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'Time Cells' Discovered in Human Brains
- acrefoot 6y agoI thought we had discovered pacemaker cells over 20 years ago. I'd be very surprised if that didn't already factor into hypotheses of how episodic memory is ordered. Either this article is disingenuous, or neuroscience suffers from deep fragmentation that is hindering progress. https://www.hhmi.org/news/researchers-discover-molecular-pacemakers-heart-and-brain https://www.hhmi.org/news/researchers-discover-molecular-pac...
- acrefoot 6y agoRelated: breathing is semi-autonomous, and controlled in the brain: https://www.ucsf.edu/news/2017/08/408006/searching-brain-cells-control-our-breathing https://www.ucsf.edu/news/2017/08/408006/searching-brain-cel... We can be aware of our breathing or not, yawn, and hold our breath. I imagine we can do similar with our sense of time: count seconds, have a sense of time, and lose our sense of time (on purpose or by accident).
- hombre_fatal 6y agoDid you actually read both studies? If so, I don't see how you could have arrived at the conclusion that the time cell paper is a rehash of what you linked. They are talking about and focusing on entirely different things.
- acrefoot 6y agoI hadn't read the paper, just the article. Which is primarily what I was commenting on. When I read "now researchers have identified cells in the human brain that make this sort of memory possible", I was lead to believe that NPR was suggesting that there weren't plausible mechanisms of timekeeping for episodic memory before now. Especially since they don't mention any other mechanisms, and Buzsáki (not a study author) and NPR together imply that people with hippocampal lesions who can't order events correctly are simply missing their time cells. Anyhow, I've now read much more of the two linked papers, and some related papers. In the 2011 paper linked from the NPR article, under "Neuronal Ensembles Signal Time, as well as Location and Behavior, during the Delay Period" (https://www.sciencedirect.com/science/article/pii/S089662731100609X#sec2.2 https://www.sciencedirect.com/science/article/pii/S089662731...) "time cells" are defined under their relation to "place cells". As far as I can tell, this paper coined the term. Now, in this paper, they aren't sure if the time cells are scalar time (Gibbon) or non-linear time (Staddon and Higa) or some combination of the two. Well, Gibbon's scalar expectancy theory for timing (SET) uses pacemaker cells in the theory. Now other papers do want to move away from pacemaker cells: Staddon and Higa point out that the "Weber law" that SET depends on doesn't scale well, so they have other theories. However, I could still imagine that pacemaker and timestamping neural circuits would work together, no? This review article of timing in the brain seems helpful, though I don't have time to read it fully today: https://www.sciencedirect.com/science/article/pii/S0896627318302514 https://www.sciencedirect.com/science/article/pii/S089662731... It covers oscillators (pacemaker-accumulator/SET), ramping, and population clocks ("time cells" and other names). I find it problematic that the NPR article only focuses on one name for one possible explanation of the observed behavior. It makes for a nice article, and the metaphor of time cells and place cells are attractive. It doesn't leave Time cells seem to invoke a chain of neurons firing, to encode events along the chain. I can believe that this orders events on the order of tens of seconds (the literature surveys from milliseconds to tens of seconds). But the NPR article suggests that the ordering of an entire tour of UCSD is also encoded in time cells. I doubt that there was one unending chain of ordering for that entire tour. Personally, I find that I have to reason about time on longer time scales, or I might mix up a recollection of how a story goes. (Once I tell a story a few times, I've learned a new skill--how to tell the story--so it becomes easier to recall a sequence I've chosen to highlight.)
- SubiculumCode 6y agoThe prior probability of you being wrong about facts in another field is fairly high. The prior probability of the researcher being wrong about facts in their own field is much lower. Therefore the default assumption one should have when reviewing research from a field that is NOT their own is closer to "I am the idiot" than "The researchers are the idiots". in my humble opinion.
- acrefoot 6y agoThe years I've gone to SFN, I've been amazed at how fragmented the field is. People get into neuroscience from all sorts of places. Neurosurgery, C. elegans research, optogenetic studies, fmri studies, biochemistry: these approaches to neuroscience are often so different they don't know about the advances of the others.
- SubiculumCode 6y agoShould have gone to HBM I guess ;) I suppose my comment was a bit strong. My Ph.D was on the the hippocampus and the development of binding operations supporting episodic memory using standard MRI and cognitive tasks, and I already know I don't understand half of what they are doing in more basic neuroscience articles.
- acrefoot 6y agoNo worries! I have no problem with the paper authors. Most of the authors on the paper come from neurosurgery/neurology, and I don't doubt for one second that they have a strong grasp of "I can mess with the human brain in these ways and I'll get these behaviors". They shouldn't be expected to know everything we've ever looked at for time in the brain. I am frustrated at one of the ways science journalism tends to report on neuroscience. I think they want to do it like they do physics, and it affects how people outside the field think. Rather than considering the brain as a complex system, we're looking for the Jennifer Anniston neuron, or time cells, or some single component that explains consciousness, much like we looked for the "god particle" (Higgs) or gravitational waves. It's not a great way to look at things. My original comment on fragmentation is just my own opinion. Maybe it's not as much of a barrier as I think it is.
- cgriswald 6y agoThe bike example is interesting because I remember learning how to ride a bike. I remember lots of details which others can confirm. But my perspective is external to my past self and I’m free to meander about in the memory, pause it, etc. It’s not particularly movie-like. I have a difficult time dipping into a first person perspective. And despite the article’s suggestion, even though I remember a spill in some detail (although in that case it’s more like a first-person snapshot than a movie) and although I know there was pain, I don’t remember the pain, just the fact of it. I do remember the feeling of anger and frustration as a result of the fall. Anyway, anyone who found the article interesting might be interested in Moonwalking with Einstein: The Art and Science of Remembering Anything by Joshua Foer. In the book, Foer talks about his experiences with memory championships and fills that in with information about then-current understanding of human memory. The place I learned to ride a bike is a place I know very well and I’ve used it as a memory palace. I wonder if doing that has somehow modified the perspective on that particular memory. I certainly have other memories which are episodic. Or maybe it’s just so far back in my past and I’ve reconstructed it enough times that it’s not quite as personal or visceral.
- hellectronic 6y agoI read the book and can recommend it. Very interesting!
- danwills 6y agoEven just the idea that there are specific cells for this is fascinating, and the fact that they change their 'tick' speed based on mood/interest? I should read the paper!: https://www.pnas.org/content/early/2020/10/26/2013250117 https://www.pnas.org/content/early/2020/10/26/2013250117
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- notRobot 6y agoMemory is a crazy thing. What I find particularly interesting is that some people recall memories in first person, and others in third person. Baffling.
- apples_oranges 6y agoI never thought about this, but if there's two ways to remember events there's probably also three, four.. or more?
- hhjinks 6y agoAll my memories have George Clooney in the role as me.
- carapace 6y agoYes. There's a whole field of study (often decried as pseudoscience) of the structure of subjective experience called Neurolinguistic Programming. Within it there's a constellation of concepts and techniques around deliberately altering your subjective experience. For example, the first person / third person difference is referred to as "associated" / "disassociated" in the NLP jargon, and you can change which "mode" you use for a given memory and that will (typically) change the subjective effects of the memory. You can use this to e.g., fall in(out) of love with someone. Recall all the good times with that person in associated(disassociated) mode and all the bad times with that person in disassociated(associated) mode and it will (typically) have a profound effect on your feeling towards that person. Neat, eh? There's a whole body of work around manipulation of time-coding. Some people see e.g. the past to the left and the future to the right,while others have the past behind them and the future ahead of them. Those are just two common styles of "timeline". Changing your time-coding can have profound effects on your psychology. The real information revolution has only just begun and it doesn't have a lot to do with tiny transistors, if you catch my drift.
- hackinthebochs 6y agoAll my childhood memories are in the third person. But I'm not sure if its due to the influence of pictures from those eras influencing how I visualize the memory or that its intrinsically third-person.
- nihilius 6y agoJust want to mention here that people exist wich can’t recall a memory trough mental images. It’s called aphantasia. https://en.wikipedia.org/wiki/Aphantasia https://en.wikipedia.org/wiki/Aphantasia
- wongarsu 6y agoI can't really relate to the article's description of episodic memory. I'm also aphantastic. I wonder if there is a correlation or if it's just coincidence. These things are surprisingly little studied, for example aphantasia has only really seen scientific interest in the last ten years. We all seem to assume that everyone's experience is the same as ours, only slowly discovering how untrue that really is. Even something "obvious" like colour blindness in only known for about 250 years.
- scollet 6y agoThis has been particularly interesting to me because I can usually only relate to system design in software visually. It works wonders for me personally to see code blocks as literal blocks that do X and connect to other blocks via graph edges. Then I pseudocode what I want and replace. Whiteboarding is a bit difficult if I can't visualize transformations or stores of data in some way, or if I can't see a theoretical big picture for a particular function.
- Spare_account 6y agoNot long after finding out about Aphantasia I found out about Severely Deficient Autobiographical Memory (SDAM) which I felt described my experience of life very well. SDAM isn't a recognised 'condition' as such, but it has a subreddit with some active users to compare your experiences with which you may find useful. https://old.reddit.com/r/SDAM/ https://old.reddit.com/r/SDAM/
- scruple 6y agoThank you for pointing this out. I wasn't aware of SDAM and it ticks a few boxes for me. On a related note... If you suspect that you have one of these conditions, is there someone you can talk to for confirmation? Are there people who specialize in... bad brain RAM?
- senectus1 6y agohuh... I dont have any movie like memories... is this something I should be concerned about?
- jchw 6y agoI don’t think so. If you don’t have any memories that are visual at all, you probably just have aphantasia.
- Tarq0n 6y agoThere are individual differences in autobiographical memory [1]. I don't have any memories like this either. [1] https://pubmed.ncbi.nlm.nih.gov/29807853/ https://pubmed.ncbi.nlm.nih.gov/29807853/
- jug 6y agoYes, I mean I can certainly vaguely visualize past moments in some 50/50 abstract/visual form I guess, but movie like... I'm unsure what they mean to be honest... and I'm sure that would be hard to explain as well. I guess I can see these "movies" mentally in the same way as how I vaguely remember the sequence of events in a recent dream. Unsure if I'd call that a movie though. Sounds like a pretty crappy one at that!
- orbifold 6y agoI always wondered this during meditation in high school: Do people actually see things when they close their eyes? The whole “you are at a beach, there is a gentle breeze...” never did anything for me. I can remember colors, relative positions, even how a specific place looked overall fairly well, but I don’t see anything.
- yesenadam 6y agoI guess this is a different thing, but... When I was a kid I read a book that said if before you go to sleep you think "I will wake up at Xam" (whatever time you want) then you wake up at exactly that time. Which is pretty weird! We can't do that when we're awake. It actually works, and I've never needed an alarm clock. For a few ultra-important days I used one, like catching a plane, but I was always awake before it went off. I have no idea how it works.
- artonge 6y agoI do it to when I need to wake up early so my body is not "surprised" by the low amount of sleep. Works well I think. Do you calculate how many hours you will sleep ? Maybe the brain set some kind of a timer.
- shannifin 6y agoI heard this from someone who swore it worked for her too, but it has never worked for me. It must be a superpower! :)
- csomar 6y agoIt's not a superpower. For me it's a combination of two: Urgency and having had enough sleep. If I have a flight, I almost always wake up 30 minutes before my timer go off; even if I didn't get enough sleep. If I have nothing important to do the next day, my brain will usually ignore the waking up part and carries on. One thing I noticed is that in the last year I have been waking up just a few minutes before my alarm goes off. My postulation is the iPhone alarm sound. It's bizarrely painful that I think I'm waking up just before it to avoid hearing it.
- rtx 6y agoYup, have experienced it personally. I usually wake up few mins before the alarm goes off. Though not proven through science you know something is there. Another thing I would like to add is that scientific community should be more open to test conventional wisdom.
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- IAmNotAFix 6y agoAre we supposed to have non-movie-like memories about the past? I mean, other than remembering "knowledge" such as sentences or dates or numbers or geography, etc, it seems that all memory about my "actual life" is movie-like.
- magicalhippo 6y agoI remember both moments and "movies". Some memories are more like pictures, usually accompanied with emotions. Other memories are more like movies, where I visualize the events unfold. I seldom remember what I dream, but when I do it's usually right before I wake up in the morning, and it feels like being in a movie. I often get aware that I'm dreaming and can control the movie (dream) to some extent. I can then get really annoyed when the alarm clock goes off before the exciting part is over.
- wongarsu 6y agoI experience movie-like dreams, but not movie-like memories. Not just the imagery (which is obvious, I'm aphantastic), but my memories aren't episodic at all. I have a sense of happened-after relations, but those are different from experiencing things one after another. Somewhat related, while I can't visualize memories I do visualize dreams. That would leave me to believe that dreams are fundamentally different (see also how the body has to seize many motor functions during dreaming, but we can use all of them during remembering).
- lexicality 6y agoI would be very interested to see a study about how these cells function under ADHD, because as I'm sure any sufferer would tell you - our time perception is very very weird.
- Loughla 6y agoMy experience is that it is much more difficult to focus on any individual task, but much easier to enter a 'flow' state with ADHD. If I can manage to do 'thing a', I find that often, all the world falls away - regardless of what the thing is. I also have a theory, completely unfounded and out of my own ass, that ADHD and other similar issues are just part of the spectrum that is autism. Any scientist want to confirm my personal belief?
- sosodev 6y agoFrom what I understand ADHD and Autism share some symptoms but ADHD isn’t part of the spectrum because the causes are different. It’s generally understood that the effects of ADHD diminish as you get older but the effects of Autism do not.
- lexicality 6y agoMy current understanding from the research I've read but don't have to hand: a) A lot of people with ADHD also have autism so the symptoms get lumped together but ADHD's actual symptoms (executive function issues, time blindness, rejection sensitivity, unexpected drug interactions etc) are completely unrelated b) ADHD symptoms never go away, adults just learn to hide them and develop coping strategies because it's largely socially unacceptable to be weird
- 2Gkashmiri 6y agoSo Jack reacher was not lying then. Good to know
- sebastian_j 6y agovery interesting discovery!
- meroes 6y agoThis isn't unique to humans or even animals https://youtu.be/CA-YsWXRSHU?t=448 https://youtu.be/CA-YsWXRSHU?t=448 https://en.wikipedia.org/wiki/Arabidopsis_thaliana#Light_sensing,_light_emission,_and_circadian_biology https://en.wikipedia.org/wiki/Arabidopsis_thaliana#Light_sen... It records ~40 days of temperature in a certain range, and remembers it till it senses the light of spring. If it's put into a dark room after 40 days, it waits till it senses light to flower, so it must be remembering those memories of cold temperatures.
- haolez 6y agoWhen I was young, I received a serious blow to my head while playing soccer that broke my skull and caused all sorts of issues at the time. I've managed a full recovery, but in the days following the accident, I lost my intuition of time. It's difficult to explain: I knew, logically, that I had lunch before I had dinner - and I had memory of doing both - but I couldn't "feel" that lunch was before dinner. It's pretty hard to explain and it was pretty weird to experience, but this symptom faded away after a couple of days.
- SpeckOfDust 6y agoI kind of know what you mean. In my case, it was due a psychedelic substance. I vividly remember being inside, walking out in the street and opening the door to go out, in that order. Made me feel very confused because I knew that logically it could not have gone that way, yet that was the chronology in my mind.
- KingFelix 6y agoTrytpamines are such a great way to look at the brain! Disruption of time / space / body / mind. Robin Carhart-Harris has done some great work, MAPS, etc.
- polytely 6y agoI wonder if this is something that is going wrong in my brain lol. I have a hard time remembering when exactly things happened (to figure out in what year I started school I basically have to walk backwards through my memories keeping track of some kind of time marker like seasons, like traversing a linked list). I often joke that if I ever was a suspect in a criminal investigation it would be very difficult for me to provide an alibi. It feels like a lot of day to day memories don't get 'time-stamped' at all. I always thought this mainly had to do with ADD related working memory problems, but maybe it's more of an episodic memory problem?
- ekanes 6y agoI have this too, and would describe it exactly the same. I think this is common with ADD.
- davidmurdoch 6y agoI think that's normal and precisely the mechanism the article is referring to? Not being able to recall the year something occurred if you don't reflect on that memory every so often seems "normal" as well.
- eloisius 6y agoThis sounds exactly how my sense of chronology works. I have to find time markers and work my way from those to arrive at when a related memory occurred. I'll frequently reference photos that I happen to know has some obscure clue in it like a shirt a family member was wearing because I knew they had that shirt when I went to X event, which I still have a ticket stub memento for, therefor it was Y date. I always attributed this to being home schooled (really just kind of free-range unschooled) until I was 14. I feel like I'm missing a lot of date-significant markers like passing from one grade to the next that most people have.
- floathub 6y agoThis title seems very misleading given the study described. They have found a correlation between some neurons firing in sequence and a list of words being spoken from memory. We don't have any concrete understanding of how memories are really encoded, stored, and recalled. Indeed, we don't even know if "encoded", "stored", and "recalled" are useful approximations for what's really going on in there. So suggesting that we have found some specific time keeping module seems awfully hand-wavy (at best) to me.
- PIKAL 6y agoIn Sasha Shulgin’s book PIKAL, he describes mixing two drugs, I think it was MMA and cannabis, and experiencing perceived time dilation. He describes it as looking at the hands of a clock and experiencing much more time between the movement of the hands than one normally would. He said it was frightening, so he called his friend to come help. He was able to speak normally and hear people speak normally. While he was on the phone, he asked for a timer to be set while he went to go retrieve something. His experience of walking down the hall and back felt to him like twenty minutes. When he returned to the phone, he was told it had only been two minutes. The effect wore off by the next day. He was never able to recreate the effect, but he kept a battery of experiments at the ready of it ever happened again. He expressed regret at not being able to carry them out. He once said that the experience changed his perception of death. If time were to continue dilating, asymptotically approaching a halting of time, then one might never die in their own experience.
- sixdimensional 6y agoOk, armchair theory here, let's for a moment assume Einstein's belief that time is the fourth dimension. We use our senses to detect/experience dimensions, right? I mean, we use sight, hearing, touch to detect 3-D space, for example (not forgetting taste and smell too). If time is the fourth dimension, maybe these cells are our evolutionary attempt to sense/detect and operate within that dimension. Which explains how the experience of time travel could be possible in at least one way - if we can change/affect our sense/perception of time (um.. navigating time?), it can seem to us like time travel. I'm not saying we would be affecting the timeline itself in this case, I mean more like messing with the sense of time that causes us to "experience" time travel. Ok sorry, that does too sound like too much armchair pseudoscience, but this article and some of the other comments just got me thinking.