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.
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