Distant from input: Evidence of regions within the default mode network supporting perceptually-decoupled and...

Area of Science:

• Neuroscience
• Cognitive Neuroscience
• Cognitive Psychology

Background:

• The default mode network (DMN) underpins diverse mental functions like semantic processing, memory retrieval, and mind-wandering.
• The precise commonalities and underlying mechanisms of these DMN functions remain incompletely understood.
• Two prominent hypotheses suggest the DMN supports environment-independent cognition or higher-order conceptual representations.

Purpose of the Study:

• To investigate the functional role of the DMN by manipulating environmental information availability and representational complexity.
• To identify brain regions supporting cognition that integrates stimulus independence with multi-modal information processing.
• To examine the relationship between DMN activity, task demands, and macroscale cortical gradients.

Main Methods:

• A novel experimental paradigm was employed, varying perceptual information availability and representational complexity during decision-making tasks.
• Task-based functional magnetic resonance imaging (fMRI) was utilized to identify task-related neural activity.
• Analysis of macroscale cortical gradients was performed to situate identified regions within the broader functional architecture of the brain.

Main Results:

• Specific regions, including the left and right angular gyri and left middle temporal gyrus, responded to cognition combining stimulus independence and multi-modal information.
• These identified DMN regions showed greater activation during demanding memory judgments compared to simpler perceptual tasks.
• The activated regions were located at the transmodal end of a sensorimotor-to-transmodal cortical gradient.

Conclusions:

• The findings challenge the notion that DMN regions exclusively support automatic cognitive processes.
• Neural activity within the DMN, particularly in transmodal areas, may facilitate the generation of conceptually rich cognitive states detached from immediate sensory input.
• The study highlights the role of the DMN in supporting complex, internally-driven cognition through its position along macroscale cortical gradients.