Does Our Brain Have Quantum Computer Components?

In preparing a brief presentation for our DSU lunch I found in my writing stack an article on Quantum Entanglement in Neurons May Actually Explain Consciousness which points out that Shanghai University physicists in China explain how entangled photons emitted by carbon-hydrogen bonds in nerve cell insulation could synchronize activity within the brain.

Their findings draw attention to a highly speculative theory on consciousness called the Penrose-Hameroff 'orchestrated-objective reduction' model. Proposed by the highly respected physicist Roger Penrose and the American anesthesiologist Stuart Hameroff, the model suggests networks of cytoskeleton tubules that lend structure to cells – in this case, our neurons – act as a kind of quantum computer that somehow shapes our thinking.

The trio notes the fatty coating called myelin around the nerve cell's axon 'tail' could

conceivably serve as a suitable cylindrical cavity for the amplification of infrared photons

generated elsewhere in the cell, causing carbon-hydrogen bonds to occasionally spit out

pairs of photons that would have a high degree of correlation between their properties.

Movements of these entangled photons through the ionic tides of the brain's biochemistry just might drive correlations between processes that play a central role in the organ's ability to synchronize. Mounting evidence suggests the fuzzy superposition states of electron spins in proteins called cryptochromes can be influenced by magnetic fields in a way that helps explain long-distance navigation in some animals.

Another article notes that seeing our world through the eyes of a migratory bird would be a rather spooky experience. Something about their visual system allows them to 'see' our planet's magnetic field, a clever trick of quantum physics and biochemistry that helps them navigate vast distances.

Now, for the first time ever, scientists from the University of Tokyo have directly observed a key reaction hypothesised to be behind birds' (and many other creatures') talents for sensing the direction of the planet's poles.  Importantly, this is evidence of quantum physics directly affecting a biochemical reaction in a cell.

Using a tailor-made microscope sensitive to faint flashes of light, the team watched a culture of human cells containing a special light-sensitive material respond dynamically to changes in a magnetic field.

The change the researchers observed in the lab match just what would be expected if a quirky quantum effect was responsible for the illuminating reaction.  “We've not modified or added anything to these cells. We think we have extremely strong evidence that we've observed a purely quantum mechanical process affecting chemical activity at the cellular level."

So how are cells, particularly human cells, capable of responding to magnetic fields? Many researchers think the ability is due to a unique quantum reaction involving photoreceptors called cryptochromes.  Cryptochromes are found in the cells of many species and are involved in regulating circadian rhythms. They're linked to the mysterious ability to sense magnetic fields. Our own cells definitely contain cryptochromes. And there's evidence that even though it's not conscious, humans are actually still capable of detecting Earth's magnetism

To see the reaction within cryptochromes in action, the researchers bathed a culture of human cells containing cryptochromes in blue light caused them to fluoresce weakly. As they glowed, the team swept magnetic fields of various frequencies repeatedly over the cells. They found that each time the magnetic field passed over the cells, their fluorescence dipped around 3.5 percent – enough to show a direct reaction. 

How can a magnetic field affect a photoreceptor? It all comes down to something called spin – an innate property of electrons. We already know that spin is significantly affected by magnetic fields. Arrange electrons in the right way around an atom, and collect enough of them together in one place, and the resulting mass of material can be made to move using nothing more than a weak magnetic field like the one that surrounds our planet.

In 1975, a Max Planck Institute researcher named Klaus Schulten developed a theory on how magnetic fields could influence chemical reactions. It involved something called a radical pair. A garden-variety radical is an electron in the outer shell of an atom that isn't partnered with a second electron. Sometimes these bachelor electrons can adopt a wingman in another atom to form a radical pair. The two stay unpaired but thanks to a shared history are considered entangled, which in quantum terms means their spins will eerily correspond no matter how far apart they are.  In the hustle-bustle of a living cell, their entanglement will be fleeting. But even these briefly correlating spins should last just long enough to make a subtle difference in the way their respective parent atoms behave.

In this experiment, as the magnetic field passed over the cells, the corresponding dip in fluorescence suggests that the generation of radical pairs had been affected.An interesting consequence of the research could be in how even weak magnetic fields could indirectly affect other biological processes. While evidence of magnetism affecting human health is weak, similar experiments as this could prove to be another avenue for investigation.

Having evidence that at least one of them connects the weirdness of the quantum world with the behaviour of a living thing is enough to force us to wonder what other bits of biology arise from the spooky depths of fundamental physics.