Radical pairs may play a role in microtubule reorganization

TL;DR

This paper proposes a radical pair model to explain how magnetic fields influence microtubule organization, potentially linking quantum effects to consciousness and anesthesia mechanisms.

Contribution

It introduces a simple radical pair mechanism model that predicts magnetic field effects on microtubule density and isotope-dependent effects of zinc, connecting quantum theories of consciousness.

Findings

Magnetic fields modulate microtubule density via radical pair spin dynamics.

The model reproduces observed magnetic field effects on microtubules.

Predicted isotope-dependent effects of zinc on microtubules.

Abstract

The exact mechanism behind general anesthesia remains an open question in neuroscience. It has been proposed that anesthetics selectively prevent consciousness and memory via acting on microtubules (MTs). It is known that the magnetic field modulates MT organization. A recent study shows that a radical pair model can explain the isotope effect in xenon-induced anesthesia and predicts magnetic field effects on anesthetic potency. Further, reactive oxygen species are also implicated in MT stability and anesthesia. Based on a simple radical pair mechanism model and a simple mathematical model of MT organization, we show that magnetic fields can modulate spin dynamics of naturally occurring radical pairs in MT. We show that the spin dynamics influence a rate in the reaction cycle, which translates into a change in the MT density. We can reproduce magnetic field effects on the MT concentration that have been observed. Our model also predicts additional effects at slightly higher fields. Our model further predicts that the effect of zinc on the MT density exhibits isotopic dependence. The findings of this work make a connection between microtubule-based and radical pair-based quantum theories of consciousness.