Neural signaling is conventionally described through the action potential—a sodium-potassium exchange generating electrical impulse. This model, while mechanistically accurate, treats ions as interchangeable charge carriers and overlooks the distinct functional roles each ion plays in the complete electrochemical architecture of neural computation. This paper proposes the Ion Circuit Hypothesis (ICH): that sodium, chloride, magnesium, calcium, potassium, and water constitute a functionally integrated six-component system in which each element performs a distinct role in the translation between electrochemical signal and biological response. We propose the following functional architecture: Sodium (Na⁺) generates the inward electrochemical gradient that initiates excitatory signaling. Chloride (Cl⁻) provides the inward inhibitory counterpart, hyperpolarizing the membrane and suppressing premature signal propagation. Magnesium (Mg²⁺) serves as the voltage-dependent gatekeeper at NMDA receptors and other critical junctions, preventing premature or inappropriate signal transmission. Calcium (Ca²⁺) functions as the actuator—the ion whose intracellular release drives cellular response, gene transcription, and synaptic plasticity. Potassium (K⁺) provides the outward return current that repolarizes membranes and resets the system. Water (H₂O) serves as the essential medium—the structured solvent that maintains ions in their functional hydrated states and enables the entire circuit to operate. These six components were selected because each performs a direct, non-substitutable role in the signal-to-response chain: no other ion can replicate sodium’s excitatory drive, chloride’s inhibitory counterbalance, magnesium’s voltage-dependent gating, calcium’s actuator function, or potassium’s repolarizing return, and no other molecule provides water’s role as the structuring medium for all five. This framework synthesizes established neurophysiology (Hille, 2001), calcium signaling research (Clapham, 2007), and magnesium biology (de Baaij et al., 2015; Kirkland et al., 2018) into a coherent functional model. The hypothesis proposes that modern environmental and dietary factors systematically disrupt multiple nodes of this circuit simultaneously, and that such multi-node disruption may be synergistic rather than additive—producing effects greater than the sum of individual impairments. Keywords: ion circuit, sodium, chloride, magnesium, calcium, potassium, water, neural signaling, NMDA receptor, GABA-A receptor, electrochemical architecture, inhibition, hydration, Ca:Mg ratio
Rebolledo, Jacinda S., BSN RN (Sat,) studied this question.