Brain networks are decoupled from external stimuli during internal cognition

Area of Science:

• Neuroscience
• Cognitive Science

Background:

• Cognition can focus on external stimuli or internal information, like mind-wandering or memory recall.
• Internal cognition is characterized by perceptual decoupling, a state independent of immediate sensory input.
• Brain activity shifts between stimulus-processing and internally-processing modes during these cognitive states, but this has not been directly quantified.

Purpose of the Study:

• To develop and test a framework for quantifying how much brain networks reflect external stimulus processing.
• To investigate the neural basis of perceptual decoupling during internal cognition.

Main Methods:

• Developed a conceptual and analysis framework to measure stimulus processing in brain networks.
• Used functional MRI (fMRI) to measure brain activity in subjects performing external attention tasks versus internal tasks (mental imagery, recall, arithmetic).

Main Results:

• Stimulus responses were generally reduced during internal tasks.
• In some tasks and brain networks, stimulus responses increased, but brain networks became less reflective of stimulus processing overall.
• The new framework quantitatively demonstrated perceptual decoupling during internal cognition.

Conclusions:

• Brain networks become decoupled from external stimuli during internal cognition.
• This provides a quantitative method for understanding the neural mechanisms of internal thought processes.