Purpose: The Spinal cord and brain form the human central nervous system which is to control the majority of the functions of both the body and the mind. The brain interprets all of the information we receive from the senses and internal organs, processes them, and then tells our body how to react. The spinal cord is the main conduit between the brain and the body. Many functional MRI studies of brain have discovered that temporally coherent spontaneous fluctuations constitute several anatomically consistent “resting state networks” (RSNs), such as visual, auditory, sensory-motor, executive control, and default mode networks [1, 2]. In addition, very recent studies have also detected intrinsic functional circuits in human spines using resting-state fMRI [3, 4]. Especially, sensory and motor messages are relayed by the spinal cord and processed by the brain. However, it still remains unknown that whether rsFCs are synchronous within brain and spinal cord. The present study aimed to better understand the relationship between rsFCs within the brain and the spinal cord using resting-state fMRI. Methods: Sixteen typical youth (eight females, 22.3± 2.7 years) participated in this study. Subjects provided written informed consent prior to the experiment, and all procedures were approved to be in accordance with the Institutional Review Board of Xijing Hospital. All subjects were scanned on a 3-Tesla GE Discovery 750 MRI scanner at the Xijing Hospital. Whole-brain anatomical images were acquired using a 3D Fast SPGR scan (188 sagittal slices, resolution 1 mm x 1 mm x 1 mm). Resting-state functional MRI images were acquired using an EPI sequence (32 slices, 3.44 mm x 3.44 mm x 4mm, TR=2s, 180 volumes). The spinal cord anatomical images were acquired using a MPRAGE sequence (16 slices, 1 mm x 1mm x 1mm, covering vertebrae C4-C7). Resting state spinal cord fMRI data were acquired with GE-EPI sequence (16 slices, 1.25 mm x 1.25 mm x 5 mm, 180 volumes). The brain fMRI images were preprocessed using SPM toolbox (www.fil.ion.ucl.ac.uk/spm/). EPI volumes were performed in turn removal of the first three volumes, slice-timing correction, spatial realignment, normalization to the MNI 152 standard space, and smoothed using an isotropic 6-mm Gaussian kernel. A high-pass filter with a cutoff period of 128s was applied to remove low frequency noise possibly containing scanner drift. For spinal cord images, spatial preprocessing were performed with Spinal Cord Toolbox (http://sourceforge.net/projects/spinalcordtoolbox/), including spinal cord segmentation, making mask, motion correction and realignment, and 8-mm Gaussian kernel smoothing. A group ICA was then performed within the spinal cord area (using 20 independent components (ICs)) and whole-brain area (using 60 ICs) respectively to obtain IC spatial maps (p<0.05, FDR corrected). RSNs of interest within spinal cord and brain were selected visually, based on their anatomical location. Results: In the cord IC spatial maps, 3 ICs (scIC1-scIC3) were identified for ventral and dorsal RSNs. The ventral networks were predominantly bilateral, whereas dorsal networks were predominantly unilateral (fig. 1). The results confirmed previous fMRI findings, of which a bilateral activation during motor tasks [3] and a clearly lateralized activation during painful sensory stimulation [5]. In the brain ICs spatial maps, 4 ICs (bIC1-bIC4) were identified for sensory-motor RSNs (fig. 2). Interestingly, ICs within spinal cord ventral RSNs significantly correlate with brain motor RSNs, and ICs within spinal cord dorsal RSNs significantly correlate with brain sensory RSNs, which indicate that sensory and motor information are transferred by different nerve tracts to corresponding brain regions and processed (Tab. 1). Discussion: Our results showed that spinal cord RSNs were separated into distinct dorsal and ventral RSNs, this separation can reflect the features of functional neuroanatomy of the spinal cord. The dorsal cord processes the sensory information and the ventral cord processes the motor information. In addition, the ventral cord activates bilaterally and the dorsal cord activates unilateral, which mean that human movement involve whole body, but sensory signal can be perceived and processed by the way of unilateral body. The results of significant correlations between sensory-motor RSNs and dorsal and ventral cord suggest that the spontaneous fluctuations of brain and spinal cord are precisely synchronized and readying for sensory-motor signal relaying and processing. Conclusions: In this study, we demonstrated that features of RSNs represent the functional neuroanatomy of spinal cord and a synchronizing network between spinal cord and brain are existing and readying for sensory-motor information perceiving and processing. Our results suggest that investigation of RSNs of spinal cord and its correlation with brain can improve the understanding of the nature of the entire central nervous system.