Quantum effects in the brain: A review

TL;DR

This review explores the emerging evidence and theories suggesting quantum effects may influence brain function and consciousness, highlighting recent developments in quantum biology related to neural processes.

Contribution

It synthesizes current research on quantum effects in the brain, evaluating experimental support and biological sites, and connects broader quantum biology advances to neural theories.

Findings

Quantum effects are implicated in biological processes like photosynthesis and avian navigation.

Multiple theories propose quantum mechanisms in consciousness and neural activity.

Experimental evidence remains limited but suggests potential quantum contributions to brain function.

Abstract

In the mid-1990s it was proposed that quantum effects in proteins known as microtubules play a role in the nature of consciousness. The theory was largely dismissed due to the fact that quantum effects were thought unlikely to occur in biological systems, which are warm and wet and subject to decoherence. However, the development of quantum biology now suggests otherwise. Quantum effects have been implicated in photosynthesis, a process fundamental to life on earth. They are also possibly at play in other biological processes such as avian migration and olfaction. The microtubule mechanism of quantum consciousness has been joined by other theories of quantum cognition. It has been proposed that general anaesthetic, which switches off consciousness, does this through quantum means, measured by changes in electron spin. The tunnelling hypothesis developed in the context of olfaction has been applied to the action of neurotransmitters. A recent theory outlines how quantum entanglement between phosphorus nuclei might influence the firing of neurons. These, and other theories, have contributed to a growing field of research that investigates whether quantum effects might contribute to neural processing. This review aims to investigate the current state of this research and how fully the theory is supported by convincing experimental evidence. It also aims to clarify the biological sites of these proposed quantum effects and how progress made in the wider field of quantum biology might be relevant to the specific case of the brain.