Mandarin functional MRI Language paradigms

iTBS reveals the roles of domain-general cognitive control and language-specific brain regions during word formation rule learning

Repeated exposure to word forms and meanings improves lexical knowledge acquisition. However, the roles of domain-general and language-specific brain regions during this process remain unclear. To investigate this, we applied intermittent theta burst stimulation over the domain-general (group left dorsolateral prefrontal cortex) and domain-specific (Group L IFG) brain regions, with a control group receiving sham intermittent theta burst stimulation. Intermittent theta burst stimulation effects were subsequently assessed in functional magnetic resonance imaging using an artificial word learning task which consisted of 3 learning phases. A generalized psychophysiological interaction analysis explored the whole brain functional connectivity, while dynamic causal modeling estimated causal interactions in specific brain regions modulated by intermittent theta burst stimulation during repeated exposure. Compared to sham stimulation, active intermittent theta burst stimulation improved word learning performance and reduced activation of the left insula in learning phase 2. Active intermittent theta burst stimulation over the domain-general region increased whole-brain functional connectivity and modulated effective connectivity between brain regions during repeated exposure. This effect was not observed when active intermittent theta burst stimulation was applied to the language-specific region. These findings suggest that the domain-general region plays a crucial role in word formation rule learning, with intermittent theta burst stimulation enhancing whole-brain connectivity and facilitating efficient information exchange between key brain regions during new word learning.

Reorganization of motor network in patients with Parkinson's disease after deep brain stimulation

AIMS

Parkinson's disease (PD) patients experience improvement in motor symptoms after deep brain stimulation (DBS) and before initiating stimulation. This is called the microlesion effect. However, the mechanism remains unclear. The study aims to comprehensively explore the changes in functional connectivity (FC) patterns in movement-related brain regions in PD patients during the microlesion phase through seed-based FC analysis.

METHODS

The study collected the resting functional magnetic resonance imaging data of 49 PD patients before and after DBS surgery (off stimulation). The cortical and subcortical areas related to motor function were selected for seed-based FC analysis. Meanwhile, their relationship with the motor scale was investigated.

RESULTS

The motor-related brain regions were selected as the seed point, and we observed various FC declines within the motor network brain regions. These declines were primarily in the left middle temporal gyrus, bilateral middle frontal gyrus, right supplementary motor area, left precentral gyrus, left postcentral gyrus, left inferior frontal gyrus, and right superior frontal gyrus after DBS.

CONCLUSION

The movement-related network was extensively reorganized during the microlesion period. The study provided new information on enhancing motor function from the network level post-DBS.

Abnormal Brain Structure Is Associated with Social and Communication Deficits in Children with Autism Spectrum Disorder: A Voxel-Based Morphometry Analysis

Structural magnetic resonance imaging (sMRI) studies have shown abnormalities in the brain structure of ASD patients, but the relationship between structural changes and social communication problems is still unclear. This study aims to explore the structural mechanisms of clinical dysfunction in the brain of ASD children through voxel-based morphometry (VBM). After screening T1 structural images from the Autism Brain Imaging Data Exchange (ABIDE) database, 98 children aged 8-12 years old with ASD were matched with 105 children aged 8-12 years old with typical development (TD). Firstly, this study compared the differences in gray matter volume (GMV) between the two groups. Then, this study evaluated the relationship between GMV and the subtotal score of communications and social interaction on the Autism Diagnostic Observation Schedule (ADOS) in ASD children. Research has found that abnormal brain structures in ASD include the midbrain, pontine, bilateral hippocampus, left parahippocampal gyrus, left superior temporal gyrus, left temporal pole, left middle temporal gyrus and left superior occipital gyrus. In addition, in ASD children, the subtotal score of communications and social interaction on the ADOS were only significantly positively correlated with GMV in the left hippocampus, left superior temporal gyrus and left middle temporal gyrus. In summary, the gray matter structure of ASD children is abnormal, and different clinical dysfunction in ASD children is related to structural abnormalities in specific regions.

Individual Proportion Loss of Functional Connectivity Strength: A Novel Individual Functional Connectivity Biomarker for Subjective Cognitive Decline Populations

High individual variation in the subjective cognitive decline (SCD) population makes functional connectivity (FC) biomarkers unstable. This study proposed a novel individual FC index, named individual proportion loss of functional connectivity strength (IPLFCS), and explored potential biomarkers for SCD using this new index. We proposed an IPLFCS analysis framework and compared it with traditional FC in Chinese and Western cohorts. Post hoc tests were used to determine biomarkers. Pearson's correlation analysis was used to investigate the correlation between neuropsychological scores or cortical amyloid deposits and IPLFCS biomarkers. Receiver operating characteristic curves were utilized to evaluate the ability of potential biomarkers to distinguish between groups. IPLFCS of the left middle temporal gyrus (LMTG) was identified as a potential biomarker. The IPLFC was correlated with the traditional FC (r = 0.956, p < 0.001; r = 0.946, p < 0.001) and cortical amyloid deposition (r = -0.245, p = 0.029; r = -0.185, p = 0.048) in both cohorts. Furthermore, the IPLFCS decreased across the Alzheimer's disease (AD) continuum. Its diagnostic efficiency was superior to that of existing fMRI biomarkers. These findings suggest that IPLFCS of the LMTG could be a potential biomarker of SCD.

Shared functional network abnormality in patients with temporal lobe epilepsy and their siblings

AIM

Temporal lobe epilepsy is a neurological network disease in which genetics played a greater role than previously appreciated. This study aimed to explore shared functional network abnormalities in patients with sporadic temporal lobe epilepsy and their unaffected siblings.

METHODS

Fifty-eight patients with sporadic temporal lobe epilepsy, 13 unaffected siblings, and 30 healthy controls participated in this cross-sectional study. We examined the task-based whole-brain functional network topology and the effective functional connectivity between networks identified by group-independent component analysis.

RESULTS

We observed increased global efficiency, decreased clustering coefficiency, and decreased small-worldness in patients and siblings (p < 0.05, false discovery rate-corrected). The effective network connectivity from the ventral attention network to the limbic system was impaired (p < 0.001, false discovery rate-corrected). These features had higher prevalence in unaffected siblings than in normal population and was not correlated with disease burden. In addition, topological abnormalities had a high intraclass correlation between patients and their siblings.

CONCLUSION

Patients with temporal lobe epilepsy and their unaffected siblings showed shared topological functional disturbance and the effective functional network connectivity impairment. These abnormalities may contribute to the pathogenesis that promotes the susceptibility of seizures and language decline in temporal lobe epilepsy.

Cerebellar functional disruption and compensation in mesial temporal lobe epilepsy

Background

Cerebellar functional alterations are common in patients with mesial temporal lobe epilepsy (MTLE), which contribute to cognitive decline. This study aimed to deepen our knowledge of cerebellar functional alterations in patients with MTLE.

Methods

In this study, participants were recruited from an ongoing prospective cohort of 13 patients with left TLE (LTLE), 17 patients with right TLE (RTLE), and 30 healthy controls (HCs). Functional magnetic resonance imaging data were collected during a Chinese verbal fluency task. Group independent component (IC) analysis (group ICA) was applied to segment the cerebellum into six functionally separated networks. Functional connectivity was compared among cerebellar networks, cerebellar activation maps, and the centrality parameters of cerebellar regions. For cerebellar functional profiles with significant differences, we calculated their correlation with clinical features and neuropsychological scores.

Result

Compared to HCs and patients with LTLE, patients with RTLE had higher cerebellar functional connectivity between the default mode network (DMN) and the oculomotor network and lower cerebellar functional connectivity from the frontoparietal network (FPN) to the dorsal attention network (DAN) (p < 0.05, false discovery rate- (FDR-) corrected). Cerebellar degree centrality (DC) of the right lobule III was significantly higher in patients with LTLE compared to HC and patients with RTLE (p < 0.05, FDR-corrected). Higher cerebellar functional connectivity between the DMN and the oculomotor network, as well as lower cerebellar degree centrality of the right lobule III, was correlated with worse information test performance.

Conclusion

Cerebellar functional profiles were altered in MTLE and correlated with long-term memory in patients.

Abnormal functional connectivity profiles predict drug responsiveness in patients with temporal lobe epilepsy

OBJECTIVE

This work was undertaken to study the functional connectivity differences between non-seizure-free and seizure-free patients with temporal lobe epilepsy (TLE) and to identify imaging predictors for drug responsiveness in TLE.

METHODS

In this prospective study, 52 patients with TLE who presented undetermined antiseizure medication responsiveness and 55 demographically matched healthy controls were sequentially recruited from Xiangya Hospital. Functional magnetic resonance imaging data were acquired during a Chinese version of the verbal fluency task. The patients were followed up until the outcome could be classified. The subject groups were compared in terms of activation profile, task-residual functional connectivity (trFC), and generalized psychophysiological interaction (gPPI) analyses. Moreover, we extracted imaging characteristics for logistic regression and receiver operating characteristic evaluation.

RESULTS

With a mean follow-up of 1.1 years, we identified 27 non-seizure-free patients and 19 seizure-free patients in the final analyses. The Chinese character verbal fluency task successfully activated the language network and cognitive control network (CCN) and deactivated the default mode network (DMN). In the non-seizure-freedom group, the trFC between the hippocampus and bilateral brain networks was attenuated (p < .05, familywise error corrected). For the gPPI analysis, group differences were mainly located in the precuneus, middle frontal gyrus, and inferior parietal lobule (p < .001, uncorrected; k ≥ 10). The regression model presented high accuracy when predicting non-seizure-free patients (area under the curve = .879, 95% confidence interval = .761-.998).

SIGNIFICANCE

In patients with TLE who would not achieve seizure freedom with current antiseizure medications, the functional connectivity between the hippocampus and central nodes of the DMN, CCN, and language network was disrupted, leading to language decline. Independent of hippocampal sclerosis, abnormalities, especially the effective connectivity from the hippocampus to the DMN, were predictive biomarkers of drug responsiveness in patients with TLE.

Functional magnetic resonance imaging based on Chinese tasks to protect language function in epileptics

OBJECTIVE

To evaluate the efficacy of functional magnetic resonance imaging (fMRI) based on Chinese tasks to protect the language function in epileptics.

MATERIALS AND METHODS

A total of 34 native Chinese patients with epilepsy were enrolled and examined with BOLD-fMRI scan based on six Chinese tasks. The epileptics were randomly divided into the control group (n = 15) and the experimental group (n = 19). The control group underwent the hollowing and multiple subpial transection operation only based on intraoperative EEG, while the experimental group was under notification of task-state fMRI results in addition. Whereafter, the language ability of patients was evaluated by ABC assessment.

RESULTS

The brain regions related to Chinese function activated by different tasks were remarkably distinct and mainly concentrated in the temporal lobe and frontal lobe. In ontoanalysis, the activation signals of the fusiform gyrus, parahippocampal gyrus, hippocampus, and precentral gyrus were generally low or even could not be detected. Unlike ontoanalysis, group analysis showed that the main effect regions of AN and PN task were in right superior temporal gyrus. The main effect regions of FF and VFC task were in right middle temporal gyrus. The main effect region of SF task was in left superior temporal gyrus. The main effect region of VFL task was in right middle frontal gyrus. The ABC assessment score of the control group 6 months after surgery was significantly lower than that 1 week before surgery (p < .05), while there was no significant difference in the experimental group, and the score of the experimental group was higher than that of the control group.

CONCLUSION

In the surgical treatment of epilepsy, a personalized surgical plan, based on task-state fMRI and intraoperative EEG, can be developed according to the difference of activation areas to protect the language function and improve the quality of life in postoperative patients.

Cortical auditory evoked potentials and hemispheric specialization of speech in individuals with learning disability and healthy controls: A preliminary study

Background: Dichotic listening (DL) technique is a behavioral non-invasive tool which is used in studying hemispheric lateralization. Previous studies using behavioral DL have hypothesized that individuals with learning disabilities (LD) exhibit a lack of cortical specialization for processing speech stimulus. However, there is no event related potential (ERP) evidence, hence the main objective of the study is to explore hemispheric asymmetry using cortical auditory evoked potential (CAEPs) in normal hearing adults and also to compare the same in children with LD and healthy controls.

Methods: CAEPs were recorded in 16 normal hearing young adults, eight right-handed children with LD and their age matched controls. Two stop constants (/Pa/ – voiceless, bilabial, stop: /Ta/ - voiceless, alveolar, stop) were chosen for this experiment and presented in each ear and dichotically in two different orders (/pa-ta/, /ta-pa/). ERPs were processed using a standard pipeline, and electrodes readings over the left and right hemispheres were averaged to create left and right regions of interest (ROI). The CAEPs were analyzed for mean amplitude and peak latency of P1-N1-P2 components.

Results: The current study results suggest no statistically significant difference between the two stimulus in monaural condition and absence of order effect in dichotic condition. In healthy controls the CAEP latencies were shorter over the left hemisphere in both monaural and dichotic conditions in adults and control children. However, it was very evident that such a difference was lacking in children with LD.

Conclusions: Hemispheric asymmetry can be detected using CAEPs for speech stimulus. The measures are consistent and void of stimulus or order effect. Taken together, the findings of current study, both monaural and dichotic condition illustrates the hemispheric differences in processing speech stimuli in normal hearers. Absence of latency differences between hemispheres in children with LD indicate a lack of hemispheric asymmetry.

Clinical characteristics of cognitive impairment in patients with Parkinson's disease and its related pattern in 18 F-FDG PET imaging

This study aimed to characterize the clinical features and the related cerebral glucose metabolism pattern of cognitive impairments in Parkinson's disease (PD) with positron emission tomography (PET) imaging. We recruited 168 PD patients and 100 age-matched healthy controls of similar education and gender distribution. All of those enrolled underwent clinical assessment including the unified Parkinson's disease rating scale motor score, Hoehn and Yahr scale, and comprehensive neuropsychological tests including domains of executive function, attention, memory, visuospatial function, and language. Demographics and the results of cognitive measures were compared between patients and healthy controls. Cognition status was classified as PD patients with dementia (PD-D), PD patients with mild cognitive impairment (PD-MCI), or PD patients with normal cognition (PD-NC). In 53 PD patients who underwent ¹⁸ F-fluorodeoxyglucose (¹⁸ F-FDG) PET imaging, correlations between Z-score values of the different cognitive domains and cerebral ¹⁸ F-FDG uptake were assessed using statistical parametric mapping (SPM8) corrected for age and motor severity. A total of 23.2% of PD patients were PD-MCI and 8.9% were PD-D. In the group of PD-MCI, 96.3% showed multiple-domain deficits, with executive function and attention impairment most predominantly involved. All the cognitive domain scores with the exception of language correlated with ¹⁸ F-FDG metabolisms, primarily in posterior temporo-parieto-occipital association cortical areas. This study found that cognitive impairment in PD particularly encompasses frontal/executive deficits. Posterior cortical areas, containing multiple neurotransmitters and neural circuits, may play an important role in the pathogenesis of cognitive impairment in PD.

Mandarin functional MRI Language paradigms

OBJECTIVE

The objective of this study was to implement convenient, fast, and accurate Mandarin task paradigms for functional MRI, and to locate the Chinese language functional areas in frontal and temporal lobes.

MATERIALS AND METHODS

Nineteen healthy Chinese volunteers participated in this study, which utilized a block design with four language tasks: auditory naming (AN), picture naming (PN), verbal fluency-character (VFC), and verbal fluency-letter (VFL). All functional images were preprocessed by SPM 8, followed by first- and second-level analyses and lateralization index calculation.

RESULTS

Group analyses showed that for AN and PN, maximal responses were located in the right superior temporal gyrus. The picture naming-scrambled pictures and faces contrast gave maximal responses in the left fusiform gyrus; VFC in the left middle frontal gyrus and the left superior frontal gyrus. For VFL the maximal response was in the left superior temporal gyrus. There was some inconsistency of activations for individual subjects. At a threshold of Z > 2.5, 10 voxels extent, activations were seen in >50% subjects for AN in the right superior temporal gyrus, the right middle frontal gyrus, and the left middle temporal gyrus, for PN in the right superior temporal gyrus and for picture naming-scrambled pictures and faces in left inferior frontal gyrus. As a group, the lateralization index of all contrasts were left hemisphere dominant in the frontal lobes. In the temporal lobe, the hemispheric dominance differed for different contrasts.

CONCLUSION

These Chinese language stimulus paradigms activated language areas, and the functional regions of brain in different language tasks, and can now be piloted in clinical studies.