“The great mixing machine”: multisensory integration and brain-breath coupling in the cerebral cortex

Abstract

It is common to distinguish between "holist" and "reductionist" views of brain function, where the former envisions the brain as functioning as an indivisible unit and the latter as a collection of distinct units that serve different functions. Opposing reductionism, a number of researchers have pointed out that cortical network architecture does not respect functional boundaries, and the neuroanatomist V. Braitenberg proposed to understand the cerebral cortex as a "great mixing machine" of neuronal activity from sensory inputs, motor commands, and intrinsically generated processes. In this paper, we offer a contextualization of Braitenberg's point, and we review evidence for the interactions of neuronal activity from multiple sensory inputs and intrinsic neuronal processes in the cerebral cortex. We focus on new insights from studies on audiovisual interactions and on the influence of respiration on brain functions, which do not seem to align well with "reductionist" views of areal functional boundaries. Instead, they indicate that functional boundaries are fuzzy and context dependent. In addition, we discuss the relevance of the influence of sensory, proprioceptive, and interoceptive signals on cortical activity for understanding brain-body interactions, highlight some of the consequences of these new insights for debates on embodied cognition, and offer some suggestions for future studies.

Body and mind: how somatic feedback signals shape brain activity and cognition

“…In this Special Issue, Folschweiller and Sauer [12] describe how respiration entrains frontal cortical networks such that the formation and activation of neuronal assemblies is supported. Heck and Varga [17] provide an even broader framework for distributed brain activity which suggests that external (sensory) and internal (proprio-or interoceptive) signals contribute to the distributed, yet context-dependent activity patterns of the brain enabling adapted behavior. This view may posit somatic feedback in a much wider, integrative concept of physiology within the tradition of embodied cognition [3].…”

“…The Special Issue unites four comprehensive reviews on somatic feedback signals and brain function, covering its potential cognitive-behavioral significance [12,17], the role of slow (respiratory) nasal feedback signals for brain dynamics [19] and the role of rhythmic oxygen pressure oscillations for potential neuronal effects of respiration [39]. Five original articles address specific effects of respiration on gamma oscillations [14], the state-dependence of respiration-cortical activity coupling [18], entrainment of brainstem neurons of the reticular formation by cardiac activity Kocsis and Topchyi [23], the molecular mechanisms linking hypoxia-mediated activation of carotid bodies to increased ventilation [25] and a new neuromodulatory effect on respiratory rhythm generation in brainstem networks by the peptide bombesin [27].…”