Abstract
The default-mode network (DMN) is believed to be associated with levels of consciousness, but how the functional connectivity (FC) of the DMN changes across different states of consciousness is still unclear. In the current work, we addressed this issue by exploring the coactive micropattern (CAMP) networks of the DMN according to the CAMPs of rat DMN activity during the sleep-wake cycle and tracking their topological alterations among different states of consciousness. Three CAMP networks were observed in DMN activity, and they displayed greater FC and higher efficiency than the original DMN structure in all states of consciousness, implying more efficient information processing in the CAMP networks. Furthermore, no significant differences in FC or network properties were found among the three CAMP networks in the waking state. However, the three networks were distinct in their characteristics in two sleep states, indicating that different CAMP networks played specific roles in distinct sleep states. In addition, we found that the changes in the FC and network properties of the CAMP networks were similar to those in the original DMN structure, suggesting intrinsic effects of various states of consciousness on DMN dynamics. Our findings revealed three underlying CAMP networks within the DMN dynamics and deepened the current knowledge concerning FC alterations in the DMN during conscious changes in the sleep-wake cycle.
Highlights
Sleep is associated with the fading of consciousness, and it is manifested objectively as a reduction in responsiveness to environmental stimuli [1, 2]
To derive the functional connectivity (FC) networks from rat defaultmode network (DMN) dynamics, we proposed a novel coactive micropattern network (CAMP network) method to construct the FCs among DMN regions based on the coactive micropatterns (CAMPs) from DMN dynamics described in our previous work [29]
Using the phase-locking value (PLV) method, we constructed three CAMP networks from the DMN activity for three different states of consciousness during the sleep-wake cycle based on the CAMPs we described in our prior study
Summary
Sleep is associated with the fading of consciousness, and it is manifested objectively as a reduction in responsiveness to environmental stimuli [1, 2]. Over the past few decades, the changes in functional connectivity (FC) across multiple brain regions during sleep have been recognized as a key issue in investigating the electrophysiological mechanism of consciousness [3,4,5]. Segregated network modules can be observed in deep sleep [9], implying a close relationship between reduced functional integration and the loss of consciousness. One of the most studied brain networks during sleep is the defaultmode network (DMN) [10,11,12], which is believed to be closely related to consciousness and cognitive functions in both humans and animals [13,14,15]. The underlying neural mechanism of the alterations in DMN connectivity during changes in consciousness remains unclear
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