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Results for “sensorimotor function”

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PubMed2006

Minocycline attenuates hypoxia-ischemia-induced neurological dysfunction and brain injury in the juvenile rat.

To investigate whether minocycline provides long-lasting protection against neonatal hypoxia-ischemia-induced brain injury and neurobehavioral deficits, minocycline was administered intraperitoneally in postnatal day 4 Sprague-Dawley rats subjected to bilateral carotid artery occlusion followed by exposure to hypoxia (8% oxygen for 15 min). Brain injury and myelination were examined on postnatal day 21 (P21) and tests for neurobehavioral toxicity were performed from P3 to P21. Hypoxic-ischemic insults resulted in severe white matter injury, enlarged ventricles, deficits in the hippocampus, reduction in numbers of mature oligodendrocytes and tyrosine hydroxylase-positive neurons, damage to axons and dendrites, and impaired myelination, as indicated by the decrease in myelin basic protein immunostaining in the P21 rat brain. Hypoxic-ischemic insult also significantly affected physical development (body weight gain and eye opening) and neurobehavioral performance, including sensorimotor and locomotor function, anxiety and cognitive ability in the P21 rat. Treatments with minocycline significantly attenuated the hypoxia-ischemia-induced brain injury and improved neurobehavioral performance. The protection of minocycline was associated with its ability to reduce microglial activation. The present results show that minocycline has long-lasting protective effects in the neonatal rat brain in terms of both hypoxia-ischemia-induced brain injury and the associated neurological dysfunction.

Age Factors↗

PubMed2006

Cortico-cerebellar coherence during a precision grip task in the monkey.

We studied the synchronization of single units in macaque deep cerebellar nuclei (DCN) with local field potentials (LFPs) in primary motor cortex (M1) bilaterally during performance of a precision grip task. Analysis was restricted to periods of steady holding, during which M1 oscillations are known to be strongest. Significant coherence between DCN units and M1 LFP oscillations bilaterally was seen at approximately 10-40 Hz (contralateral M1: 25/87 units; ipsilateral: 9/87 units). Averaged coherence between DCN units and contralateral M1 LFP showed a prominent approximately 17-Hz coherence peak and an average phase of approximately -pi/2 radians, implying that the DCN units fired around the time of maximal depolarization of M1 cells. The lack of a time delay between DCN and M1 activity suggests that the cerebellum and cortex may form a pair of phase coupled oscillators. Although coherence values were low (mean peak coherence, 0.018), we used a computational model to show that this probably resulted from the nonlinearity of spike generating mechanisms within the DCN. DCN unit discharge and DCN LFPs also showed significant coherence at approximately 10-40 Hz, with similarly low magnitude (mean peak coherence, 0.012). The average coherence phase was -2.5 radians for the 6- to 14-Hz range and -1.1 radians for the 17- to 41-Hz range, suggesting different frequency-specific underlying mechanisms. Finally, 4/40 pairs of simultaneously recorded DCN units showed a significant cross-correlation peak, and 16/40 pairs showed significant unit-unit coherence. The extensive oscillatory synchronization observed between cerebellum and motor cortex may have functional importance in sensorimotor processing.

Action Potentials↗

PubMed2001

Malignant rolandic-sylvian epilepsy in children: diagnosis, treatment, and outcomes.

OBJECTIVE: To describe the diagnosis, treatment, and outcomes in children with malignant rolandic-sylvian epilepsy (MRSE), defined as a form of epilepsy characterized by sensorimotor seizures, medical refractoriness, normal MRI, frontocentrotemporal EEG spikes, rolandic-sylvian spike sources on magnetoencephalography (MEG), and cognitive problems. METHODS: A retrospective chart analysis of seven patients who had shown these characteristics and undergone extensive diagnostic testing, including MEG and intracranial video-EEG was performed. RESULTS: Interictal scalp EEG spikes were seen over the frontocentrotemporal regions bilaterally (6) and unilaterally (1). MEG showed spike sources in the perisylvian region in two patients (both bilateral) and in the perirolandic fissure in five (two bilateral). Three patients required bilateral subdural strips to lateralize seizures before electrocorticography. Final electrocorticograms showed an ictal onset zone around the rolandic (four cases) and rolandic-sylvian regions (three cases). Six patients showed neuropsychological deficits. After cortical excision and multiple subpial transection, three were seizure free and four had seizures rarely (30 months' mean follow-up). No child had a permanent deficit in sensorimotor or cognitive functions, although two showed exacerbation of preexisting attentional deficits. Tissue analysis showed definite evidence of neuronal migration disorders (3) and gliosis (2). CONCLUSIONS: MEG was helpful for localizing both malignant rolandic-sylvian neuronal activities and functional cortex. Successive neuropsychological assessments are necessary to detect cognitive deterioration and indicate remedial programming. If, after careful observation over at least 5 years, surgery is considered to control refractory seizures, intracranial video-EEG is needed to localize the epileptogenic zone.

Adolescent↗

PubMed1989

Cortical sensorimotor integration: a hypothesis.

A hypothesis is proposed that neocortex is constructed from structural neuronal modules (columns and rings). Each module is considered as unit for cortical sensorimotor integration. Complex functional relationships between modules can be arranged by intracortical inhibition participation. High pronounced neocortical plasticity ensures the process of continuous formation of various dominating operative constellations comprising stable neuronal modules whose component structure and distributive characteristic are determined by the dominant motivation and the central motor program.

Cerebral Cortex↗

PubMed1993

Inverse relationship between the size of pattern reversal visual evoked potentials from the left brain and the degree of left-hand preference in left-handed normal subjects: importance of the left brain.

The relation of the degree of left-hand preference to pattern reversal visual evoked potentials (VEPs) from right and left brain was studied in male left-handers. The degree of the left-hand preference was assessed by the Waterloo Handedness Questionnaire. Visual stimuli consisted of black and white checkerboard patterns generated on a TV screen. VEPs were simultaneously recorded from occipital leads of the right and left hemispheres. The degree of left-hand preference was found to be inversely and significantly related to size of VEPs only from left brain, not from right brain. That is, the conduction time, amplitude, duration, and area of N1-P1 waves linearly decreased as the degree of left-hand preference increased. These results were in accord with the testosterone hypothesis of cerebral lateralization, but not compatible with the right shift theory of handedness. It was concluded that visuomotor control by the left brain would be the main biological correlate of left-hand preference with regard to sensorimotor and cognitive functions.

Adolescent↗

PubMed2005

Cervicogenic headache: a review of diagnostic and treatment strategies.

Cervicogenic headache is a syndrome characterized by chronic hemicranial pain that is referred to the head from either bony structures or soft tissues of the neck. The trigeminocervical nucleus is a region of the upper cervical spinal cord where sensory nerve fibers in the descending tract of the trigeminal nerve (trigeminal nucleus caudalis) are believed to interact with sensory fibers from the upper cervical roots. This functional convergence of upper cervical and trigeminal sensory pathways allows the bidirectional referral of painful sensations between the neck and trigeminal sensory receptive fields of the face and head. A functional convergence of sensorimotor fibers in the spinal accessory nerve (CN XI) and upper cervical nerve roots ultimately converge with the descending tract of the trigeminal nerve and might also be responsible for the referral of cervical pain to the head. Diagnostic criteria have been established for cervicogenic headache, but its presenting characteristics occasionally may be difficult to distinguish from primary headache disorders such as migraine, tension-type headache, or hemicrania continua. This article reviews the clinical presentation of cervicogenic headache, proposed diagnostic criteria, pathophysiologic mechanisms, and methods of diagnostic evaluation. Guidelines for developing a successful multidisciplinary pain management program using medication, physical therapy, osteopathic manipulative treatment, other nonpharmacologic modes of treatment, and anesthetic interventions are presented.

Analgesics↗

PubMed2006

Gene expression profiling in the hippocampus of rats subjected to focal cerebral ischemia and enriched environment housing.

PURPOSE: Enriched environment housing enhances brain plasticity and improves recovery of impaired sensorimotor and cognitive functions of rats subjected to transient middle cerebral artery occlusion (MCAO). The present study applied microarray technique to investigate the molecular basis through which enriched environment might improve spatial learning in MCAO rats. METHODS: MCAO rats were housed in enriched environment or in standard single cages, and sham-operated rats were housed in standard single cages. Spatial learning was assessed using the Morris water-maze on postoperative days 22 to 24. Total RNA from the ipsilateral hippocampus was extracted for microarray analysis after the follow-up period. RESULTS: Water-maze performance on postoperative days 22 to 24 showed that rats subjected to transient MCAO were impaired in the hippocampus-dependent Morris water-maze test. Enriched environment housing reversed the spatial learning impairment on postoperative day 23. Gene expression in the hippocampus was not affected by MCAO or following enriched environment housing. CONCLUSION: Spatial learning impairment following transient MCAO in rats and cognitive improvement following housing in enriched environment is not related to % related to extrahippocampal brain regions rather than altered hippocampal gene expression.

Animals↗

PubMed1989

[Morphologic and quantum characteristics of sensomotor neuron synapses in isolated rat spinal cord].

The structural-functional relationships of sensorimotor connections were studied in isolated lumbar cord segments of 7-14 day-old rats. Individual motoneurons were found to have synaptic contacts only with a single collateral of the afferent fibre. The number of contacting boutons gained 10. The n parameter of the binomial model was established to reflect the number of contacts at the sensorimotor connection. The analysis of sensorimotor EPSPs by convolution with two binomial distributions has shown that sites of the transmitter release were different in their probability (efficiency) of response to nerve impulse.

Animals↗

PubMed2003

Imaging human mesolimbic dopamine transmission with positron emission tomography. Part II: amphetamine-induced dopamine release in the functional subdivisions of the striatum.

The human striatum is functionally organized into limbic, associative, and sensorimotor subdivisions, which process information related to emotional, cognitive, and motor function. Dopamine projections ascending from the midbrain provide important modulatory input to these striatal subregions. The aim of this study was to compare activation of dopamine D2 receptors after amphetamine administration in the functional subdivisions of the human striatum. D2 receptor availability (V3") was measured with positron emission tomography and [11C]raclopride in 14 healthy volunteers under control conditions and after the intravenous administration of amphetamine (0.3 mg/kg). For each condition, [11C]raclopride was administered as a priming bolus followed by constant infusion, and measurements of D2 receptor availability were obtained under sustained binding equilibrium conditions. Amphetamine induced a significantly larger reduction in D2 receptor availability (DeltaV3") in limbic (ventral striatum, -15.3 +/- 11.8%) and sensorimotor (postcommissural putamen, -16.1 +/- 9.6%) regions compared with associative regions (caudate and precommissural putamen, -8.1 +/- 7.2%). Results of this region-of-interest analysis were confirmed by a voxel-based analysis. Correction for the partial volume effect showed even greater differences in DeltaV3" between limbic (-17.8 +/- 13.8%), sensorimotor (-16.6 +/- 9.9%), and associative regions (-7.5 +/- 7.5%). The increase in euphoria reported by subjects after amphetamine was associated with larger DeltaV3" in the limbic and sensorimotor regions, but not in the associative regions. These results show significant differences in the dopamine response to amphetamine between the functional subdivisions of the human striatum. The mechanisms potentially accounting for these regional differences in amphetamine-induced dopamine release within the striatum remain to be elucidated, but may be related to the asymmetrical feed-forward influences mediating the integration of limbic, cognitive, and sensorimotor striatal function via dopamine cell territories in the ventral midbrain.

Affect↗

PubMed1996

Functional disorders of the small intestine.

Sensorimotor disturbances of the small bowel are implicated increasingly in the pathogenesis of the functional gastrointestinal disorders. In irritable bowel syndrome (IBS), alterations in both interdigestive and postprandial motility have been described, for example, the specific peristaltic contractions that are normally present in the ileum appear to occur more frequently and to be associated with abdominal pain in some patients. The latter finding is likely to be related to the selective mechanoreceptor hypersensitivity that has been demonstrated in the small bowel of IBS patients. The level of this afferent dysfunction has, however, not been established; some evidence suggests that personality traits, which predispose to a more severe and prolonged sympathetic response to stressors, may hasten the development of such sensorimotor disturbances.

Colonic Diseases, Functional↗

PubMed2003

Lesions of the Basal forebrain cholinergic system impair task acquisition and abolish cortical plasticity associated with motor skill learning.

The contribution of the basal forebrain cholinergic system in mediating plasticity of cortical sensorimotor representations was examined in the context of normal learning. The effects of specific basal forebrain cholinergic lesions upon cortical reorganization associated with learning a skilled motor task were investigated, addressing, for the first time, the functional consequences of blocking cortical map plasticity. Results demonstrate that disrupting basal forebrain cholinergic function disrupts cortical map reorganization and impairs motor learning. Cholinergic lesions do not impair associative fear learning or overall sensorimotor function. These results support the hypothesis that the basal forebrain cholinergic system may be specifically implicated in forms of learning requiring plasticity of cortical representations.

Acetylcholine↗

PubMed1998

Functional image-guided surgery of intracranial tumors located in or near the sensorimotor cortex.

OBJECT: The purpose of this study was to evaluate the efficacy of noninvasive preoperative functional imaging data used in an interactive fashion in the operating room. The authors describe a method of registering preoperative functional magnetic resonance (fMR) imaging localization of sensorimotor cortex with a frameless stereotactic surgical navigation device. METHODS: The day before surgery, patients underwent blood oxygen level-dependent fMR imaging while performing a finger-tapping motor paradigm. Immediately afterward an anatomical stereotactic MR image was acquired. Raw fMR imaging data were analyzed offline at a separate workstation, and the resulting functional maps were registered to a high-resolution anatomical scan. The fused functional-anatomical images were then downloaded onto a surgical navigation computer via an ethernet connection. At surgery, the brain was exposed in the standard fashion, and the sensorimotor cortex was identified by direct cortical stimulation, the use of somatosensory evoked potentials, or both. This localization was then compared with that predicted by the registered fMR study. Thirteen procedures were performed in 12 patients. The mean registration error was 2.2 mm. The predicted location of motor and/or sensory cortex matched that found on intraoperative mapping in all 12 patients tested. Maximal tumor resection was accomplished in each case and no new permanent neurological deficits resulted. CONCLUSIONS: Compared with conventional brain mapping techniques, fMR image-guided surgery may allow for smaller brain exposures, localization of the language cortex with the patient under general anesthesia, and the mapping of multiple functional sites. The scanning equipment used in this method may be more readily available than for other functional imaging techniques such as positron emission tomography or magnetoencephalography.

Adult↗

PubMed1997

[Tumor surgery of the speech cortex in local anesthesia. Neuropsychological and neurophysiological monitoring during operations in the dominant hemisphere].

We report on 30 cases where we have used cortical stimulation mapping to define the areas representing sensorimotor, language and speech functions under local anesthesia to facilitate resection of space-occupying lesions near these areas. Under the simplistic concept that Broca's area lies in the frontal operculum (inferior frontal gyrus) and that Wernicke's area is located in the posterior perisylvian area (superior temporal, angular and supramarginal gyri), we found language and speech function to be represented outside these areas in up to 4 stimulation sites of 15 patients. The results of cortical stimulation mapping were therefore essential to decide on the optimal access route to the lesions that were located subcortically and on the optimal resection plane in gliomas. After the limits of these areas and of the lesions had been established with stimulation mapping and with intrasurgical microscopic smear preparations, respectively, lesions were safely removed under continuous monitoring of sensorimotor, language and speech function. Immediately after surgery we encountered language and speech deficits in 9 patients (30%), which resolved completely in 5 and incompletely in 4 instances. Thus, language functions were normal in 26 patients (87%) at the end of the follow-up period. It is concluded that use of this technique allows safe and extensive resection of lesions that would otherwise have been considered hazardous to remove or inexcisable.

Adolescent↗

PubMed2003

Should the injured and intact hemispheres be treated differently during the early phases of physical restorative therapy in experimental stroke or parkinsonism?

Over a century ago the intact cortex was proposed to contribute to recovery from unilateral brain injury, but its possible role in functional outcome has become more appreciated in recent years as a result of anatomic, metabolic and behavioral studies. Although use of the contralesional limb is naturally impaired after sensorimotor cortex injury, neural and astrocytic events in the intact hemisphere may give rise to, and may be influenced by, an enhanced ability to compensate for lost motor function. The debate is still open as to whether the neural changes are generally compensatory in nature, with activity in the homotopic cortex leading to greater capability in the nonimpaired limb, or whether they are actually a matter of reorganization in the homotopic cortex leading to connections to denervated targets in the opposite hemisphere, thus allowing the homotopic cortex to control motor programs there. Although both phenomena may occur to some degree, there is mounting evidence in support of the former view. Careful behavioral techniques have been developed that can expose compensatory tricks, and the time course of these behaviors correlates well with anatomic data. Moreover, if the intact cortex sustains a second lesion after recovery from the first, forelimb sensorimotor function specific to the first-impaired side of the body is not worsened. Partial denervation of callosal fibers coming from the injured hemisphere, plus preferential use of the good forelimb caused by a cortical injury, may increase trophic factors in the intact hemisphere. These and related events seem to provide a growth-favorable environment there that permits motor learning in the intact forelimb at a level of skill exceeding that which a normal animal can attain in the same period of time. There are anecdotal cases in human neurologic patients that are consistent with these findings. For example, a colleague of the authors who sustained a unilateral infarction that rendered his dominant right hand severely impaired noticed that soon after the stroke he was able to use his left hand for writing and computers as well as he had ever used his right hand. Cross-midline placing tests also indicate that the structural events observed in the intact cortex may potentiate projections to the damaged hemisphere. These changes may help restore the capacity of tactile information projecting to the intact hemisphere to control limb placing in the impaired forelimb. Neural events in the injured hemisphere can be affected by behavior differently than the neural events in the intact hemisphere. Different therapeutic strategies might well be used on opposing limbs at different times after unilateral sensorimotor cortex injury to optimize recovery (and, indeed, to avoid exaggerating the insult). Finally, the details of reorganization in both hemispheres differ greatly depending on the type of brain injury sustained (eg, in stroke versus Parkinson's disease), suggesting that an approach that considers the role of both hemispheres is likely to be beneficial in research on a broad variety of brain pathologies.

Animals↗

PubMed1981

Organization of corticospinal neurons in the monkey.

The retrograde axonal transport method has been employed to identify the cell bodies of cortical neurons projecting directly to the spinal cord in the monkey. The investigation has focused on aspects of the laminar, columnar, and somatotopic organization of corticospinal neurons within each of the cytoarchitectural and functional subdivisions of the sensorimotor cortex. The principle findings of these experiments are that: i) cortical regions containing cell bodies of corticospinal neurons are the first motor cortex (area 4), the first somatic sensory cortex (areas 3a, 3b, 1, and 2), and part of the immediately adjacent posterior parietal cortex (area 5), the second somatic sensory cortex, the supplementary motor cortex (the medial aspect of area 6), and the medial part of the posterior parietal cortex in a region termed the supplementary sensory area; ii) corticospinal neurons display a somatotopic organization within each of these functional subdivisions of the sensorimotor cortex; iii) all corticospinal neurons arise from layer V of the cortex; and iv) corticospinal neurons within the first motor and first somatic sensory cortex often occur in clusters, perhaps reflecting a columnar organization in the sensorimotor cortex. These findings demonstrate the origins of the corticospinal system to be more extensive than previously recognized and show that a number of common features characterize the organization of corticospinal neurons in all cortical areas. Across cortical subdivisions, however, major differences exist in the extent of spinal segmental representations, in the manner in which corticospinal neurons occur in groups, and in the numerical density and sizes of corticospinal neurons. These aspects of the organization of the corticospinal system presumably reflect specialization of the different cortical areas in spinal cord sensory and motor control.

Animals↗

PubMed1994

EEG rhythms of the sensorimotor region during hand movements.

The aim of this study was to determine what motor behaviors or conditions were associated with an increased occurrence of beta activity in the sensorimotor region of human subjects. EEG recordings were obtained from 8 electrodes symmetrically arranged around C3, with 3 cm interelectrode spacing. The electrode montage allowed calculation of the Laplacian operator at two positions, C3r and C3c, overlying the hand area of the motor cortex and of the somatosensory cortex, respectively. A variety of tasks involving right-hand movements of different levels of complexity, attention and preparation were performed. The corresponding EEG power spectra were subsequently computed for frequencies between 7 and 50 Hz. Repetitive hand movements alone (either drawing circles or writing one's signature) did not result in significantly increased beta activity in the sensorimotor region compared to relaxed conditions. However, both motor preparations and focused attention, whether movements were performed or not, were associated with an increase of high frequency beta activity (30-50 Hz) in the sensorimotor region. Therefore, the facilitatory effect of attention and motor preparation and not the functional activation of the sensorimotor cortex by hand movements was associated with an increase in synchronized fast beta activity.

Adolescent↗

PubMedDate not supplied

Human hand and lip sensorimotor cortex as studied on electrocorticography.

We investigated functional topography of human hand and lip sensorimotor cortex using somatosensory evoked potentials (SEPs) from chronically indwelling subdural grid electrodes (ECoG) in 3 epilepsy patients during stimulation of median nerve, ulnar nerve, and lower lip. We used dipole modeling to determine the cortical location of each peripheral sensory field. The cortical locations were in the postcentral gyrus and showed a clear somatotopic organization from medial superior to lateral inferior in the order: ulnar nerve, median nerve, and lip. The source localizations agreed with the results of cortical stimulations and anatomical features on intraoperative photographs. The cortical regions of median and ulnar nerve each could be modeled by sequential tangential and radial dipoles. The cortical region of lip was different and could be explained mostly by tangential dipoles. These findings suggest a difference in the cortical organization of human lip and hand sensory cortex and are consistent with a larger representation of lip in the posterior bank of central fissure in area 3b than on the gyral surface in area 1, similar to findings in macaque. Further studies in a larger population of patients with ECoG or normal subjects with scalp-EEG and MEG are warranted to test this hypothesis.

Brain Mapping↗

PubMed1989

Functional organization of interzonal transcallosal connections in the sensorimotor cortex.

Transcallosal evoked potentials (EP) in cat sensorimotor cortex, arising in response to stimulation of the visual or auditory zone of an opposite hemisphere, were investigated. Interzonal transcallosal responses (TCR) were shown to be present along the entire surface of the sensorimotor cortex. Videomotor EPs were mainly in the form of responses with initial negativity. The latent periods of audiomotor EPs were longer than those of videomotor EPs. Negative-positive videomotor responses had greater amplitudes as compared to the amplitudes of synphasic or audiomotor EPs. Responses with initial positivity, on the contrary, had greater amplitudes during Field AI stimulation than they had during the stimulation of Field 19. Interzonal transcallosal responses in MI zone were characterized by interhemispheric asymmetry. In a per-pair comparison of the amplitudes of response components, individual asymmetry was revealed for videomotor EPs. Audiomotor responses in the majority of investigated animals were of greater magnitude in the left hemisphere. The left hemisphere dominance for audiomotor EPs was mainly observed in females, whereas in males the asymmetry revealed was individual. It is suggested that the peculiarities of the interhemispheric asymmetry of interzonal audio- and videomotor functional transcallosal connections are determined by specificity of the intrazonal asymmetry of transcallosal streams in projection and association cortical areas.

Animals↗