--- Log opened Wed Jan 04 00:00:05 2023
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06:27 < kanzure> hmph
08:49 < lsneff> wow, that is spectacularly sparse
08:50 < lsneff> how on earth does enough information travel through only a few thousand axons between functional areas
08:52 < muurkha> that's a few megabits per second, maybe?
08:54 < lsneff> distributed over all connections
08:54 < muurkha> we know that sound localization uses phase information up to 1 kHz, so submillisecond neural spike timing can convey information even if the spike frequency is only 100 Hz or so
08:55 < lsneff> that's true
08:56 < muurkha> so you might get 3 or 4 bits per spike, if phase relative to some "clock signal" is significant in things that aren't sound localization
08:57 < muurkha> maybe as much as 7
08:57 < muurkha> https://en.wikipedia.org/wiki/Sound_localization says "Humans can discern interaural time differences of 10 microseconds or less."
08:59 < lsneff> this further bolsters my hunch that the brain is very compute sparse compared to ANNs
09:00 < lsneff> So the cortex overall has around 2.7 * 10⁹ spikes per second
09:00 < lsneff> "So the cortex overall has around 2.7 * 10⁹ spikes per second"
09:00 < lsneff> https://aiimpacts.org/metabolic-estimates-of-rate-of-cortical-firing/#:~:text=per%20transported%20molecule).-,Spikes%20per%20neuron%20per%20second,2.7%20*%2010%E2%81%B9%20spikes%20per%20second.
09:32 < muurkha> yeah, I was thinking more about the inter-regional connectivity bottlenecks 
10:12 < kanzure> .title http://www.ncbi.nlm.nih.gov/pmc/articles/PMC2776484/
10:12 < saxo> The Human Brain in Numbers: A Linearly Scaled-up Primate Brain - PMC
10:12 < kanzure> "These studies also showed that the human brain is not exceptional in its cellular composition, as it was found to contain as many neuronal and non-neuronal cells as would be expected of a primate brain of its size. Additionally, the so-called overdeveloped human cerebral cortex holds only 19% of all brain neurons, a fraction that is similar to that found in other mammals. In what regards ...
10:12 < kanzure> ...absolute numbers of neurons, however, the human brain does have two advantages compared to other mammalian brains: compared to rodents, and probably to whales and elephants as well, it is built according to the very economical, space-saving scaling rules that apply to other primates; and, among economically built primate brains, it is the largest, hence containing the most neurons. These ...
10:12 < kanzure> ...findings argue in favor of a view of cognitive abilities that is centered on absolute numbers of neurons, rather than on body size or encephalization, and call for a re-examination of several concepts related to the exceptionality of the human brain."
10:12 < kanzure> .title http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3973910/
10:12 < saxo> Evolution of the human brain: when bigger is better - PMC
10:12 < kanzure> "The tremendous increase in the cortical surface without a comparable increase in its thickness during mammalian evolution has been explained in the context of the radial-unit hypothesis of cortical development (for reviews, see Rakic, 2007, 2009). According to this model, neocortical expansion is the result of changes in proliferation kinetics that increase the number of radial columnar units ...
10:12 < kanzure> ...without changing the number of neurons within each unit significantly. Therefore the evolutionary expansion of the neocortex in primates is mainly the result of an increase in the number of radial columns."
10:13 < kanzure> "The geometric structure of the brain fiber pathways" http://people.psych.cornell.edu/~jec7/pcd%202012-13%20pubs/weedensci.pdf
10:14 < nmz787> 27 spikes per second seems egregiously low
10:15 < kanzure> "A mechanism for the origin of the human brain: a hypothesis" http://www.gwern.net/docs/algernon/1998-henneberg.pdf
10:16 < kanzure> "Constancy and trade-offs in the neuroanatomical and metabolic design of the cerebral cortex" http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3920482/
10:17 < kanzure> "How does connectivity between cortical areas depend on brain size? Implications for efficient computation" https://arxiv.org/abs/q-bio/0310015
10:17 < kanzure> "The second principle is that brains try to maintain a constant connectivity between cortical areas regardless of brain size; this is what the results of Sec. 3 may suggest. The third principle, which is closely related to the second, is that intra- and inter-hemispheric temporal delay should not increase with the brain volume. The last two requirements prevent isolation of cortical areas and ...
10:17 < kanzure> ...additionally enhance the efficiency of information transfer between them, thus providing the link between local and global information processing (Sporns et al, 2000). Although, it has been argued before that delays do increase with brain size (Ringo et al, 1994), we treat the third principle as a first order approximation of what one may naively expect to be a perfect design."
10:18 < kanzure> there was a "principle of minimal axon length" previously established by Mitchison, 1992; Cajal, 1995; Cherniak, 1995; Murre and Sturdy, 1995; Stevens, 1999.
10:23 < kanzure> and here is someone doing estimates of neuron count in dinosaur telencephelon? https://www.biorxiv.org/content/10.1101/2022.06.20.496834v3.abstract
10:24 < kanzure> er, telencephalon
10:29 < kanzure> hm interesting author: https://www.suzanaherculanohouzel.com/lab.html "The Herculano-Houzel lab started in 2005, with the publication of the cell-counting method created by the PI, the isotropic fractionator, which really consists of... turning brains into soup. The motivation was figuring out how many cells composed the brains of different animals, because only one thing was certain then: the ...
10:29 < kanzure> ...human brain was NOT made of "100 billion neurons and 10 times as many glial cells", for the simple reason that nobody had really counted yet."
10:34 < lsneff> what is the current ratio now of neurons to glial?
10:36 < nmz787> FYI the number should have been pasted as "2.7 * 10^9" spikes per second
10:37 < nmz787> although now that I copy the blank characters and paste them into my Chrome browser URL bar, I do see they render as a superscript 9
10:37 < nmz787> :/
10:37 < nmz787> do other folks see the superscript in their IRC program???
10:40 < kanzure> "The search for true numbers of neurons and glial cells in the human brain: A review of 150 years of cell counting" https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5063692/
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10:41 < kanzure> nmz787: ½
10:41 < kanzure> x³
10:41 < kanzure> see https://en.wikipedia.org/wiki/Unicode_subscripts_and_superscripts
10:41 < nmz787> whatever you just typed looks like zelda game script characters
10:42 < nmz787> or something similarly ficticious
10:42 < kanzure> your computer is broken
10:42 < nmz787> is it IRSSI?
10:42 < nmz787> or the terminal I am connecting from?
10:42 < kanzure> irssi can support unicode
10:43 < kanzure> are you using tmux? screen? a pty? tty? vty? i don't know.
10:43 < nmz787> oh yeah, just connected from another terminal and see different stuff
10:47 < kanzure> "No relative expansion of the number of prefrontal neurons in primate and human evolution" https://www.pnas.org/doi/full/10.1073/pnas.1610178113
10:48 < kanzure> "Human evolution is widely thought to have involved a particular expansion of prefrontal cortex. This popular notion has recently been challenged, although controversies remain. Here we show that the prefrontal region of both human and nonhuman primates holds about 8% of cortical neurons, with no clear difference across humans and other primates in the distribution of cortical neurons or white ...
10:48 < kanzure> ...matter cells along the anteroposterior axis [...] We thus propose that the most distinctive feature of the human prefrontal cortex is its absolute number of neurons, not its relative volume."
10:57 < nsh> worth spending a few days entertaining the ideas of David Bohm and Karl Pribram 
10:58 < nsh> as regards the way in which the brain and mind and information and space/geometry/time intersect
10:59 < nsh> i can tell you this much for free, if you've no notion of holography in your understanding of these things then you're gonna be beating around the bush longer than you might
11:03 < nsh> this person made some useful videos: https://www.youtube.com/@stephene.robbins6273/videos
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11:08 < nmz787> holography is an overused term
11:09 < nsh> do you understand its precise usage?
11:09 < nsh> mathematically, that is
11:09 < nmz787> I mean the suffix root is relating to images
11:10 < nsh> if you had to define what it means that something is holographic wrt to something else
11:10 < nsh> could you?
11:11 < nsh> you can at least sense that it has to do with dimensional reduction
11:12 < nmz787> the stupid definition is "a method of creating a 3d looking visual image, using interference patterns based on the original objects"
11:13 < nmz787> maybe I'm stupid/ignorant/uneducated about the specific term?
11:13 < nsh> so when we say that we have a holographic correspondence in the context of physics it is *between* a theory that lives in some space of dimensionality N+1 (the "bulk") and a theory that lives in a space of dimensionality N (the "surface") 
11:16 < nsh> so when you go into a nice gallery and you see a beautiful hologram (noun, substantive, object of art) you are experiencing a relationship between an object that was captured holographically through optics and represented in a medium of a lower number of dimensions  
11:16 < nsh> the holographic plate
11:16 < kanzure> mammalian brains by numbers (see the tables) https://www.karger.com/Article/PDF/437413
11:16 < nsh> and through the properties of coherent light there is the reproduction of the perception of a higher dimensionality
11:17 < kanzure> "The elephant brain in numbers" https://www.frontiersin.org/articles/10.3389/fnana.2014.00046/full
11:18 < kanzure> "We find that the African elephant brain, which is about three times larger than the human brain, contains 257 billion (109) neurons, three times more than the average human brain; however, 97.5% of the neurons in the elephant brain (251 billion) are found in the cerebellum. This makes the elephant an outlier in regard to the number of cerebellar neurons compared to other mammals, which might ...
11:18 < kanzure> ...be related to sensorimotor specializations. In contrast, the elephant cerebral cortex, which has twice the mass of the human cerebral cortex, holds only 5.6 billion neurons, about one third of the number of neurons found in the human cerebral cortex. This finding supports the hypothesis that the larger absolute number of neurons in the human cerebral cortex (but not in the whole brain) is ...
11:18 < kanzure> ...correlated with the superior cognitive abilities of humans compared to elephants and other large-brained mammals."
11:18 < kanzure> did they really fractionate an entire elephant brain
11:20 < kanzure> if it really is just absolute number of cortical neurons, plus a handful of specialized long-range axon projections, then the absolute number of cortical neurons can probably be put under control of an inducible promoter/overexpression system
11:27 < kanzure> nsh: much of it is probably lower-dimensional geometry, simple things like small world graphs and folding/tension
11:32 < kanzure> is this the only lab with a cortical fractionator??
11:35 < kanzure> https://medium.com/neodotlife/koniku-biological-chips-osh-agabi-f1de4bf48fa7 https://neo.life/2018/05/the-birth-of-wetware/
11:35 < kanzure> https://koniku.com/
11:36 < kanzure> looks like they have pivoted to olfactory/odor sensing?
11:36 < lsneff> I swear that company used to be called something else
11:36 < kanzure> you might be thinking of "cortical labs" or "dishbrain" https://www.genengnews.com/neuroscience/human-brain-cells-in-a-dish-learn-to-play-pong/
11:37 < kanzure> https://corticallabs.com/
11:39 < lsneff> https://www.cell.com/neuron/fulltext/S0896-6273(22)00806-6
11:39 < kanzure> .title
11:39 < saxo> In vitro neurons learn and exhibit sentience when embodied in a simulated game-world: Neuron
11:48 < kanzure> i wonder if the fractionator is able to keep the neurons in tact, like with their entire dendritic tree
11:50 < kanzure> seems to be more about counting nuclei and less about preserved neuron structure
11:51 < kanzure> world's worst jigsaw puzzle
11:52 < kanzure> did they ever actually get a connectome from the neuronal DNA barcoding/synapse tracing stuff?
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12:40 < L29Ah> Muaddib: what is more expensive: Alphabet Inc., or a self-sustaining human colony on the asteroid belt?
12:40 < Muaddib> L29Ah: It's a toss-up. On one hand, you have almost infinite potential for growth in Alphabet Inc. On the other hand, you have almost infinite potential for growth in a self-sustaining human colony on the asteroid belt.
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13:14 < muurkha> how could something be "almost infinite"?
13:16 < muurkha> does my body contain an almost infinite amount of mass because it has about 10²⁴ atoms?
13:16 < muurkha> and about 10³⁰ electron masses
13:17 < kanzure> in tissue culture, most neural metabolism can be replaced by blood substitute
13:19 < muurkha> hmm, apparently about 10³² electron masses, I wonder how I got that 100× wrong
13:19 < kanzure> .title https://news.ycombinator.com/item?id=34238028
13:19 < saxo> Can self-replicating species flourish in the interior of a star? (2020) [pdf] | Hacker News
13:32 < nmz787> watched "lawnmower man" recently, it was a good flick
13:34 < kanzure> nmz787: https://movielens.org/
13:38 < superkuh> Neat. I feel like the cool layer of the chromosphere would be a better bet. There's the largest free energy gradient, transient molecules, and it's where magnetic pressure begins to dominate over thermal pressure lots of weird magnetic stuff like plasmoids obviously happen from radio observation. And the helicity of the locked in magnetic fields may play a role in enabling energy release (or not).
13:42 < kanzure> have you read the robert forward dragon egg take on it?
13:45 < lsneff> love that book
13:45 < lsneff> very interesting
13:46 < kanzure> .wik ontogeny recapitulates phylogeny
13:47 < saxo> "The theory of recapitulation, also called the biogenetic law or embryological parallelism—often expressed using Ernst Haeckel's phrase  'ontogeny recapitulates phylogeny'—is a historical hypothesis that the development of the embryo of an animal, from fertilization to [...]" - https://en.wikipedia.org/wiki/Ontogeny_recapitulates_phylogeny
13:47 < kanzure> huh, for some reason i remember high school biology not disputing this
13:48 < kanzure> "The Haeckelian form of recapitulation theory is considered defunct.[18] Embryos do undergo a period or phylotypic stage where their morphology is strongly shaped by their phylogenetic position,[19] rather than selective pressures, but that means only that they resemble other embryos at that stage, not ancestral adults as Haeckel had claimed.[20] The modern view is summarised by the University ...
13:48 < kanzure> ...of California Museum of Paleontology: Embryos do reflect the course of evolution, but that course is far more intricate and quirky than Haeckel claimed."
13:49 < kanzure> "ancestral adults" ok that's obviously wrong but i thought the main point was different evolutionary periods (like before the development of tubes, or separate tissues, or multicellularity, etc)
13:54 < kanzure> "Wilhelm His and mechanistic approaches to development at the time of Entwicklungsmechanik" https://link.springer.com/article/10.1007/s40656-017-0148-z
13:55 < kanzure> (apparently there was both a wilhelm his and wilhelm roux working on this?)
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15:09 < kanzure> another workshop on open-source cryptographic hardware (this time featuring bunnie) https://www.eventbrite.com/e/silicon-salon-3-tickets-492802494527
15:09 < kanzure> (let me know if anyone would like a ticket)
15:15 < superkuh> Yes, re: dragon egg. My favorite aliens are the magnetic field plasma ones that live at the heliopause in Gregory Benford's "The Sunborn". David Brin's "Sundiver" also has good star living aliens.
17:38 < kanzure> is michael levin just crazy or what's the story and why does he quote rudolf steiner
17:44 < muurkha> most people believe a lot of crazy things
17:45 < L29Ah> how about https://en.wikipedia.org/wiki/The_Integral_Trees
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18:03 < kanzure> "Multi-scale chimerism: An experimental window on the algorithms of anatomical control" https://www.sciencedirect.com/science/article/abs/pii/S266729012100098X
18:03 < kanzure> "Here, we review an important and fascinating body of data from experiments utilizing DNA transfer, cell transplantation, organ grafting, and parabiosis. We suggest that these are all instances (at different levels of organization) of one general phenomenon: chimerism"
18:09 < kanzure> .tw https://twitter.com/teraxurato/status/1608928543261741057
18:09 < saxo> New preprint alert!! / We made the first transgenic ants, expressing GCaMP in the antennae (pic), to study how the ant brain encodes social signals. We discovered a core glomerulus in the brain that responds to alarm pheromones. // https://www.biorxiv.org/content/10.1101/2022.12.04.518909v1 / [1/XX] https://pbs.twimg.com/media/FlQNL32XEAALl5d.jpg (@teraxurato) psa from .tw cmd: fuck twitter
18:09 < kanzure> we did not have transgenic ants before?
18:09 < kanzure> this is how you get transgenic ants
19:23 < kanzure> i would like to find a good homeobox/hox review article that focuses on embryology, kind of like "Embryonic transplantation experiments" https://www.ncbi.nlm.nih.gov/pmc/articles/PMC6800665/   but not necessarily about transplants.
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--- Log closed Thu Jan 05 00:00:05 2023