The default mode network (DMN) is a set of brain regions important for complex thought and behavior. By combining postmortem tissue analysis and brain scans, researchers found that the DMN contains different types of cells, some specialized for processing single senses, others for combining information, and still others for memory. The DMN includes regions that receive input from sensory areas and a core that is relatively cut off from direct sensory information. Analysis of how signals flow through the DMN showed it uniquely balances output across different levels of sensory processing. These findings provide a structural basis for understanding the DMN's broad role in brain function and cognition.
The brain's default mode network (DMN) contains spatially distinct subregions that support different cognitive processes: some DMN areas are more active during perceptual decisions about faces, while others are more active during memory-guided decisions based on previously seen images. These subregions differ in their connectivity profiles—perception-related areas have receiver-like, afferent-biased connections across the heteromodal cortex, whereas memory-related areas have sender-like, efferent-biased connections with perceptual-motor and attentional systems beyond the DMN. This double dissociation, found across three fMRI datasets, suggests that DMN architecture is organized to flexibly support both external perception and internal memory-guided thought.