It has been suggested that resting-state functional magnetic resonance imaging (RS-fMRI) is a promising tool to study the relation between spontaneous brain activity and behavioral performance. ...However, little is known about whether the local synchronization of spontaneous brain activity could predict response inhibition. In the current study, we used regional homogeneity (ReHo) to measure the local synchronization of RS-fMRI signals, and then investigated the relationship between ReHo and individual differences in response inhibition, as evaluated by the stop signal reaction time (SSRT) in a Stop signal task. The results showed that ReHo of RS-fMRI signals could successfully predict SSRT. Specifically, positive ReHo-SSRT correlations were observed in the bilateral inferior frontal cortex (IFC) and three critical components of the default mode network (DMN), and negative ReHo-SSRT correlations were observed in the rolandic area/posterior insula and the bilateral middle occipital cortex. The present results indicate the possible influence of the IFC and rolandic area/posterior insula on the efficiency of response inhibition, and demonstrate the importance of the DMN for the efficiency of cognitive task performance.
► Individual variation in inhibition was analyzed based on resting fMRI (RS-fMRI). ► Inhibition abilities were evaluated by the stop signal reaction time (SSRT). ► The spontaneous activity was evaluated by regional homogeneity (ReHo) of RS-fMRI. ► Significant ReHo-SSRT relationships were found in the IFC and default mode network. ► The IFC and default mode network may influence the efficiency of inhibition.
Conceptual processing is a crucial brain function for humans. Past research using neuropsychological and task-based functional brain-imaging paradigms indicates that widely distributed brain regions ...are related to conceptual processing. Here, we explore the potential contribution of intrinsic or spontaneous brain activity to conceptual processing by examining whether resting-state functional magnetic resonance imaging (rs-fMRI) signals can account for individual differences in the conceptual processing efficiencies of healthy individuals. We acquired rs-fMRI and behavioral data on object conceptual processing tasks. We found that the regional amplitude of spontaneous low-frequency fluctuations in the blood oxygen level-dependent signal in the left (posterior) middle temporal gyrus (LMTG) was highly correlated with participants' semantic processing efficiency. Furthermore, the strength of the functional connectivity between the LMTG and a series of brain regions-the left inferior frontal gyrus, bilateral anterior temporal lobe, bilateral medial temporal lobe, posterior cingulate gyrus, and ventromedial and dorsomedial prefrontal cortices-also significantly predicted conceptual behavior. The regional amplitude of low-frequency fluctuations and functionally relevant connectivity strengths of LMTG together accounted for 74% of individual variance in object conceptual performance. This semantic network, with the LMTG as its core component, largely overlaps with the regions reported in previous conceptual/semantic task-based fMRI studies. We conclude that the intrinsic or spontaneous activity of the human brain reflects the processing efficiency of the semantic system.
Recent functional imaging studies have indicated that the pathophysiology of Alzheimer’s disease (AD) can be associated with the changes in spontaneous low-frequency (<0.08 Hz) blood oxygenation ...level-dependent fluctuations (LFBF) measured during a resting state. The purpose of this study was to examine regional LFBF coherence patterns in early AD and the impact of regional brain atrophy on the functional results. Both structural MRI and resting-state functional MRI scans were collected from 14 AD subjects and 14 age-matched normal controls. We found significant regional coherence decreases in the posterior cingulate cortex/precuneus (PCC/PCu) in the AD patients when compared with the normal controls. Moreover, the decrease in the PCC/PCu coherence was correlated with the disease progression measured by the Mini-Mental State Exam scores. The changes in LFBF in the PCC/PCu may be related to the resting hypometabolism in this region commonly detected in previous positron emission tomography studies of early AD. When the regional PCC/PCu atrophy was controlled, these results still remained significant but with a decrease in the statistical power, suggesting that the LFBF results are at least partly explained by the regional atrophy. In addition, we also found increased LFBF coherence in the bilateral cuneus, right lingual gyrus and left fusiform gyrus in the AD patients. These regions are consistent with previous findings of AD-related increased activation during cognitive tasks explained in terms of a compensatory-recruitment hypothesis. Finally, our study indicated that regional brain atrophy could be an important consideration in functional imaging studies of neurodegenerative diseases.
There has been growing interest recently in the use of multivariate pattern analysis (MVPA) to decode information from high-dimensional neuroimaging data. The present study employed a support vector ...machine-based MVPA approach to identify the complex patterns of sex differences in brain structure and resting-state function. We also aimed to assess the role of anatomy on functional sex differences during rest. One hundred and forty healthy young Chinese adults (70 men and 70 women) underwent structural and resting-state functional MRI scans. Gray matter density and regional homogeneity (ReHo) were used to map brain structure and resting-state function, respectively. After combining these two feature vectors into one union-vector, a pattern classifier was designed using principal component analysis and linear support vector machine to identify brain areas that had distinct characteristics between the groups. We found that: (1) male and female brains were different with a mean classification accuracy of 89%; (2) sex differences in gray matter density were widely distributed in the brain, notably in the occipital lobe and the cerebellum; (3) men primarily showed higher ReHo in their right hemispheres and women tended to show greater ReHo in their left hemispheres; (4) about 50% of brain areas with functional sex differences exhibited significant positive correlations between gray matter density and ReHo. Our results suggest that sex is an important factor that account for interindividual variability in the healthy brain.
Numerous studies argue that cortical reorganization may contribute to the restoration of motor function following stroke. However, the evolution of changes during the post-stroke reorganization has ...been little studied. This study sought to identify dynamic changes in the functional organization, particularly topological characteristics, of the motor execution network during the stroke recovery process. Ten patients (nine male and one female) with subcortical infarctions were assessed by neurological examination and scanned with resting-state functional magnetic resonance imaging across five consecutive time points in a single year. The motor execution network of each subject was constructed using a functional connectivity matrix between 21 brain regions and subsequently analysed using graph theoretical approaches. Dynamic changes in topological configuration of the network during the process of recovery were evaluated by a mixed model. We found that the motor execution network gradually shifted towards a random mode during the recovery process, which suggests that a less optimized reorganization is involved in regaining function in the affected limbs. Significantly increased regional centralities within the network were observed in the ipsilesional primary motor area and contralesional cerebellum, whereas the ipsilesional cerebellum showed decreased regional centrality. Functional connectivity to these brain regions demonstrated consistent alterations over time. Notably, these measures correlated with different clinical variables, which provided support that the findings may reflect the adaptive reorganization of the motor execution network in stroke patients. In conclusion, the study expands our understanding of the spectrum of changes occurring in the brain after stroke and provides a new avenue for investigating lesion-induced network plasticity.
The characterization of topological architecture of complex brain networks is one of the most challenging issues in neuroscience. Slow (<0.1 Hz), spontaneous fluctuations of the blood oxygen level ...dependent (BOLD) signal in functional magnetic resonance imaging are thought to be potentially important for the reflection of spontaneous neuronal activity. Many studies have shown that these fluctuations are highly coherent within anatomically or functionally linked areas of the brain. However, the underlying topological mechanisms responsible for these coherent intrinsic or spontaneous fluctuations are still poorly understood. Here, we apply modern network analysis techniques to investigate how spontaneous neuronal activities in the human brain derived from the resting-state BOLD signals are topologically organized at both the temporal and spatial scales. We first show that the spontaneous brain functional networks have an intrinsically cohesive modular structure in which the connections between regions are much denser within modules than between them. These identified modules are found to be closely associated with several well known functionally interconnected subsystems such as the somatosensory/motor, auditory, attention, visual, subcortical, and the "default" system. Specifically, we demonstrate that the module-specific topological features can not be captured by means of computing the corresponding global network parameters, suggesting a unique organization within each module. Finally, we identify several pivotal network connectors and paths (predominantly associated with the association and limbic/paralimbic cortex regions) that are vital for the global coordination of information flow over the whole network, and we find that their lesions (deletions) critically affect the stability and robustness of the brain functional system. Together, our results demonstrate the highly organized modular architecture and associated topological properties in the temporal and spatial brain functional networks of the human brain that underlie spontaneous neuronal dynamics, which provides important implications for our understanding of how intrinsically coherent spontaneous brain activity has evolved into an optimal neuronal architecture to support global computation and information integration in the absence of specific stimuli or behaviors.
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DOBA, IZUM, KILJ, NUK, PILJ, PNG, SAZU, SIK, UILJ, UKNU, UL, UM, UPUK
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