The ascending arousal system shapes neural dynamics to mediate awareness of cognitive states

Abstract

Models of cognitive function typically focus on the cerebral cortex and hence overlook functional links to subcortical structures. This view does not consider the role of the highly-conserved ascending arousal system’s role and the computational capacities it provides the brain. We test the hypothesis that the ascending arousal system modulates cortical neural gain to alter the low-dimensional energy landscape of cortical dynamics. Here we use spontaneous functional magnetic resonance imaging data to study phasic bursts in both locus coeruleus and basal forebrain, demonstrating precise time-locked relationships between brainstem activity, low-dimensional energy landscapes, network topology, and spatiotemporal travelling waves. We extend our analysis to a cohort of experienced meditators and demonstrate locus coeruleus-mediated network dynamics were associated with internal shifts in conscious awareness. Together, these results present a view of brain organization that highlights the ascending arousal system’s role in shaping both the dynamics of the cerebral cortex and conscious awareness.

Genetic polymorphisms in COMT and BDNF influence synchronization dynamics of human neuronal oscillations

“…i.e., with greater net excitatory drive or neuronal gain 51 . This is in accordance with the framework in which neuromodulatory drive influences whole-brain neural states 90,91 .…”

Increased fMRI connectivity upon chemogenetic inhibition of the mouse prefrontal cortex

“…However, the neural mechanisms linking regional brain activity to large-scale rsfMRI network connectivity remain unclear. For example, growing experimental evidence suggests that, while tightly constrained by underlying anatomy, rsfMRI connectivity may only partially reflect direct interactions between areas, as widespread BOLD signal modulation might arise via subcortical connections, whether through the thalamus via long-range loops 11 , or as a result of diffuse neuromodulation mediated by brainstem nuclei 12 , 13 . This notion is epitomized by the observation of intact rsfMRI coupling among brain regions not directly structurally connected as in the case of acallosal humans, primates, and rodents 7 , 14 , 15 .…”

Symmetry breaking organizes the brain's resting state manifold

“…An intriguing direction for the extension of the framework presented here is in more refined inclusion of the subcortical structures. Notably, recent works (Shine, 2020;Müller et al, 2020;Munn et al, 2021) exploring the role of thalamus, locus coeruleus, and basal nucleus of Meynert in shaping of the dynamical landscape of the cortical activity are already formulated in the dynamical systems language while incorporating carefully the detailed anatomical and cytoarchitectural knowledge. Integrating these advances in the SFM framework is a natural next step towards the original motivation of SFM, that is to link the mesoscopic neuronal activity to the behaviour, as the intricate interactions between cortex and the subcortical areas are one of the organizing principles of the underlying the biological mechanisms supporting behaviour (Cisek, 2019).…”