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Primary Sensorimotor Cortex (primary + sensorimotor_cortex)

Distribution by Scientific Domains

Medical Sciences	50%

Selected Abstracts

Levodopa affects functional brain networks in parkinsonian resting tremor,

MOVEMENT DISORDERS, Issue 1 2009
Bettina Pollok PhD
Abstract Resting tremor in idiopathic Parkinson's disease (PD) is associated with an oscillatory network comprising cortical as well as subcortical brain areas. To shed light on the effect of levodopa on these network interactions, we investigated 10 patients with tremor-dominant PD and reanalyzed data in 11 healthy volunteers mimicking PD resting tremor. To this end, we recorded surface electromyograms of forearm muscles and neuromagnetic activity using a 122-channel whole-head magnetometer (MEG). Measurements were performed after overnight withdrawal of levodopa (OFF) and 30 min after oral application of fast-acting levodopa (ON). During OFF, patients showed the typical antagonistic resting tremor. Using the analysis tool Dynamic Imaging of Coherent Sources, we identified the oscillatory network associated with tremor comprising contralateral primary sensorimotor cortex (S1/M1), supplementary motor area (SMA), contralateral premotor cortex (PMC), thalamus, secondary somatosensory cortex (S2), posterior parietal cortex (PPC), and ipsilateral cerebellum oscillating at 8 to 10 Hz. After intake of levodopa, we found a significant decrease of cerebro-cerebral coupling between thalamus and motor cortical areas. Similarly, in healthy controls mimicking resting tremor, we found a significant decrease of functional interaction within a thalamus,premotor,motor network during rest. However, in patients with PD, decrease of functional interaction between thalamus and PMC was significantly stronger when compared with healthy controls. These data support the hypothesis that (1) in patients with PD the basal ganglia and motor cortical structures become more closely entrained and (2) levodopa is associated with normalization of the functional interaction between thalamus and motor cortical areas. © 2008 Movement Disorder Society [source]

Functional changes of the cortical motor system in hereditary spastic paraparesis

ACTA NEUROLOGICA SCANDINAVICA, Issue 3 2009
B. Koritnik
Background,,, Hereditary spastic paraparesis (HSP) is a heterogeneous group of disorders characterized by progressive bilateral lower limb spasticity. Functional imaging studies in patients with corticospinal tract involvement have shown reorganization of motor circuitry. Our study investigates functional changes in sensorimotor brain areas in patients with HSP. Methods,,, Twelve subjects with HSP and 12 healthy subjects were studied. Functional magnetic resonance imaging (fMRI) was used to measure brain activation during right-hand finger tapping. Image analysis was performed using general linear model and regions of interest (ROI)-based approach. Weighted laterality indices (wLI) and anterior/posterior indicies (wAI and wPI) were calculated for predefined ROIs. Results and discussion,,, Comparing patients and controls at the same finger-tapping rate (1.8 Hz), there was increased fMRI activation in patients' bilateral posterior parietal cortex and left primary sensorimotor cortex. No differences were found when comparing patients and controls at 80% of their individual maximum tapping rates. wLI of the primary sensorimotor cortex was significantly lower in patients. Subjects with HSP also showed a relative increase in the activation of the posterior parietal and premotor areas compared with that of the primary sensorimotor cortex. Our findings demonstrate an altered pattern of cortical activation in subjects with HSP during motor task. The increased activation probably reflects reorganization of the cortical motor system. [source]

Sensorimotor network rewiring in mild cognitive impairment and Alzheimer's disease

HUMAN BRAIN MAPPING, Issue 4 2010
Federica Agosta
Abstract This study aimed at elucidating whether (a) brain areas associated with motor function show a change in functional magnetic resonance imaging (fMRI) signal in amnestic mild cognitive impairment (aMCI) and Alzheimer's disease (AD), (b) such change is linear over the course of the disease, and (c) fMRI changes in aMCI and AD are driven by hippocampal atrophy, or, conversely, reflect a nonspecific neuronal network rewiring generically associated to brain tissue damage. FMRI during the performance of a simple motor task with the dominant right-hand, and structural MRI (i.e., dual-echo, 3D T1-weighted, and diffusion tensor [DT] MRI sequences) were acquired from 10 AD patients, 15 aMCI patients, and 11 healthy controls. During the simple-motor task, aMCI patients had decreased recruitment of the left (L) inferior frontal gyrus compared to controls, while they showed increased recruitment of L postcentral gyrus and head of L caudate nucleus, and decreased activation of the cingulum compared with AD patients. Effective connectivity was altered between primary sensorimotor cortices (SMC) in aMCI patients vs. controls, and between L SMC, head of L caudate nucleus, and cingulum in AD vs. aMCI patients. Altered fMRI activations and connections were correlated with the hippocampal atrophy in aMCI and with the overall GM microstructural damage in AD. Motor-associated functional cortical changes in aMCI and AD mirror fMRI changes of the cognitive network, suggesting the occurrence of a widespread brain rewiring with increasing structural damage rather than a specific response of cognitive network. Hum Brain Mapp, 2010. © 2009 Wiley-Liss, Inc. [source]

Resting state sensorimotor functional connectivity in multiple sclerosis inversely correlates with transcallosal motor pathway transverse diffusivity

HUMAN BRAIN MAPPING, Issue 7 2008
Mark J. Lowe
Abstract Recent studies indicate that functional connectivity using low-frequency BOLD fluctuations (LFBFs) is reduced between the bilateral primary sensorimotor regions in multiple sclerosis. In addition, it has been shown that pathway-dependent measures of the transverse diffusivity of water in white matter correlate with related clinical measures of functional deficit in multiple sclerosis. Taken together, these methods suggest that MRI methods can be used to probe both functional connectivity and anatomic connectivity in subjects with known white matter impairment. We report the results of a study comparing anatomic connectivity of the transcallosal motor pathway, as measured with diffusion tensor imaging (DTI) and functional connectivity of the bilateral primary sensorimotor cortices (SMC), as measured with LFBFs in the resting state. High angular resolution diffusion imaging was combined with functional MRI to define the transcallosal white matter pathway connecting the bilateral primary SMC. Maps were generated from the probabilistic tracking employed and these maps were used to calculate the mean pathway diffusion measures fractional anisotropy ,FA,, mean diffusivity ,MD,, longitudinal diffusivity ,,1,, and transverse diffusivity ,,2,. These were compared with LFBF-based functional connectivity measures (Fc) obtained at rest in a cohort of 11 multiple sclerosis patients and ,10 age- and gender-matched control subjects. The correlation between ,FA, and Fc for MS patients was r = ,0.63, P < 0.04. The correlation between all subjects ,,2, and Fc was r = 0.42, P < 0.05. The correlation between all subjects ,,2, and Fc was r = ,0.50, P < 0.02. None of the control subject correlations were significant, nor were ,FA,, ,,1,, or ,MD, significantly correlated with Fc for MS patients. This constitutes the first in vivo observation of a correlation between measures of anatomic connectivity and functional connectivity using spontaneous LFBFs. Hum Brain Mapp, 2008. © 2008 Wiley-Liss, Inc. [source]