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Query: UMLS:C0013421 (dystonia)
 8,418 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Previous studies have shown that intracortical inhibition (ICI) plays an important role in shaping the output from primary motor cortex, and that ICI may be impaired in people with Focal Hand Dystonia (FHD). This study explored the muscle-specificity and temporal modulation of ICI during the performance of a phasic index finger flexion task. Eight control subjects and seven with FHD were asked to rest their dominant hand upon a computer mouse, and depress the mouse button using their index finger in time with a 1 Hz auditory metronome, while keeping the rest of their hand as relaxed as possible. Responses to single and paired-pulse transcranial magnetic stimulation were recorded from the first dorsal interosseous (FDI) and abductor pollicis brevis (APB) muscles while subjects were at rest and during 'on' and 'off' phases of the task. For control subjects during the movement (i). FDI motor evoked potential (MEP) amplitude and pretrigger EMG increased, and ICI decreased, as expected, and (ii). there was no significant facilitation of MEP amplitude or pretrigger EMG for APB, which was associated with a significant increase in ICI during the movement. This may have helped prevent the unwanted activation of this muscle. While FHD subjects demonstrated the same patterns of modulation of both MEP amplitude and pretrigger EMG for both FDI and APB, their levels of ICI were not modulated by task performance. This was despite no difference between subject groups in the level of ICI observed at rest. These findings suggest that FHD is associated with impaired modulation of ICI during performance of a precise manual task, which may contribute to a lack of specificity in the output from M1 and the development of dystonic symptoms.
Cereb Cortex 2004 May
PMID:Impaired modulation of intracortical inhibition in focal hand dystonia. 1505 71

Temporal lobe seizures are accompanied by complex behavioral phenomena including loss of consciousness, dystonic movements and neuroendocrine changes. These phenomena may arise from extended neural networks beyond the temporal lobe. To investigate this, we imaged cerebral blood flow (CBF) changes during human temporal lobe seizures with single photon emission computed tomography (SPECT) while performing continuous video/EEG monitoring. We found that temporal lobe seizures associated with loss of consciousness produced CBF increases in the temporal lobe, followed by increases in bilateral midline subcortical structures. These changes were accompanied by marked bilateral CBF decreases in the frontal and parietal association cortex. In contrast, temporal lobe seizures in which consciousness was spared were not accompanied by these widespread CBF changes. The CBF decreases in frontal and parietal association cortex were strongly correlated with increases in midline structures such as the mediodorsal thalamus. These results suggest that impaired consciousness in temporal lobe seizures may result from focal abnormal activity in temporal and subcortical networks linked to widespread impaired function of the association cortex.
Cereb Cortex 2004 Aug
PMID:Positive and negative network correlations in temporal lobe epilepsy. 1508 94

Tardive dystonia (TD) is a disabling disorder induced by neuroleptics. Internal globus pallidus (GPi) stimulation can dramatically improve TD. The present positron emission tomography and H(2)(15)O study aimed to characterize the abnormalities of brain activation of TD and the impact of GPi stimulation on these abnormalities in five TD patients treated with GPi stimulation and eight controls. Changes of regional cerebral blood flow (rCBF) were determined: (i) at rest; (ii) when moving a joystick with the right hand in three freely chosen directions in on and off bilateral GPi stimulation. A significant increase of rCBF was found in TD patients in off-stimulation condition compared to controls: (1) during motor execution in the prefrontal, premotor lateral, and anterior cingulate cortex; (2) at rest, in the prefrontal and anterior cingulate cortex and the cerebellum. Internal globus pallidus stimulation led to a reduction of rCBF (1) during motor execution, in the primary motor and prefrontal cortex and the cerebellum; (2) at rest, in the primary motor and anterior cingulate cortex and supplementary motor area. The results are as follows: (1) TD is related to an excess of brain activity notably in the prefrontal and premotor areas; (2) GPi stimulation reduces the activation of motor, premotor, and prefrontal cortex as well as cerebellum.
J Cereb Blood Flow Metab 2008 Jun
PMID:Globus pallidus stimulation reduces frontal hyperactivity in tardive dystonia. 1823 Nov 15

Task-specific focal dystonia is thought to have a neurological basis where stereotypical synchronous inputs and maladaptive plasticity play a role. As afferent input is a powerful driver of cortical reorganization, we propose that a period of asynchronous afferent stimulation may reverse maladaptive cortical changes and alleviate symptoms. Using transcranial magnetic stimulation (TMS), 3 hand muscles were mapped in 10 dystonics and 10 healthy controls. Mapping occurred before and after 1 h of nonassociative stimulation (NAS) to first dorsal interosseous (FDI) and abductor pollicis brevis (APB). Participants performed grip lift, handwriting, and cyclic drawing before and after NAS. Prior to NAS, dystonics had larger maps, and the centers of gravity (CoGs) of the FDI and APB maps were closer together. Dystonics demonstrated impairments in grip-lift, handwriting, and cyclic drawing tasks. Following NAS, map size was reduced in all muscles in dystonic participants and FDI and APB CoGs moved further apart. Among dystonics, NAS produced a reduction in movement variability during cyclic drawing. Thus, 1 h of NAS can reduce the magnitude, and increase the separation, of TMS representational maps. We suggest that these changes reflect some normalization of the representational abnormalities seen in focal dystonia and provide initial, limited evidence that such changes are associated with improvements in circle drawing.
Cereb Cortex 2009 Sep
PMID:Normalizing motor cortex representations in focal hand dystonia. 1907 53

Deep brain stimulation (DBS) represents a major advance in the treatment of various severe movement disorders or neuropsychiatric diseases. Our understanding of the mechanism of action of this surgical treatment has greatly benefited from functional imaging studies. Most of these studies have been conducted in patients with Parkinson's disease (PD) treated by bilateral subthalamic nucleus (STN) stimulation. These studies have notably underlined the fact that STN stimulation influences motor, limbic, or associative cortical-subcortical loops in various (sometimes contradictory) ways. We present an up-to-date review of the information provided by functional imaging studies in surgery for PD, dystonia, tremor, as well as in psychiatric disorders such as depression or obsessive-compulsive disorder. On the basis of this information, proposed mechanisms of action of DBS are discussed, as well as the need for additional approaches such as improved anatomical localization of the contact used for stimulation or a better understanding of the electrical distribution around the electrode.
J Cereb Blood Flow Metab 2009 Nov
PMID:PET functional imaging of deep brain stimulation in movement disorders and psychiatry. 1965 84

Spasmodic dysphonia (SD) is a task-specific focal dystonia of unknown pathophysiology, characterized by involuntary spasms in the laryngeal muscles during speaking. Our aim was to identify symptom-specific functional brain activation abnormalities in adductor spasmodic dysphonia (ADSD) and abductor spasmodic dysphonia (ABSD). Both SD groups showed increased activation extent in the primary sensorimotor cortex, insula, and superior temporal gyrus during symptomatic and asymptomatic tasks and decreased activation extent in the basal ganglia, thalamus, and cerebellum during asymptomatic tasks. Increased activation intensity in SD patients was found only in the primary somatosensory cortex during symptomatic voice production, which showed a tendency for correlation with ADSD symptoms. Both SD groups had lower correlation of activation intensities between the primary motor and sensory cortices and additional correlations between the basal ganglia, thalamus, and cerebellum during symptomatic and asymptomatic tasks. Compared with ADSD patients, ABSD patients had larger activation extent in the primary sensorimotor cortex and ventral thalamus during symptomatic task and in the inferior temporal cortex and cerebellum during symptomatic and asymptomatic voice production. The primary somatosensory cortex shows consistent abnormalities in activation extent, intensity, correlation with other brain regions, and symptom severity in SD patients and, therefore, may be involved in the pathophysiology of SD.
Cereb Cortex 2010 Nov
PMID:Abnormal activation of the primary somatosensory cortex in spasmodic dysphonia: an fMRI study. 2019 86

Homeostatic metaplasticity is important to maintain overall synaptic weight in neuronal networks. Previous work suggested that homeostatic metaplasticity in motor cortex is impaired in writer's cramp, the most common form of task-specific focal dystonia, when explored by the interactions between 2 successive plasticity inducing transcranial brain stimulation protocols (Quartarone Rizzo V, Bagnato S, Morgante F, Sant'angelo A, Romano M, Crupi D, Girlanda P, Rothwell JC, Siebner HR. 2005. Homeostatic-like plasticity of the primary motor hand area is impaired in focal hand dystonia. Brain. 128:1943-1950.). To which extent deficient homeostatic metaplasticity applies also to the behavioral level of practice-dependent plasticity is unknown. Here, we examined the interactions of 3 paired associative transcranial magnetic stimulation protocols (motor cortical excitability-enhancing paired associative stimulation (PAS)(25ms), excitability-depressing PAS(10ms), and control PAS(100ms)) with subsequent practice-dependent plasticity. Ten patients with writer's cramp and 10 healthy controls practiced rapid thumb abductions for 30 min. Practice-dependent plasticity was quantified by the increase in peak acceleration of the trained movement. The healthy controls but not the writer's cramp patients showed homeostatic suppression of practice-dependent plasticity after PAS(25ms) when compared with practice-dependent plasticity after PAS(10ms) and PAS(100ms). The lack of the PAS(25ms)-induced suppression of practice-dependent plasticity in writer's cramp correlated with clinical severity of the focal hand dystonia. Findings support the notion that deficient homeostatic metaplasticity of practice-dependent plasticity plays a significant role in the pathophysiology of writer's cramp.
Cereb Cortex 2011 May
PMID:Deficient homeostatic regulation of practice-dependent plasticity in writer's cramp. 2097 89

Spasmodic dysphonia (SD) is a primary focal dystonia characterized by involuntary spasms in the laryngeal muscles during speech production. Although recent studies have found abnormal brain function and white matter organization in SD, the extent of gray matter alterations, their structure-function relationships, and correlations with symptoms remain unknown. We compared gray matter volume (GMV) and cortical thickness (CT) in 40 SD patients and 40 controls using voxel-based morphometry and cortical distance estimates. These measures were examined for relationships with blood oxygen level-dependent signal change during symptomatic syllable production in 15 of the same patients. SD patients had increased GMV, CT, and brain activation in key structures of the speech control system, including the laryngeal sensorimotor cortex, inferior frontal gyrus (IFG), superior/middle temporal and supramarginal gyri, and in a structure commonly abnormal in other primary dystonias, the cerebellum. Among these regions, GMV, CT and activation of the IFG and cerebellum showed positive relationships with SD severity, while CT of the IFG correlated with SD duration. The left anterior insula was the only region with decreased CT, which also correlated with SD symptom severity. These findings provide evidence for coupling between structural and functional abnormalities at different levels within the speech production system in SD.
Cereb Cortex 2012 Feb
PMID:Abnormal structure-function relationship in spasmodic dysphonia. 2166 31

The detection and assessment of errors are a prerequisite to adapt behavior and improve future performance. Error monitoring is afforded by the interplay between cortical and subcortical neural systems. Ample evidence has pointed to a specific cortical error-related evoked potential, the error-related negativity (ERN), during the detection and evaluation of response errors. Recent models of reinforcement learning implicate the basal ganglia (BG) in early error detection following the learning of stimulus-response associations and in the modulation of the cortical ERN. To investigate the influence of the human BG motor output activity on the cortical ERN during response errors, we recorded local field potentials from the sensorimotor area of the internal globus pallidus and scalp electroencephalogram representing activity from the posterior medial frontal cortex in patients with idiopathic dystonia (hands not affected) during a flanker task. In error trials, a specific pallidal error-related potential arose 60 ms prior to the cortical ERN. The error-related changes in pallidal activity-characterized by theta oscillations-were predictive of the cortical error-related activity as assessed by Granger causality analysis. Our findings show an early modulation of error-related activity in the human pallidum, suggesting that pallidal output influences the cortex at an early stage of error detection.
Cereb Cortex 2014 Jun
PMID:Involvement of human internal globus pallidus in the early modulation of cortical error-related activity. 2334 22

Dystonia is a brain disorder characterized by abnormal involuntary movements without defining neuropathological changes. The disease is often inherited as an autosomal-dominant trait with incomplete penetrance. Individuals with dystonia, whether inherited or sporadic, exhibit striking phenotypic variability, with marked differences in the somatic distribution and severity of clinical manifestations. In the current study, we used magnetic resonance diffusion tensor imaging to identify microstructural changes associated with specific limb manifestations. Functional MRI was used to localize specific limb regions within the somatosensory cortex. Microstructural integrity was preserved when assessed in subrolandic white matter regions somatotopically related to the clinically involved limbs, but was reduced in regions linked to clinically uninvolved (asymptomatic) body areas. Clinical manifestations were greatest in subjects with relatively intact microstructure in somatotopically relevant white matter regions. Tractography revealed significant phenotype-related differences in the visualized thalamocortical tracts while corticostriatal and corticospinal pathways did not differ between groups. Cerebellothalamic microstructural abnormalities were also seen in the dystonia subjects, but these changes were associated with genotype, rather than with phenotypic variation. The findings suggest that the thalamocortical motor system is a major determinant of dystonia phenotype. This pathway may represent a novel therapeutic target for individuals with refractory limb dystonia.
Cereb Cortex 2015 Sep
PMID:Thalamocortical Connectivity Correlates with Phenotypic Variability in Dystonia. 2486 17


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