Search

Developmental dyslexia (DD) is a specific impairment during the acquisition of reading skills and may have a lifelong negative impact on individuals. Reliable estimates of the prevalence of DD serve as the basis for evidence-based health resource allocation and policy making. However, the prevalence of DD in primary school children varies largely across studies. Moreover, it is unclear whether there are differences in prevalence in different genders and writing systems. Hence, the present study aims to conduct a systematic review and meta-analysis to assess the global prevalence of DD and to explore related factors.We will undertake a comprehensive literature search in 14 databases, including EMBASE, PubMed, Web of Science, China National Knowledge Infrastructure and Cochrane, from their inception to June 2021. Cross-sectional and longitudinal studies that describe the prevalence of DD will be eligible. The quality of the included observational studies will be assessed using the Strengthening the Reporting of Observational Studies in Epidemiology statement. The risk of bias will be determined by sensitivity analysis to identify publication bias.One meta-analysis will be conducted to estimate the prevalence of DD in primary school children. Heterogeneity will be assessed in terms of the properties of subjects (e.g., gender, grade and writing system) and method of diagnosis in the included primary studies. Subgroup analyses will also be performed for population and secondary outcomes.The results will synthesize the prevalence of DD and provide information for policy-makers and public health specialists.

Sui SG, Wu MX, King ME, Zhang Y, Ling L, Xu JM, Weng XC, Duan L, Shan BC, Li LJ. Abnormal grey matter in victims of rape with PTSD in Mainland China: a voxel-based morphometry study.Objective:This study examined changes in brain grey matter in victims of rape (VoR) with and without post-traumatic stress disorder (PTSD). Previous research has focused on PTSD caused by various traumatic events, such as war and disaster, among others. Although considerable research has focused on rape-related PTSD, limited studies have been carried out in the context of Mainland China.Methods:The study included 11 VoR with PTSD, 8 VoR without PTSD and 12 healthy comparison (HC) subjects. We used voxel-based morphometry to explore changes in brain grey-matter density (GMD) by applying statistical parametric mapping to high-resolution magnetic resonance images.Results:Compared with HC, VoR with PTSD showed significant GMD reductions in the bilateral medial frontal cortex, left middle frontal cortex, middle temporal gyrus and fusiform cortex and significant GMD increases in the right posterior cingulate cortex, postcentral cortex, bilateral precentral cortex and inferior parietal lobule. Compared to VoR without PTSD, VoR with PTSD showed significant GMD reductions in the right uncus, left middle temporal gyrus, and the fusiform cortex, and increases in the left precentral cortex, inferior parietal lobule and right post-central cortex.Conclusion:The findings of abnormal GMD in VoR with PTSD support the hypothesis that PTSD is associated with widespread anatomical changes in the brain. The medial frontal cortex, precentral cortex, posterior cingulate cortex, post-central cortex and inferior parietal lobule may play important roles in the neuropathology of PTSD.

Objective The left-lateralized N170, an event-related potential component consistently shown in response to alphabetic words, is a robust electrophysiological marker for reading expertise in an alphabetic language. In contrast, such a marker is lacking for expertise in reading Chinese, because the existing results about the lateralization of N170 for Chinese characters are mixed, reflecting complicated factors such as top-down modulation that contribute to the relative magnitudes of N170 in the left and right hemispheres. The present study aimed to explore a potential electrophysiologi- cal marker for reading expertise in Chinese with minimal top-down influence. Methods We recorded N170 responses to Chinese characters and three kinds of control stimuli in a content-irrelevant task, minimizing potential top-down effects. Results Direct comparison of the N170 amplitude in response to Chinese characters between the hemispheres showed a marginally significant left-lateralization effect. However, detailed analyses of N170 in each hemisphere revealed a more ro- bust pattern of left-lateralization — the N170 in the left but not the right hemisphere differentiated Chinese characters from control stimuli. Conclusion These results suggest that the selectivity of N170 (a greater N170 in response to Chinese characters than to control stimuli) within the left hemisphere rather than the hemispheric difference of N170 with regard to Chinese characters is an electrophysiological marker for expertise in reading Chinese.

Introduction: Based on early studies of non-motor function in the cerebellum and dysfunction in the cerebellum of post-traumatic stress disorder ( PTSD) patients, we presumed that the cerebellum was involved in the neuropathology of cognitive and emotional processing of PTSD patients, while the density of some sub-areas of the cerebellum of PTSD patients was most likely abnormal. Methods: Eleven female victims of rape with PTSD and 12 age-matched female normal controls received 1.5 T 3D magnetic resonance imaging (MRI) scan. The scans were then analyzed using the voxel-based morphometry 2 ( VBM2) toolbox. Results: Victims of rape with PTSD showed increased cerebellum density on the left side compared with normal controls (P

Efforts to identify meaningful functional imaging-based biomarkers are limited by the ability to reliably characterize inter-individual differences in human brain function. Although a growing number of connectomics-based measures are reported to have moderate to high test-retest reliability, the variability in data acquisition, experimental designs, and analytic methods precludes the ability to generalize results. The Consortium for Reliability and Reproducibility (CoRR) is working to address this challenge and establish test-retest reliability as a minimum standard for methods development in functional connectomics. Specifically, CoRR has aggregated 1,629 typical individuals’ resting state fMRI (rfMRI) data (5,093 rfMRI scans) from 18 international sites, and is openly sharing them via the International Data-sharing Neuroimaging Initiative (INDI). To allow researchers to generate various estimates of reliability and reproducibility, a variety of data acquisition procedures and experimental designs are included. Similarly, to enable users to assess the impact of commonly encountered artifacts (for example, motion) on characterizations of inter-individual variation, datasets of varying quality are included.

To explore the reproducibility and stability of brain functional area in the response of language tasks during Chinese word processing with functional magnetic resonance imaging (fMRI) by follow-up scanning so as to provide rationales for clinical preoperative localization and the mechanisms of recovery from aphasia.The fMRI data were collected by scanning semantic and phonologic judgments in 15 healthy volunteers. Each subject was scanned twice by the same fMRI procedure of both language tasks with an interval of 1 month. By analyzing the effective overlapping average activation maps, the reproducibility of inter-subject imaging result for two language tasks were estimated by selecting the main language areas, such as Broca's area and Wernicke's area as the region of interest (ROI). By individually calculating the spatial distance of ROI centroid coordinates in the same activating range before and after test, the inter-subject stability in between-session was calculated quantitatively.Both language tasks activated more than one language-related brain areas in cerebral hemispheres. Both language tasks induced significant BOLD response in Broca's and Wernicke's areas with a tendency of left lateralization. The number of subjects in terms of the activation of both language tasks in Broca's and Wernicke's areas accounted over a half of the total subjects. As compared with the phonologic judgment task, the semantic judgment task showed better reproducibility in Broca's area. In the same spatial distance of ROI centroid coordinates, the stability of Broca's area was higher than that of Wernicke's area while the stability of semantic judgment in Broca's area higher than that of phonologic judgment.Such main language domains as Broca's and Wernicke's areas can be effectively activated by both semantic and phonologic judgments. By comparison, semantic judgment in Broca's area shows a higher level of reproducibility and stability. Thus it is applicable for clinical preoperative localization and the mechanisms of recovery from aphasia.

Although it is being successfully implemented for exploration of the genome, discovery science has eluded the functional neuroimaging community. The core challenge remains the development of common paradigms for interrogating the myriad functional systems in the brain without the constraints of a priori hypotheses. Resting-state functional MRI (R-fMRI) constitutes a candidate approach capable of addressing this challenge. Imaging the brain during rest reveals large-amplitude spontaneous low-frequency (www.nitrc.org/projects/fcon_1000/ .

In this study, 4 male Qigong masters (aged 60 ± 12) who had Qigong practicing experience for more than 30 years were tested. By using the technique of fMRI, the change of brain function under the state of Qigong was observed through the peripheral pain stimulation generated by potassium penetrating method. The fMRI examination was running on a GE signa VH/3.0 T MRI machine and block design was used. The test was repeated several times, which was carried out before and 15 min after Qigong practicing. The heart and respiration rate of these 4 Qigong masters were monitored during the whole test. SPM2 was used for the data analysis, and the result showed that before Qigong practicing, besides SI and SII-insula regions, many other Brodmann areas, the cigulate cortex, the thalamus, and the cerebellum were all activated, while 15 min after that, the activated areas were decreased obviously, which were mainly at the SII-insula region and some other Brodmann areas. Since the SII-insula region was activated in both of these two states, further analysis of the response curve was focused on it. Its response amplitude under the state of Qigong (3.5%) was greater than that before Qigong (1.2%). Our result indicated that the main manifestation of brain functional change under Qigong was functional suppressing, but in some particular regions such as SII-insula region in our study, the response amplitude was increased. Further study of the exact physiological mechanism of Qigong is needed.

To investigate the roles the different functional activation areas in whole human brain related to movement play during motor preparation (CUE) and execution (GO).Event-related functional MRI technique was used on 12 right-handed healthy subjects to record the brain activation in a manner of delayed sequential finger movement. Activation maps and time-signal intensity curves were generated.Bilateral anterior parts of supplementary motor area (Pre-SMA), bilateral posterior parietal cortex (PPC), and bilateral anterior premotor cortex (PMC) were strongly activated during the preparation period, while bilateral SMA proper, and contralateral primary motor cortex (M1) were strongly activated during the execution period, Cerebellar cortex was activated during both periods. The time-signal intensity curves based on single voxel indicated that above-mentioned brain areas were activated during both periods to different degrees; however, the characteristics of distribution in every area were different.The brain areas related to movement are activated differently during preparation period and execution period, areas close to M1 participate in the motor execution process mainly, and the areas away from M1 are concerned with motor preparation process chiefly.

To detect the differences in subcortical structures between patients with paroxysmal kinesigenic dyskinesia (PKD) and normal subjects during movement preparation and execution.The PKD patients performed a movement task, in which a CUE signal (preparation) indicated the movement sequence prior to the appearance of an imperative GO signal (execution). Event-related functional magnetic resonance imaging (fMRI) and 3dDeconvolve program of AFNI were used to estimate the hemodynamic response function and to generate activation maps.During movement preparation, the activated brain areas in PKD patients were less than those of normal subject, and there was no activation in basal ganglia in PKD patients. During execution, the activation was also less in PKD patients except in bilateral M1.During intermission, abnormalities of the brain still exist in PKD patients when during preparing or performing movement. The movement circuit in the brain displays an unusual state. The attack may be caused by reducing of inhibition in brain areas.

To investigate the brain functional laterality in motor areas during motor execution systematically.Functional magnetic resonance imaging (fMRI) was employed combined with right hand sequential finger movement task to investigate brain activation pattern and laterality in 8 right-handed subjects. 3dDeconvolve program of AFNI was used to estimate the hemodynamic response function and to generate activation maps. Then the laterality index (LI) was calculated and tested statistically.All motor areas including the areas which were previously considered to be engage in movement preparation only were activated in movement execution. In the activation map, it appeared left lateralization in cerebra and right lateralization in cerebella. After further statistical test, it was found that in primary motor area (M1), supplementary motor area (SMA) and posterior parietal cortex (PPC), there were left lateralization. While in premotor cortex (PMC), cingulate gyrus and basal ganglia (BG), the lateralization tendency was not obvious. The activation in cerebella is characterized with right lateralization.Though there are tiny differences among subjects, most of the motor areas appear lateralized activation. Past studies only observed laterality in several motor areas. It may be due to the difficulty of the task or the experimental design.

To explore the heterogeneity of aging brain.Blood oxygenation level dependent functional magnetic resonance imaging was performed on 10 subjects meeting the standards of successful aging (SA), 9 subjects meeting the standards of usual aging (UA), and 9 subjects meeting the criteria of mild cognitive impairment (MCI), all age, and sex-matched, under stimulation of verbal fluent test (VFT). The activation level of different regions of interest (ROI), laterality index, and the activation level of occipital lobe were analyzed.The achievement in VFT of the SA group was greater than that of the UA group, and much greater than that of the MCI group with significant differences between any 2 groups (all P0.05) except in the task of "names of vegetables". The activation volume of the SA group was greater than that of the UA group, and much greater than that of the MCI group. The main activated regions of the SA and UA groups included left precuneus, anterior cingulate gyrus, middle frontal gyrus, superior frontal gyrus and inferior parietal lobule, and bilateral occipital lobes. The main activated regions of the MCI group included the bilateral prefrontal lobe. The intensity of activation was not significantly different between the SA and UA groups, however, was significantly different between the SA and MCI groups and between the UA and MCI groups. The laterality index (LI) was 0.46 in the SA group, significantly higher than those of the UA group (-0.12) and MCI group (-0.06) (both P0.01), however, without a significant difference between the UA group and MCI group. The activation of left prefrontal lobe in the SA group was more obvious than that in the UA group, and much more obvious than that in the MCI group with a significant difference between the UA and MCI groups as well (all P0.01). The activation volume of the left dorsal lateral prefrontal cortex (DLPFC) in the SA group was 787 voxels, significantly greater than that in the UA group (292 voxels) and MCI group (0 voxel) (all P0.01).Heterogeneity exists in the course of aging, associated with complicated brain mechanism. The activation level of DLPFC and LI may be used as sensitive indexes in evaluation of the brain function of the elderly.

To explore the differences in brain activation between musicians and non-musicians by use of functional MRI.Twelve right-handed musicians and twelve right-handed non-musicians were recruited in the study. During a listening task, they were scanned on the Sigma 1.5T scanner (GE) while they were passively listening to several segments of music of "the Butterfly Love" and the white noise with same physical energy.Both musicians and non-musicians demonstrated bilateral transverse gyrus weak activated while listening to the white noise. But when listening to music, they showed bilateral temporal areas strongly activated including superior temporal gyrus, transverse gyrus and some middle temporal areas. Moreover, musicians showed relative left dominance (10/12), whereas non-musicians demonstrated right dominance(11/12). Furthermore,besides bilateral temporal areas, more and stronger activated areas were found in musicians such as cuneus, precuneus,medial frontal and left middle occipital gyrus.There are different neuro-patterns between musicians and non-musicians.

Functional magnetic resonance imaging (fMRI) has become a powerful tool for tracking human brain activity in vivo. This technique is mainly based on blood oxygenation level dependence (BOLD) contrast. In the present study, we employed this newly developed technique to characterize the neural representations of human portraits and natural sceneries in the human brain.Nine subjects were scanned with a 1.5 T magnetic resonance imaging (MRI) scanner using gradient-recalled echo and echo-planar imaging (GRE-EPI) pulse sequence while they were visually presented with 3 types of white-black photographs: natural scenery, human portraits, and scrambled nonsense pictures. Multiple linear regression was used to identify brain regions responding preferentially to each type of stimulus and common regions for both human portraits and natural scenery. The relative contributions of each type of stimulus to activation in these regions were examined using linear combinations of a general linear test.Multiple linear regression analysis revealed two distinct but adjacent regions in both sides of the ventral temporal cortex. The medial region preferentially responded to natural scenery, whereas the lateral one preferentially responded to the human portraits. The general linear test further revealed a distribution gradient such that a change from portraits to scenes shifted areas of activation from lateral to medial.The boundary between portrait-associated and scenery-associated areas is not as clear as previously demonstrated. The representations of portraits and scenes in ventral temporal cortex appear to be continuous and overlap.

Functional neuroimaging has been used in neurolinguistic research on normal subjects and on patients with brain damage. This study was designed to investigate the differences of the neural basis underlying language processing between normal subjects and aphasics.Functional magnetic resonance imaging (fMRI) was used to map the language network in 6 normal subjects and 3 patients with aphasia who were in the stage of recovery from acute stroke. The participants performed a word generation task during multi-slice functional scanning for the measurement of signal change associated with regional neural activity induced by the task.In normal subjects, a distributed language network was activated. Activations were present in the frontal, temporal, parietal and occipital regions. In the patient group, however, no activation was detected in the left inferior frontal gyrus whether the patient had a lesion in the left frontal lobe or not. Two patients showed activations in some right hemisphere regions where no activation appeared in normal subjects.fMRI with word generation task is feasible for evaluating language function in aphasic patients. Remote effect of focal lesion and functional redistribution or reorganisation can be found in aphasic patients.

Representational similarity analysis (RSA) is a rapidly developing multivariate platform to investigate the structure of neural activities. Similarity/dissimilarity is the core concept of RSA, realized by the construction of a representational dissimilarity matrix, that addresses the closeness/distance for each pair of research elements (e.g., one minus the correlation between the brain responses to 2 different stimuli) and in turn, constitutes a multivariate pattern as its analytic foundation. This approach is also welcome for its sensitivity in detecting subtle differences of distributed experimental effects in the brain. Importantly, RSA is not only an experimental tool but a promising data-analytical framework that can integrate cross-modal imaging signals, explore brain-behavior link, and verify computational models according to measured neural activities. RSA substantiates its integrative power by relating similarity structure in one domain (e.g., stimulus features) to that in another domain (e.g., neural activities). This review summarizes dissimilarity/similarity definition of RSA, introduces how to derive the dissimilarity structure in neural response pattern, and carry out connectivity analysis based on RSA platform. Several recent advances are highlighted, such as the extraction of across-subjects regularity, cross-validation of brain reactivity in human beings and monkeys, the incorporation of computational models and behavioral profiles into RSA. Voxel receptor field modeling, another promising multivariate tool of pattern elucidation, is presented and compared. The application of RSA is expected to surge and extend in many fields of neuroscience, computation, psychology and medicine. We also discuss the limitations of RSA and some critical questions that need to be addressed in future research.