Abstract
Understanding encoded languages, such as written script or Morse code, requires nonlexical and lexical processing components that act in a parallel and interactive fashion. Decoding written ...script—as for example in reading—is typically very fast, making the investigation of the lexical and nonlexical components and their underlying neural mechanisms challenging. In the current study, we aimed to accomplish this problem by using Morse code as a model for language decoding. The decoding of Morse code is slower and thus allows a better and more fine‐grained investigation of the lexical and nonlexical components of language decoding. In the current study, we investigated the impact of various components of nonlexical decoding of Morse code using magnetoencephalography. For this purpose, we reconstructed the time–frequency responses below 40 Hz in brain regions significantly involved in Morse code decoding and word comprehension that were identified in a previous study. Event‐related reduction in beta‐ and alpha‐band power were found in left inferior frontal cortex and angular gyrus, respectively, while event‐related theta‐band power increase was found at frontal midline. These induced oscillations reflect working‐memory encoding, long‐term memory retrieval as well as demanding cognitive control, respectively. In sum, by using Morse code and MEG, we were able to identify a cortical network underlying language decoding in a time‐ and frequency‐resolved manner.
Pain thresholds vary considerably across individuals and are influenced by a number of behavioral, genetic and neurobiological factors. However, the neurobiological underpinnings that account for ...individual differences remain to be fully elucidated. In this study, we used voxel‐based morphometry (VBM) and graph theory, specifically the local clustering coefficient (CC) based on resting‐state connectivity, to identify brain regions, where regional gray matter volume and network properties predicted individual pain thresholds. As a main finding, we identified a cluster in the left posterior insular cortex (IC) reaching into the left parietal operculum, including the secondary somatosensory cortex, where both regional gray matter volume and the local CC correlated with individual pain thresholds. We also performed a resting‐state functional connectivity analysis using the left posterior IC as seed region, demonstrating that connectivity to the pre‐ as well as postcentral gyrus bilaterally; that is, to the motor and primary sensory cortices were correlated with individual pain thresholds. To our knowledge, this is the first study that applied VBM in combination with voxel‐based graph theory in the context of pain thresholds. The co‐location of the VBM and the local CC cluster provide first evidence that both structure and function map to the same brain region while being correlated with the same behavioral measure; that is, pain thresholds. The study highlights the importance of the posterior IC, not only for pain perception in general, but also for the determination of individual pain thresholds.
Pain thresholds vary considerably across individuals. In our study both regional gray matter volume and specific network properties in the left posterior insula and secondary somatosensory cortex correlated with individual pain thresholds, so did functional resting state connectivity of this region with the primary somatosensory cortices.
MRI is a helpful tool for monitoring disease progression in late‐onset Pompe disease (LOPD). Our study aimed to evaluate if muscle diffusion tensor imaging (mDTI) shows alterations in muscles of LOPD ...patients with <10% fat‐fraction. We evaluated 6 thigh and 7 calf muscles (both legs) of 18 LOPD and 29 healthy controls (HC) with muscle diffusion tensor imaging (mDTI), T1w, and mDixonquant sequences in a 3T MRI scanner. The quantitative mDTI‐values axial diffusivity (λ1), mean diffusivity (MD), radial diffusivity (RD), and fractional anisotropy (FA) as well as fat‐fraction were analyzed. 6‐Minute Walk Test (6‐MWT) data were correlated to diffusion metrics. We found that mDTI showed significant differences between LOPD and HC in diffusion parameters (P < .05). Thigh muscles with <10% fat‐fraction showed significant differences in MD, RD, and λ1‐3. MD positively correlated with 6‐MWT (P = .06). To conclude, mDTI reveals diffusion restrictions in muscles of LOPD with and without fat‐infiltration and reflects structural changes prior to fatty degeneration.
Purpose
To investigate to what extent inter‐ and intramuscular variations of diffusion parameters of human calf muscles can be explained by age, gender, muscle location, and body mass index (BMI) in ...a specific age group (20–35 years).
Materials and Methods
Whole calf muscles of 18 healthy volunteers were evaluated. Magnetic resonance imaging (MRI) was performed using a 3T scanner and a 16‐channel Torso XL coil. Diffusion‐weighted images were acquired to perform fiber tractography and diffusion tensor imaging (DTI) analysis for each muscle of both legs. Fiber tractography was used to separate seven lower leg muscles. Associations between DTI parameters and confounds were evaluated. All muscles were additionally separated in seven identical segments along the z‐axis to evaluate intramuscular differences in diffusion parameters.
Results
Fractional anisotropy (FA) and mean diffusivity (MD) were obtained for each muscle with low standard deviations (SDs) (SDFA: 0.01–0.02; SDMD: 0.07–0.14(10−3)). We found significant differences in FA values of the tibialis anterior muscle (AT) and extensor digitorum longus (EDL) muscles between men and women for whole muscle FA (two‐sample t‐tests; AT: P = 0.0014; EDL: P = 0.0004). We showed significant intramuscular differences in diffusion parameters between adjacent segments in most calf muscles (P < 0.001). Whereas muscle insertions showed higher (SD 0.03–0.06) than muscle bellies (SD 0.01–0.03), no relationships between FA or MD with age or BMI were found.
Conclusion
Inter‐ and intramuscular variations in diffusion parameters of the calf were shown, which are not related to age or BMI in this age group. Differences between muscle belly and insertion should be considered when interpreting datasets not including whole muscles.
Level of Evidence: 3
Technical Efficacy: Stage 1
J. Magn. Reson. Imaging 2017;46:1137–1148.
In addition to its role in visuospatial navigation and the generation of spatial representations, in recent years, the hippocampus has been proposed to support perceptual processes. This is ...especially the case where high‐resolution details, in the form of fine‐grained relationships between features such as angles between components of a visual scene, are involved. An unresolved question is how, in the visual domain, perspective‐changes are differentiated from allocentric changes to these perceived feature relationships, both of which may be argued to involve the hippocampus. We conducted functional magnetic resonance imaging of the brain response (corroborated through separate event‐related potential source‐localization) in a passive visuospatial oddball‐paradigm to examine to what extent the hippocampus and other brain regions process changes in perspective, or configuration of , three‐dimensional structures. We observed activation of the left superior parietal cortex during perspective shifts, and right anterior hippocampus in configuration‐changes. Strikingly, we also found the cerebellum to differentiate between the two, in a way that appeared tightly coupled to hippocampal processing. These results point toward a relationship between the cerebellum and the hippocampus that occurs during perception of changes in visuospatial information that has previously only been reported with regard to visuospatial navigation.
Background.— Persistent idiopathic facial pain (PIFP) is defined as a persistent, unilateral facial pain, not associated with sensory loss or other physical signs and with no obvious structural ...abnormalities that would sufficiently explain pain experience.
Objective.— We were interested whether there is evidence of altered brain morphology in patients with PIFP as it has been described in other chronic pain conditions.
Methods.— Using voxel‐based morphometry we investigated regional gray matter volume in 11 PIFP patients and 11 age‐ and sex‐matched healthy controls. Furthermore we calculated lateralization indices (LI) to investigate differences in interhemispheric gray matter asymmetries.
Results.— We report a decrease in gray matter volume in the left anterior cingulate gyrus and left temporo‐insular region, as well as in the left and right sensory‐motor area, projecting to the representational area of the face. Analyses of LI values demonstrated an increased rightward asymmetry in the middle‐anterior insular cortex in patients in comparison with healthy controls.
Conclusion.— Our data support previous findings showing that chronic pain states are display‐altered brain morphology in brain regions know to be part of the pain system.
(Headache 2010;50:1278‐1285)
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