Simultaneous deep brain stimulation (DBS) and functional magnetic resonance imaging (fMRI) constitutes a powerful tool for elucidating brain functional connectivity, and exploring neuromodulatory mechanisms of DBS therapies. Previous DBS-fMRI studies could not provide full activation pattern maps due to poor MRI compatibility of the DBS electrodes, which caused obstruction of large brain areas on MRI scans. Here, we fabricate graphene fiber (GF) electrodes with high charge-injection-capacity and little-to-no MRI artifact at 9.4T. DBS-fMRI with GF electrodes at the subthalamic nucleus (STN) in Parkinsonian rats reveal robust blood-oxygenation-level-dependent responses along the basal ganglia-thalamocortical network in a frequency-dependent manner, with responses from some regions not previously detectable. This full map indicates that STN-DBS modulates both motor and non-motor pathways, possibly through orthodromic and antidromic signal propagation. With the capability for full, unbiased activation pattern mapping, DBS-fMRI using GF electrodes can provide important insights into DBS therapeutic mechanisms in various neurological disorders.

No abstract

No abstract

Comprehensive integration of structural and functional connectivity data is required to model brain functions accurately. While resources for studying the structural connectivity of non-human primate brains already exist, their integration with functional connectivity data has remained unavailable. Here we present a comprehensive resource that integrates the most extensive awake marmoset resting-state fMRI data available to date (39 marmoset monkeys, 710 runs, 12117 mins) with previously published cellular-level neuronal tracing data (52 marmoset monkeys, 143 injections) and multi-resolution diffusion MRI datasets. The combination of these data allowed us to (1) map the fine-detailed functional brain networks and cortical parcellations, (2) develop a deep-learning-based parcellation generator that preserves the topographical organization of functional connectivity and reflects individual variabilities, and (3) investigate the structural basis underlying functional connectivity by computational modeling. This resource will enable modeling structure-function relationships and facilitate future comparative and translational studies of primate brains.

The discovery of functional gradients introduce a new perspective in understanding the cortical spectrum of intrinsic dynamics, as it captures major axes of functional connectivity in low-dimensional space. However, how functional gradients arise and dynamically vary remains poorly understood. In this study, we investigated the biological basis of functional gradients using awake resting-state fMRI, retrograde tracing and gene expression datasets in marmosets. We found functional gradients in marmosets showed a sensorimotor-to-visual principal gradient followed by a unimodal-to-multimodal gradient, resembling functional gradients in human children. Although strongly constrained by structural wirings, functional gradients were dynamically modulated by arousal levels. Utilizing a reduced model, we uncovered opposing effects on gradient dynamics by structural connectivity (inverted U-shape) and neuromodulatory input (U-shape) with arousal fluctuations, and dissected the contribution of individual neuromodulatory receptors. This study provides insights into biological basis of functional gradients by revealing the interaction between structural connectivity and ascending neuromodulatory system.

No abstract

Functional magnetic resonance imaging (fMRI) has been increasingly utilized in mice. Due to the non-negligible effects of anesthetics on mouse fMRI, it is becoming more common to perform fMRI in the awake mice. However, high stress level and head motion in awake mouse fMRI remain to be fully addressed, which limits its practical applications. Therefore, here we presented a systematically optimized awake mouse fMRI paradigm as a practical and open-source solution. First, we designed a soundproof habituation chamber in which multiple mice can be habituated simultaneously and independently. Then, combining corticosterone, body weight and behavioral measurements, we systematically evaluated the potential factors that may contribute to animals' stress level for awake imaging. Among many factors, we found that the restraining setup allowing forelimbs freely moving and head tilted at 30-degree was optimal for minimizing stress level. Importantly, we implemented multiband simultaneous multi-slice imaging to enable ultrafast fMRI acquisition in awake mice. Compared to conventional single-band EPI, faster acquisition enabled by multiband imaging were more robust to head motion and yielded higher statistical power. Thus, more robust resting-state functional connectivity was detected using multiband acquisition in awake mouse fMRI, compared to conventional single-band acquisition. In conclusion, we presented an awake mouse fMRI paradigm that is highly optimized in both awake mice habituation and fMRI acquisition, and such paradigm minimized animals' stress level and provided more resistance to head motion and higher statistical power. Keywords: awake mice, fMRI, stress level, head motion, simultaneous multi-slice.

The comprehensive integration of structural and functional connectivity data is required for the accurate modeling of brain functions. While resources for studying structural connectivity of non-human primate marmoset brains already exist, their integration with functional connectivity data has remained unavailable. Therefore, we present a comprehensive resource for marmoset brain mapping, which integrates the largest awake resting-state fMRI dataset to date (39 marmosets, 709 runs, and 12053 mins), cellular- level neuronal-tracing dataset (52 marmosets and 143 injections), and multi-resolution diffusion MRI dataset. The combination of these data into the same MRI space allowed us to 1). map the fine-detailed functional networks and cortical parcellations; 2). develop a deep-learning-based parcellation generator to preserve the topographical organization of functional connectivity and reflect individual variabilities; 3). investigate the structural basis underlying functional connectivity by computational modeling. Our resource will broadly model the marmoset brain architecture and facilitate future comparative and translational studies of primate brains.