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Task-free functional connectivity in animal models provides an experimental framework to examine connectivity phenomena under controlled conditions and allows for comparisons with data modalities collected under invasive or terminal procedures. Currently, animal acquisitions are performed with varying protocols and analyses that hamper result comparison and integration. Here we introduce StandardRat, a consensus rat functional magnetic resonance imaging acquisition protocol tested across 20 centers. To develop this protocol with optimized acquisition and processing parameters, we initially aggregated 65 functional imaging datasets acquired from rats across 46 centers. We developed a reproducible pipeline for analyzing rat data acquired with diverse protocols and determined experimental and processing parameters associated with the robust detection of functional connectivity across centers. We show that the standardized protocol enhances biologically plausible functional connectivity patterns relative to previous acquisitions. The protocol and processing pipeline described here is openly shared with the neuroimaging community to promote interoperability and cooperation toward tackling the most important challenges in neuroscience., (© 2023. The Author(s), under exclusive licence to Springer Nature America, Inc.)

Homotopic functional connectivity reflects the degree of synchrony in spontaneous activity between homologous voxels in the two hemispheres. Previous studies have associated increased brain homotopy and decreased white matter integrity with performance decrements on different cognitive tasks across the life-span. Here, we correlated functional homotopy, both at the whole-brain level and specifically in fronto-parietal network nodes, with task-switching performance in young adults. Cue-to-target intervals (CTI: 300 vs. 1200 ms) were manipulated on a trial-by-trial basis to modulate cognitive demands and strategic control. We found that mixing costs, a measure of task-set maintenance and monitoring, were significantly correlated to homotopy in different nodes of the fronto-parietal network depending on CTI. In particular, mixing costs for short CTI trials were smaller with lower homotopy in the superior frontal gyrus, whereas mixing costs for long CTI trials were smaller with lower homotopy in the supramarginal gyrus. These results were specific to the fronto-parietal network, as similar voxel-wise analyses within a control language network did not yield significant correlations with behavior. These findings extend previous literature on the relationship between homotopy and cognitive performance to task-switching, and show a dissociable role of homotopy in different fronto-parietal nodes depending on task demands., (© 2021. The Author(s).)

The first postnatal year is characterized by the most dramatic functional network development of the human lifespan. Yet, the relative sequence of the maturation of different networks and the impact of socioeconomic status (SES) on their development during this critical period remains poorly characterized. Leveraging a large, normally developing infant sample with multiple longitudinal resting-state functional magnetic resonance imaging scans during the first year (N = 65, scanned every 3 months), we aimed to delineate the relative maturation sequence of 9 key brain functional networks and examine their SES correlations. Our results revealed a maturation sequence from primary sensorimotor/auditory to visual to attention/default-mode, and finally to executive control networks. Network-specific critical growth periods were also identified. Finally, marginally significant positive SES-brain correlations were observed at 6 months of age for both the sensorimotor and default-mode networks, indicating interesting SES effects on functional brain maturation. To the best of our knowledge, this is the first study delineating detailed longitudinal growth trajectories of all major functional networks during the first year of life and their SES correlations. Insights from this study not only improve our understanding of early brain development, but may also inform the critical periods for SES expression during infancy., (© The Author 2014. Published by Oxford University Press. All rights reserved. For Permissions, please e-mail: journals.permissions@oup.com.)

Although commonly viewed as a sensory information relay center, the thalamus has been increasingly recognized as an essential node in various higher-order cognitive circuits, and the underlying thalamocortical interaction mechanism has attracted increasing scientific interest. However, the development of thalamocortical connections and how such development relates to cognitive processes during the earliest stages of life remain largely unknown. Leveraging a large human pediatric sample (N = 143) with longitudinal resting-state fMRI scans and cognitive data collected during the first 2 years of life, we aimed to characterize the age-dependent development of thalamocortical connectivity patterns by examining the functional relationship between the thalamus and nine cortical functional networks and determine the correlation between thalamocortical connectivity and cognitive performance at ages 1 and 2 years. Our results revealed that the thalamus-sensorimotor and thalamus-salience connectivity networks were already present in neonates, whereas the thalamus-medial visual and thalamus-default mode network connectivity emerged later, at 1 year of age. More importantly, brain-behavior analyses based on the Mullen Early Learning Composite Score and visual-spatial working memory performance measured at 1 and 2 years of age highlighted significant correlations with the thalamus-salience network connectivity. These results provide new insights into the understudied early functional brain development process and shed light on the behavioral importance of the emerging thalamocortical connectivity during infancy., (Copyright © 2014 the authors 0270-6474/14/349067-09$15.00/0.)

The neurophysiological mechanism underlying sedation, especially in school-aged children, remains largely unknown. The recently emerged resting-state functional magnetic resonance imaging (rsfMRI) technique, capable of delineating brain's functional interaction pattern among distributed brain areas, proves to be a unique and powerful tool to study sedation-induced brain reorganization. Based on a relatively large school-aged children population (n=28, 10.3±2.6 years, range 7-15 years) and leveraging rsfMRI and graph theoretical analysis, this study aims to delineate sedation-induced changes in brain's information transferring property from a whole brain system perspective. Our results show a global deterioration in brain's efficiency properties (p=0.0085 and 0.0018, for global and local efficiency, respectively) with a locally graded distribution featuring significant disruptions of key consciousness-related regions. Moreover, our results also indicate a redistribution of brain's information-processing hubs characterized by a right and posterior shift as consistent with the reduced level of consciousness during sedation. Overall, our findings inform a sedation-induced functional reorganization pattern in school-aged children that greatly improve our understanding of sedation's effect in children and may potentially serve as reference for future sedation-related experimental studies and clinical applications.

Resting state networks such as the default mode network have been widely reported. Although a plethora of information on its functional relevance has been generated, little is known about lateralization or hemisphere asymmetry within the DMN. We used high-resolution resting state fMRI and T1 3D data to investigate such asymmetries in two groups of healthy subjects, one right-handed and one left-handed. Independent component analysis and the dual regression approach were carried out to identify functional asymmetries, while voxel-based morphometry was used to identify structural asymmetries in grey matter volume within the DMN. Greater leftward functional connectivity was observed in the posterior cingulate gyrus (PCG) for both groups. Leftward functional asymmetry was observed in the thalamus and rightward functional asymmetries were observed in the middle frontal and middle/superior temporal gyrus in the right-handed group. Rightward asymmetries in grey matter volume were observed in the posterior portion of the PCG for both groups. The right-handed group exhibited leftward structural asymmetries in the anterior portion of the PCG and in the middle frontal and posterior portion of the middle temporal gyrus, while rightward asymmetries were observed in the posterior portion of the PCG and anterior portions of temporal regions. These results suggest that functional connectivity and grey matter volume are not equally distributed between hemispheres within the DMN, and that functional asymmetries are not always reflected or determined by structural asymmetries., (Copyright © 2012 Elsevier Ltd. All rights reserved.)