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"Since we don't know of another (i.e,. classical) way that anesthetic binding to microtubules would generally reduce brain activity and cause unconsciousness,"
by bbor 2y ago
"Since we don't know of another (i.e,. classical) way that anesthetic binding to microtubules would generally reduce brain activity and cause unconsciousness," Wiest says, "this finding supports the quantum model of consciousness."… "When it becomes accepted that the mind is a quantum phenomenon, we will have entered a new era in our understanding of what we are," he says.
Wow, that’s absurdly biased. Talk about jumping to conclusions! Here’s the actual paper: https://www.eneuro.org/content/11/8/ENEURO.0291-24.2024 https://www.eneuro.org/content/11/8/ENEURO.0291-24.2024
Take this summary, for example:
Cytoskeletal microtubules (MTs) have been considered as a candidate target of anesthetic action for over 50 years (Allison and Nunn, 1968; S. Hameroff, 1998). Other membrane receptor and ion channel proteins were ruled out as possible unitary targets by exhaustive studies culminating in Eger et al. (2008). However, MTs (composed of tubulin subunits) were not ruled out and remain a candidate for a unitary site of anesthetic action.
But if you actually click the paper:
The essay continues with an examination of the potential contributions of specific ligand-gated channels, concluding that one or two such channels (e.g., glycine) might play a role, but that present evidence suggests that no one channel can explain more than a portion of anesthetic-induced immobility. Voltage-gated potassium channels seem unable to explain the production of immobility, but the voltage-gated sodium channels remain a plausible candidate. How inhaled anesthetics act to block this and other sites remains a mystery, but some new concepts are proposed.
Sure, it could be microtubules, it’s not ruled out by that paper - they also don’t rule out witchcraft or god or little tiny ratmen that run the brain. I don’t understand how that absurdly misleading citation usage got through peer review; it makes it seem like MTs are one of the few remaining answers, which is very far from the truth.
The other big paper in the intro is this one from Hammerhoff n co:
We found that these gases alter collective terahertz dipole oscillations in a manner that is correlated with their anesthetic potency.
It doesn’t take a neuroscientist to see that “anesthetics impede one kind of electrical (atom? Quantum?) activity in the brain” is far from proving “that activity is essential for consciousness”. To adapt the old SMBC joke: a bullet would impede terahertz dipole oscillations in the brain, too!
I would consider this study — and today’s, really - as confirming that we can’t say for sure that it’s not related to microtubules. Which, hey, that’s useful science! But the way they described it to this science journalist is just intellectually disrespectful, and incredibly misleading. IMO, as someone with a PhD in DoingMyOwnResearch ;)
They casually drop this then move on never to mention it again, which I feel like is a fantastical example of scientific bias via burying the lede:
Isoflurane directly activates sleep-promoting neurons of the hypothalamic ventrolateral preoptic nucleus, and this contributes to causing unconsciousness.
And this:
It is conceivable that binding to MTs by volatile anesthetics could impair intracellular transport, which might disrupt synaptic transmission, which might reduce neural activity generally.
Yeah… yeah that does sound conceivable. “Anesthetics inhibit neurons” seems a LOT more likely than “anesthetics inhibit the unimaginably tiny + completely unexplained quantum entanglements that control neurons”.
They then, briefly, repeat my exact criticism from above. Somehow this didnt seem important enough for the journalist to quote, tho? Namely:
Our results are potentially consistent with classical models of consciousness, but they represent a more stringent test of these MT-based models
Where “test” means “doesn’t yet rule out”.
Overall the Orch OR theory, in which MTs mediate anesthetic action, has more explanatory power, biological connection, and experimental validation than the classical theories.
That is an absurd summary of the available evidence. Just absurd. Even if you restrict it just to the papers they cite here.
And then, wow, it ends. I really really want to support these folks as a fellow brain/consciousness crank, but they make it hard. If you’re on the fence on whether they’re fairly framing the results of this (n=8!!) study or not, just read the last sentence:
These recent technical developments support the hope that “some who are standing here will not taste death before they see” conclusive experimental tests of the quantum consciousness hypothesis.
- dekhn 2y agoYou're absolutely right to point out all the methological errors their chain of thought shows. Honestly after many years, I've learned it's best to simply ignore the entire "brains run on quantum woo" crowd. It's unlikely they will be able to conjure up a convincing experiment that shows anything stupendous. You will just exhaust yourself arguing with folks who want to believe in quantum woo. To me the biggest issue is the obsessive focus on a mechanism; instead, any experiments should be focused on demonstrating that some QM property is necessary (through association), then looking for mechanistic causality.