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Motor Activation (motor + activation)

Distribution by Scientific Domains

Medical Sciences	80%

Selected Abstracts

Intracortical inhibition and facilitation upon awakening from different sleep stages: a transcranial magnetic stimulation study

EUROPEAN JOURNAL OF NEUROSCIENCE, Issue 11 2004
Luigi De Gennaro
Abstract Intracortical facilitation and inhibition, as assessed by the paired-pulse transcranial magnetic stimulation technique with a subthreshold conditioning pulse followed by a suprathreshold test pulse, was studied upon awakening from REM and slow-wave sleep (SWS). Ten normal subjects were studied for four consecutive nights. Intracortical facilitation and inhibition were assessed upon awakening from SWS and REM sleep, and during a presleep baseline. Independently of sleep stage at awakening, intracortical inhibition was found at 1,3-ms interstimulus intervals and facilitation at 7,15-ms interstimulus intervals. Motor thresholds were higher in SWS awakenings, with no differences between REM awakenings and wakefulness, while motor evoked potential amplitude to unconditioned stimuli decreased upon REM awakening as compared to the other conditions. REM sleep awakenings showed a significant increase of intracortical facilitation at 10 and 15 ms, while intracortical inhibition was not affected by sleep stage at awakening. While the dissociation between motor thresholds and motor evoked potential amplitudes could be explained by the different excitability of the corticospinal system during SWS and REM sleep, the heightened cortical facilitation upon awakening from REM sleep points to a cortical motor activation during this stage. [source]

A Method for the Automated Assessment of Temporal Characteristics of Functional Hemispheric Lateralization by Transcranial Doppler Sonography

JOURNAL OF NEUROIMAGING, Issue 3 2004
M. Deppe
ABSTRACT Background and Purpose. Transcranial Doppler sonography (TCD) can guide and complement investigations based on functional magnetic resonance and positron emission tomography imaging by providing continuous information on cerebral perfusion changes correlated to cerebral activation. So far, however, the role of functional TCD has been limited by a lack of sensitivity.Methods. Here, the authors present an outline of a method that increases the potential of TCD to detect perfusion changes within a vascular territory. Sensitivity on the order of 1% can be achieved by transformation of Doppler envelope curves, which accounts for systemic quasi-periodic and irregular spontaneous blood flow modulations and artificial disturbances related to the recording. A statistical technique is introduced that allows the automatic detection of time periods of significant hemispheric lateralization in evoked flow studies. Furthermore, an index of laterality is defined quantifying the extent of hemispheric dominance during stimulus processing.Results and Discussion. The analysis technique described in this article has been successfully employed in recent examinations on vision, motor activation, language, language recovery, and other cognitive tasks. Conclusion. The novel functional TCD technique permits valid and reproducible assessments of the temporal characteristics of functional hemispheric lateralization. [source]

Measuring the effects of indomethacin on changes in cerebral oxidative metabolism and cerebral blood flow during sensorimotor activation,

MAGNETIC RESONANCE IN MEDICINE, Issue 1 2003
K.S. St. Lawrence
The work presented here uses combined blood oxygenation level-dependent (BOLD) and arterial spin tagging (AST) approaches to study the effect of indomethacin on cerebral blood flow (CBF) and oxygen consumption (CMRO2) increases during motor activation. While indomethacin reduced the CBF increase during activation, it did not significantly affect the CMRO2 increase during activation. The ratio of the activation-induced CBF increase in the presence and absence of indomethacin was 0.54 ± 0.08 (±SEM, n = 8, P < 0.001), while the ratio of the CMRO2 increase in the presence and absence of the drug was 1.02 ± 0.08 (±SEM, N = 8, ns). Potential difficulties in estimating CMRO2 changes from combined BOLD/AST data are discussed. Magn Reson Med 50:99,106, 2003. Published 2003 Wiley-Liss, Inc. [source]

Rhythmic cortical myoclonus in Niemann,Pick disease type C

MOVEMENT DISORDERS, Issue 9 2006
Laura Canafoglia MD
Abstract We here describe a patient with late-infantile Niemann,Pick disease type C (NPC) presenting with worsening myoclonus, seizures, cerebellar symptoms, mild mental impairment, and gaze palsy. Electroencephalographic (EEG) ,polymyographic examinations showed abnormally high and diffuse background alpha-activity, enhanced by intermittent photic stimulation. The electromyographic (EMG) showed quasirhythmic myoclonic jerks during motor activation. EEG,EMG frequency analysis (better than jerk-locked back-averaging) demonstrated the cortical origin of the myoclonus. Our observations indicate that cortical myoclonus may occur as the main symptom of NPC. © 2006 Movement Disorder Society [source]

Reperfusion normalizes motor activation patterns in large-vessel disease,

ANNALS OF NEUROLOGY, Issue 2 2009
Mohamad Chmayssani MD
Objective Hemodynamic impairment in one hemisphere has been shown to trigger ipsilateral motor activation in the opposite hemisphere on functional imaging. We hypothesized that reversing the hypoperfusion would normalize the motor activation pattern. Methods We studied four patients with high-grade stenosis and impaired vasomotor reactivity (VMR) but no stroke. Functional magnetic resonance imaging motor activation pattern before and after VMR normalization was compared with seven healthy control subjects scanned at an interval of 3 months using voxel-wise statistical parametric maps and region of interest analysis. Subjects performed a repetitive hand closure task in synchrony with 1Hz metronome tone. We used repeated-measures analysis of variance to compute the interaction between group (patients/control subjects) and time by obtaining the average blood oxygen level dependent signal of three motor regions of interest in each hemisphere. Results Two patients normalized their VMR after spontaneous resolution of dissection, and two after revascularization procedures. Both voxel-wise statistical maps and region of interest analysis showed that VMR normalization was associated in each case with a reduction in the atypical activation in the hemisphere opposite to the previously hypoperfused hemisphere (p < 0.001). Interpretation In the presence of a physiological stressor such as hypoperfusion, the brain is capable of dynamic functional reorganization to the opposite hemisphere that is reversible when normal blood flow is restored. These findings are important to our understanding of the clinical consequences of hemodynamic failure and the role of the ipsilateral hemisphere in maintaining normal neurological function. Ann Neurol 2009;65:203,208 [source]