Neuroscience, evolution and all the other stuff
Science is a lot like sex. Sometimes something useful comes of it, but that's not the reason we're doing it.
--Richard Feynman- Welcome to the weblog of Björn Brembs, the owner of brembs.net. I'm a neurobiologist working at the Freie Universität Berlin studying learning and decision-making in invertebrate animals.
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The English language service of Deutsche Welle Spectrum has just broadcast a short report on our study on the first operant learning gene. You can get the whole program at this link, or just the short clip on our research. I'm really excited about this exposure as this is broadcast all over the entire world both in old fashioned radio and online.
See this video for some visuals with the audio:
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I met Columbia neurologist John Krakauer (who has a very interesting brother at the Santa Fe Institute, by the way) at the 2006 SfN meeting in Atlanta after his PLoS Biology paper on how motor learning transfers differently from easy to difficult tasks and vice versa. He's a very smart guy with an interesting background. John has now written a short article for Scientific American entitled: "Why do we like to dance--And move to the beat?". He could be onto something, but I think he's not taking the idea far enough: Many things stimulate our brains' reward centers, among them, coordinated movements. Consider the thrill some get from watching choreographed fight or car chase scenes in action movies. What about the enjoyment spectators get when watching sports or actually riding on a roller coaster or in a fast car?
Scientists aren't sure why we like movement so much, but there's certainly a lot of anecdotal evidence to suggest we get a pretty big kick out of it. When I read this I was a little confused as to what is actually stimulating our reward centers, moving ourselves or watching movements of others, but he clarfiied this later in the article with a reference to mirror neurons (which is not what I'm going to discuss now).
Anyway, not only we get a kick out of moving. Controlling one's own movements in space can be shown to be inherently rewarding in many animals, including insects. For instance, the fruit fly Drosophila prefers to fly in flight directions where there is no artifically added "wobble" of its visual environment. This preference is so strong, that we can use it as reward in a conditioning experiment. Visual patterns (say, upright and inverted Ts) denote different flight directions in a cylindrical environment where the fly has been fixed in the center (see video). Whenever the fly is flying towards, for instance, the upright T, the computer makes the environment oscillate around the flight path such that the fly can still see the target and is able to steer away from it. If it flies towards the other, inverted T, no such oscillations occur. After a few minutes of such training, the flies will show a preference for the inverted T, even if there are no more oscillations. Thus, having full behavioral control over its movements in the environment is a strong reward for the fly, rivalling that of primary rewards such as food and water. The tranmitter involved in processing reward in insects is octopamine. Octopamine is also involved in behavior initiation and control. For example, firing octopaminergic neurons in locusts triggers flight behavior. Interestingly, the neurons triggering flight in locusts are homologous to the neurons thought to be involved in reward in honeybees.
Thus, at least on the surface, there is a tight connection between behavioral initiation and control and reward in insects.
In mammals, the transmitter involved in processing reward is dopamine. John writes in his article: "some reward-related areas in the brain are connected with motor areas". He is talking about the striatum which is involved in action selection as well as operant learning in mammals. The dopaminergic neurons are the ones degenerating in Parkinson's disease. Parkinon's patients show the typical tremors and inabilities to initiate and control movements and also have impairments in operant learning. Music also stimulates the striatum, John writes in the article. Thus, also in mammals, the transmitter system involved in movement initiation and control is the same as (and morphologically related to) the system processing rewards.
Is this all coincidence? Superficial similarities, like human faces in clouds found by human brains looking for patterns? Or is there an underlying evolutionary reason, maybe that one of the first control system early ambulatory animals needed was one for behavioral control? The solution to controlling behavior was to invent a teaching signal which was derived from continuously monitoring the animal's output and compared it with its sensory input. Such a comparison yields a difference signal between stimuli generated externally and stimuli generated by self-mtion. If minimizing externally generated stimulation were rewarding, animals would always strive to control their behavior. Reinforcement learning and optimal control theory provide the theoretical background for such simple systems. Could it be that all other reward systems stem from this initial reward system? Or why is motor control so tightly coupled with reward?
Now, in the postgenomic age, I wonder if one could look at what is known about the genes involved in setting up the reward centers in mammals and insects. Maybe there is a simple master gene (or gene cassette) which organizes the system with dopamine in one variant and with octopamine in one variant. Any bioinformaticians out there who'd like to study this?
UPDATE: John has replied via email and said "I agree with you more than you realize: I am attaching a paper we published in J.Neurosci last year which argues very much for your idea." Here's the reference and link to the paper: The Journal of Neuroscience, July 4, 2007 • 27(27):7105–7116: Why Don’t We Move Faster? Parkinson’s Disease, Movement Vigor, and Implicit Motivation. Pietro Mazzoni, Anna Hristova, and John W. Krakauer.
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 The most well-known molecular mechanism of learning involves coincidence detection. In post-synaptic LTP, the NMDA receptor only opens fully if a postsynaptic depolarization has removed the magnesium block by the time glutamate arrives at the receptor. In pre-synaptic facilitation, adenylyl cycase only generates large amounts of cAMP when stimulated both by transmitter and by coincident Ca2+ influx. Thus, in both cases, you need neural activity (i.e., action potentials or spikes) to coincide onto the synapse in question. Insect learning, specifically clasical olfactory conditioning, has been instrumental in developing this model of "spike timing-dependent plasticity" (STDP). For delay conditioning in which the conditioned stimulus (CS) overlaps with the unconditioned stimulus (US), this is not a problem: the spikes of the CS are still arriving at the convergence point when the spikes from the US start to come in. However, in trace conditioning, when there is a delay between the end of the CS and the onset of th US (of up to 24h in the case of conditioned taste aversion), it is difficult to imagine how the well-known mechanisms of STDP could occur. What happens during the interval between CS offset and US onset for trace conditioning to occur?
To say it right away, we just discussed the new paper in Nature Neuroscience from the lab of Mark Stopfer (NNeuro preview) in our journal club and it doesn't answer this question either. What it does show is that in the paradigm which was so instrumental in develping STDP (classical olfactory learning in insects), STDP appears not to be able to explain trace conditioning either. The authors recorded from projection neurons (projecting from the antennal lobes to the mushroom bodies) and from Kenyon cells (intrinsic mushroom-body neurons) in moths (Manduca sexta). They showed that after odor alone presentations (no conditioning) no more spikes are fired in the Kenyon cells at a time point where they had demonstrated a US presentation to lead to maximum learning behaviorally. This is remarkable, because the Kenyon cells are considered to be the site where the associative memory is stored in this paradigm. The really new aspect of this work was that electrophysiological recordings (albeit not during conditioning) were combined with a behavioral approach analyzing optimal inter-stimulus intervals for classical conditioning. What the authors found was basically a negative result: STDP in the Kenyon cells cannot account for the learning exhibited by the insects. This is reminiscent of trace and delay conditioning in mammals: "In delay eyeblink conditioning, the CS overlaps with the US and only a brainstem-cerebellar circuit is necessary for learning. In trace eyeblink conditioning, the CS ends before the US is delivered and several forebrain structures, including the hippocampus, are required for learning, in addition to a brainstem-cerebellar circuit." (source).
Maybe also in insect trace conditioning, both Kenyon cells and some other structure are required? Maybe this other structure works as a buffer to store the eligibility trace of the CS until the US arrives? Another option could be residual calcium (or some second-messenger) lingering for a few seconds until the US spikes arrive in the Kenyon cells. Only Kenyon cell recordings during conditioning can show the behavior of the Kenyon cells when the US arrives (to fully rule out STDP). I also think a trace conditioning paradigm for Drosophila needs to be developed in order to harness the genetic power also for this type of learning (this would address the calcium or second messenger hypothesis). This paper didn't really answer any questions, but it was so thoroughly done and well-designed that it threw up a lot of interesting ones which will hopefully lead to a completely new line of learning research in insects.
Citation:
Iori Ito, Rose Chik-ying Ong, Baranidharan Raman, Mark Stopfer (2008). Sparse odor representation and olfactory learning Nature Neuroscience, 11 (10), 1177-1184 DOI: 10.1038/nn.2192
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Dave Munger over at Cognitive Daily has a great post on how zoos use operant conditioning for the welfare of their animals. They use operant conditioning on basically all mammals, maybe even most vertebrates there, for everything from teeth brushing to herding of animals in case of an emergency: Conditioning, Jayne told us, was a much safer and effective way to care for the animals than older methods like shooting the animals with tranquilizer darts. Even dangerous animals like grizzly bears can be trained to rear up onto a special apparatus, placing their claws and snouts in designated spots, and exposing their razor-sharp teeth for brushing. "The animals love to be trained," she said. The sea lions used to get so excited in anticipation of a training session that their behavior became unnatural for several hours each day, so trainers had to vary the training schedule in order to avoid this problem.
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Muslim creationist and author of "Atlas of Creation" Harun Yahya (yes, the guy who uses fishing lures to argue his creationism) has been interviewed by the eminent German weekly DER SPIEGEL. The title is the same as the one in this post: "All terrorists are Darwinists". In the interview, Yahya claims that there are 100 million fossils that show that they have been created (in the really short interview he never goes into how all these species had room at the same time or why the are so clearly ordered geological in strata). He gos on to say that Satan has misled legions of scientists and interested laymen for 150 years and that his book will finally open their eyes and convince everyone that Allah has created everything. Asked about whether he was inspired by christian fundamentalists in the US, he derides intelligent design as dishonest: "the people should just come out and say that god did it!". Asked about Dawkin's "God delusion" now appearing in Turkey and apparently quickly becoming a best-seller, he emphasizes that he thinks all evil (Hitler, Stalin, Mussolini and today's islamic terrorists) stems from Darwinism. Asked by the interviewer if he honestly thinks islamic terrorists are closet Darwinists, he says that nobody who prays every day could ever carry out a terroristic act and that all terrorists are only foreign-educated Darwinists who just afterwards use the cloke of Islam (he never says why they would be doing that). Asked how he funds his campaign, he says that he doesn't earn any money from the sales of his book and since it's such a great success, he can afford all the free copies he sends around.
This guy clearly needs new advisors. Interviews like these can only backfire. It's so clear that this dude is a total nutcase, the interviewer didn't even have to go after him, lol 
UPDATE: there's now also an English version from the SPIEGEL.
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 The economist has a nice, short article out featuring two science sites: researchblogging.org and Nature Networks. The author finds that Although Web 2.0, with its emphasis on user-generated content, has been derided as a commercial cul-de-sac, it may prove to be a path to speedier scientific advancement. There can be no doubt that the scientific community is starting to use the socal web tool more and more and that it is accelerating science. That media outside of science are noticing this is evidence of these developments. Along with the incorporation of these social tools will come publishing reform, i.e. the move away from pre-publication editor-based assessment towards post-publication peer-based assessment. The article didn't really go into the intricacies of this movement and actually got a few things slightly wrong (or at least ambiguous) about blogs and traditional, peer-reviewed publications. But even still, the developments have gone so far by now, that even outsiders a beginning to take note of a change in how we do science.
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This story has so many connotations on so many levels, I don't even know where to start. Of course, we all know about the history of the fish and the Christians and the bumper sicker wars. In July surfaced the first stories about the connections beween radical Islam and Christian creationists. Now the guy involved in the islamic creationism movement, Harun Yahya (Adnan Oktar) has actually succeeded in getting a court order to block Turkey’s access to the web site of Richard Dawkins. This story (and the thread on RichardDawkins.net) also featured this picture from Yahya's book:
 Apparently, the book uses this picture to make the claim that these caddisflies haven't changed for a few million years, so no animals have ever changed (great logic, isn't it?). If you look closely (as PZ has done already in January), you'll see that it actually depicts a fishing lure! It's a dummy only mimicking a caddis to lure fish to bite. Obviously, the flies made by Graham Owen are good enough to lure not only fish, but also creationists! 
This whole thing is just too good to be true! And yet, despite so many incidents like this, stupidity rules and creationism is still not dead after 150 years of evolutionary theory. There must be something strangely attractive to pseudo- or non-science.
Thursday 18 September 2008 - 04:42:47
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I've just converted the old chatbox to a new experiment: microblogging. You can see the result on the right. In order for this to work the way I want, I need to hook the feed up to my Friendfeed feed (many feeds in there, lol). I tried to do this and it sort of worked: the posts appeared but with "no title" displayed, instead of the post body as a message (duh, not that I couldn't have figured that ou before trying!). So I tried to delete the feed again. However, in FF, there is only one URL for both feeds, so I had a 50% chance of deleting the wrong one. Guess which feed got deleted? Of course the one of this blog and not the one from the other feed. So now all my old posts and their comments and likes are probably gone forever. Anybody know how to get them back?
I also need to find out how I can register my MicroBlog posts such that they appear with the posts as messages. Any ideas, tips, hints??
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My thesis advisor Matin Heisenberg (left) introduced the speaker for the José Campos-Ortega memorial lecture, Bert Hölldobler (right, sorry, really bad picture, despite several tries) at the 12th European Drosophila Neurobiology Conference:
 
Bert Hölldobler's topic is ants and he does know his ants! What a great talk! Some of the content of the talk was familiar , from when Bert Hölldobler still was at the University of Würzburg, where I studied. It was from his lectures back then where learned a large part of what I know about evolution. During the talk, I tried to take some pictures of the slides with the ants. Some of them turned out pretty good for being shot from projected images:
Ants communicate both on a one-on-one basis and en masse. In the latter case, ant use phermones. Hölldobler: "ants are walking batteries of pheromone glands". "Pheromones often not only release behaviors but also act as identifiers". He goes on to describe the amazing structures used to disperse pheromones, for instance the intricate morphology of the pygidial gland with which some ant species mark their trails.
He then describes the recruitment behavior of scouts after they returned to their colony after having laid the trail from the prey item (in the case of this particular species a termite mound).
Another gland some ant species use sits in the legs and they drag their legs to deposit long lasting orientation trails which the animals use to come back to the colony after a raid.
 
Bert then turned towards leaf cutter ants. These ants cut leaves, transport them to their nest, grow fungi on them and then eat the fruits of the fungi. These ants travel up to 300m to get their leaves and lay down trails to be able to find back to their colony. These trail pheromones constitute a world record: one of them is so powerful that 1mg of it could be used to lay an effective rail six times around the earth. On one particular tree, some leaves get cut while others don't. How do the animals decide which leaves to cut and which ones to leave alone? Apparently, the animals which first start cutting a leaf stridulate on this leaf to call in their close-by nest-mates to help them cut the leaf to pieces. This only works if the branches of the tree are either all maerked with the trail pheromone or not at all. If only one branch of several is marked with pheromone, the pheromone signal is stronger than the stridulation and all the ants go to the pheromone scented branch and leave the stridulating, non-pheromone branch alone. Another function of the stridulation is to attract a caste of ants which hitchhike on the leaves to protect the carriers of the leaves from parasitic flies:
Oecophylla ants also are masters of chemical communication. For instance, discharging their mandibular gland during an attack on a prey animal quickly recruits many conspecifics to help with the attack. These are the species which build their colonies by glueing together leaves to a nest. They are very aggressive against members of other nests. These animals use a territorial pheromone from a specialized rectal gland to mark their home range. "No other ant is so territorial."
  
As a final example, Bert was telling us about a species in Arizona, the honey ants. These ants have a caste which just stores honey, hanging from the ceiling of their underground nest. Unfortunately, the picture I took from the honey-pots was all blurry and unusable. These animals only defend the piece of their territory where they are currently fighting termites. In such territorial fights, it may happen that one colony raids the other, stealing all their honey-pots. They even transfer pupae to their nest to have the ants hatching from these pupae work for their colony (slavery?). Several colonies in an area may form hierarchies by small display fights among themselves in so-called tournaments. The colonies fight among themselves and somehow figure out which of them is the strongest one. This remains stable for some time, but if one colony becomes too small and weak, it gets raided. Apparently, there is a specialized caste of ants involved which runs between tournament and colony to recruit more fighters if needed. Weak colonies have a strategy to prevent raids: they can retreat into their nest and block the entrance with stones and debries.
  
But what Bert Hölldobler didn't tell us is that ants love Rammstein: 
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I'm here at the 12th European Drosophila Neurobiology Conference, in short Neurofly2008. I actually got here 3 days ago already. I had planned to blog from the meeting, but things have just been so hectic that I haven't had a chance to do any blogging at all. Incidentally, the meeting is in my home town of Würzburg in Germnay, which has contributed to the meeting becoming sort of hectic, trying to balance family an old friends with the conference schedule. Moreover, large time slots have been allotted to posters, and it's hard to blog when standing in front of a poster 
Now that the meeting is slowly drawing to a close, I've finally settled down enough to sit down and write a short post.
The meeting despite being on Drosophila fruit fly research alone, is extremely diverse and it's a real challenge to try and follow all the talks.
The first day was about (believe it or not!) diseases and aging with topics such as neuronal degeneration including models for Parkinson and Alzheimer's (fly mutants had such descriptive names as "swiss cheese"), the role of dopamine in ethanol-induced behaviors, or the neuroprotective effects of RNA Editing.
The second day was about the developmental biology of neuronal patterning and cell fate determination of neurons and glia with talks about the genetics of asymmetric cell division. neural stems cells, inter-segmental neuroblast lineage diversification, survival of differentiated motorneurons, cell singalling and adhesion and the organization of nervous system architecture, glial cel migration, the genetics of odorant receptor specification, or the role of the ecdyson receptor in mushroom body pruning.
The third day (yesterday) was all about channels: K and Ca channels in synaptogenesis, Ca homeostasis in the flight circuit, or G-Protein signalling in olfactory signal transduction. In the evening, there was the banquet dinner at the fortress of Würzburg, the Festung Marienberg. It's been a very pleasant evening with a delightful conclusion in a nearby bar, the Brauhaus. According to my personal observations, it is quite possible that some of the particpants may feel the physiological reminder of fine brew at this place this morning. 
Today's program has two sessions, one of synapses (that's the one I'm sitting in right now) and one on circuits in the afternoon. Between these two sessions I will present my poster. Let's see if I find someone to record one presentation for a postercast! The day will end with the José Campos-Ortega memorial lecture by Bert Hölldobler of "The Ants" fame.
Maybe I'll find the time to cover some of what is going to happen on the last day (behavior) in another blog post, but don't count on it
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This year, the Neurofly meeting will be in my home town of Würzburg in Germany. I'm really looking forward to going home for a few days, it's been so long since last time. As usual, I've already uploaded my poster in advance, so you can have a look at what I'll be talking about there on Tuesday.
This time, however, I'm planning to record one of the presentations and then publish it as a postercast on SciVee like this one. I think this is just a fantastic way to keep all your presentations alive after the posters are already torn, crumpled up and decomposed.
I'll try to do some live-blogging from the conference as well, so stay tuned if you're a neurofly enthusiast!
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In addition to the PubMed-listed scientific protocols we will start to experiment with a broader scientific content at JoVE. On the teaching front, one project is to record students' experiments in our regular undergraduate courses here at our university. The idea is to generate a repository for tried and tested experimental protocols which will be much easier to incorporate into new courses than from old notebooks or papers. We hope that other universities around the world will follow our lead, so that every new or revised course will have plenty of useful experiments to chose from in order to create the best learning experience for the students. At this stage this is all very much an experiment and we are trying to think in all possible directions. Maybe we could offer video streams which deal with individual universities or labs. Scientific content, interviews or short data presentations grouped by locality to give an impression of what this particular university is doing. Or maybe a "Science 2.0" discussion channel where people can voice their opinion on open access, open science, post-publication review or any other aspect of open science and publishing reform. The important aspect of this topic should be that we want to try to find working solutions as we have heard all the arguments over and over again -Â it is time to reach across the aisle and we feel that JoVE would be a rather unbiased forum. What else could this feature be used for? What would scientists want to watch at JoVE besides video protocols? What do you think of undergrad teaching protocols or of Science 2.0 discussions? Help us brainstorm and leave your ideas in the comments section.
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Thursday 04 September 2008 - 12:13:31
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Maybe I'm naive. Maybe I'm just too thick to get it. But over the last few days I've been on the receiving end of quite some flak for my criticisms of Thomson Scientific's impact factor (IF) by, of all poeple, open access supporters! The discussion has been going on behind closed doors in two different threads on a message board for editors of PLoS One. Obviously, these discussions are confidential, so there won't be any names, but let me give you the gist of the debate.
Currently, Thomson Scientific (TS) is not listing PLoS One. Therefore, PLoS One does not have an IF. PLoS One editors are negotiating with TS to get listed, but so far without effect. Given the current weight of the IF in promotion, grants and tenure, it's understandable that people would like to have PLoS One listed with TS. But the whole philosophy behind PLoS One is that it shouldn't matter where something is published. Post-publication review is what should determine the quality of a publication after it was published, not some editor at some journal before peer-review. This may be one of the reasons (my speculation here) that TS is so reluctant to list PLoS One: if this concept is successful, it would eradicate the IF along with journals. So on the message board, I have been arguing that instead of bolstering the value of the IF, We, the scientists, should declare our independence of the IF and start creating a fairer, better publishing system, where scientists and not editors decide what is high-qality and breakthrough research, what is the kind of bread-and-butter research without which no breakthroughs can happen and which studies are not worth the bytes they occupy in cyberspace. The weaknesses of the IF are well known and covered. Despite the flawed nature of the IF, quite a number of people are defending its use and demand PLoS One should do everything possible to get listed. Here are a few quotes from my fellow PLoS One academic editors:I agree with all that has been stated about the negative aspects of the IF. However, the REALITY is that the uninitiated, such as a Committe judging tenure, or a Committee deciding on a new Chair appointment, absolutely require Impact Factors for each article. [...] Therefore there is no use in arguing against the importance or lack of same of the IF.....lets just get it. [...] Scientists (sad but true) belong to the most conservative professionals in general. Despite anything that is counting agaist the IF, this will remain the measure for 99% of us for time to come. [...] Authors will still care about it, although they will officially say that IF's are ridiculuous. But scientists are hypocrits (like most people) and they will continue to send their papers to high-IF journals, whether we like it or not. [...] I say this with some sadness, because I myself do not care much about IF:s, but I know a terrible lot who does and I have given up all my attempts to discuss this with people, since it seems hopeless to argue about. That's human nature, I guess. [...] People are still quite concerned about IF:s, although they admit that they are misleading, but as long as the research finance system favours authors who publish articles in high-IF journals, they will continue to try get published there, whether we like it or not. [...] I couldn't agree more with all that is being said about IFs. Unfortunately, the reality for most academics is that all kinds of ev aluation committees use IFs to ev aluate a researcher's output. [...] I know how flawed IF is, but we just cannot be blind to the reality and should still make a best effort to have PLoS ONE indexed by Thomson. [...] The reasons you enumerate against the IF system are of course valid. However, IFs are still the most used way of ev aluating a researcher's career and value. Even if we find this ridiculous, it's just the way it is. Therefore, I find it very important for PLoS ONE to try to get an IF, independently of the other suggestions that have been made.
And so on and so on. It's basically always: "I know the IF is really bad, but what could be possibly do about it? So let's try to arrange ourselves with it".
How can people who donate time and enthusiasm for the open access movement and publishing reform be so fatalistic? WE are the customers of the monopolist private company that TS is. WE decide who we promote and who gets tenure. How can something as flawed and pernicious as the IF have so much control over people? I just don't get it. Do you?
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Wednesday 03 September 2008 - 15:27:21
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comments: 5
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