Does the brain use quantum mechanics?

[Demirci Kawa]

We need quantum physics for cognitive neuroscience ?

 

[Demystifier]

Probably not. See e.g. https://arxiv.org/abs/quant-ph/9907009

 

[akvadrako]

If not the physics, there is some evidence the brain uses quantum models to drive decision making: https://www.sciencedirect.com/science/article/abs/pii/S0165489615000165

 

[Hypercube]

Wouldn't it depend on how small the brain is... [emoji848]

 

[haushofer]

My brain is purely Newtonian.

 

[AlexCaledin]

My brain is purely Newtonian.

Mine is ever so Everettian, the thought pattern branching like heck.

 

[entropy2information]

We need quantum physics for cognitive neuroscience ?

I would say yes. The growing field of Quantum Biology I think points to this. You have many good theories of a Quantum Mind out there but keep in mind, there's little to no research or real money put into these areas because many people will say consciousness must emerge from the material brain and that's the end of the story. They don't know how this happened but they know this must be the case.

Here's a video of Penrose talking about the problem.



At the end of the day, you can't say Evolution and Natural Selection are so powerful and these quantum effects are seen throughout nature adding to efficiency and advantage yet it's barred from being connected to consciousness. Why wouldn't Evolution make use of Quantum Biology when it comes to consciousness to give a species a huge advantage?

Here's an article called:

The future of quantum biology

Abstract

Biological systems are dynamical, constantly exchanging energy and matter with the environment in order to maintain the non-equilibrium state synonymous with living. Developments in observational techniques have allowed us to study biological dynamics on increasingly small scales. Such studies have revealed evidence of quantum mechanical effects, which cannot be accounted for by classical physics, in a range of biological processes. Quantum biology is the study of such processes, and here we provide an outline of the current state of the field, as well as insights into future directions.

https://royalsocietypublishing.org/doi/full/10.1098/rsif.2018.0640

 

[Nugatory]

You have many good theories of a Quantum Mind

"Good theories" is something of an overstatement. Geometrical optics is an example of a good theory; general relativity is another. Discussions of Quantum Mind are better described as "interesting conjectures".

At the end of the day, you can't say Evolution and Natural Selection are so powerful and these quantum effects are seen throughout nature adding to efficiency and advantage yet it's barred from being connected to consciousness.

I don't think that anyone is trying to say that it is "barred". However, two different claims are often conflated in these discussions:
1) When we study any system at a sufficiently small scale quantum effects become relevant. Biological systems are so complex that we are only starting to explore them at this scale, but we should expect quantum mechanics to be as relevant for atomic-scale descriptions of biological processes as they are for atomic-scale descriptions of non-biological processes. We have no remotely convincing/complete hypothesis for how consciousness emerges from the physical processes that take place in the brain, but we won't be surprised to find that a full description of these processes involves quantum mechanics.
2) Consciousness is somehow intimately connected to the unique features of quantum mechanics. Perhaps free will is a macroscopic manifestation of quantum indeterminacy, perhaps superpositions are involved, perhaps... One way or another, through some incompletely specified mechanism consciousness emerges from the quantum mechanical processes in the brain in more than the trivial sense that everything is quantum mechanical at a sufficiently small scale.

That Royal Society article you posted is in the spirit of #1, and it is not especially controversial. It is certainly not "barred".

Penrose and others have offered up Quantum Mind ideas along the lines of #2, but nothing has moved beyond the point of interesting conjecture. There's nothing inherently wrong with this speculation, but it's hard to argue that QM will explain consciousness without actually explaining it.

 

[entropy2information]

Penrose and others have offered up Quantum Mind ideas along the lines of #2, but nothing has moved beyond the point of interesting conjecture. There's nothing inherently wrong with this speculation, but it's hard to argue that QM will explain consciousness without actually explaining it.

I think it's much more than just speculation. For instance, Penrose and Hameroff predicted quantum vibrations in microtubules.

Discovery of quantum vibrations in 'microtubules' inside brain neurons supports controversial theory of consciousness

https://www.sciencedaily.com/releases/2014/01/140116085105.htm

Here's another one:

Electron spin changes during general anesthesia in Drosophila

https://www.pnas.org/content/111/34/E3524

Matthew Fisher from UCSB has raised 1.2 million for the Quantum Brain Project.

Much has been made of quantum computing processes using ultracold atoms and ions, superconducting junctions and defects in diamonds, but could we be performing them in our own brains?

It’s a question UC Santa Barbara theoretical physicist Matthew Fisherhas been asking for years. Now, as scientific director of the new Quantum Brain Project (QuBrain), he is seeking to put this inquiry through rigorous experimental tests.

“Might we, ourselves, be quantum computers, rather than just clever robots who are designing and building quantum computers?” Fisher asks.

https://www.news.ucsb.edu/2018/018840/are-we-quantum-computers

I think with Quantum Biology, it's more likely that nature has figured out a way to use quantum mechanical effects seen in nature as a way to give a species (ours) a huge advantage and this huge advantage is self consciousness.

 

[bhobba]

Well we do have the interesting phenomena of bird migration:
https://www.sciencealert.com/watch-this-is-how-birds-use-quantum-mechanics-to-navigate

Thanks
Bill

 

[stevendaryl]

My feeling is that the work on quantum brains is interesting, but I can't actually believe that it addresses the mysteries of consciousness that prompted Penrose in the first place. Penrose, in "The Emperor's New Mind" gives a (fallacious, in my opinion) argument that Godel's incompleteness theorem implies that human reasoning is noncomputable. Then he started looking into microtubules as a way of explaining how brains can do something noncomputable. I consider the motivation completely bogus, even if the study of microtubules turns into something interesting. The original motivation for research doesn't have to be sound in order for the research itself to be worth-while.

 

[Quantum Physics]

I believe that the neural networking and QM are linked. But I don't think that we need QM for cognitive neuroscience.

 

[vanhees71]

Hm, here are my 2cts. I think the answer to any kind of this question is very simple. According to our present knowledge all of matter "uses quantum mechanics", which is of course an overstatement since quantum mechanics (or rather quantum theory, because at the presently most fundamental level it's quantum field theory rather than quantum mechanics that is "used by nature") is just a human construct to order our quantitative observations about the "real world" or "Nature". Since classical physics is not even fully consistent but together with the observed fact that matter (and who knows if not also spacetime) has an atomistic structure, is necessarily an emergent phenomenon from QT. There'd not be any stable matter to begin with Newtonian mechanics of macrscopic (more or less) rigid bodies which is the subject of the very first physics lessons we have to learn to get started with learning to think in terms of physics!

We are of course far from being able to understand the workings of human brains and esoterics like what we call "consciousness" (which is a very vague and undefined word, much confused by nearly thousend years of philosophers' work on it). You find even in otherwise serious publishers' science-book (sic!) programs like Springer boos with titles like "Consciousness and Quantum Mechanics". I was really shocked when I've seen this for the first time at a science conference, where the science-textbook publishers often present their products ;-))). I think there is not much merit in such esoterical ideas. To the contrary physics (as well as the other natural sciences) teach us quite some modesty in telling us, how much we don't know. Among many much simpler things, the fundamental workings of the human brain (or even much less complicated neural networks like that of some worm with only several 100 of neurons in its nervous system) are far out of reach to be understood from the underlying fundamental physical theories, including quantum theory.

 

[Lord Jestocost]

Regarding consciousness, at least the classical physicist might say - to use Amit Goswami’s words: “A physicist is [merely] an atom's way of knowing about atoms."

 

[AlexCaledin]

A great wiki-quote of Niels Bohr, seems explaining Feynman's "Nature knows":
"I consider those developments in physics during the last decades which have shown how problematical such concepts as "objective" and "subjective" are, a great liberation of thought. The whole thing started with the theory of relativity. In the past, the statement that two events are simultaneous was considered an objective assertion, one that could be communicated quite simply and that was open to verification by any observer. Today we know that 'simultaneity' contains a subjective element, inasmuch as two events that appear simultaneous to an observer at rest are not necessarily simultaneous to an observer in motion. However, the relativistic description is also objective inasmuch as every observer can deduce by calculation what the other observer will perceive or has perceived. For all that, we have come a long way from the classical ideal of objective descriptions.
In quantum mechanics the departure from this ideal has been even more radical. We can still use the objectifying language of classical physics to make statements about observable facts. For instance, we can say that a photographic plate has been blackened, or that cloud droplets have formed. But we can say nothing about the atoms themselves. And what predictions we base on such findings depend on the way we pose our experimental question, and here the observer has freedom of choice. Naturally, it still makes no difference whether the observer is a man, an animal, or a piece of apparatus, but it is no longer possible to make predictions without reference to the observer or the means of observation. To that extent, every physical process may be said to have objective and subjective features. The objective world of nineteenth-century science was, as we know today, an ideal, limiting case, but not the whole reality. Admittedly, even in our future encounters with reality we shall have to distinguish between the objective and the subjective side, to make a division between the two. But the location of the separation may depend on the way things are looked at; to a certain extent it can be chosen at will."

 

[king vitamin]

Matthew Fisher has recently discussed the possibility of our brains using quantum mechanics at the biological level, see here for a very readable overview: https://www.kitp.ucsb.edu/sites/default/files/users/mpaf/QuRobots_2_25_17_1.pdf (he also has some more technical papers on his work).

He has a very measured approach. He admits that most biological processes are far too wet/warm for quantum coherence to persist, but asks the question whether there is any process in the brain which has coherence on fairly long scales. He identifies a particular set of nuclear spins which do, and makes some reasonable suggestions for further testing on them to possibly rule out whether quantum mechanics/computation is important to neuroscience. It's a pretty good read.

 

[DennisN]

We need quantum physics for cognitive neuroscience ?

I don't think so, I think it is very unlikely.

Quantum physics (quantum field theory) is at the moment one of the fundamental cores of our understanding and descriptions of the physical world, and general relativity is another core.

Regarding cognitive neuroscience, I think biology, chemistry and psychology are the main branches needed for understanding the brain of humans and other animals.

I think that using quantum physics to understand the brain could be likened to using chemistry to understand how to to sail on an ocean; in sailing, it is not particularly helpful to know that water consists of H₂O molecules, which in turn are made out of two hydrogen atoms and one oxygen atom. What you need is knowledge about how a boat works, how water behaves on a large scale and also how wind and weather work on a large scale, and perhaps how to navigate if you are taking long trips.

 

[DennisN]

as a way to give a species (ours) a huge advantage and this huge advantage is self consciousness.

I think it is likely that the human species is the most self-conscious species on this planet, but I'd like to add that there are studies which have shown that a couple of other species have self-awareness (which is a part of self-consciousness), e.g. various primates, elephants, dolphins and, quite amazingly considering their relatively small size, magpies;

Prior, Schwarz, Güntürkün, "Mirror-Induced Behavior in the Magpie (Pica pica): Evidence of Self-Recognition" (PMC, Published online 2008 Aug 19. doi: 10.1371/journal.pbio.0060202)
Paper: http://www.ncbi.nlm.nih.gov/pmc/articles/PMC2517622/

Abstract:
"Comparative studies suggest that at least some bird species have evolved mental skills similar to those found in humans and apes. This is indicated by feats such as tool use, episodic-like memory, and the ability to use one's own experience in predicting the behavior of conspecifics. It is, however, not yet clear whether these skills are accompanied by an understanding of the self. In apes, self-directed behavior in response to a mirror has been taken as evidence of self-recognition. We investigated mirror-induced behavior in the magpie, a songbird species from the crow family. As in apes, some individuals behaved in front of the mirror as if they were testing behavioral contingencies. When provided with a mark, magpies showed spontaneous mark-directed behavior. Our findings provide the first evidence of mirror self-recognition in a non-mammalian species. They suggest that essential components of human self-recognition have evolved independently in different vertebrate classes with a separate evolutionary history."