Here at the Grail we've covered the controversial idea of 'quantum consciousness' many times over the years (we interviewed prominent researcher Stu Hameroff way back in 2005). A recent mention of the topic here was in the news briefs a few weeks ago, where we linked to a great piece at the BBC titled "The Strange Link Between the Human Mind and Quantum Physics".
Given the length of the piece, and the 'heavy' topics discussed, I thought it would be worth pointing out a fascinating part of that article that some readers may not have made it to. It is where it discusses the research of physicist Matthew Fisher, of the University of California, in which he suggests an explanation for how quantum effects could persist in the brain for decent periods of time (there is a lot of skepticism about 'quantum consciousness' due to the 'warm and wet' conditions in the human brain, both of which destroy quantum effects very quickly).
In his study ("Quantum cognition: The possibility of processing with nuclear spins in the brain"), Fisher argued that the brain might contain molecules that are capable of sustaining robust quantum superpositions for up to a day.
Specifically, he thinks that the nuclei of phosphorus atoms may have this ability.
Phosphorus atoms are everywhere in living cells. They often take the form of phosphate ions, in which one phosphorus atom joins up with four oxygen atoms. Such ions are the basic unit of energy within cells.
The phosphorus nuclei have a quantum property called spin, which makes them rather like little magnets with poles pointing in particular directions. In an entangled state, the spin of one phosphorus nucleus depends on that of the other.
Put another way, entangled states are really superposition states involving more than one quantum particle. Fisher says that the quantum-mechanical behaviour of these nuclear spins could plausibly resist decoherence on human timescales.
According to Fisher, this could happen if the phosphorus atoms are incorporated into larger objects called "Posner molecules" (clusters of six phosphate ions, combined with nine calcium ions).
What I found really interesting is the medical anomaly that led Fisher to formulating this hypothesis:
He first got this idea when he started thinking about mental illness.
"My entry into the biochemistry of the brain started when I decided three or four years ago to explore how on earth the lithium ion could have such a dramatic effect in treating mental conditions," Fisher says.
Lithium drugs are widely used for treating bipolar disorder. They work, but nobody really knows how.
"I wasn't looking for a quantum explanation," Fisher says. But then he came across a paper reporting that lithium drugs had different effects on the behaviour of rats, depending on what form – or "isotope" – of lithium was used.
On the face of it, that was extremely puzzling. In chemical terms, different isotopes behave almost identically, so if the lithium worked like a conventional drug the isotopes should all have had the same effect.
But Fisher realised that the nuclei of the atoms of different lithium isotopes can have different spins. This quantum property might affect the way lithium drugs act. For example, if lithium substitutes for calcium in Posner molecules, the lithium spins might "feel" and influence those of phosphorus atoms, and so interfere with their entanglement.
If this is true, it would help to explain why lithium can treat bipolar disorder.
It should be noted that Fisher himself is quite wary of being associated with mystical 'quantum woo' ideas (good luck with that once Deepak starts talking about it...). But I do think this is another wonderful case study of how looking deeper into anomalies can sometimes lead to (possible) breakthroughs in our understanding of both ourselves and the cosmos.