Nerve fibres in the brain could produce pairs of particles linked by quantum entanglement. If backed by experimental observations, this phenomenon could explain how millions of cells in the brain synchronise their activity to make it function.
鈥淲hen a brain is active, millions of neurons fire simultaneously,鈥� says at Shanghai University in China. Doing so requires even distant cells to coordinate their timing, which has led some researchers to wonder if this coordination could be due to what Einstein called 鈥渟pooky action at a distance鈥� 鈥� the instantaneous communication that occurs between particles linked by quantum entanglement. 鈥淚f the power of evolution was looking for handy action over a distance, quantum entanglement would be [an] ideal candidate for this role,鈥� Chen says.
So Chen and his colleagues mathematically investigated one way in which quantum entanglement could originate inside the brain and give rise to the extra-fast communication between neurons.
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They focused on the interactions between myelin sheaths, protective coatings of fat molecules surrounding the fibres that connect neurons, and particles of electromagnetic radiation, or photons, produced within the brain. Such radiation hasn鈥檛 been detected directly, but it has been theorised to originate in neurons鈥� mitochondria as part of a cycle of chemical reactions that produces energy.
The researchers鈥� calculations showed that, when infrared photons collide with a myelin sheath 鈥� modelled as a cylindrical cavity capable of storing and amplifying that electromagnetic radiation 鈥� they would impart extra energy to the myelin鈥檚 chemical bonds. The bonds would then release some of their energy by emitting two photons, one after the other 鈥� and many of the pairs would be entangled.
Once the brain creates entangled photons, the property of entanglement could be passed onto other parts of neurons, like the protein pores that play a role in electrical signalling across the brain, says Chen. When any two objects are quantum entangled, changes in one immediately cause changes in the other 鈥� so if different parts of the brain were entangled, they could synchronise much more quickly than through any other type of connection.
Bo Song at the University of Shanghai for Science and Technology and at Fudan University, both in China, wrote in an email that the new result 鈥渙ffers a potential source of continuous generation of quantum entanglement in the central nervous system closely related to our cognition鈥�.
However, Song and Shu also say that adding quantum entanglement into brain science 鈥渋s rather speculative in nature鈥�. Both researchers have previously studied myelin sheaths, including in where infrared photons were successfully used to affect the neural activity of a mouse.
Finding proof of the entangled photons theorised in this new work 鈥� for example, directly detecting them in a living system like a mouse 鈥� would be quite difficult, says Chen. Instead, he and his colleagues are next planning to study how entanglement can theoretically impact the functions of the brain. After all, the mere fact that entangled photons could exist in the brain does not, by itself, prove that they drive the synchrony of millions of neurons.
Until there is more evidence, the role of quantum phenomena in cognition will remain unproven. 鈥淨uantum cognition is itself a controversial subject under heavy debates,鈥� says Chen. 鈥淲e won鈥檛 say there is a direct connection.鈥�
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