Search results for "RESONANCE"
showing 10 items of 6625 documents
Release of premotor activity after repetitive transcranial magnetic stimulation of prefrontal cortex
2008
In the present study we aimed to explore by means of repetitive transcranial magnetic stimulation (rTMS) the reciprocal influences between prefrontal cortex (PFC) and premotor cortex (PMC). Subjects were asked to observe on a computer monitor different pictures representing manipulations of different kind of tools. They had to produce a movement (go condition) or to keep the resting position (no-go condition) at the appearance of different cue signals represented by different colors shown alternatively on the hands manipulating the tools or on the picture background. Motor evoked potentials (MEPs) were collected at the offset of the visual stimuli before and after a 10 minute, 1 Hz rTMS tra…
COMT genotype predicts BOLD signal and noise characteristics in prefrontal circuits.
2006
Abstract Objective: Prefrontal dopamine (DA) is catabolized by the COMT (catechol- O -methyltransferase) enzyme. Literature suggests that the Val/Met single nucleotide polymorphism (SNP) in the COMT gene predicts executive cognition in humans with Val carriers showing poorer performance due to less available synaptic DA. Recent fMRI studies are thought to agree with these studies having demonstrated prefrontal hyperactivation during n -back and attention-requiring tasks. This was interpreted as “less efficient” processing due to impaired signal-to-noise ratio (SNR) of neuronal activity. However, electrophysiological studies of neuronal SNR in primates and humans imply that prefrontal cortex…
Localization of emotional and volitional facial paresis.
1992
Emotional facial paresis is characterized by impaired activation of face muscles with emotion but normal voluntary activation. We report seven patients with this sign. Their lesions involved the frontal lobe white matter, the striatocapsular territory, the anterolateral thalamus and insula, the posterior thalamus and operculum, and the mesial temporal lobe and insula each in one patient, and the posterior thalamus in two patients. Volitional facial paresis affects facial movements with voluntary effort, sparing activation on emotion. We report four such patients, with lesions involving the motor cortex in one and the pyramidal tract in the cerebral hemisphere in three.
MRI in DNM2-related centronuclear myopathy: Evidence for highly selective muscle involvement
2006
Dynamin 2 has recently been recognized as a causative gene for the autosomal dominant form of centronuclear myopathy (dominant centronuclear myopathy). Here we report an affected father and daughter with dynamin 2 related AD CNM with predominantly distal onset of weakness. In addition to the diagnostic central location of myonuclei the muscle biopsy also showed core-like structures. Muscle MRI in the lower leg revealed prominent involvement of the soleus, but also of the gastrocnemius and the tibialis anterior whereas in the thigh there was a consistent pattern of selective involvement of adductor longus, semimembranosus, biceps femoris, rectus femoris, and vastus intermedius with relative …
Evidence for a white matter lesion size threshold to support the diagnosis of relapsing remitting multiple sclerosis
2018
Abstract Background The number of white matter lesions (WML) in brain MRI is the most established paraclinical tool to support the diagnosis of multiple sclerosis (MS) and to monitor its course. Diagnostic criteria have stipulated a minimum detectable diameter of 3 mm per WML, although this threshold is not evidence-based. We aimed to provide a rationale for a WML size threshold for three-dimensional MRI sequences at 3 T by comparing patients with relapsing-remitting MS (RRMS) to control subjects (CS). Methods We analyzed MR images from two cohorts, obtained at scanners from two different vendors, each comprising patients with RRMS and CS. Both cohorts were examined with FLAIR and T1w seque…
Patterned functional network disruption in amyotrophic lateral sclerosis
2019
Abstract Amyotrophic lateral sclerosis (ALS) is a progressive neurodegenerative disease primarily affecting motor function, with additional evidence of extensive nonmotor involvement. Despite increasing recognition of the disease as a multisystem network disorder characterised by impaired connectivity, the precise neuroelectric characteristics of impaired cortical communication remain to be fully elucidated. Here, we characterise changes in functional connectivity using beamformer source analysis on resting‐state electroencephalography recordings from 74 ALS patients and 47 age‐matched healthy controls. Spatiospectral characteristics of network changes in the ALS patient group were quantifi…
Diffusion-tensor MR imaging at 1.5 and 3.0 T: initial observations.
2001
Diffusion-tensor MR imaging was compared at 1.5 and 3.0 T. With sufficient signal-to-noise ratio, we found no differences in fractional anisotropy. With a 40% higher signal-to-noise ratio at 3.0 T, higher resolution could be obtained without introduction of noise-related errors, albeit at the cost of increased geometric distortions caused by 3.0-T magnetic field inhomogeneities.
Static magnetic fields generated by a 0.5T MRI unit affects in vitro expression of activation markers and interleukin release in human peripheral blo…
2001
To investigate the effects of the static magnetic field (SMF) generated by a 0.5 T superconducting MRI unit on in vitro activation marker expression and interleukin release in human peripheral blood mononuclear cell (PBMC) samples from healthy volunteers.PBMC samples were split into two groups: exposed and sham-exposed under isothermal conditions. PBMC were exposed for 2 h at 24 degrees C to the SMF of a 0.5 T superconducting MRI unit. Immediately after exposure, both samples were cultured for 24 h at 37 degrees C with or without mitogenic stimulation by phytohaemagglutinin (PHA). PBMC were examined for expression of CD25, CD69 and CD71 by immunofluorescence analysis and supernatants were a…
Model order effects on ICA of resting-state complex-valued fMRI data : application to schizophrenia
2018
Abstract Background Component splitting at higher model orders is a widely accepted finding for independent component analysis (ICA) of functional magnetic resonance imaging (fMRI) data. However, our recent study found that intact components occurred with subcomponents at higher model orders. New method This study investigated model order effects on ICA of resting-state complex-valued fMRI data from 82 subjects, which included 40 healthy controls (HCs) and 42 schizophrenia patients. In addition, we explored underlying causes for distinct component splitting between complex-valued data and magnitude-only data by examining model order effects on ICA of phase fMRI data. A best run selection me…
Abnormal Somatosensory Evoked Potentials Indicate Compressive Cervical Myelopathy in Mucopolysaccharidoses
2000
Compressive myelopathy at the cranio-cervical junction is a complication of mucopolysaccharidoses (MPS). To detect cervical myelopathy we recorded median and posterior tibial nerve SEPs in 15 patients aged 2.4 - 33.4 years (median 8.8 years) with MPS I-S (n = 3), MPS IVA (n = 8) and MPS VI (n = 4). In addition to the cortical waveforms we recorded the subcortical median nerve SEPs N13b and P13 generated near the cranio-cervical junction and the lemniscal P30 after posterior tibial nerve stimulation. MRI studies in 13 subjects revealed spinal cord compression at the cranio-cervical junction in 10 patients; 5 patients had an increased signal intensity on the T2-weighted initial MRI indicating…