A few carnival announcements:
The next Tangled Bank will be held next Wednesday at The Inoculated Mind (yes, it’s back up!). Send your submissions to karl AT inoculatedmind DOT com with “Tangled Bank Submission” in the subject line, or send it to me or host@tangledbank.net.
As always, carnival barking threads are also open threads—talk about what you will.
New apologetics needed to fight ‘new atheism’
Glad to see the medication’s working. Take care of yourself.
Thank you, Paul.
As I said, I just saw “What The Bleep Do We Know” and I recalled that you were not impressed by it. In fact, that may be an understatement!
While I did find it a bit silly in spots, the science that was discussed was on solid ground. Besides, who could object to seeing Marlee Matlin in her underwear?
One point resonated. We create our own reality. I have believed this for a very long time. In addition, the problem of consciousness is not trivial. Conscious awareness of the world is not a meaningless or incidental quirk of nature, but a fundamental aspect of reality. Mind and consciousness are woven into the fabric of the universe.
I was pleased to see Stuart Hameroff in the film, whose work on consciousness with Roger Penrose I have long followed. It lent a certain credibility to the subject being presented.
http://www.quantumconsciousness.org/
I have long held the view that every thought that we think creates our future. Clearly that means that we, each of us, is fully responsible for our experiences. What we think about ourselves becomes our “truth”. We can’t be blaming other persons, other things because we think they have control over us. We are the only thinkers in our mind and therefore we are fully responsible for our reality.
One thing that I’ve learned (it took some time, I might add) is that the universe is not good or bad, it’s indifferent. We can choose to think positive thoughts, and expect positive outcomes, or we can choose to think negative thoughts and have negative outcomes.
When Amanda stands in front of the mirror and screams “I HATE you” that has it’s origin in a thought that she has about herself. These thoughts produce an emotional reaction, a feeling, that we buy into. Clearly, you can abort this process by simply not having the thought, or replacing it with a less malignant thought. Thoughts can be changed, hence feelings can be changed.
What we must realize is that the point of power does not lie in the past, it is in the present moment. Much of modern psychiatry has begun to recognize that. We don’t need to dredge up the hurtful past, to change present thoughts and future outcomes.
So, despite it’s obvious flaws, I think the film did a good job of introducing some of these concepts. If nothing else, it gave the viewer something to ponder.
Just a heads-up that your Forbes reinvention article got posted on Slashdot, so the hordes may be incoming shortly…?
A friend/coworker of mine showed me some information some months ago about which he was deeply skeptical (as was I). He heard about it on Coast-to-Coast, which sets off alarms right there. The subject was “Abiotic Oil.”
This may seem peripheral to biology, but I’m not sure. After all, bacteria are involved.
The whole thing sounds like Oil Geology for Creationists to me, but I wanted to ask as a sort of general question, does this position seem correct?
The article is here:
http://www.fromthewilderness.com/free/ww3/100404_abiotic_oil.shtml
One question
When did the two primate chromosomes fuse to form the human primate #2 chromosome?
I’m not seeing much of the hordes here…they’re all rampaging over forbes.com, I suspect. That’s good — with all the attention, maybe they’ll think about commissioning other pieces from me!
While I did find it a bit silly in spots, the science that was discussed was on solid ground.
Ummm, I don’t think so. The “science” in that movie has a lot of problems, the main one in my mind being their conflation of the quantum and classical realms. A basketball does not obey quantum mechanics, in other words. Yes, I know it was a macroscopic demonstration of a microscopic phenomenon, but they didn’t say that. If you like, the science may not have been technically wrong, but the presentation was dishonest as hell.
Also, that thing about the Indians not being able to see Columbus’ ship because “they couldn’t imagine anything like that” is bull, plain and simple. It’s a legend that the filmmakers presented as fact. Yet another example of dishonesty.
We create our own reality. I have believed this for a very long time.
That’s another problem I have with the movie. We don’t create our own reality, or else I’d be a lot better looking and a lot richer. What we can do is change the way we experience our own reality, with positive thinking and whatnot. If your sentiment is true, nobody would ever get cancer, let alone die from it.
I could say more about that movie, but I’ll stop now.
If the “Indians” could not see the Nina, Pinta and Santa Maria, then logically Columbus and his men could not see the land they reached, and if they did, they would have seen it as Japan. Had perceptions the power to shape reality, Columbus would have returned to Queen Isabella with a bounty of spices, rather than a bad map and a boatful of syphilis.
Suppose for a moment that our reality truly cannot contain that with which we are not familiar. The Danish cartoonists would be home free, since all the world’s Muslims would see cartoons of Mohommed as blank pages. Pick your favorite scandal: America’s overprotective parents would never have seen Janet Jackson’s nipple. If the will of millions can shape reality, if all events and perceptions must conform to the zeitgeist, then surely science-fiction fandom would have prevented the Matrix and Star Wars sequels from sucking, and without doubt the collective love of limitless music lovers would have prevented the Beatles from breaking up.
This is life. This is reality. Sure, it blows dead goats. But it’s happening and it’s not gonna stop on account of a piece of wishy-washy, New Age solipsism tarted up with quantum mumbo-jumbo.
Re the idea of reproductive organs in the mouth, my favourite comment so far has been, “It’s not normally that small — I’ve been eating ice cream!”
I know the software will shut out my comment if I post all the relevant links to the Bleep-ing foolishness, so I’ll just give one which in turn links to a whole bunch of others. Check out Jennifer Ouellette at Cocktail Party Physics on this very subject.
Uh, Blake, are you saying that the original Star Wars trilogy did not suck?
Alon:
That’s sort of like asking Jerry Falwell “have you stopped beating your gay lover yet?” I have the feeling that no answer can be correct, or certainly no brief one. In a kitschy, pseudo-Zen way, my best response may be to say “Mu” and un-ask the question. Let me state my beliefs more clearly: the second set of three Star Wars movies took everything which was wrong with the first, systematically purged the concept of value and pumped up the wretchedness with all the vigour of Alan Guth’s inflationary universe.
The Empire Strikes Back is the only movie out of the six that I’d watch willingly, unless Mystery Science Theater 3000 suddenly came back to life and required my services. I caught the last third of Return of the Jedi a few months ago because a friend was watching a DivX rip on his computer. It was like driving past a six-car pileup on an interstate: I rubbernecked in the manner of an innocent bystander witnessing a horrible catastrophe.
“This is my generation’s mythology?” I asked.
“Yeah,” my friend said. “I don’t know how it happened, but this movie got a lot less cool in the past fifteen years.”
The Disgruntled Chemist wrote:
“Also, that thing about the Indians not being able to see Columbus’ ship because “they couldn’t imagine anything like that” is bull, plain and simple. It’s a legend that the filmmakers presented as fact. Yet another example of dishonesty.”
There is a basis in fact for believing this. Columbus was looking for land, but the Indians were not looking for ships and had no previous awareness that they existed.
Perception. 1999;28(9):1059-74.
Gorillas in our midst: sustained inattentional blindness for dynamic events.
Simons DJ, Chabris CF.
Department of Psychology, Harvard University, Cambridge, MA 02138, USA. dsimons@wjh.harvard.edu
“With each eye fixation, we experience a richly detailed visual world. Yet recent work on visual integration and change direction reveals that we are surprisingly unaware of the details of our environment from one view to the next: we often do not detect large changes to objects and scenes (‘change blindness’). Furthermore, without attention, we may not even perceive objects (‘inattentional blindness’). Taken together, these findings suggest that we perceive and remember only those objects and details that receive focused attention. In this paper, we briefly review and discuss evidence for these cognitive forms of ‘blindness’. We then present a new study that builds on classic studies of divided visual attention to examine inattentional blindness for complex objects and events in dynamic scenes. Our results suggest that the likelihood of noticing an unexpected object depends on the similarity of that object to other objects in the display and on how difficult the priming monitoring task is. Interestingly, spatial proximity of the critical unattended object to attended locations does not appear to affect detection, suggesting that observers attend to objects and events, not spatial positions. We discuss the implications of these results for visual representations and awareness of our visual environment.”
“That’s another problem I have with the movie. We don’t create our own reality, or else I’d be a lot better looking and a lot richer.”
It sounds like you don’t believe that you’re good looking enough or rich enough. By whose standards? There is no objective way to quantify these things, they are your beliefs. If you choose to believe this, then your unconscious mind will accept that and the world will support your belief. And what you believe about yourself and about your life comes true for you. If you want to create a new reality, go right ahead!
“If your sentiment is true, nobody would ever get cancer, let alone die from it.”
Indeed. There is a lot of anecdotal evidence that long held resentment, criticism, guilt and fear are major contributors to a variety of medical problems including cancer, arthritis and back pain.
I cite myself as an example. I had a CABG about a year ago and a variety of other medical problems. But I soon found out that my pereception of my health was as important as the medical evaluation. For a while I stopped doing a lot of stuff and shuffled around all day in my slippers. I believed I was sick and that I was declining into old age and infirmity. It wasn’t a happy time.
But I’m glad to report that I’m doing much better, I’m more active, started doing projects around the house, travel to see my grandkids and basically appear healthy and well. How did this happen?” I don’t know for sure. But I spend time each morning creating my day. I have a strong feeling that I’m connected to the rest of the world and that the universe will support whatever beliefs I have about myself. So I believe that I am the person that I want to be.
And it works.
I know a number of quantum physicists, and a number of cognitive scientists, and a number of philosophers of mind, and a few anthropologists—and not one of them believes the kind of stuff presented in What the Bleep Do We Know?
That doesn’t make it false; perhaps all the scientists I know are way behind the curve of a scientific revolution, but it does show how deceptive the movie is.
Most of the laypeople I’ve discussed the movie with think that it’s mostly presenting pretty well-understood and agreed-on scientific facts, rather than a bunch of theories and interpretations that most scientists in the relevant fields think are (a) crazy, (b) probably false, and/or (c) clearly false.
For example, my anthropologist friends work with one of the “last first contact” stone-age peoples in the Amazon. (That is, they didn’t even know of the existence of white people or modern societies until recently.)
These people have never had a problem seeing things like airplanes that flew over them. They were perfectly well able to make out the shapes, colors and textures, and sounds of airplanes, and to infer that they are large, fast-moving, mostly-rigid flying objects; they just didn’t know that they were human artifacts, or that there were humans inside them.
It’s pretty well-understood now why Amazon natives have no problem whatsoever seeing airplanes, without having the concept of “airplane.” We have a whole lot of information-processing machinery in our heads that is highly evolved to perceive objects like rocks, trees, birds, people, and even airplanes. There are dozens of information-processing tricks involved, for enhancing edges, recognizing blobs and occlusions, inferring 3D shape from 2D shading, etc., etc., etc.
Every bit of that information-processing machinery works by classical mechanical and computational principles, in the physical brain. Quantum physics is entirely irrelevant to understanding those aspects of the mind, and scientists know that.
But the moviemakers don’t want you to know that. They want you not to, so that you’ll buy the more central bullshit theses of the movie.
They’re setting you up to buy a certain naive inference: that quantum mechanics is strange, and the mind is strange, and they’re strange in related ways, so they’re likely the same thing, or at least that the strangeness of one is well-accounted-for by the other.
But the mind isn’t that strange, or strange in that way. Quantum mechanics isn’t strange in the ways they say, either. And the one doesn’t explain the other worth a damn.
The movie is a big lie supported by a cynical tissue of lies and distortions of everything it touches on. The moviemakers may sincerely believe their conclusions, but the cynical, deceptive presentation is not an accident.
Paul W. wrote:
“Quantum physics is entirely irrelevant to understanding those aspects of the mind, and scientists know that.”
Which scientists?
Certainly not Stuart Hameroff:
“Consciousness defines our existence and reality, but the mechanism by which the brain generates thoughts and feelings remains unknown.
Most explanations portray the brain as a computer, with nerve cells (“neurons”) and their synaptic connections acting as simple switches. However computation alone cannot explain why we have feelings and awareness, an “inner life.”
It’s the attack of the millipedes in Australia.
http://www.news.com.au/story/0,10117,18755044-1246,00.html
Yuck.
“Some people can sweep up a 10-litre bucket from their veranda every day.”
Columbus was looking for land, but not the land that he found. He was looking for the Japan described by Conti and the China described by Marco Polo.
Take the movie’s sort of “logic” to its logical conclusion: if preconceptions totally rule perceptions, how do any of us ever see anything that doesn’t look like the inside of a womb?
Paul W.: Now I want to know what they did think about the planes!
I’ve also wondered if Plains Indians made stories about how they got the horse. And less relatedly, whether the near presence of monkeys — a much more humanlike animal than Europe had — affected the development of religion in the East, relative to that of the West. (And yeah, the West knew about monkeys at some point, but I imagine it might be different if they’re common pests vs. exotic legends.)
Stuart Hameroff is an anesthesiologist, not a physicist. He’s babbled about “quantum consciousness”, an entirely speculative concept. The only physicist who has done notable work in anything related to this is Roger Penrose, who has hypothesized that small structures called “microtubules” inside nerve cells may take advantage of quantum-mechanical effects to do computations. No one knows if this is true or not. People have produced calculations which suggest that it is possible, at least given some approximations and assumptions. Further, more detailed calculations may show otherwise. An experiment would be necessary to give a real verdict.
It is worth noting that if it were true, there would be nothing in principle to stop the biologists and the genetic engineers from using these same small structures to build artificial computers. (People are trying to build quantum computers right now, but no one knows how to make them feasible. It’s not a philosophical problem; it’s an engineering one.)
By the way, microtubules perform other functions within cells, functions we definitely know about. They act as a cell’s inner skeleton, providing a framework which gives the cell some rigidity. “Molecular motors” made of proteins like the kinesins attach to microtubules and walk along them, carrying stuff around the cell. It is conceptually possible that microtubules evolved for this sort of purpose, and natural selection later adapted them to serve as computing elements inside neurons. I say it is possible; again, nobody knows whether or not it’s true.
And even if it were true, how much would it matter? All the machinery inside a neuron just determines when the neuron fires off a synaptic pulse to the one next door. We may need quantum mechanics to understand what goes on inside a tiny microtubule, but on a larger scale, the dynamics of what goes on between neurons is still classical. Even if Nature somehow lucked onto a way of using microtubules to boost a neuron’s computational power, we can still treat the neuron as a “black box” and discuss what goes on among these black boxes using classical methods.
Penrose has argued that the “incompleteness theorems” which Kurt Godel cooked up in the 1930s can be used to prove that human consciousness cannot be expressed in an algorithm. Many people see his arguments as specious. Neither Penrose nor anybody else has produced a reason which has convinced the scientific community that quantum theory is a necessary ingredient for consciousness. Even if it were demonstrated that the microtubules inside nerve cells use quantum effects to perform computations — and I repeat, this has not been shown, although an experiment could do so in principle — there is no reason to assume that these quantum effects do anything other than make an ordinary computer faster.
Quantum mechanics is just a set of rules which explain the behavior of things on very small scales. These rules of behavior are almost totally unlike those which govern the familiar, large-scale world: they involve probability in an exotic way, and so forth. However, the esoteric mathematics involved in these rules is not an excuse to descend into mysticism.
The ones who study perception. People like Hubel & Weisel, David Marr, Stephen Kosslyn, and hundreds of others since the 1960’s.
Notice that I said “those aspects of the mind.” You omitted the context, which was about how we perceive objects as objects.
I’m not talking about qualia or anything like Penroses’s alleged super-Turing insight. As I said, I was talking about things like edge detection, blobs, occlusion, shape from shading, etc.
All of this stuff is pretty well understood, in the relevant senses. The brain has dozens of regions with identifiable functions, and a whole bunch of known stages of mostly-bottom-up evolved-in image processing. We’re spectacularly well-evolved to recognize things like ships and airplanes as large mostly-rigid moving objects, and to recognize their shapes and textures quite precisely, whether or not we have any understanding that they are ships or airplanes, or how they actually work.
It would be truly astonishing if this machinery didn’t do its normal jobs that it’s been doing for millions of years, such that native Americans couldn’t see ships, white men, etc. The story in the movie is utter bullshit in service to utter bullshit.
A stone-age native American has no more difficulty seeing these things than your average jet-setting rock musician, who has little more understanding of how they work. If Eddie Van Halen can see a 757, a native American can see the Nina, Pinta, and Santa Maria. No problem.
Native Americans had boats, even. They’d probably have recognized a really big boat as a really big boat, though they would likely have been uncertain about it, because they’d never seen boats quite like that. But get them close enough, and they’d have recognized the sails as cloth, the wooden parts as wooden, the ropes as ropes, etc. At a middle distance, they’d certainly have categorized the hull as large and rigid, the sails as flexible clothlike sheets, and the ropes as ropey.
Likewise, people are spectacularly well-evolved to recognize jointed, walking animals with faces, irrespective of their skin color, etc. A white man is no more invisible to a stone-age American than, say, Barney is to a modern American three-year-old. The three-year-old may not really get the concept of “purple dinosaur,” but that doesn’t mean he/she can’t perceive Barney as recognizably a person who just happens to be purple and rather differently-shaped from mommy and daddy.
The idea that native Americans couldn’t even see ships full of white people until the shaman said the magic words is just ludicrious brain-damaging judgement-impairing pseudo-deep crap.
charlie wagner wrote:
Quantum computation is still computation, just with better switches.
Hey, all you population geneticists and biomathematicians out there! I’d never thought about this problem in quite this way before, but if — let me emphasize that if in a big way — QM were relevant to brain function in any significant way, then the genes which control the growth of these “quantum switches” (be they microtubules or whatever) would be determined by evolution, natch’. But evolution acts on big things, organisms of billions or trillions of cells, reproducing and dying. The biggest scale QM could be relevant at is the size of a neuron, call it a few microns. Beyond that generous threshold, you get decoherence and everything looks classical again.
I wonder if one could do some math to see how well an optimization scheme which works on classical probabilities like natural selection would work for optimizing a quantum mechanism. This is necessarily a vague and fuzzy idea because the nature of the “quantum switches” is completely up in the air. (I’ve heard that Penrose had already decided that consciousness must be quantum-mechanical in nature and picked microtubules as the first mechanism which came to mind… not exactly a stellar way to do real science. Let’s see, The Emperor’s New Mind came out in 1990, and the microtubule stuff started at least four years later…)
See also Max Tegmark’s work on the problem:
http://space.mit.edu/home/tegmark/brain.html
Despite some back-and-forth in the scientific literature, these basic results still stand.
If I recall correctly what my anthro friends said, the natives mostly said “what the fuck?” and went about their business of hunting and gathering, raising kids, getting drunk en masse every couple of weeks, etc. They didn’t construct a lot of elaborate explanations or give a lot of credence to any of them. They didn’t panic, or worship the planes, or anything like that.
Given more time between plane-sightings and first contact, they might have generated an elaborate mythology, but we’ll never know now. Now they know a little about white people, planes, medicine, reading, writing, arithmetic…. and—as of the last few years—money, the universal acid that dissolves all cultures.
Oh, and the Bible. Missionaries came in close on the heels of the anthropologists, and killed not a few of the natives with their poorly-constructed latrines too near the river.
That happens a lot. Missionaries are typically more concerned with saving souls than with not killing people with their European white-people diseases, and my anthro friends have to warn the natives about the lethality of missionaries’ shit and poor sanitation practices.
Some of the “lethal crap” that happened with the Catholic Spaniards still happens with the American Protestant missionaries, to this day.
Paul:
For want of a better phrase. . . that’s phucked up. Are there any books or stuff which talk about that?
Oh, and here’s my bumper-sticker quote about the quantum consciousness flapdoodle: Saying that quantum mechanics is the secret of consciousness because it is strange and unfamiliar is like saying French must be the language of love because one does not speak it.
Which part?
Two books I like a lot for a general, reasonably educated audience are How the Mind Works by Stephen Pinker and Guns, Germs, and Steel (which got a Pulitzer) by Jared Diamond.
The first half or two thirds of each book is awesome. I disagree with both authors on some comparatively minor stuff, especially toward the end of each book, but they’re extremely informative, well-written, and enjoyable, and would open a lot of eyes. They’re the most “recommendable” books I know on cognitive science and anthropology, respectively.
Another book you might be interested in is “The Fabric of Reality” by the quantum cosmologist Peter Deutsch. He’s the guy who formalized the Universal Quantum Computer, which IIRC shows how Universal Quantum Computers can emulate Universal Turing Machines and vice versa with “only” a vast (exponential) difference in efficiency—given the known laws of physics, a quantum computer can’t compute anything a Turing machine can’t, although it could make a lot of infeasible computations feasible.
If I recall correctly—and again, I may not—Penrose has to assume that the laws of quantum mechanics are different than most physicists think they are, in order to claim that the brain can use quantum physics to bypass Goedel’s incompleteness theorem. (E.g., to give human mathematicians “incomputable” mathematical insight.)
He’s not just explaining known human cognition in terms of quantum mechanics; he’s explaining unknown and quite controversial cognition in terms of unknown and quite controversial physics.
So far as I know, very few cognitive scientists or philosophers of mind think that human mathematicans have the kind of incomputable insight Penrose argues that they do. And very few physicists think that quantum physics is weird in the way he must assume that it is, in order to support such “incomputable” cognition.
(And very few biologists think that microtubules are computing devices; they’re structural gadgets that support eukaryotic cell shapes and act as rails for intracellular transport of chromosomes and other stuff. It’s theoretically possible that they’ve been exapted for quantum computing, but it’s far from obvious that they’re even a good candidate for that.)
That doesn’t necessarily mean he’s wrong; I’m only saying that most physicists and most neuroscientists and cognitivists think he’s a bit of a crank on this particular subject. (So far as I know, nobody thinks that Roger Penrose is “just a crank”; he’s obviously a brilliant mathematician and mathematical physicist, within his areas of expertise.)
The carnival of education should meet one of the farces of education – a relatively traditional mockery of those few students who still attempt to study proper subjects:
http://film.guardian.co.uk/news/story/0,,1756714,00.html
If they are going to give out fake degrees to non-students, they should at least be consistent and make them things like media studies and the other pretend subjects taken by make-weight students.
Thanks, Paul. The Jared Diamond book was already on my reading list, happily, and I’d managed to hear the gist of the others from my friends in brain/cognitive science and quantum-computing land. (One of my old flatmates did a thesis on the latter, so I hear lots of stuff second-hand.)
One of the standing jokes around MIT was to attribute all revolutionary psychological theories — correct or not — to Steven Pinker, who teaches one of the introductory classes in the brain/cog sci department. Thus, when my Shakespeare professor was discussing the Freudian interpretation of Hamlet (yes, I took a year of Shakespeare at MIT), he then went on to say, “Of course, all of Freud’s work has been disproved by Steven Pinker. . . .”
The more I read and think about this microtubule stuff, the less plausible the idea of “quantum consciousness” sounds. If I had nothing else to do with my life, I’d write up an essay on the subject and see where I could get it published. From what I can tell, the “quantum consciousness” ballyhoo breaks down into three parts:
1. Mind Over Matter — the idea that consciousness, awareness or what-have-you can sway or even determine reality, such as the story about Columbus’s ships. This part is total bleep-ing nonsense.
2. Trans-Goedel Hypercomputation — Penrose’s notion that non-Turing computation is necessary for consciousness. This is dubious at best, and I’m being generous there.
3. Microtubules as quantum switches — pretty much ruled out by Tegmark’s calculation of decoherence times. As every cell biologist knows, microtubules have better things to be doing, like providing railways for kinesin motors.
Yes. I’m pretty sure that even Penrose would find that ludicrous. He believes there’s a deep connection between quantum weirdness and consciousness, but only one that allows you to “perceive” certain things you otherwise couldn’t. (Like roughly neoplatonic mathematical truths.)
That’s a far cry from being able to literally create your own reality and I’d guess that Penrose would say the opposite of what the Bleepers do. For him, the whole point is apprehending an independent objective truth, in a way a Turing machine couldn’t—not just making stuff up and conjuring it into reality by force of will.
One of the deep problems with the Bleepers’ view is that quantum physics is random. Even under Copenhagenish interpretations, you may be able to force the collapse of the wave function by observation, but you can’t choose which way it will collapse. (Schrodinger can look into the box and make his cat alive or dead, but he doesn’t get to pick which.)
Like the issues of scale, that’s a crucial thing the moviemakers want you not to know, despite physicists explaining its importance at length; they carefully left those parts on the cutting-room floor.
I agree—and either way, it doesn’t get you the kind of “Better Living Through Reality Creation” the New Agers want to sell you.
Yep. To be fair, I don’t think microtubules per se are central to Penrose’s argument, but Tegmark and others cast grave doubt on the more general claim, too. It’s just not plausible.
It’s also not very plausible from a basic cognitive neuroscience point of view. If we had such magical hypercomputation, why would we need all these trillions of synapses doing things the hard way, by brutal classical computation? Why all the lateral inhibition in the retina, retinotopic maps of the visual field spread across the backs of our brains, etc.?
…which reminds me of a vivid example that maybe belongs in the grody-rat-stories thread:
One early example of the neuroscience of vision was an experiment they did with tagged glucose (I think) injected into rats. The tagged glucose would concentrate in more metabolically active tissues, e.g., the neurons that were busy firing.
So they got a rat to fixate on a patterned image, and then killed the rat. They took out its brain, and put it in a chemical that would latch onto the tagged glucose and darken it, like developing a photographic print.
And lo, an image appeared on the rat’s optic lobes of what it had been looking at when it was killed. (A bit stretched and distorted, due to the vagaries of deveopment of sheets of feature-detecting neurons, but clearly the same image.)
A rat doesn’t need a magic word from a shaman to notice a ship or a white man. (“A cat may look upon a king.”) So why should a human—or rather, why would these bleeping moviemakers want you to think so?
“The man behind the curtain isn’t real. And now… heeere’s Ramtha!”
It’s memetic HIV, undermining your immunity to the other bullshit. (Not that I think a lot of people are going to go for the Ramtha lunacy; it’s all the other opportunistic infections I’m worried about.) Creepy.
I dimly recall some work in the last five years or so which shows that certain neurons act as AND gates: two dendrites in, one axon out. If pulses arrive on the dendrites at the same time (within some tolerance) a signal fires off down the axon. This is a very useful gate to have, and barn owls even use them to locate the sources of sounds.
One ear of the animal points upward and the other is tilted downward, so comparing relative volumes can tell the animal whether a sound is coming from above or below. To get left-right location, the owl brain uses a nifty neural construction where the axon carrying signals from the right ear comes in from one direction and the axon from the left ear comes in the other. Projections come off the axons and meet on AND gates, so that each gate receives one input from each ear. A signal propagates down an axon with a definite speed, so if a sound source is directly in front (or behind) of the owl, the pulses meet in the middle and trigger the center AND-gate. If the squeaking mouse is on the left, the left ear picks it up first and the pulse enters that side a little bit earlier. It then travels over to the far end of the AND-gate bank before the pulse from the right ear can arrive, so a gate neuron on the right-ear end will fire.
I used to know all the neuroanatomy, timing factors and such for this, but in the last year and a half the details have been crowded out of my limited brain capacity. The kicker, though, is this: one can understand how a neuron can act as an AND gate just by modeling the flow of ions through its cell membrane, not considering the cytoskeleton at all! So much for needing microtubules to do a damn thing. . . .
Link to “Binaural cross-correlation and auditory localization in the barn owl: a theoretical study”, M. Rucci and J. Wray, Neural Netw. 12, 1 (Jan 1999): 31-42. This paper and those it cites/is cited by basically give the low-down on what I was trying to remember.
See also “Dendritic Computation” by M. London and M. Hausser, Annu. Rev. Neurosci. 2005.
Incidentally, Penrose’s argument is wrongheaded even modulo the physics stuff, since the incompleteness theorem applies to any sufficiently complex fragment of formalized mathematics, not just to computable theories. He’s basically run together uncomputable and (formally) incomplete, and the two are fundamentally different. I noticed this as soon as I did enough logic, which is embarassing for Penrose. Solomon Feferman (I think it was) raised the same point in a review, as I found out later.
As for the physics, well, look at Pat Churchland and Rick Grush’s paper “Gaps in Penrose’s Toilings” for an elementary look at biophysics of neurons. Vic Stenger also has some stuff on this; the former two also go through how ridiculously unsupported the P. argument really is.
Off the above topic: Montrealers can come and support a local human rights NGO tonight – Global Music 4 Social Justice at Kola Note.