12 ms·
How much bandwidth does the spinal cord have?
- nielsbot 7y agoI laughed at this quote (tl;dr) from the article: "about a 4K movie every two seconds". Hope that doesn't qualify as a spoiler.
- noir_lord 7y agoIf his answer is on the right order magnitude it's kinda interesting that our signalling technology is getting up there in bandwidth.
- Ididntdothis 7y agoLatency is quite high though as far as I know.
- mhh__ 7y agoSpeaking of latency, one of the most bizarre experiences I can think of is when (on a certain cough substance beginning whose name is a type of broadband spelt backwards) one's reaction times double to about 500-600 ms and trying to do a reaction test. Really fascinating but also hilarious to watch someone else try.
- lagadu 7y agoInteresting, do you have a source for that? I'd love to read it. I'm interested because my experience with that differs strongly (though it's with shrooms, not LSD): while tripping on low doses I was a god* at guitar hero, significantly better than I was at playing sober, the same was true for another friend of mine as well. Maybe the task being rhythm-related offsets the increased delay. *sober I mastered Hard but had some trouble on the harder songs on expert, under the influence was the first time I managed to do several of them in expert.
- mhh__ 7y agoI don't have a source other than a ... friends experience (wink wink, "which means I am lying"). It's the only area of medicine I'd do research in, Psychedelics seem to have dramatically different effects while still having some constants - across different people. I could type 10 WPM faster than I usually could but my companion couldn't get above 15 WPM (He's usually bad not that bad). Once you get going it seems to be manageable, as if you have thought-momentum, i.e. Maybe it's a movement issue rather than literally reaction time directly. > Maybe the task being rhythm-related offsets the increased delay. I think that may have an effect. I can play actual guitar fairly well (I can still play pretty fast Yngwie stuff) under the influence but only once I've "warmed up" but then I'm effectively just reciting motion from memory rather than reacting to anything There are papers/research on this but they're all behind paywalls, which I can't be bothered to get around rn.
- lagadu 7y agoThe feeling of playing was very different; it felt like my hands were playing the controller by themselves without any real input or reactions on part of "me".
- gingabriska 7y agoBut I read somewhere that the brain is able to adjust heart beats and breathing at a very fine frequency and and keeping it in sync requires good latency and all this is done without concurrency locks. So does brain have massively parallel architecture where key things have their own core?
- inciampati 7y agoIn biology every single protein (or other biochemical entity) can be thought of as it's own core. It's parallel in an amazing and beautiful way. Or the most boring way possible. It just depends on if you are a computer scientist or biologist how you would see it.
- bdamm 7y agoThere are to this day computer science researchers having conniptions about the impossibility of massively parallel lock-free architectures based on eventual consistency. Yet literally all they must do is open their eyes and see the truth!
- jplayer01 7y agoIt helps that our brains and bodies are analog. It doesn't matter if a particular variable is changed by different factors at the same time. The total magnitude of all the changes is far more important. Thus, lock-free.
- farazbabar 7y agoKind of like CRDT (conflict free replicated data types for the biologists amongst us).
- whatshisface 7y agoProtiens? Every particle in every atom is solving exponential-time problems constantly, in parallel. That's the quantum chemistry perspective. :)
- alevskaya 7y agoThis is an excessive overestimate by not carefully considering the known types of afferent (incoming) fibers and their average firing statistics (most neurons fire sparsely). See the comment on that thread by "JohnShaft" who noodles a better estimate of around 200MB/s (incoming) by taking anatomy into account. The motor efferent signals are going to be a lot lower bandwidth still...
- jonshariat 7y ago- Modem - Cable - Fiber Maybe in the future we'll have... Spinal Tap
- grayed-down 7y agoThis is a place for serious discussion. No humor or attempts thereof will be tolerated as evidenced by the steadily graying color of your comment text.
- wcoenen 7y agoThe top voted answer is assuming a neuron firing/not firing (once per refractory period) can be counted as a bit for the purpose of calculating bandwidth. But I think the peripheral nerve system uses firing frequency to encode intensity, so I'm not sure you can really equate 1 firing with one bit. For example, over 15 refractory periods there could be anywhere between 0 and 15 firings, thereby encoding 16 different possible intensities. That would effectively be only a 4 bit message per 15 periods, not 15 bit per 15 periods.
- zamadatix 7y agoThe classic goodput vs throughput debate. E.g. Gigabit Ethernet is most commonly actually physically transmitted at 1.25 gigabit/s because of 8b10b coding. Ethernet requires interpacket gaps, and the packetization itself changes overhead. Then of course you have other protocol overheads underneath you could consider, and how much overhead the data you were transmitting has due to encoding of it itself. In the end there is really "bandwidth" which is how much symbol "space" is available and various levels of "goodput" which is the rate of whatever you're calling useful data.
- rzzzt 7y agobaud vs. bps
- zamadatix 7y agoOther things like unusable symbols (e.g. IFG added to above) make it more nuanced than that.
- Dylan16807 7y ago> Gigabit Ethernet is most commonly actually physically transmitted at 1.25 gigabit/s because of 8b10b coding. Fiber often uses 8b/10b. Over copper it's much more complicated. USB 3.0 is an example of simple 8b/10b. 4Gbps data, sent at 5Gbps. Ethernet over twisted pair, well... 10mbit Ethernet turns each bit into either a 01 or a 10 and sends those on the line. 100mbit Ethernet applies 4b5 encoding to get a 125MHz signal, then it uses this to drive an encoding called MLT-3. In MLT-3, the final output cycles through -1, 0, +1, 0 over and over, and each bit decides whether it advances or doesn't advance. Gigabit Ethernet does a complicated encoding to turn batches of 8 bits into 4 separate voltages from -2 to +2 (so 5 levels). It then sends these simultaneously over all four wire pairs at a grand total of 125MHz.
- ramshanker 7y agoFollow up question I googled. What is the resolution of our Eyes? Ans: 576 Megapixels [1]..... Holy..... And here we are, trying to rely on couple of cameras for autopilot. [1]http://www.clarkvision.com/articles/eye-resolution.html http://www.clarkvision.com/articles/eye-resolution.html
- alevskaya 7y agoYes but keep in mind that this data is immediately and heavily compressed and encoded - the data sent into the brain from the retinal ganglion cells has been estimated to be on the order of 10s Mbit/sec from careful studies on rodent RGN statistics. https://doi.org/10.1016/j.cub.2006.05.056 https://doi.org/10.1016/j.cub.2006.05.056
- cmenge 7y agoNot an expert, but this is also my understanding: The nerves are more like a neural network, not just wiring to the brain: https://heartbeat.fritz.ai/the-ancient-secrets-of-computer-vision-2-by-joseph-redmon-condensed-934e16eacb44 https://heartbeat.fritz.ai/the-ancient-secrets-of-computer-v...
- googlemike 7y agoResolution has very little to do with object detection and obstacle avoidance. (not saying Musk isn't full of shit)
- HillRat 7y agoIt’s not just resolution; the dynamic range (the “f-stops”) of the human visual system is incredibly wider than even high-quality film and digital cameras, meaning that cameras are much less capable at handling details between wide ranges of light and dark.
- Veedrac 7y agoThough post-processing from neural nets seems to close this gap. https://www.youtube.com/watch?v=bcZFQ3f26pA https://www.youtube.com/watch?v=bcZFQ3f26pA
- DonHopkins 7y agoSomething I posted earlier about spinal cords and high fidelity music: https://news.ycombinator.com/item?id=18750902 https://news.ycombinator.com/item?id=18750902 Speaking of spines and copyright issues: In K W Jeter's excellent dark cyberpunk novel "Noir", intellectual property theft is viewed as literally killing people by removing their livelihood, so copyright violators were punished by having their still-living spinal cords stripped out and made into high quality speaker cords in which their consciousness is preserved, usually presented to the copyright owner as a trophy. "In the cables lacing up Alex Turbiner's stereo system, there was actual human cerebral tissue, the essential parts of the larcenous brains of those who'd thought it would be either fun or profitable to rip off an old, forgotten scribbler like him." https://marzaat.wordpress.com/2018/01/27/noir/ https://marzaat.wordpress.com/2018/01/27/noir/ >There’s a lot to like in the novel. >My favorite section is the middle section where the origin of the asp-heads is detailed via McNihil’s pursuit of a small time book pirate and the preparation of the resulting trophy. The information economy did, in this future, largely come to place. As a result, intellectual property theft is viewed as literally killing people by removing their livelihood. Therefore, death is a fitting punishment. McNihil, in his point by point review of the origin of asp-heads, notes that even in the 20th Century there was the phrase: “There’s a hardware solution to intellectual property theft. It’s called a .357 magnum.” >Actually it’s decided that death is too good and too quick for pirates. >Their consciousness is preserved by having their neural network incorporated in various devices. (Turbiner likes to use stripped down spinal cords for speaker wire.) >This sounds like a cyberpunk notion but, in other parts of the novel, Jeter takes a swipe at such hacker/information economy/internet cliches as information wanting to be free (McNihil destroys a nest of such net hippies) or the future economy being based on information. Villain Harrisch sneers at the notion stating that information can be distorted but atoms – and the wealth they represent – endure. >Still, his novel is chock full of the high-tech, low-life that characterizes cyberpunk. (I'd quote some more, but as a high-tech, low-life net hippie, I'm afraid of having my nest destroyed and getting my spine ripped out!)
- diehunde 7y agoI think google used to ask this question to candidates.
- cr4zy 7y agoSimilar question on Quora from 2012[1] per sense: Vision: 10Mb/s => 100Mb/s Hearing: 30Mb/s Touch: 135Mb/s Smell: 100k neurons Taste: 100kb/s Proprioception: ?? Balance: ?? Total: ~10Mb/s=>~1Gb/s Internal brain bandwidth is also worth mentioning as this is the last remaining wetware advantage over hardware due to the three dimensionally fully connected heterogeneous cortical substrate. I can't seem to find a figure on that though. https://www.quora.com/How-much-bandwidth-does-each-human-sense-consume-relatively-speaking https://www.quora.com/How-much-bandwidth-does-each-human-sen...
- jlawson 7y agoI really question the hearing one, at least. Shouldn't this basically just be the bandwidth of a headphone signal which is at the lowest quality where you can hear degradation if it goes any lower? For me that's something like 3MB per minute, per well-compressed ogg files, or 50KB per second. Yet that answer says my hearing bandwidth is actually 600x higher than that. I can imagine some small difference, but to say my ear has evolved to transmit 600x more sound data than I can actually perceive sounds off.
- Terr_ 7y ago> Shouldn't this basically just be the bandwidth of a headphone signal One issue with this approach is that it's very hard to tell the difference between data that was never sent versus data that is there but our developing brains were trained to ignore because it didn't turn out to be useful. A simple example of this would be language differences, where certain important language features simply aren't noticeable to non-native speakers, despite having the same sensor-hardware.
- parentheses 7y agoSolid back of the envelope job.
- kadendogthing 7y agoHere is a rule: >Please don't submit comments saying that HN is turning into Reddit. It's a semi-noob illusion, as old as the hills. Allow me to point out a few characteristics of this post: * A submission to reddit * No actual scientific or academic details supporting his statements. Just some known other quantitive data about the spinal cord. OP even characterizes most of his statements as "gross assumptions" * This post to HN has been upvoted. Here is a scientifically reasonable perspective on this subject: https://www.reddit.com/r/askscience/comments/7l56sb/how_much_bandwidth_does_the_spinal_cord_have/drkxah0/ https://www.reddit.com/r/askscience/comments/7l56sb/how_much...
- stevenjgarner 7y agoDo bundles of nerves (such as a spinal cord) have cross-over attenuation, limiting their bandwidth like copper cables? This was one of the drivers in telecommunications towards adoption of fiber optics over copper cables. The 600+ pair copper telco cables could not sustain 600 separate DSL circuits, as the high frequency signals would interfere and cause attenuation. In many FTTH deployments, fiber was a cheaper transport than installing additional multiple pair copper cables to support the required customer demand. Of course, the enhanced bandwidth capability of fiber optics, together with the ability to have many more "circuits" over a a single fiber, were other drivers towards adoption of optical broadband. If there is not cross-over attenuation with bundles of nerves, is that only because of the mylar sheath? Obviously any significant interference might have an effect on the calculations of spinal cord bandwidth.
- tantalor 7y agoSometimes, it's called "multiple sclerosis"
- ksaj 7y agoAnd sometimes ALS. There are a few diseases related to sheath deterioration, weakening, shortening, etc. It's pretty important stuff.
- smegger001 7y agoThe nerves have a layer of fatty acids called Myelin that act as a sheathing/sheilding around the nerve fibers to prevent crosstalk. https://en.wikipedia.org/wiki/Myelin https://en.wikipedia.org/wiki/Myelin
- swordsmith 7y agoMyelin's function is to speed up signal conduction along the axon, not crosstalk between axon fibers.
- garbre 7y agoI reject the premise that the nervous system has "bandwidth" in a sense comparable to digital communications. Yes, nerves fire in discrete action potentials, but every step of nervous transmission also involves a processing step. Let's not forget: a huge benefit of neural nets is dimensionality reduction, which is at once compression but also the extraction and abstraction of salient information. Does this represent the gain or loss of information? It's a basically meaningless question; the question is how does the system as a whole work, and how well? Nor is it clear what the endpoint of a communication is. This is another issue. Does information get counted twice if it's used by both unconsciously by the brainstem as well as rising into awareness and is used by the neocortex? The list of questions can go on. This bandwidth thing is one of the questions I find frustrating, on par with people wondering if a simulated piece of brain has feelings (the answer is NO). Why is left as an exercise for the reader.
- carrozo 7y agoI keep thinking of this piece: https://aeon.co/essays/your-brain-does-not-process-information-and-it-is-not-a-computer https://aeon.co/essays/your-brain-does-not-process-informati...
- feedbeef 7y agoI keep thinking of this: https://waitbutwhy.com/2017/04/neuralink.html https://waitbutwhy.com/2017/04/neuralink.html
- codetrotter 7y agoFrom the page you linked: > The better we could communicate on a mass scale, the more our species began to function like a single organism, with humanity’s collective knowledge tower as its brain and each individual human brain like a nerve or a muscle fiber in its body. With the era of mass communication upon us, the collective human organism—the Human Colossus—rose into existence. I like thinking about us this way too, as being both individuals but at the same time also forming a sorts of organism together. What originally got me thinking about us this way was something that Sun Tzu wrote in his book The Art of War. I think this might be the part of that book that made me think of it like this: > The skillful tactician may be likened to the shuai-jan. Now the shuai-jan is a snake that is found in the ChUng mountains. Strike at its head, and you will be attacked by its tail; strike at its tail, and you will be attacked by its head; strike at its middle, and you will be attacked by head and tail both. > Asked if an army can be made to imitate the shuai-jan, I should answer, Yes. For the men of Wu and the men of Yueh are enemies; yet if they are crossing a river in the same boat and are caught by a storm, they will come to each other's assistance just as the left hand helps the right. http://classics.mit.edu/Tzu/artwar.html http://classics.mit.edu/Tzu/artwar.html
- CodiePetersen 7y agoYou aren't really "sending data" though. Each one of the neruons just ends up triggering a circuit. And some of the fire signals are actually inhibitory signals to stop other neurons from firing. Not to mention all of the chemical signaling going on and the different types of patterns/behaviors that get activated through repetitive or limited activity. So really to calculate bandwidth is kind of pointless. One the neurons use more dimensions than just on and off electrical signals as their state and two, neurons don't really pass information along when you think about it they just trigger circuitry.
- bryanrasmussen 7y agoI didn't read through everything but it seems people are assuming some sort of 'normal' spinal cord without specifying what that is - so in this bandwidth analogy they have for spinal cords, what is the affect of age, disease, and injury on it.