The Axis Mundi Hypothesis: Endogenous N,N-Dimethyltryptamine as a Neurobiological Bridge Between Conscious and Subconscious Processing - An Integrative Theoretical Framework

Multiple lines of neuroscientific evidence have converged on a set of closely related findings: the mammalian brain endogenously synthesizes N,N-dimethyltryptamine (DMT) at neurotransmitter-comparable concentrations (Dean et al., 2019); psychedelic compounds suppress the default mode network (DMN) and dissolve ego boundaries (Carhart-Harris et al., 2012; Tagliazucchi et al., 2016); the brain actively suppresses unwanted memories through prefrontal-hippocampal inhibitory gating (Anderson & Green, 2001; Schmitz et al., 2017); psychedelic-induced relaxation of high-level priors permits the surfacing of suppressed content (Carhart-Harris & Friston, 2019); and shared visual phenomenology under DMT is explained by conserved neural architecture (Bressloff et al., 2002). Despite this convergence, no existing theoretical framework integrates these findings into a unified model that explains why the brain produces a psychedelic compound and what function endogenous DMT serves at the level of consciousness. The present paper proposes the Axis Mundi hypothesis: endogenous DMT serves a dual evolutionary function operating across two distinct biological layers. At the cellular layer, DMT acts as an endogenous sigma-1 receptor agonist providing neuroprotection during hypoxic and ischemic stress. At the network layer, DMT modulates the permeability of the conscious-subconscious boundary by acting on 5-HT2A receptors within DMN circuitry, thereby regulating the degree to which subconscious content is accessible to conscious awareness. This dual-function model is synthesized from five pillars of empirical evidence: endogenous DMT biochemistry, DMN neuroimaging, active memory suppression mechanisms, shared visionary neural architecture, and evolutionary receptor conservation. Seven testable predictions are derived from the framework, providing a concrete empirical program for its evaluation.