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Results for “sensorimotor function”

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PubMed1998

Successful resection of arteriovenous malformations in eloquent areas diagnosed by surface anatomy scanning and motor evoked potential.

Successful resection of cerebral arteriovenous malformations (AVMs) involving the sensorimotor cortex was achieved in 17 cases. The theoretical basis for performing resection of AVMs in eloquent areas is the fact that the brain in and around the nidus about 1 mm in thickness is considered not to be functioning. It is also considered that any center of important function, when an AVM is involved, shifts to the near-by cortex from the original site. Nevertheless, it is critically important to recognize the cortex functioning as sensorimotor centers before and during operation. For this purpose, we have used surface anatomy scanning (SAS) in combination with magnetic resonance angiography. SAS is found to be very useful for the recognition of the topographical relationship between the surface anatomy and AVM. During operation, the motor cortex is identified with motor evoked potential. We have found that, in some cases, the motor center has shifted to the accessory motor cortex. With these information, it is possible to start resection of the lesion from dissection of the main feeders and dissection of the nidus from a silent cortex toward the critical area. Apparent neurological improvements were achieved in 15 of 17 patients treated surgically (88%). With this result, we think that AVMs in eloquent areas can be treated successfully when the surgery is well-designed and well-oriented with the combined use of diagnostic imaging and monitoring. As for control of intraoperative bleeding, careful attention to small but important surgical techniques avoids troublesome bleeding during AVM surgery.

Arteriovenous Malformations↗

PubMed1999

L-DOPS-Accelerated recovery of locomotor function in rats subjected to sensorimotor cortex ablation injury: pharmacobehavioral studies.

Central norepinephrine (NE) has been shown to play a beneficial role in amphetamine-facilitated recovery of behavior. To give insight into understanding the mechanism, the present studies were conducted to examine (a) the effects of L-threo-3,4-dihydroxyphenylserine (L-DOPS) combined with benserazide (BSZ; a peripheral aromatic amino acid decarboxylase inhibitor) and L-3,4-dihydroxyphenylalanine (L-DOPA), precursors of NE and dopamine (DA), respectively, on the recovery from beam-walking performance deficits in rats subjected to unilateral sensorimotor cortex ablation injury, and (b) the relationships between the behavioral recovery and the frequency of postoperative training and the size of ablation injury. It was found that the combined treatments with L-DOPS and BSZ promoted the recovery of locomotor function as early as 24 hours after injury. L-DOPA alone, however, did not facilitate behavioral recovery. The results of assay for the tissue levels of NE and its major metabolite (3-methoxy-4-hydoxyphenylethylene glycol; MHPG) in the brain using high-pressure liquid chromotography showed MHPG, but not NE, significantly increased in the cerebellum and the hippocampus. The behavioral recovery was also significantly correlated with the frequency of training subsequent to injury, but inversely with the size of cortex ablation. These results suggest that NE is likely to modulate functional recovery in this rodent model.

Animals↗

PubMed2002

Somatotopic mapping of the human primary sensorimotor cortex during motor imagery and motor execution by functional magnetic resonance imaging.

The human primary sensorimotor cortex was investigated for somatotopic organization during motor imagery (IM) which was compared to motor execution (EM). Block designed BOLD (blood oxygen level dependent)-functional magnetic resonance imaging at 1.5 Tesla was applied in 14 right handed volunteers during imagined and executed tongue, finger and toe movements. BOLD-clusters were assessed for anatomically correct sensorimotor localization. Euklidian coordinates, relative signal change and correlation to the applied reference function were determined. Statistical means were calculated. IM recruited somatotopically organized primary sensorimotor representations of the precentral gyrus that reflected the homunculus and overlapped in part with EM representations. Mean BOLD-signals ranged from 1.93 to 3.18% for EM, and from 0.73 to 1.47% for IM. The results support the hypothesis that the primary sensorimotor cortex is active during IM and that IM and EM share common functional circuits.

Adult↗

PubMed2001

Recovery of motor functions following hemiparetic stroke: a clinical and magnetic resonance-morphometric study.

Predictors for the degree of clinical recovery after stroke are still poorly defined. In this study we tried to assess the predictive value of clinical data and of lesion size for motor recovery after ischemic stroke. In 52 hemiparetic patients we monitored the course of clinical recovery by a dedicated score of sensorimotor hand function after their first stroke. The course of the lesion size was measured in proton density magnetic resonance images. Three groups of patients were identified. Patients with moderate initial motor deficit recovered almost completely within 9 days (17/17, group 1). From the patients with severe initial motor deficit, about equal numbers recovered (16/35, group 2) or remained severely impaired during the entire observation period of more than 6 months (19/35, group 3). There was no correlation between changes of lesion size and motor deficit. Logistic regression of probability of good clinical outcome on initial lesion size, initial motor score and subcortical versus cortical location of lesion showed that only the initial motor score was predictive (p = 0.006). A relative improvement of the initial motor score of about 20% in the first 4 weeks after stroke appeared to be a relevant cut point for good outcome. The data indicate that patients with mild initial motor deficits recover well, whereas severely affected patients may differ in outcome. Since lesion size was not correlated with outcome the amount of spared residual function appeared as major determinant for the capacity for motor recovery.

Activities of Daily Living↗

PubMed2006

Mechanisms of orofacial pain control in the central nervous system.

Recent advances in the study of pain have revealed somatotopic- and modality-dependent processing and the integration of nociceptive signals in the brain and spinal cord. This review summarizes the uniqueness of the trigeminal sensory nucleus (TSN) in structure and function as it relates to orofacial pain control. The oral nociceptive signal is primarily processed in the rostral TSN above the obex, the nucleus principalis (Vp), and the subnuclei oralis (SpVo) and interpolaris (SpVi), while secondarily processed in the subnucleus caudalis (SpVc). In contrast, the facial nociceptive signal is primarily processed in the SpVc. The neurons projecting to the thalamus are localized mostly in the Vp, moderately in the SpVi, and modestly in the ventrolateral SpVo and the SpVc. Orofacial sensory inputs are modulated in many different ways: by interneurons in the TSN proper, through reciprocal connection between the TSN and rostral ventromedial medulla, and by the cerebral cortex. A wide variety of neuroactive substances, including substance P, gamma-aminobutyric acid, serotonin and nitric oxide (NO) could be involved in the modulatory functions of these curcuits. The earliest expression of NO synthase (NOS) in the developing rat brain is observed in a discrete neuronal population in the SpVo at embryonic day 15. NOS expression in the SpVc is late at postnatal day 10. The neurons receiving intraoral signals are intimately related with the sensorimotor reflexive function through the SpVo. In summary, a better understanding of the trigeminal sensory system--which differs from the spinal system--will help to find potential therapeutic targets and lend to developing new analgesics for orofacial-specific pain with high efficacy and fewer side effects.

Animals↗

PubMed2005

Accessory stimulation in the time course of visuomotor information processing: stimulus intensity effects on reaction time and response force.

A series of three visual choice-reaction time experiments were performed to systematically investigate the effects of accessory auditory stimulation on response time (RT) and response force (RF). In Experiment 1, the effect of accessory auditory stimulation on early visual information processing was investigated. Experiments 2 and 3 were designed to examine the effects of accessory intensity on RT and RF across the entire time course of sensorimotor processing. Accessory stimulation accelerated response speed only when presented within 100 ms after onset of the visual response signal. An enhancing effect of accessory stimulation on RF, however, was found as late as 220 ms after onset of the response signal. These findings support the notion that response speed and response dynamics represent functionally independent sensorimotor phenomena.

Female↗

PubMed2005

Selective inhibition of inducible nitric oxide synthase reduces neurological deficit but not cerebral edema following traumatic brain injury.

The role of inducible nitric oxide synthase (iNOS) in cerebral edema and neurological deficit following traumatic brain injury (TBI) is not yet clear-cut. Therefore, the aim of this study was to investigate the effect of three different iNOS inhibitors on cerebral edema and functional outcome after TBI. First, the time courses of blood--brain barrier (BBB) breakdown, cerebral edema, and neurological deficit were studied in a rat model of fluid percussion-induced TBI. The permeability of BBB to Evans blue was increased from 1 h to 24 h after TBI. Consistently, a significant increase in brain water content (BWC) was observed at 6 and 24 h post-TBI. A deficit in sensorimotor neurological functions was also observed from 6 h to 7 days with a maximum 24 h after TBI. Second, a single dose of aminoguanidine (AG; 100 mg/kg, i.p.), L-N-iminoethyl-lysine (L-NIL; 20 mg/kg, i.p.), or N-[3-(aminomethyl)benzyl]acetamide (1400W; 20 mg/kg, s.c.) was administered at 6 h post-TBI. Treatment with AG reduced by 71% the increase in BWC evaluated at 24 h, while L-NIL and 1400W had no effect. In contrast, the three iNOS inhibitors reduced the neurological deficit from 30% to 40%. Third, 1400W (20 mg/kg, s.c.) was administered at 5 min, 8 and 16 h post-TBI. Although this treatment paradigm had no effect on cerebral edema evaluated at 24 h, it significantly reduced the neurological deficit and iNOS activity. In conclusion, iNOS contributes to post-TBI neurological deficit but not to cerebral edema. The beneficial effect of iNOS inhibitors is not due to their anti-edematous effect, and the reduction of cerebral edema by AG is unlikely related to iNOS inhibition. The 6 h therapeutic window of iNOS inhibitors could allow their use in the treatment of functional deficit at the acute phase of TBI.

Amidines↗

PubMed1995

Dynamic neuroimaging of brain function.

To fully characterize the brain processes underlying sensorimotor and cognitive function, the spatial distribution of active regions, their interconnected regions must be measured. We describe methods for imaging brain sources from surface-recorded EEG and magnetoencephalographic data, called electromagnetic source imaging (EMSI). EMSI provides brain source locations within the common framework of magnetic resonance (MR) images of brain anatomy. This allows integration of data from other functional brain imaging methods, like positron emission tomography and functional MR imaging, which can improve the accuracy of EMSI localization. EMSI also provides submillisecond temporal resolution of the dynamic processes within brain systems. Examples are given of applications to visual perceptual and attentional studies.

Arousal↗

PubMed1996

Synaptic plasticity of the interpositorubral pathway functionally related to forelimb flexion movements.

1. Some connections from the afferents to the magnocellular red nucleus (RNm), like the corticorubral synapses, have plastic properties that are thought to contribute to long-term changes such as functional readaptation, motor learning, and the establishment of conditioned responses. Because previous studies have focused on corticorubral synaptic reorganization after these events, we attempted to investigate cerebellorubral connections in intact adult cats during associative conditioning by pairing electrical stimulation of interpositus nucleus [the conditional stimulus (CS)] with electrical simulation of the forelimb [the unconditional stimulus (UCS)]. A large increase in the amplitude of the forelimb flexion (conditioned response) induced by the CS was observed after several days of paired CS-UCS presentations. 2. For this purpose, both behavioral and electrophysiological methods were used to correlate synaptic plasticity with changes in the motor responses. The somatotopically organized sensorimotor network functionally related to the control of the elbow joint movements was studied in awake adult cats. This circuit was defined on the basis of sites at which elbow flexions could be evoked both as a CS and a UCS. The CS was applied in the cerebellar interpositus nucleus (IN) site and the UCS was given to the skin on the dorsum of the distal part of the forepaw. Daily classical conditioning consisted of repetitive pairings of CS and UCS with an interstimulus interval (ISI) of 100 ms. 3. The transmission efficacy resulting from the conditioning was tested in various targets of the cerebellar efferent pathway, including the RNm. Electrophysiological responses evoked in these relay structures by the CS and the forelimb angular deviations were simultaneously recorded throughout each daily conditioning session. The surface areas of the rubral responses to CS and the percentage response rate, the angular deviation (amplitude), and the latency of the motor responses were systematically measured throughout the conditioning procedure. Test sessions were also performed before and after each period of conditioning. Quantification and statistical analysis were carried out to determine whether changes observed in interpositorubral synaptic transmission and in the motor responses evoked by the CS were correlated. 4. Daily repetition of paired CS and UCS according to a predefined and fixed temporal schedule led to an increase in the response rate and amplitude of the forelimb flexions. A procedure with repeated presentation of CS preceded by UCS was used to produce extinction of the enhanced motor responses. The associative nature of these changes was confirmed by the fact that the CS given alone for 11 days in a control condition failed to produce any modification of the motor response. 5. The changes in the flexion movements were accompanied by a nearly parallel increase of the amplitude of the "postsynaptic field potentials" evoked in the RNm by the CS (IN stimulation). Changes in the transmission efficacy of the interpositorubral synapses stayed stable even after several days of interruption and remained constant up the extinction period. Changes affecting both the motor and the central responses were significantly correlated, suggesting that modifications in the interpositorubral transmission efficacy might be one of the plastic correlates of forelimb flexion conditioning. 6. Examination of the neuronal excitability within either the IN or the RNm or in the spinal cord failed to show any evidence of facilitation suggesting that the increases in the postsynaptic rubral field potential were attributable to a plasticity of the interpositorubral connections. The long-lasting duration of the increase of cerebellorubral synaptic transmission suggests that structural changes were induced by conditioning in the intact animal. (ABSTRACT TRUNCATED)

Animals↗

PubMed2001

Beyond parallel fiber LTD: the diversity of synaptic and non-synaptic plasticity in the cerebellum.

In recent years, it has become clear that motor learning, as revealed by associative eyelid conditioning and adaptation of the vestibulo-ocular reflex, contributes to the well-established cerebellar functions of sensorimotor integration and control. Long-term depression of the parallel fiber-Purkinje cell synapse (which is often called 'cerebellar LTD') is a cellular phenomenon that has been suggested to underlie these forms of learning. However, it is clear that parallel fiber LTD, by itself, cannot account for all the properties of cerebellar motor learning. Here we review recent electrophysiological experiments that have described a rich variety of use-dependent plasticity in cerebellum, including long-term potentiation (LTP) and LTD of excitatory and inhibitory synapses, and persistent modulation of intrinsic neuronal excitability. Finally, using associative eyelid conditioning as an example, we propose some ideas about how these cellular phenomena might function and interact to endow the cerebellar circuit with particular computational and mnemonic properties.

Animals↗

PubMed1989

Unit activity in monkey parietal cortex related to haptic perception and temporary memory.

The neural responses of 456 single units were recorded in parietal cortex of behaving monkeys during a haptic delayed matching-to-sample task. (1) In areas 2 and 5 together, 22% of the neurons were activated by the auditory cue that signalled the beginning of a trial. Virtually all of these cells were also activated during the arm movements required by the task. These neurons, showing both auditory-related and movement-related responses, may function in sensorimotor integration. (2) Responses related to arm projection frequently began before movement onset, sometimes as much as 320 ms before. Such "premovement" responses were approximately equally common, and showed the same latency distribution, in areas 2, 5a, and 5b. (3) There was a topographic rostral-to-caudal gradient of decreasing neural responsiveness to the animal's manipulation of the cue (sample) objects. Eleven percent of manipulation-activated cells responded preferentially to one of the sample objects. (4) Many cells showed sustained (greater than 3 s) activation during the delay period (the time between handling of the sample object and palpation of the choice objects), even though at that time the monkey was sitting quietly and without stimulation. (5) Cells with sustained activation throughout most or all of the 18-s delay period were rare in all areas tested except area 5a. These cells, especially those that were preferentially activated depending on which sample object was palpated, may function in the temporary retention of haptic attributes. (6) The population of cells activated during sample manipulation was largely distinct from the population of cells showing sustained activation during the delay period. These two cell populations may represent different but complementary aspects of haptic perception. (7) The most common response during the delay period was sustained inhibition. This may be an expression of a nonspecific mechanism for decreasing background noise and enhancing neural responses to an anticipated perceptual event. (8) Relatively little evidence was found to support a functional distinction between the neural response properties of areas 2 and 5a. This suggests that area 2 may be at a higher level in the somatosensory hierarchy of the posterior parietal cortex than usually considered.

Acoustic Stimulation↗

PubMedDate not supplied

Changes in power and coherence of brain activity in human sensorimotor cortex during performance of visuomotor tasks.

Electrocorticograms (ECoG) were recorded using subdural grid electrodes in forearm sensorimotor cortex of six human subjects. The subjects performed three visuomotor tasks, tracking a moving visual target with a joystick-controlled cursor; threading pieces of tubing; and pinching the fingers sequentially against the thumb. Control conditions were resting and active wrist extension. ECoGs were recorded at 14 sites in hand- and arm-sensorimotor area, functionally identified with electrical stimulation. For each behavior we computed spectral power of ECoG in each site and coherence in all pair-wise sites. In three out of six subjects, gamma-oscillations were observed when the subjects started the tasks. All subjects showed widespread power decrease in the range of 11-20 Hz and power increase in the 31-60 Hz ranges during performance of the visuomotor tasks. The changes in gamma-range power were more vigorous during the tracking and threading tasks compared with the wrist extension. Coherence analysis also showed similar task-related changes in coherence estimates. In contrast to the power changes, coherence estimates increased not only in gamma-range but also at lower frequencies during the manipulative visuomotor tasks. Paired sites with significant increases in coherence estimates were located within and between sensory and motor areas. These results support the hypothesis that coherent cortical activity may play a role in sensorimotor integration or attention.

Epilepsy↗

PubMed2000

Functional recovery of paraplegic rats and motor axon regeneration in their spinal cords by olfactory ensheathing glia.

Axonal regeneration in the lesioned mammalian central nervous system is abortive, and this causes permanent disabilities in individuals with spinal cord injuries. In adult rats, olfactory ensheathing glia (OEG) transplants successfully led to functional and structural recovery after complete spinal cord transection. From 3 to 7 months post surgery, all OEG-transplanted animals recovered locomotor functions and sensorimotor reflexes. They presented voluntary hindlimb movements, they supported their body weight, and their hindlimbs responded to light skin contact and proprioceptive stimuli. In addition, relevant motor axons (corticospinal, raphespinal, and coeruleospinal) regenerated for long distances within caudal cord stumps. Therefore, OEG transplantation provides a useful repair strategy in adult mammals with traumatic spinal cord injuries. Our results with these cells could lead to new therapies for the treatment of spinal cord lesions in humans.

Animals↗

PubMed1998

Cognitive performance during a simulated climb of Mount Everest: implications for brain function and central adaptive processes under chronic hypoxic stress.

High altitude is characterized by hypoxic environmental conditions and is well known to induce both physiological and psychological disturbances. In the present study, called ”Everest-Comex 97”, the authors investigated the effects of high altitude on the psychosensorimotor and reasoning processes of eight climbers participating in a simulated climb from sea level to 8,848 m over a 31-day period of confinement in a decompression chamber. Tests of visual reaction time, psychomotor ability, and number ordination were used. The climbers’ data were compared with data from a similar laboratory study at sea level in control subjects. Continued testing of the control subjects at sea level clearly led to learning effects and improvement of performance in psychomotor ability and number ordination. In the climbers, similar learning effects occurred up to an altitude of 5,500–6,500 m. With further increases in altitude, the climbers’ psychomotor performance and mental efficiency deteriorated progressively, leading to significant differences in psychomotor ability and mental efficiency between control subjects and climbers (9 and 13% respectively at 8,000 m and 17.5 and 16.5% respectively at 8,848 m). Three days (72 h) after the climbers had returned to sea level, their mental and psychomotor performances were still significantly lower than those of control subjects (by approximately 10%). In contrast, visual reaction time showed no significant changes in either climbers or control subjects. It is suggested that chronic hypoxic stress could alter selectively mental learning processes, i.e. explicit, rather than implicit (stimulus-response learning processes) memory and cortico-limbic rather than basal ganglia-sensorimotor system function.

Adaptation, Physiological↗

PubMed1992

Attention, play, and social behavior in ADHD preschoolers.

We investigated attention, play and nonplay behavior in preschool children with attention deficit hyperactivity disorder (ADHD) and a matched control group of non-ADHD children. Forty 4- to 5-year-old children (20 ADHD and 20 matched control) participated. Across a 6-week-period, children's social and play interactions as well as nonplay behaviors were videotaped in the classroom. Videotape recordings were analyzed for the level of attention, cognitive play, and social participation. In addition, children's level of attention and cooperative behavior were observed during two group activities. Findings indicated that ADHD, relative to non-ADHD, children engaged in less overall play and greater functional or sensorimotor play. ADHD children also engaged in more transitional behavior, were less competent with peers, and were less attentive and cooperative during group activities.

Attention↗

PubMedDate not supplied

Effects of electrical stimulation of the caudate nucleus on functionally identified neurons of the sensorimotor cortex in the cat brain.

Paired stimulation was used to study the effects of the caudate nucleus on the specific and nonspecific responses of projection neurons of the sensorimotor cortex in the cat brain. Caudal influences on the neurons being studied had insignificant effects on specific peripheral evoked responses. Nonspecific peripherally evoked activity was in most cases inhibited by caudate spike activity, and the pattern of evoked activity underwent significant modulation in conditions of a constant type of peripherally evoked response. It is suggested that the caudate nucleus acts as a filter of proprioceptive information in the cortex or in pathways to the cortex: specific corticopetal information is passed unchanged, while nonspecific signals are predominantly inhibited or significantly modulated.

Animals↗

PubMed2006

Phasic increases in cortical beta activity are associated with alterations in sensory processing in the human.

Oscillatory activity in the beta (beta)-frequency band (13-35 Hz) can be recorded over the sensorimotor cortex in humans. It is coherent with electromyographic activity (EMG) during tonic contraction, but whether the cortical beta-oscillations are primarily motor or sensorimotor in function remains unclear. We tested the hypothesis that cortical beta-activity is associated with an up-regulation of sensory inputs that may be relevant to the organization of the motor response. We recorded cortical somatosensory potentials (SEPs) elicited by electrical stimuli to the median nerve at the wrist triggered by increases of electroencephalographic (EEG) beta-activity in the contralateral fronto-central EEG and compared these to SEPs presented at random intervals. The involvement of motor cortex in the triggering EEG activity was confirmed by a simultaneous elevation of cortico-spinal synchrony in the beta-band. The negative cortical evoked potential peaking at 20 ms and the positive evoked potential peaking at 30 ms after median nerve shocks were increased in size when elicited after phasic increases in beta-activity. The functional coupling of sensory and motor cortices in the beta-band was confirmed in recordings of electrocorticographic activity in two patients with chronic pain syndromes, suggesting a means by which beta-activity may simultaneously influence cortical sensory processing, motor output and promote sensory-motor interaction.

Adult↗

PubMed1981

Effect of oxotremorine on local cerebral glucose utilization in motor system regions of the rat brain.

The [14C]2-deoxy-D-glucose technique was used to test the effects of central muscarinic stimulation on local cerebral glucose utilization (LCGU) in rats. Systemic administration of the muscarinic agonist oxotremorine (OXO, 0.7 mg/kg, ip) increased LCGU in brain regions involved in motor function: the sensorimotor cortex; the extrapyramidal motor system, including the striatum, globus pallidus, red nucleus, substantia nigra, subthalamus and ventral nucleus of the thalamus; the cerebellar vermis, fastigial nucleus and nucleus interpositus; and the vestibular nucleus. No effects were observed in the fibers of the pyramidal tract, internal capsule, cerebellar white matter and the dentate nucleus. Increases were not affected by methylatropine (1 mg/kg sc), but were completely antagonized by scopolamine (2.5 mg/kg, ip). The anatomic distribution and magnitude of the LCGU response to OXO were not simply correlated with the reported densities of muscarinic receptors.

Animals↗