New scientific progress in groundbreaking analysis of a fly’s brain
Scientists researching the brain of a fly have identified the position, shape and connections of every single one of its neurons. That involves 130,000 cells and 50 million connections in the most detailed brain analysis of any adult animal ever produced.
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00:00This was a big collaborative effort.
00:04It actually started 10 years ago with a colleague of mine, Davy Bock, who was able to take pictures
00:12of 7,000 salami-sliced sections of a fly brain.
00:17Each of those sections is about 2,000 times thinner than a human hair, and you can see
00:21one behind my shoulder there.
00:23This is in the memory centers of the fly, actually.
00:28Those pictures could show us all the details that we needed of the brain, but what we started
00:35doing was sort of click, click, click, tracing the shape of individual neurons through that.
00:40We estimated it would take about 4,000 person-years of effort to do that.
00:44Then in 2020, some colleagues at Princeton were able to use an artificial intelligence
00:51method to trace out the neurons automatically with machine vision.
00:58But there were still mistakes left behind, and those needed fixing.
01:01It took another 30 or 40 person-years of effort, and we actually started when we were twiddling
01:07our thumbs at home during the pandemic, to trace out this whole brain in a big international
01:14effort.
01:15Wow.
01:16Artificial intelligence is just rocketing us forward, isn't it?
01:19Was there anything that surprised you and delighted you in the things that you found?
01:24Yeah.
01:25Obviously, I'm an enthusiast.
01:28I've been studying fly brains for 20 years.
01:31It's pretty amazing to see the intricate detail of this structure.
01:36When I was a student, actually, we had to do a human neuroanatomy lab, and somebody
01:41gave me a human brain to hold, and we had to look at that.
01:44To be honest, although it was on the one hand kind of awe-inspiring, it was also a little
01:48disappointing because it's this wrinkly liter and a half of matter.
01:54When you dive inside the brain, it's just incredibly complicated and intricate at this
02:02microscopic level.
02:04I could pick so many things within that, but I think one of the exciting things with this
02:11data set is being able to go all the way from vision or smell or taste to the descending
02:18neurons that actually control the motor behaviors of the fly, so really being able to go from
02:23sensation to action.
02:25Then I think the other thing I'd highlight is that we can look not just at more reflexive
02:31actions but also at how the same circuits are used by the memory centers to produce
02:36actions in response to learned associations.
02:42The human brain is obviously so much more complicated, but is the idea that we could
02:47one day do this sort of mapping with human brains?
02:51Yeah.
02:53The difference in scale is pretty dramatic.
02:57Twenty years ago, the fly genome and then the human genome came out.
03:01The fly genome is only about a tenth, twentieth of the size of the human genome.
03:06The human brain is a million times bigger than the fly brain in terms of neurons and
03:12even actually a little bit bigger in terms of its volume.
03:15To give you an idea, this fly brain occupied about 100 terabytes, about 100 laptops' worth
03:22of image data.
03:24A mouse brain would be about a thousand times that, and a human brain, as I said, a million
03:29times.
03:30So you can think about it as if everybody on this planet had a smartphone and they were
03:36ready to store a bit of one human brain, we could just about fit it.
03:41It would challenge Google's infrastructure right now.
03:45We think to collect those data, we're probably talking 20 years of technology development.
03:51Wow.
03:52I mean, assuming that that development did happen and we found a way to store these enormous
03:58amounts of data, ultimately is the idea that we could maybe take control of our own neural
04:06pathways and maybe rewire our brains?
04:09Is that something in our distant future that you think about?
04:12Yeah.
04:13I think these kind of maps really let us think about the mechanics of thought.
04:21How is it actually working?
04:22The technology is actually similar to what chip manufacturers use to spy on their competitors
04:27if they want to decode the circuits of another chip.
04:31That's kind of what we're trying to do here.
04:33Of course, when we understand it, hopefully then we can rewire it or fix it in cases where
04:40things go wrong.
04:41There are many mental health disorders where it's suspected that there's a wiring deficit,
04:46some kind of change in the circuits of the brain, but we don't understand that.
04:50I'm sure that eventually these kinds of methods will contribute to solving those puzzles.
04:57Fascinating stuff.
04:58We'll leave it there.
04:59Greg Jeffress from the Medical Research Council's Laboratory of Molecular Biology.
05:03Thank you so much for your time this morning.
05:06Pleasure to meet you, the Urubi.