Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts:   Target Concepts:
Query: UNIPROT:Q16637 (SMA)
 8,107 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Arm displacements applied to the passive, but awake monkey are powerful stimuli for activating neurones in somatotopically appropriate areas of the precentral cortex. We have found that neurones in medial area 6 (SMA) and in lateral area 6 (PMC) may likewise be activated by such kinesthetic stimuli, at latencies which are only slightly longer than in area 4. Confirming previous findings, PMC neurones were sometimes also responsive to visual stimuli. The 'somatosensory' cells in the SMA were found in the microexcitable zone of the more posterior part of the SMA from where motor effects were elicited in arm and trunk muscles. These sensory neurones tended to be clustered together and they were only exceptionally excited antidromically by peduncular stimulation. Thus, somatosensory signals have access to both the PMC and SMA suggesting that both areas may be implicated in sensory-guided or sensory-triggered movements.
 ...
PMID:Sensory input to the motor fields of the agranular frontal cortex: a comparison of the precentral, supplementary motor and premotor cortex. 393 86

Using fMRI, we investigated the neuronal structures controlling bimanual coordination applying a visuomotor coordination task. Recent studies suggest the existence of a widespread network for the neuronal control of bimanual coordination including primary sensorimotor cortices (M1/S1), lateral and medial premotor cortices (PMC, SMA), cingulate motor area (CMA), and cerebellum (CB). In the present study, subjects performed bimanual and unimanual tasks requiring the coordination of two fingers at a time to navigate a cursor on a computer screen. Thus, in contrast to previous studies, we are using appropriate unimanual control (UNI) tasks. By using this new motor task, we identified a similar activation network for uni- and bimanual movements. Subjects exhibited bilateral activations in PMC, SMA, posterior-parietal cortex (PPC), occipital, and inferiotemporal cortex, as well as in the contralateral M1/S1 and ipsilateral CB. We did not find any additional activation when comparing bimanual with unimanual conditions. The lack of significant activation in the comparison "bimanual > unimanual" gives reason to suggest that this network is not limited to the control of bimanual motor actions, but responsible for unimanually coordinated movements as well. Interestingly, we found stronger activations for unimanual as compared to bimanual coordination. We hypothesize that task difficulty (degrees of freedom to control, e.g., number of limbs) is more important in determining which network components are activated and to what extent, compared to the factor of bimanuality. It even seemed to be less demanding for the motor system to control the cursor bimanually compared to the unimanual performance with two adjacent fingers.
 ...
PMID:Bimanual versus unimanual coordination: what makes the difference? 1521 6

In this chapter we summarize findings of our group in which we studied the neural underpinnings of finger tapping control using different methods (functional magnetic resonance imaging: fMRI, electroencephalography: EEG, transcranial magnetic stimulation: TMS, and behavioural experiments). First, we found that maximum finger tapping speed is a matter of training as shown for professional musicians. Secondly, we demonstrated that different finger tapping speeds are accompanied by different hemodynamic responses in the primary hand motor area (M1), the cerebellum and partly in pre-motor areas. With increasing tapping speed there is an increase of hemodynamic response in these areas (rate effect). Thirdly, the effect measured with fMRI is substantiated by rate effects measured by means of task-related power decreases in the upper alpha-band (10-12 Hz) over the primary motor cortex. In case of sequential finger movement learning, we observed decreases in task-related alpha-power in lateral PMC (event-related desynchronization: ERD) and simultaneous alpha-power increases in SMA (event-related synchronization: ERS) that came along with training-induced increases in movement rate. This pattern is discussed in relation to the "focal ERD/surround ERS" phenomenon suggested by Pfurtscheller and Lopes da Silva. Finally, we demonstrated that finger tapping speed was slowed by selectively inhibiting the primary hand motor area using TMS. Taken together, these studies demonstrate on the basis of converging evidence that the primary hand motor area is the basic control centre for controlling the movement parameter tapping speed. However, the neural efficiency to control finger tapping speed (as measured with hemodynamic responses or ERD/ERS patterns) is a matter of training.
 ...
PMID:Converging evidence of ERD/ERS and BOLD responses in motor control research. 1707 Dec 37

BACKGROUND AND PURPOSE The antiakinetic effect of internal Globus pallidus deep brain stimulation (Gpi-DBS) in Parkinson's disease is not clear and not either how this effect is modulated by L-dopa. METHODS Left Gpi-DBS and/or L-dopa effect was studied with auditory paced right-handed sequential movements on (15)O-butanol positron emission tomography (PET) in five patients. Rest and for conditions during movements (DBS off/L-dopa off; DBS on/L-dopa off; DBS off/L-dopa on; DBS on/L-dopa on) were compared with statistical parametric mapping. RESULTS Gpi-DBS activated the right supplementary motor area/premotor (SMA/PMC), and right insular cortex (IC), and as L-dopa decreased the left sensorimotor cortex (M1/S1) activity. L-dopa increased the left ventrolateral thalamus (VLTH), and decreased the left superior parietal cortex (PC) activity. Gpi-DBS and L-dopa interaction showed right SMA/PMC, IC, and left PC activation, decrease of left VLTH, PMC, and dorsolateral prefrontal cortex (PFC) activity. CONCLUSIONS The improvement of bradykinesia with Gpi-DBS is secondary and contributed to the regress of M1/S1-related rigidity and compensatory SMA/PMC, and IC activation. L-dopa and Gpi-DBS alone each reduces M1/S1 overactivity. Interaction ignores this effect, moreover has akinetic effect in the left VLTH, PMC, and PFC. Motor improvement possibly related to left PC and compensatory right SMA/PMC, and IC activation.
 ...
PMID:Pallidal deep brain stimulation and L-dopa effect on PET motor activation in advanced Parkinson's disease. 1902 48

Precise timing as determined by sensorimotor synchronization is crucial for a wide variety of activities. Although it is well-established that musicians show superior timing as compared to non-musicians, the neurophysiological foundations - in particular the underlying functional brain network - remain to be characterized. To this end, drummers, professional pianists and non-musicians performed an auditory synchronization task while neuromagnetic activity was measured using a 122-channel whole-head magnetoencephalography (MEG) system. The underlying functional brain network was determined using the beamformer approach Dynamic Imaging of Coherent Sources (DICS). Behaviorally, drummers performed less variably than non-musicians. Neuromagnetic analysis revealed a cerebello-thalamo-cortical network in all subjects comprising bilateral primary sensorimotor cortices (S1/M1), contralateral supplementary motor and premotor regions (SMA and PMC), thalamus, posterior parietal cortex (PPC), ipsilateral cerebellum and bilateral auditory cortices. Stronger PMC-thalamus and PPC-thalamus interactions at alpha and beta frequencies were evident in drummers as compared to non-musicians. In professional pianists stronger PMC-thalamus interaction as compared to non-musicians at beta frequency occurred. The present data suggest that precise timing is associated with increased functional interaction within a PMC-thalamus-PPC network. The PMC-thalamus connectivity at beta frequency might be related to musical expertise, whereas the PPC-thalamus interaction might have specific relevance for precise timing.
 ...
PMID:Functional network interactions during sensorimotor synchronization in musicians and non-musicians. 2036 37

Previous brain imaging studies suggest that stroke alters functional connectivity in motor execution networks. Moreover, current understanding of brain plasticity has led to new approaches in stroke rehabilitation. Recent studies showed a significant role of effective coupling of neuronal activity in the SMA (supplementary motor area) and M1 (primary motor cortex) network for motor outcome in patients after stroke. After a subcortical stroke, functional magnetic resonance imaging (fMRI) during movement reveals cortical reorganization that is associated with the recovery of function. The aim of the present study was to explore connectivity alterations within the motor-related areas combining motor fMRI with a novel MR-compatible hand-induced robotic device (MR_CHIROD) training. Patients completed training at home and underwent serial MR evaluation at baseline and after 8 weeks of training. Training at home consisted of squeezing a gel exercise ball with the paretic hand at ~75% of maximum strength for 1 h/day, 3 days/week. The fMRI analysis revealed alterations in M1, SMA, PMC (premotor cortex) and Cer (cerebellum) in both stroke patients and healthy controls after the training. Findings of the present study suggest that enhancement of SMA activity could benefit M1 dysfunction in stroke survivors. These results also indicate that connectivity alterations between motor areas might assist the counterbalance of a functionally abnormal M1 in chronic stroke survivors and possibly other patients with motor dysfunction.
 ...
PMID:fMRI as a molecular imaging procedure for the functional reorganization of motor systems in chronic stroke. 2390 Mar 49

Spinal muscular atrophy (SMA) is a neuromuscular disorder caused by the mutations in survival motor neuron 1 gene (SMN1). The molecular pathology of missense mutations in SMN1 is not thoroughly investigated so far. Therefore, we collected all missense mutations in the SMN1 protein, using all possible search terms, from three databases (PubMed, PMC and Google Scholar). All missense mutations were subjected to in silico pathogenicity, conservation, and stability analysis tools. We used statistical analysis as a QC measure for validating the specificity and accuracy of these tools. PolyPhen-2 demonstrated the highest specificity and accuracy. While PolyPhen-1 showed the highest sensitivity; overall, PolyPhen2 showed better measures in comparison to other in silico tools. Three mutations (D44V, Y272C, and Y277C) were identified as the most pathogenic and destabilizing. Further, we compared the physiochemical properties of the native and the mutant amino acids and observed loss of H-bonds and aromatic stacking upon the cysteine to tyrosine substitution, which led to the loss of aromatic rings and may reduce protein stability. The three mutations were further subjected to Molecular Dynamics Simulation (MDS) analysis using GROMACS to understand the structural changes. The Y272C and Y277C mutants exhibited maximum deviation pattern from the native protein as compared to D44V mutant. Further MDS analysis predicted changes in the stability that may have been contributed due to the loss of hydrogen bonds as observed in intramolecular hydrogen bond analysis and physiochemical analysis. A loss of function/structural impact was found to be severe in the case of Y272C and Y277C mutants in comparison to D44V mutation. Correlating the results from in silico predictions, physiochemical analysis, and MDS, we were able to observe a loss of stability in all the three mutants. This combinatorial approach could serve as a platform for variant interpretation and drug design for spinal muscular dystrophy resulting from missense mutations.
 ...
PMID:Impact of missense mutations in survival motor neuron protein (SMN1) leading to Spinal Muscular Atrophy (SMA): A computational approach. 3000 96

This study empirically investigated the effects of backpack weight on the performance of three basic short-term/working memory (STM/WM) tasks during flat-surface standing. Four levels of backpack weight were considered: 0, 15, 25 and 40% of the body weight. The three STM/WM tasks were the Corsi block, digit span and 3-back tasks, corresponding to the visuo-spatial sketchpad, phonological loop and central executive of WM, respectively. Thirty participants conducted the STM/WM tasks while standing with loaded backpack. Major study findings were that (1) increased backpack weight adversely affected the scores of all three STM/WM tasks; and, (2) the adverse effect of backpack weight was less pronounced for the phonological loop STM task than the other STM/WM tasks. The study findings may help understand and predict the impacts of body-worn equipment weight on the worker's mental task performance for various work activities requiring simultaneous performance of mental and physical tasks. Practitioner summary: The current study empirically examined the effects of backpack weight on the performance of three basic STM/WM tasks. The study findings entail that reduces the weight of body-worn equipment can positively impact the worker's mental task performance in addition to reducing the worker's bodily stresses. Abbreviations: ACC: anterior cingulate cortex; AP: anterior-posterior; BW: body weight; CoP: centre of pressure; C-S: central executive working memory task and standing; DLPFC: dorsolateral prefrontal cortex; HIP: human information processing; ML: medio-lateral; PMC: premotor cortex; P-S: phonological loop short-term memory task and standing; SMA: supplementary motor area; STM: short-term memory; VLPFC: ventrolateral prefrontal cortex; V-S: visuo-spatial short-term memory task and standing; WM: working memory.
 ...
PMID:Effects of backpack weight on the performance of basic short-term/working memory tasks during flat-surface standing. 3083 25