Previous studies distinguish between right hemisphere-dominant processing of prosodic/tonal information and left-hemispheric modulation of grammatical information as well as lexical tones. Swedish word accents offer a prime testing ground to better understand this division. Although similar to lexical tones, word accents are determined by words' morphosyntactic structure, which enables listeners to use the tone at the beginning of a word to predict its grammatical ending. We recorded electrophysiological and hemodynamic brain responses to words where stem tones matched or mismatched inflectional suffixes. Tones produced brain potential effects after 136 ms, correlating with subject variability in average BOLD in left primary auditory cortex, superior temporal gyrus, and inferior frontal gyrus. Invalidly cued suffixes activated the left inferior parietal lobe, arguably reflecting increased processing cost of their meaning. Thus, interaction of word accent tones with grammatical morphology yielded a rapid neural response correlating in subject variability with activations in predominantly left-hemispheric brain areas.
The current event-related fMRI study examined the relative involvement of different parts of the medial temporal lobe (MTL), particularly the contribution of hippocampus and perirhinal cortex, in either intentional or incidental recognition of famous faces in contrast to unfamiliar faces. Our intention was to further explore the controversial contribution of MTL in the processing of semantic memory tasks. Subjects viewed a sequence of famous and unfamiliar faces. Two tasks were used encouraging attention to either fame or gender. In the fame task the subjects were requested to identify the person when seeing his/her face and also to try to generate the name of this person. In the gender task the subjects were asked to conduct a judgement of a person's gender when seeing his/her face. The visual processing was hence directed to gender and thereby expected to diminish attention to semantic information leading only to a "passive" registration of famous and non-familiar faces. Recognition of famous faces, in both contrasts, produced significant activations in the MTL. First, during the intentional recognition (the person identification task) increased activity was observed in the anterolateral part of left hippocampus, in proximity to amygdala. Second, during the incidental recognition of famous faces (the gender classification task) there was increased activity in the left posterior MTL with focus in the perirhinal cortex. Our results suggest that the hippocampus may be centrally involved in the intentional retrieval of semantic memories while the perirhinal cortex is associated with the incidental recognition of semantic information.
BackgroundThe purpose of this study was to investigate whether white matter microstructure is altered in patients suffering from systemic lupus erythematosus (SLE), and if so, whether such alterations differed between patients with and without neuropsychiatric symptoms.MethodsStructural MRI and diffusion tensor imaging (DTI) were performed in 64 female SLE patients (mean age 36.9 years, range 18.2–52.2 years) and 21 healthy controls (mean age 36.7 years, range 23.3–51.2 years) in conjunction with clinical examination, laboratory tests, cognitive evaluation, and self-assessment questionnaires. The patients were subgrouped according to the American College of Rheumatology Neuropsychiatric Systemic Lupus Erythematosus case definitions into non-neuropsychiatric SLE (nonNPSLE) and neuropsychiatric SLE (NPSLE).ResultsComparisons between the SLE group and healthy controls showed that the mean fractional anisotropy (FA) was significantly reduced in the right rostral cingulum (p = 0.038), the mid-sagittal corpus callosum (CC) (p = 0.050), and the forceps minor of the CC (p = 0.015). The mean diffusivity (MD) was significantly increased in the left hippocampal cingulum (p = 0.017). No significant differences in MD or FA values were identified between NPSLE and nonNPSLE patients. Disease duration among all SLE patients correlated significantly with reduced FA in the CC (p < 0.05). No correlations were found between DTI parameters and white matter hyperintensities, SLE Disease Activity Index-2000, Systemic Lupus International Collaborating Clinical/ACR Organ Damage Index, or Montgomery Asberg Depression Rate Score Self-report.ConclusionsWe found alterations of white matter microstructure in SLE patients that were related to disease duration and fatigue. Our results indicate that cerebral involvement in SLE is not isolated to the NPSLE subgroup.Electronic supplementary materialThe online version of this article (10.1186/s13075-018-1516-0) contains supplementary material, which is available to authorized users.
To investigate resting-state functional connectivity of lupus patients and associated subgroups according to the ACR NPSLE case definitions (ACR ad hoc). In addition, we investigated whether or not the observed alterations correlated with disease duration, the systemic lupus erythematosus (SLE)-Disease Activity Index-2000 (SLEDAI-2k), and Systemic Lupus International Collaborating Clinical/ACR organ damage index (SDI)-scores. Anatomical 3T magnetic resonance imaging (MRI) and resting-state functional MRI were performed in 61 female lupus patients (mean age = 37.0 years, range = 18.2-52.0 years) and 20 gender- and age-matched controls (mean age = 36.2 years, range = 23.3-52.2 years) in conjunction with clinical examination and laboratory testing. Whole-brain voxelwise functional connectivity analysis with permutation testing was performed to extract network components that differed in lupus patients relative to healthy controls (HCs). Lupus patients exhibited both inter- and intranetwork hypo- and hyperconnectivity involving several crucial networks. We found reduced connectivity within the default mode network (DMN), the central executive network (CEN), and in-between the DMN and CEN in lupus patients. Increased connectivity was primarily observed within and between the sensory motor network in lupus patients when compared to HCs. Comparing lupus patients with and without neuropsychiatric symptoms, hypoconnectivity was more pronounced in the group with neuropsychiatric complaints. The functional connectivity of SLE patients was both positively and negatively correlated to duration of disease. We conclude that SLE patients in general and neuropsychiatric SLE patients in particular experience altered brain connectivity. These patterns may be due both to direct neuronal damage and compensatory mechanisms through neuronal rewiring and recruitment and may partly explain neuropsychiatric symptoms in SLE patients.
Purpose: To investigate if resting-state functional MRI (fMRI) reliably can serve as a complement to task-based fMRI for presurgical mapping of the sensorimotor cortex. Materials and Methods:Functional data were obtained in 10 healthy volunteers using a 3 Tesla MRI system. Each subject performed five bilateral finger tapping experiments interleaved with five resting-state experiments. Following preprocessing, data from eight volunteers were further analyzed with the general linear model (finger tapping data) and independent component analysis (rest data). Test-retest reliability estimates (hit rate and false alarm rate) for resting-state fMRI activation of the sensorimotor network were compared with the reliability estimates for task-evoked activation of the sensorimotor cortex. The reliability estimates constituted a receiver operating characteristics curve from which the area under the curve (AUC) was calculated. Statistical testing was performed to compare the two groups with respect to reliability.Results: The AUC was generally higher for the task experiments, although median AUC was not significantly different on a group level. Also, the two groups showed comparable levels of within-group variance.Conclusion: Test-retest reliability was comparable between resting-state measurements and task-based fMRI, suggesting that presurgical mapping of functional networks can be a supplement to task-based fMRI in cases where patient status excludes task-based fMRI.
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