Official websites use. Share sensitive information only on official, secure websites. Email: Danilo. Bzdok mcgill. The default mode network DMN is believed to subserve the baseline mental activity in humans. Its higher energy consumption compared to other brain networks and its intimate coupling with conscious awareness are both pointing to an unknown overarching function.
Many research streams speak in favor of an evolutionarily adaptive role in envisioning experience to anticipate the future. In the present work, we propose a process model that tries to explain how the DMN may implement continuous evaluation and prediction of the environment to guide behavior. The main purpose of DMN activity, we argue, may be described by Markov decision processes that optimize action policies via value estimates through vicarious trial and error.
Our formal perspective on DMN function naturally accommodates as special cases previous interpretations based on a predictive coding, b semantic associations, and c a sentinel role. Moreover, this process model for the neural optimization of complex behavior in the DMN offers parsimonious explanations for recent experimental findings in animals and humans.
In the absence of external stimulation, the human brain is not at rest. At its opposite, during sleep, the decoupling of brain structures discarded the idea of the DMN being only a passive network resonance and rather supported an important role in sustaining conscious awareness Horovitz et al. This dark matter of brain physiology Raichle, begs the question of the biological purpose underlying neural activity in the DMN. Its time dynamics, however, still remain elusive at the electrophysiological level Baker et al.
Axonal tracing injection in such parts of the association cortex in monkeys were shown to resemble connectivity links between nodes of the human DMN see here for details on anatomical connections: [Buckner et al. Additionally, myelination patterns of axon connections were found to complete particularly late in these cortical areas Flechsig, , often believed to reflect sophistication of subserved neural processes Sowell et al.
