness outlines the functional role of gravity in motor and postural organization. The recent accessibility of the MIR Space Station has allowed for the first time experimental quantitative kinematic analysis of long-term sensorimotor and postural adaptation to the weightless environment though opto-electronic techniques. In the frame of the EUROMIR'95 Mission, two protocols of voluntary posture perturbation (erect posture, EP; forward trunk bending, FTB) were carried out during four months of microgravity exposure. Results show that postural strategies for quasistatic body orientation in weightlessness are based on the alignment of geometrical body axes (head and trunk) along external references. A proper whole body positioning appears to be recovered only after months of microgravity exposure. By contrast, typically, terrestrial strategies of co-ordination between movement and posture are promptly restored and used when performing motor activities in the weightless environment. This result is explained under the assumption that there may be different sensorimotor integration processes for static and dynamic postural function and that the organisation of coordinated movement might rely stably on egocentric references and kinematics synergies for motor control.

Adaptation, Physiological↗

PubMed2005

Short-lasting impairment of temperature perception by high frequency rTMS of the sensorimotor cortex.

OBJECTIVE: Repetitive transcranial magnetic stimulation (rTMS) has become a useful tool for investigating and even modulating human brain function. RTMS of the human motor cortex can produce changes in excitability that outlast the period of stimulation. To investigate the persistent effect of high-frequency rTMS of sensorimotor cortex (SM1) on somatosensory function. METHODS: We evaluated the thermal thresholds (cold and warm sensation) in 14 normal subjects before and after a short train of 5Hz rTMS over the SM1 or occipital cortex (OC). RESULTS: Threshold for cold perception was increased immediately after rTMS of the left SM1 and no effects at all were noticed after OC stimulation. There was a slight, not significant, increase of warm threshold immediately after the rTMS of the left SM1 and no effects at all were noticed after OC stimulation. CONCLUSIONS: High frequency rTMS over primary sensorimotor cortex seems to modulate sensory function related to thermal (cold) perception. SIGNIFICANCE: The method may be useful for both the study of normal human physiology of temperature perception and for rTMS based manipulation of brain plasticity in patients with sensory disturbances.

Adult↗

PubMedDate not supplied

[The structure of dependent relationship between neurons in the sensorimotor cortex of the left and right hemisphere in rabbits during immobilizing catatonia].

Relations between activities of neurons simultaneously recorded in the left and right sensorimotor brain cortices of rabbits were analyzed in a series of experiments before the induction of the immobilization state ("animal hypnosis"), in the state of immobilization, and after its termination. The total baseline percent of significant correlations between activities of neighboring (within 50 microns) neurons in the left hemisphere was significantly lower than in the right hemisphere. This characteristic of the left hemisphere changed neither in the immobilization state nor after its termination. In the right-hemisphere cortex, the total percent of correlations between neighboring neurons significantly decreased during immobilization and returned to the baseline level after the termination of this state. In contrast, percent of correlations between the activities of remote (within 500 microns) neurons in the right-hemisphere did not change during immobilization, whereas in the left cortex it changed significantly and reached its baseline level after the normalization of rabbit's state. Further analysis showed that the revealed cortical interhemispheric asymmetry is underlain by asymmetric activities of individual neurons and small neuronal populations. Thus, for example, changes in the structure of interneuronal correlations in cortical microareas of the left and macroareas of the right hemispheres could be of different directions, whereas correlated activities in microareas of the right and macroareas of the left-hemispheres could change synergetically. In other words, asymmetry was revealed at different levels of neuronal integration (neuronal pairs, micro- or macrogroups of neurons). This finding testifies to a mosaic character of neuronal activity, which finally results in the general functional asymmetry during the "animal hypnosis". Certain changes in the structure of functional relations between neurons of the sensorimotor cortex that developed in the state of "animal hypnosis" persisted and even augmented after the termination of this state.

Animals↗

PubMed2005

Kappa opioid receptor activation disrupts prepulse inhibition of the acoustic startle in rats.

BACKGROUND: Compelling evidence indicates that kappa opioid receptor (KOR) agonists produce perceptual distortions in animals and humans, yet the mechanism of action and clinical relevance of such effects remain unclear. Since abnormalities in preattentional functions and informational processing are hypothesized to underlie psychotic disorders, the present study has been designed to assess the role of KOR on sensorimotor gating. METHODS: The effects of the selective KOR agonist U50488 were evaluated on the behavioral paradigm of prepulse inhibition (PPI) of the acoustic startle reflex (ASR). RESULTS: U50488 (1.25, 2.5, and 5 mg/kg, subcutaneous [SC]) induced a dose-dependent reduction of PPI, which was efficiently prevented by the selective KOR antagonist norbinaltorphimine (nor-BNI, 10 mg/kg, SC), as well as by the atypical antipsychotic clozapine (5, 8 mg/kg, intraperitoneal [IP]) but not by the typical antipsychotic haloperidol (.1, .5 mg/kg, IP). Conversely, nor-BNI (10 mg/kg, SC) failed to reverse the PPI disruption mediated by both apomorphine (.25 mg/kg, SC) and dizocilpine (.1 mg/kg, SC). CONCLUSIONS: Our results support a pivotal role of KOR in the regulation of preattentional functions and sensorimotor gating, pointing to these receptors as a possible neurobiological substrate especially relevant to the clusters of psychosis unresponsive to typical antipsychotics.

3,4-Dichloro-N-methyl-N-(2-(1-pyrrolidinyl)-cycloh↗