First Movie of an Entire Brain's Neuronal Activity 44
KentuckyFC (1144503) writes "One of the goals of neuroscience is to understand how brains process information and generate appropriate behaviour. A technique that is revolutionising this work is optogenetics--the ability to insert genes into neurons that fluoresce when the neuron is active. That works well on the level of single neurons but the density of neurons in a brain is so high that it has been impossible to tell them apart when they fluoresce. Now researchers have solved this problem and proved it by filming the activity in the entire brain of a nematode worm for the first time and making the video available. Their solution comes in two parts. The first is to ensure that the inserted genes only fluoresce in the nuclei of the neurons. This makes it much easier to tell individual neurons in the brain apart. The second is a new techniques that scans the entire volume of the brain at a rate of 80 frames per second, fast enough to register all the neuronal activity within it. The researchers say their new technique should allow bigger brains to be filmed in the near future, opening up the potential to study how various creatures process information and trigger an appropriate response for the first time."
Mapping the Nematode? (Score:3)
Could a complete mapping of the neural network be accomplished?
Would it be possible to artificially trigger a neuron to verify the mapping?
Re:Mapping the Nematode? (Score:4, Interesting)
Why wouldn't it be? Light-sensitive proteins are quite well understood.
All of this leads to a really fascinating possibility down the road...
Part 1: Requirements:
1) Genes are inserted into the nucleus of every neuron.
2) Probes which can receive on one or more optical frequencies** and send directionally on other frequencies (which we'll call A, B, and C) are inserted all throughout the target brain.
3) The genes from #1 flash upon synapse**, allowing the probes in #2 to receive the signals
4) The genes from #1 force a synapse when they receive frequency A from a probe.
5) The genes from #1 suppress synapse when they receive frequency B from a probe.
6) The genes from #1 force the cell to commit apoptosis when they receive frequency C from a probe.
Part 2: For each neuron in the brain (conducted in parallel):
1) The neuron's behavior is studied relative to its neighbors in order to learn precisely what factors control its activation levels. This requires a very accurate neural model, and probably requires a lot more more than a simple one-frequency "I'm firing" signal in #2 and #3 of part 1.
2) The neuron is simulated in a computer based on said inputs
3) The neuron is ordered repressed when the simulator doesn't want it fired, and ordered fired when the simulator wants it fired.
4) The system works its way through all of its neighbors that it influences, doing steps #1-3 of this part upon them and putting them under control of the simulation as well.
5) Once a neuron is entirely isolated and can be handled entirely within the simulation, the signal is sent for apoptosis.
6) This pattern continues until the entire brain exists only in the simulation.
And thus you take any living entity and entirely digitize their consciousness, without any single moment defining their transition from the physical world to the digital one, and without "copying" them.
This is a key first step in something I've been thinking about for a long time, and I'm thrilled to see it. I doubt I'll live to see all the steps, or that anyone alive today will. But I'm thrilled to see the first steps taken down this road.
More near-term, one can envision all sorts of incredible properties with an optical communication link set up with cells. For example, imagine that you instrument cells in a cancerous organ with genes that can be instructed individually to force the cell into apoptosis, and which flash on various frequencies corresponding to various cellular activities. You look for cellular activities which correspond to cancerous behavior, and when you see them, you tell that cell to kill itself. You really have something way better than all of that unrealistic "nanomachine medicine" stuff that sci-fi writers have been obsessing over for ages.
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You look for cellular activities which correspond to cancerous behavior, and when you see them, you tell that cell to kill itself
That's kind of what's already supposed to happen naturally inside the human body. Cells are supposed to kill themselves if they are severely malfunctioned or are likely to become cancerous. However, if enough of these fail-safe mechanisms are damages within a cell, then that cell becomes cancerous. That's why cancer is so difficult to treat, and why your own immune system has difficulty attacking it -- the cancer cells have gone rogue and are no longer "following orders" to kill themselves.
So, if you were a
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Cancerous cells still have lysosomes and there's always going to be some way to open them. Cancer cells often have defective lysosome membranes that don't activate under normal circumstances, but they're still there, and still full of enzymes to break down the cell. So long as they're there, the
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You're not "back to square one", you've just done 99.9% of the job of killing the cancer, pretty much any other anti-cancer method will finish the job for you.
It's possible that at some point before a tumor developed there were 99.9% of cells that should have killed themselves actually doing so. The .1% multiplied into a tumor because there was nothing stopping it. The guy that replied to you was making the point that nature has already created multiple (I think 7 or so) mechanisms to get cells to kill themselves and eventually they all fail one by one due to mutation. Your expensive "inject every cell nucleus" method might fail just the same.
That's not to say
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An actual worm doing the Macarena deserves a +5
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The C elegans brain has been completely mapped in terms of connectivity a long time ago. See for instance:
http://www.wormatlas.org/neuro... [wormatlas.org]
Interesting thought - I'm not aware of anyone having done that but it's been a while since I followed the C elegans literature closely.
C elegans is pressurised, so you can't easily stick an electrode (assuming you had one small enoug
80 frames/second (Score:5, Interesting)
If that captures everything, that's the interesting part to me(though I'm sure it's been known to actual neurologists forever). That means the "clock speed" of the human brain is really really really really low, more or less, right? Like our consciousness is pretty much exclusively the result of massive parallelism?
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Human neurons fire around 200 times per second (max). I'm not sure about nematodes, but it's probably more than 80. I'm guessing that "captures everything" means "every neuron," not "every time a neuron fires."
But you're right when you say that massive parallelism is a core strength of the brain.
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Sure, okay. There's more than a little evolutionary separation since then. Do you think there's a good reason to assume the difference is dramatic?
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Yes. #drasticunderstatement
Analog. not digital. (Score:3)
There is no clock speed. It is asynchronous and analog. Even if it had some kind of natural timing to it, some things will fire faster others slower. Chained signals will have delays along the path. The result is something without any clock speed with operations happening at the speed of analog (as fine grained as the physics allows... so in other words, crazy fast to capture it all in digital.)
Absolute precision will not be required just as analog audio doesn't need to be converted at the rate the individu
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Well, there's no central clock speed, but there are definitely clear instances of macroscopic synchronous behaviour in the brain:
http://en.wikipedia.org/wiki/N... [wikipedia.org]
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If that captures everything, that's the interesting part to me(though I'm sure it's been known to actual neurologists forever). That means the "clock speed" of the human brain is really really really really low, more or less, right? Like our consciousness is pretty much exclusively the result of massive parallelism?
If you bothered to read the summary, you'd see it was a nematode worm brain, not a human brain. 80 fps was good enough for that worm's brain. Most likely not good enough for a human brain. but possibly good enough for bigger animal brains.
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I did read the summary. I get that there are differences.
100 step rule (Score:3)
Its amazing [teco.edu]:
For example a human can recognize the picture of another person in about 100 ms. Given the processing time of 1 ms for an individual neuron this implies that a certain number of neurons, but less than 100, are involved in serial; whereas the complexity of the task is evidence for a parallel processing, because a difficult recognition task can not be performed by such a small number of neurons, example taken from [zell94, p24,]. This phenomenon is known as the 100-step-rule.
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And (Score:2)
Ever So Much Closer... (Score:1)
Having no idea... (Score:2)
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Longer answer: There is much complexity and the real answer would probably cover a few books. But a few highlights: neurons have their firing rate and their spike levels modulated by a variety of things in the brain. Glial cells (which are 10x more numerous than neurons) inhibit and disinhibit neurons, communicate with each other and are involved in computation. Some neuron communicate with a continuous flow of protons (inner ear, acceleration detection), some fire
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I wouldn't call 20 years ago 'recent'.- Penrose Harmerhoff Orch Orr model was using the data on microtubules and anesthesia as support for the quantum conciousness theory in 1995.
translated (Score:4, Funny)
And we finally know what nematodes are thinking: http://i1.ytimg.com/vi/GpEDsoZ... [ytimg.com]
"movie" (Score:1)
Am I the only one that is annoyed whenever someone uses "movie" as a synonym for "video?" A video has to at least approach an hour long and *have a plot* before it's a movie in my book.
P.S: What the heck is up with websites with huge font sizes these days? It's like getting punched in the face. And after ctrl-scrolling out like 4 notches, the white bars on each side of the text is over twice the size of the text itself.
</curmudgeon>
Remarkable achievement? (Score:1)
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If it were my brain... (Score:2)
OT: Submitter, where'd you get your username from? (Score:1)
KentuckyFC, you seem to need a trademark license to use that username... where'd you get that from?
corrections (Score:2)
They record calcium activity in neurons. Calcium is a marker of neuronal activity (although the dynamics are slower than electrical ones). Calcium recording in the nematode is difficult, because the neurons are small, and the spread of calcium is very broad. The method is impressive and a great breakthrough. However...
1. A brain is a center of the nervous system. It's not strictly correct to speak of brains of nematodes. They don't have this separation of their nervous system. In the article they write
"First movie," srsly? (Score:1)
It's the first time this method was used to make a whole-brain record of activity. And it's cute that it uses visible light instead of magn