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PubMed2004

ELITE-S2: the multifactorial movement analysis facility for the International Space Station.

Experimental observations of adaptation processes of the motor control system to altered gravity conditions can provide useful elements to the investigations on the mechanisms underlying motor control of human subject. The microgravity environment obtained on orbital flights represents a unique experimental condition for the monitoring of motor adaptation. The research in motor control exploits the changes caused by microgravity on the overall sensorimotor process, due to the impairment of the sensory systems whose function depends upon the presence of the gravity vector. Motor control in microgravity has been investigated during parabolic flights and short-term space missions, in particular for analysis of movement-posture co-ordination when equilibrium is no longer a constraint. Analysis of long-term adaptation would also be very interesting, calling for long-term body motion observations during the process of complete motor adaptation to the weightlessness environment. ELITE-S2 is an innovative facility for quantitative human movement analysis in weightless conditions onboard the International Space Station (ISS). ELITE-S2 is being developed by the Italian Space Agency, ASI is to be delivering the flight models to NASA to be included in an expressed rack in US Lab Module in February 2004. First mission is currently planned for summer 2004 (increment 10 ULF 2 ISS).

Adaptation, Physiological↗

PubMed1984

Fentanyl-induced seizures activate subcortical brain metabolism.

Neurophysiologic studies have demonstrated epileptoid activity during high-dose narcotic anesthesia. The authors utilized the 14C-2-deoxyglucose method to evaluate the local cerebral glucose metabolism (l-CMRg) during high-dose fentanyl-induced epileptoid discharges as evaluated by electroencephalography (EEG) in ventilated rats. Fentanyl was administered intravenously at two dose levels (200 micrograms X kg-1, n = 5; and 400 micrograms X kg-1, n = 8). Seven unanesthetized animals served as controls. During fentanyl administration, the EEG was characterized by the appearance of isolated high voltage (greater than 100 microV) spike and polyspike and wave complexes at a frequency of one every 1-4 s, superimposed on a baseline of reduced frequency and voltage. Isolated ictal discharges (spike or sharp waves at a frequency of 12-20/s) rarely were superimposed upon the spike and polyspike activity. As a general trend, fentanyl administration induced a significant (P less than 0.05) decrease of the l-CMRg in the majority of the 37 brain structures surveyed. A clear relationship between l-CMRg and epileptoid activity appeared when the anatomic areas were grouped into functional systems. Cerebral metabolism was globally decreased in the visual and sensorimotor systems (53-78%), in the white matter structures (76-78%), and reticular formation (59-69%) with both fentanyl treatments. The largest deviation from this trend appeared in the limbic system. Here with both treatments, the l-CMRg in the claustrum, septal nucleus, amygdala, and ventral areas of CA1 and CA3 of the hippocampus remained at control values.(ABSTRACT TRUNCATED AT 250 WORDS)

Action Potentials↗

PubMed1998

How do we select perceptions and actions? Human brain imaging studies.

The selective nature of human perception and action implies a modulatory interaction between sensorimotor processes and attentional processes. This paper explores the use of functional imaging in humans to explore the mechanisms of perceptual selection and the fate of irrelevant stimuli that are not selected. Experiments with positron emission tomography show that two qualitatively different patterns of modulation of cerebral blood flow can be observed in experiments where non-spatial visual attention and auditory attention are manipulated. These patterns of modulation of cerebral blood flow modulation can be described as gain control and bias signal mechanisms. In visual and auditory cortex, the dominant change in cerebral blood flow associated with attention to either modality is related to a bias signal. The relation of these patterns of modulation to attentional effects that have been observed in single neurons is discussed. The existence of mechanisms for selective perception raises the more general question of whether irrelevant ignored stimuli are nevertheless perceived. Lavie's theory of attention proposes that the degree to which ignored stimuli are processed varies depending on the perceptual load of the current task. Evidence from behavioural and functional magnetic resonance imaging studies of ignored visual motion processing is presented in support of this proposal.

Attention↗

PubMed2004

Basic advances and new avenues in therapy of spinal cord injury.

The prospects for successful clinical trials of neuroprotective and neurorestorative interventions for patients with acute and chronic myelopathies depend on preclinical animal models of injury and repair that reflect the human condition. Remarkable progress continues in the attempt to promote connections between the brain and the sensory and motor neurons below a spinal cord lesion. Recent experiments demonstrate the potential for biological therapies to regenerate or remyelinate axons and to incorporate new neural cells into the milieu of a traumatic spinal cord injury. The computational flexibility and plasticity of the sensorimotor systems of the brain, spinal cord, and motor unit make functional use of new circuitry feasible in patients. To incorporate residual and new pathways, neural repair strategies must be coupled to rehabilitation therapies that drive activity-dependent plasticity for walking, for reaching and grasping, and for bowel and bladder control. Prevention of pain and dysautonomia are also clinical targets. Research aims to define the temporal windows of opportunity for interventions, test the safety and efficacy of delivery systems of agents and cells, and provide a better understanding of the cascades of gene expression and cell interactions both acutely and chronically after injury. These bench-to-bedside studies are defining the neurobiology of spinal cord injury rehabilitation.

Animals↗

PubMed1998

Spinal and pudendal nerve modulation of human corticoanal motor pathways.

We investigated the effects of lumbosacral and pudendal nerve stimulation on the corticofugal pathways to the human external anal sphincter. In 11 healthy subjects, anal sphincter electromyographic responses, evoked to transcranial magnetic stimulation of the motor cortex, were recorded 5-500 ms after lumbosacral root or pudendal nerve stimulation. Lumbosacral and pudendal nerve stimulation alone evoked responses with amplitudes of 293 +/- 73 and 401 +/- 153 microV and latencies of 3.2 +/- 0.2 and 2.2 +/- 0.2 ms, respectively. Cortical stimulation also evoked responses with amplitudes of 351 +/- 104 microV and latencies of 20.9 +/- 1.1 ms. When lumbosacral or pudendal nerve stimulation preceded cortical stimulation, the cortically evoked responses were facilitated (P < 0.01), with the effect appearing greatest at 5-20 ms after both lumbosacral and pudendal excitation and at 50-100 ms after lumbosacral excitation alone. Our results demonstrate that cortical pathways to the external anal sphincter are facilitated by prior lumbosacral and pudendal nerve stimulation, indicating that sensorimotor interactions are important in the central neural control of sphincter function.

Adult↗

PubMed1987

Parkinson's disease: sensory and motor problems in arms and hands.

Fifteen undemented patients with Parkinson's disease (PD) and 15 age-matched controls were given a battery of tests to assess sensorimotor integration in the arms. PD patients made more errors (p less than 0.01) than controls, particularly in tests of proprioception. Age was not related to errors. Compared with controls, two-point discrimination thresholds were significantly higher (p less than 0.02) on the index finger of PD patients, but not on the forearm. Results confirm the sensorimotor deficits found earlier in an orofacial study, and imply that PD involves a generalized dysfunction of sensorimotor integration and proprioception, probably a result of impaired basal ganglia function in processing and integrating sensory input to organize and guide movement.

Aged↗

PubMed1987

Topographical analysis of glucose metabolism, as measured with positron emission tomography, in dementia of the Alzheimer type: use of linear histograms.

A linear histogram method was employed to analyze brain images of glucose uptake obtained by positron emission tomography in patients with dementia of the Alzheimer type and in control subjects. A line was drawn by computer which traversed the image of a brain slice taken at 70 mm above and parallel to the inferior orbitomeatal line, and rCMRglc was plotted as a function of distance along this line in 3 brain areas: frontal, sensorimotor and parietal. Peak rCMRglc values were significantly decreased in moderately-to-severely demented patients relative to healthy age-matched controls, but not in mildly demented patients. Furthermore, both the mildly and the more severely demented patients differed from controls in having reduced ratios of parietal association to sensorimotor peak rCMRglc. The variances of right-left metabolic asymmetries did not differ significantly between Alzheimer patients and controls. Severity of dementia, as evaluated by scores on the Mini-Mental State Examination, correlated with ratios of peak rCMRglc in frontal and parietal cortex to that in sensorimotor cortex. These results indicate that measures of focal peak rCMRglc do not discriminate between mildly demented patients and controls, whereas focal ratios of rCMRglc, where the denominator corresponds to rCMRglc from a relatively spared region, provide useful measures of metabolic dysfunction in the early stages of Alzheimer's disease.

Aged↗

PubMed2002

Differential involvement of parietal and precentral regions in movement preparation and motor intention.

Flexible goal-oriented behavior relies on spatial coordinate transformations and motor control mechanisms, but also on the capability to take advantage of contextual information for steering the sensorimotor machinery. Although accurate performance of a sensorimotor task requires parietal and frontal regions, their differential contribution and functional relationship with other associative regions remains obscure. We have used event-related functional magnetic resonance imaging to measure human cerebral activity associated with motor cognitive processes in the context of delayed performance of an associative visuomotor task. Movement instruction (specified by visual cues) and motor performance (specified by an auditory cue) were separated by a variable delay period. By manipulating the predictive value of the instruction cue, we distinguished delay-related activity influenced by response probabilities (motor preparation and motor inhibition) from delay-related activity unaffected by the likelihood of providing a motor response (motor intention). We found delay-related activity distributed across a cerebral network involving not only frontal circuitry, but also extrastriate and mediotemporal regions. Areas showing motor intentions and preparatory responses were spatially intermingled. Posterior parietal cortex deviated from this pattern, showing delay-related activity regardless of movement probability, but no specific preparatory responses. These results suggest that posterior parietal cortex and dorsal precentral cortex play different strategic roles in handling associative visuomotor problems. While parietal regions cover a range of potential responses defined by the task setting, precentral regions focus on a likely movement. Temporo-prefrontal regions might incorporate contextual information in the visuomotor process by defining potential and probable responses on the basis of the task contingencies.

Acoustic Stimulation↗

PubMed2004

Cortical reorganization allows for motor recovery after crossed cerebrocerebellar atrophy.

The authors report the case of a 33-year-old woman who exhibited, at the age of 17, a left-sided hemiplegia, which was followed by good motor recovery, though with a permanent deficit in fine finger movements. She had a widespread loss of neural tissue in the right hemisphere (crossed cerebrocerebellar atrophy), including (1) marked atrophy and thinning of the precentral and postcentral gyri; (2) widespread deep white matter destruction, including the corticospinal tract; and (3) crossed cerebellar atrophy. Except over the supplementary motor area (SMA), transcranial magnetic stimulation did not elicit motor evoked potentials in the affected hand. Nevertheless, during opening and closing of the affected hand, functional magnetic resonance imaging showed an activation of the lesioned primary sensorimotor cortex (SMC), as well as of the intact SMA and the parietal areas, but not of the ipsilateral motor areas. The authors speculate that recovery was achieved by a motor command generated in the SMC and the parietal cortex, passing through corticospinal axons originating in the SMA.

Adult↗

PubMed1990

Local as well as remote functional and metabolic changes after focal ischemia in cats.

Behavior and limb placing ability were analyzed acutely and subacutely (up to 21 days) following unilateral occlusion of the middle cerebral artery (MCA) in cats. Immediately following occlusion, all tested cats started to display a sequence of different behaviors, characteristic for 1) an ipsilateral inhibition of dopaminergic activity in the caudate nucleus (CN); 2) an inhibition of GABAergic activity in the reticular substantia nigra (SNR); 3) a stimulation of GABA receptors in the deeper layers of the colliculus superior (CSDL) (starting-time of these phases: about 4, 12 and 25 min, respectively). The latter behavior was also present subacutely. In addition, unilateral orofacial dyskinetic movements were observed acutely as well as subacutely. Contralateral limb placing was deficient in all cats 60 min postocclusion; it was at least partly restored subacutely. Twenty-one days after the occlusion, [14C]-2-D-deoxyglucose uptake was relatively reduced in the ipsilateral CN (especially in its posterior part), the ipsilateral SNR and the ipsilateral CSDL. The anterior CN appeared to be less affected than the posterior CN. Metabolism was relatively reduced in the sensorimotor cortex only in part of the tested cats. The data show that unilateral MCA occlusion produces consistent functional changes in all structures studied apart from the sensorimotor cortex, viz. the CN, the SNR and the CSDL.

Animals↗

PubMed2001

Evaluating eye-body coordination during unrestrained functional activity in older persons.

BACKGROUND: Traditional paradigms for the study of ocular-motor control restrain subject motion and have not adequately quantified the sensorimotor strategies used by older persons to control gaze while performing activities of daily living. The purpose of our study was to describe eye-head-trunk coordination during a functional activity in freely moving community-dwelling older persons. METHODS: Thirty-five community-dwelling older persons (age range 71-92 years) participated in this study. Surface electro-oculography was used with an electromagnetic tracking device to measure vertical eye movement and linear and angular head position while each subject performed a stand-from-chair task. RESULTS: Standing from a chair involved low-frequency head motion (median z = 0.25 Hz; median pitch = 0.32 Hz). The distribution of phase for eyes versus vertical body motion were skewed toward head-trunk leading, suggesting that eye motion follows vertical body motion. Vertical gaze, however, was in phase with and moved in the same direction as head pitch. CONCLUSIONS: Gaze (eye position in space) was an active, integrated component of the standing motion. The results imply that both the oculomotor system and the head motor system in older persons are coordinated to direct gaze and, when necessary, work to suppress the vestibuloocular reflex. The interaction of eye-head-trunk motion provides a basis for understanding how a breakdown in the gaze control mechanisms in older persons might contribute to the risk of falling and fall-related injuries.

Aged↗

PubMed1992

Occupational adaptation: toward a holistic approach for contemporary practice, Part 1.

A theoretical perspective designed for clinical application and based on fundamental occupational therapy principles is offered. This perspective, the occupational adaptation frame of reference, is presented as an articulation of (a) a normal developmental process leading to competence in occupational functioning; (b) the process through which the benefits of occupational therapy occur; and (c) a perspective that promotes holistic practice. The person is viewed as operating occupationally through an idiosyncratic configuration of sensorimotor, cognitive, and psychosocial systems, all of which are inevitably involved in each occupational response. This occupational functioning is described as occurring through interaction of the person with a work, play and leisure, or selfcare context that has distinctive physical, social, and cultural properties (i.e., the occupational environment). Occupational adaptation is a perspective that can influence practice, education, and research.

Adaptation, Psychological↗

PubMed2000

A novel approach to stroke rehabilitation: robot-aided sensorimotor stimulation.

OBJECTIVE: In patients with stroke, the authors tested whether additional sensorimotor training of the paralyzed or paretic upper limb delivered by a robotic device enhanced motor outcome. METHODS: Fifty-six patients with stroke and hemiparesis or hemiplegia received standard poststroke multidisciplinary rehabilitation, and were randomly assigned either to receive robotic training (at least 25 hours) or exposure to the robotic device without training. Outcomes were assessed by the same masked raters, before treatment began and at the end of treatment, with the upper extremity component of the Fugl-Meyer Motor Assessment, the Motor Status score, the Motor Power score, and Functional Independence Measurement. RESULT: The robot treatment and control group had comparable clinical characteristics, lesion size, and pretreatment impairment scores. By the end of treatment, the robot-trained group demonstrated improvement in motor outcome for the trained shoulder and elbow (Motor Power score, p < 0.001; Motor Status score, p < 0. 01) that did not generalize to untrained wrist and hand. The robot-treated group also demonstrated significantly improved functional outcome (Functional Independence Measurement-Motor, p < 0. 01). CONCLUSION: Robot-delivered quantitative and reproducible sensorimotor training enhanced the motor performance of the exercised shoulder and elbow. The robot-treated group also demonstrated improved functional outcome. When added to standard multidisciplinary rehabilitation, robotics provides novel therapeutic strategies that focus on impairment reduction and improved motor performance.

Adult↗

PubMed2002

Bimanual coordination and interhemispheric interaction.

Bimanual coordination of skilled finger movements requires intense functional coupling of the motor areas of both cerebral hemispheres. This coupling can be measured non-invasively in humans with task-related coherence analysis of multi-channel surface electroencephalography. Since bimanual coordination is a high-level capability that virtually always requires training, this review is focused on changes of interhemispheric coupling associated with different stages of bimanual learning. Evidence is provided that the interaction between hemispheres is of particular importance in the early phase of command integration during acquisition of a novel bimanual task. It is proposed that the dynamic changes in interhemispheric interaction reflect the establishment of efficient bimanual 'motor routines'. The effects of callosal damage on bimanual coordination and learning are reviewed as well as functional imaging studies related to bimanual movement. There is evidence for an extended cortical network involved in bimanual motor activities which comprises the bilateral primary sensorimotor cortex (SM1), supplementary motor area, cingulate motor area, dorsal premotor cortex and posterior parietal cortex. Current concepts about the functions of these structures in bimanual motor behavior are reviewed.

Adult↗

PubMed1999

[Transmitter dysfunction in patients with schizophrenia. Significance for cognitive functioning and treatment].

The great diversity of schizophrenic symptoms rules out one simple etiological explanation. However,impairment of information processing, including disruption of sensorimotor gating, is a consistent finding in schizophrenic patients. Dysfunction in sensorimotor gating is believed to be the result of different developmentally or environmentally caused disturbances involving the neural trajectories involved in information processing. Psychopathology and cognition will depend on the primary involvement of distinct parts of these circuits and on secondarily derived time-dependent disturbances of transmitter function. This review is focused on clinical and preclinical evidence for the impact of interactions between glutamatergic, dopaminergic, serotonergic and noradrenergic brain systems on cognitive performance. The hypothetical consequences of transmitter dysfunction for progressive development of impairment in sensorimotor gating are illustrated. Finally, the broad receptor profile of second generation antipsychotics is analysed to explain the clinical improvement in neurocognition that may occur during treatment with such drugs.

Antipsychotic Agents↗

PubMed1999

Somesthetic function of supplementary motor area during voluntary movements.

To clarify the somesthetic functions of the supplementary motor area (SMA), we recorded the cortical potentials following the median nerve electric stimulation directly from the SMA and investigated the modulation caused by voluntary movements in two patients with intractable SMA seizures. The evoked potentials over the SMA consisted of positive (61.5ms) and negative (100.0 ms) peaks, which were enlarged by voluntary movements of the stimulated hand. The present finding is in strong contrast with the attenuation (gating) of the response at the primary sensorimotor area (SM1) and suggests that the voluntary movements differently modulate the somatosensory functions of SMA and SM1.

Adult↗

PubMed2002

An expanded cortical representation for hand movement after peripheral motor denervation.

OBJECTIVES: Functional reorganisation of the motor or sensory cortex has been demonstrated in animals after section of mixed peripheral nerves. Here functional changes in the motor cortex specifically after peripheral motor denervation in humans are investigated. METHODS: Functional MRI (fMRI) was used to study brain activation during a finger flexion-extension task in patients with a late onset, acquired pure motor neuropathy (n=6), contrasting results with those from patients with pure sensory neuropathies (n=4) or healthy controls (n=7). RESULTS: Increases in the extent of activation in the motor cortex both ipsilateral and contralateral to the hand moved were found in the patients with motor neuropathy. The neuroanatomical localisation of the mixed contralateral sensorimotor cortex activation volume was more posterior for the patients with motor neuropathy than for the healthy controls (mean difference, 12 mm, p<0.05). The pure sensory neuropathy group by contrast showed no change in the extent of activation relative to healthy controls and a trend for more anterior primary sensorimotor cortex activation (p<0.06). To test whether the increased activation volumes found in patients with motor neuropathy were a result simply of factors such as increased effort with movement rather than the motor denervation, patients with hand weakness from inclusion body myositis (n=4) were studied while making similar hand movements. No differences in either the numbers of significantly activated voxels or in their localisation were found relative to healthy controls (n=10). CONCLUSIONS: These results provide a novel demonstration that peripheral denervation (as distinguished from factors related to weakness) leads to functional reorganisation of the sensorimotor cortex in the adult brain. This suggests that adaptive responses to motor denervation involve the central as well as the peripheral nervous system.

Adult↗

PubMed2006

When the brain loses its self: prefrontal inactivation during sensorimotor processing.

A common theme in theories of subjective awareness poses a self-related "observer" function, or a homunculus, as a critical element without which awareness can not emerge. Here, we examined this question using fMRI. In our study, we compared brain activity patterns produced by a demanding sensory categorization paradigm to those engaged during self-reflective introspection, using similar sensory stimuli. Our results show a complete segregation between the two patterns of activity. Furthermore, regions that showed enhanced activity during introspection underwent a robust inhibition during the demanding perceptual task. The results support the notion that self-related processes are not necessarily engaged during sensory perception and can be actually suppressed.

Acoustic Stimulation↗