A brain network called the default mode network (DMN), previously studied mainly in humans and primates, also exists in rats. The DMN in rats is broadly similar to that in nonhuman primates and humans, suggesting it is a fundamental feature of mammalian brains. The network appears to integrate sensory and emotional information to guide behavior in anticipation of changing environmental conditions, despite the distinct evolutionary paths of rodents and primates. The findings help clarify the DMN's core functions, which remain poorly understood in humans.
The default mode network (DMN), a set of brain regions active at rest, shows higher functional connectivity and stronger low-frequency fluctuations when people keep their eyes open (with or without a fixation point) than when they keep them closed. Although the overall connectivity patterns look similar across conditions, statistical comparisons reveal these differences. An order effect also appears: two eyes-closed sessions differ from each other. These findings suggest that having eyes open during rest may involve more non-specific visual gathering, evaluation, and mind wandering, and that researchers should carefully choose and order resting-state conditions in experimental designs.