[Script Info]
Title: 
[Events]
Format: Layer, Start, End, Style, Name, MarginL, MarginR, MarginV, Effect, Text
Dialogue: 0,0:00:00.54,0:00:04.08,Default,,0000,0000,0000,,I grew up watching Star Trek. I love Star Trek.
Dialogue: 0,0:00:04.08,0:00:08.54,Default,,0000,0000,0000,,Star Trek made me want to see alien creatures,
Dialogue: 0,0:00:08.54,0:00:10.84,Default,,0000,0000,0000,,creatures from a far-distant world.
Dialogue: 0,0:00:10.84,0:00:13.63,Default,,0000,0000,0000,,But basically, I figured out that I could find
Dialogue: 0,0:00:13.63,0:00:16.61,Default,,0000,0000,0000,,those alien creatures right on Earth.
Dialogue: 0,0:00:16.61,0:00:19.26,Default,,0000,0000,0000,,And what I do is I study insects.
Dialogue: 0,0:00:19.26,0:00:22.52,Default,,0000,0000,0000,,I'm obsessed with insects, particularly insect flight.
Dialogue: 0,0:00:22.52,0:00:25.66,Default,,0000,0000,0000,,I think the evolution of insect flight is perhaps
Dialogue: 0,0:00:25.66,0:00:28.40,Default,,0000,0000,0000,,one of the most important events in the history of life.
Dialogue: 0,0:00:28.40,0:00:30.64,Default,,0000,0000,0000,,Without insects, there'd be no flowering plants.
Dialogue: 0,0:00:30.64,0:00:32.55,Default,,0000,0000,0000,,Without flowering plants, there would be no
Dialogue: 0,0:00:32.55,0:00:35.69,Default,,0000,0000,0000,,clever, fruit-eating primates giving TED Talks.
Dialogue: 0,0:00:35.69,0:00:37.99,Default,,0000,0000,0000,,(Laughter)
Dialogue: 0,0:00:37.99,0:00:39.98,Default,,0000,0000,0000,,Now,
Dialogue: 0,0:00:39.98,0:00:43.01,Default,,0000,0000,0000,,David and Hidehiko and Ketaki
Dialogue: 0,0:00:43.01,0:00:46.46,Default,,0000,0000,0000,,gave a very compelling story about
Dialogue: 0,0:00:46.46,0:00:49.26,Default,,0000,0000,0000,,the similarities between fruit flies and humans,
Dialogue: 0,0:00:49.26,0:00:50.75,Default,,0000,0000,0000,,and there are many similarities,
Dialogue: 0,0:00:50.75,0:00:53.76,Default,,0000,0000,0000,,and so you might think that if humans are similar to fruit flies,
Dialogue: 0,0:00:53.76,0:00:57.55,Default,,0000,0000,0000,,the favorite behavior of a fruit fly might be this, for example --
Dialogue: 0,0:00:57.55,0:00:59.83,Default,,0000,0000,0000,,(Laughter)
Dialogue: 0,0:00:59.83,0:01:03.02,Default,,0000,0000,0000,,but in my talk, I don't want to emphasize on the similarities
Dialogue: 0,0:01:03.02,0:01:06.09,Default,,0000,0000,0000,,between humans and fruit flies, but rather the differences,
Dialogue: 0,0:01:06.09,0:01:11.38,Default,,0000,0000,0000,,and focus on the behaviors that I think fruit flies excel at doing.
Dialogue: 0,0:01:11.38,0:01:14.24,Default,,0000,0000,0000,,And so I want to show you a high-speed video sequence
Dialogue: 0,0:01:14.24,0:01:18.17,Default,,0000,0000,0000,,of a fly shot at 7,000 frames per second in infrared lighting,
Dialogue: 0,0:01:18.17,0:01:22.38,Default,,0000,0000,0000,,and to the right, off-screen, is an electronic looming predator
Dialogue: 0,0:01:22.38,0:01:23.82,Default,,0000,0000,0000,,that is going to go at the fly.
Dialogue: 0,0:01:23.82,0:01:25.65,Default,,0000,0000,0000,,The fly is going to sense this predator.
Dialogue: 0,0:01:25.65,0:01:28.11,Default,,0000,0000,0000,,It is going to extend its legs out.
Dialogue: 0,0:01:28.11,0:01:29.72,Default,,0000,0000,0000,,It's going to sashay away
Dialogue: 0,0:01:29.72,0:01:32.29,Default,,0000,0000,0000,,to live to fly another day.
Dialogue: 0,0:01:32.29,0:01:34.65,Default,,0000,0000,0000,,Now I have carefully cropped this sequence
Dialogue: 0,0:01:34.65,0:01:37.81,Default,,0000,0000,0000,,to be exactly the duration of a human eye blink,
Dialogue: 0,0:01:37.81,0:01:40.64,Default,,0000,0000,0000,,so in the time that it would take you to blink your eye,
Dialogue: 0,0:01:40.64,0:01:43.91,Default,,0000,0000,0000,,the fly has seen this looming predator,
Dialogue: 0,0:01:43.91,0:01:50.08,Default,,0000,0000,0000,,estimated its position, initiated a motor pattern to fly it away,
Dialogue: 0,0:01:50.08,0:01:54.54,Default,,0000,0000,0000,,beating its wings at 220 times a second as it does so.
Dialogue: 0,0:01:54.54,0:01:56.51,Default,,0000,0000,0000,,I think this is a fascinating behavior
Dialogue: 0,0:01:56.51,0:02:00.43,Default,,0000,0000,0000,,that shows how fast the fly's brain can process information.
Dialogue: 0,0:02:00.43,0:02:03.28,Default,,0000,0000,0000,,Now, flight -- what does it take to fly?
Dialogue: 0,0:02:03.28,0:02:06.14,Default,,0000,0000,0000,,Well, in order to fly, just as in a human aircraft,
Dialogue: 0,0:02:06.14,0:02:08.87,Default,,0000,0000,0000,,you need wings that can generate sufficient aerodynamic forces,
Dialogue: 0,0:02:08.87,0:02:12.42,Default,,0000,0000,0000,,you need an engine sufficient to generate the power required for flight,
Dialogue: 0,0:02:12.42,0:02:14.13,Default,,0000,0000,0000,,and you need a controller,
Dialogue: 0,0:02:14.13,0:02:16.76,Default,,0000,0000,0000,,and in the first human aircraft, the controller was basically
Dialogue: 0,0:02:16.76,0:02:21.07,Default,,0000,0000,0000,,the brain of Orville and Wilbur sitting in the cockpit.
Dialogue: 0,0:02:21.07,0:02:23.82,Default,,0000,0000,0000,,Now, how does this compare to a fly?
Dialogue: 0,0:02:23.82,0:02:27.07,Default,,0000,0000,0000,,Well, I spent a lot of my early career trying to figure out
Dialogue: 0,0:02:27.07,0:02:31.41,Default,,0000,0000,0000,,how insect wings generate enough force to keep the flies in the air.
Dialogue: 0,0:02:31.41,0:02:33.02,Default,,0000,0000,0000,,And you might have heard how engineers proved
Dialogue: 0,0:02:33.02,0:02:35.65,Default,,0000,0000,0000,,that bumblebees couldn't fly.
Dialogue: 0,0:02:35.65,0:02:38.27,Default,,0000,0000,0000,,Well, the problem was in thinking that the insect wings
Dialogue: 0,0:02:38.27,0:02:41.39,Default,,0000,0000,0000,,function in the way that aircraft wings work. But they don't.
Dialogue: 0,0:02:41.39,0:02:44.24,Default,,0000,0000,0000,,And we tackle this problem by building giant,
Dialogue: 0,0:02:44.24,0:02:47.68,Default,,0000,0000,0000,,dynamically scaled model robot insects
Dialogue: 0,0:02:47.68,0:02:51.01,Default,,0000,0000,0000,,that would flap in giant pools of mineral oil
Dialogue: 0,0:02:51.01,0:02:53.29,Default,,0000,0000,0000,,where we could study the aerodynamic forces.
Dialogue: 0,0:02:53.29,0:02:55.44,Default,,0000,0000,0000,,And it turns out that the insects flap their wings
Dialogue: 0,0:02:55.44,0:02:58.04,Default,,0000,0000,0000,,in a very clever way, at a very high angle of attack
Dialogue: 0,0:02:58.04,0:03:01.16,Default,,0000,0000,0000,,that creates a structure at the leading edge of the wing,
Dialogue: 0,0:03:01.16,0:03:04.36,Default,,0000,0000,0000,,a little tornado-like structure called a leading edge vortex,
Dialogue: 0,0:03:04.36,0:03:07.31,Default,,0000,0000,0000,,and it's that vortex that actually enables the wings
Dialogue: 0,0:03:07.31,0:03:10.67,Default,,0000,0000,0000,,to make enough force for the animal to stay in the air.
Dialogue: 0,0:03:10.67,0:03:13.10,Default,,0000,0000,0000,,But the thing that's actually most -- so, what's fascinating
Dialogue: 0,0:03:13.10,0:03:16.07,Default,,0000,0000,0000,,is not so much that the wing has some interesting morphology.
Dialogue: 0,0:03:16.07,0:03:19.72,Default,,0000,0000,0000,,What's clever is the way the fly flaps it,
Dialogue: 0,0:03:19.72,0:03:22.85,Default,,0000,0000,0000,,which of course ultimately is controlled by the nervous system,
Dialogue: 0,0:03:22.85,0:03:25.50,Default,,0000,0000,0000,,and this is what enables flies to perform
Dialogue: 0,0:03:25.50,0:03:28.31,Default,,0000,0000,0000,,these remarkable aerial maneuvers.
Dialogue: 0,0:03:28.31,0:03:30.40,Default,,0000,0000,0000,,Now, what about the engine?
Dialogue: 0,0:03:30.40,0:03:32.90,Default,,0000,0000,0000,,The engine of the fly is absolutely fascinating.
Dialogue: 0,0:03:32.90,0:03:34.79,Default,,0000,0000,0000,,They have two types of flight muscle:
Dialogue: 0,0:03:34.79,0:03:37.78,Default,,0000,0000,0000,,so-called power muscle, which is stretch-activated,
Dialogue: 0,0:03:37.78,0:03:41.50,Default,,0000,0000,0000,,which means that it activates itself and does not need to be controlled
Dialogue: 0,0:03:41.50,0:03:44.84,Default,,0000,0000,0000,,on a contraction-by-contraction basis by the nervous system.
Dialogue: 0,0:03:44.84,0:03:49.45,Default,,0000,0000,0000,,It's specialized to generate the enormous power required for flight,
Dialogue: 0,0:03:49.45,0:03:51.53,Default,,0000,0000,0000,,and it fills the middle portion of the fly,
Dialogue: 0,0:03:51.53,0:03:53.08,Default,,0000,0000,0000,,so when a fly hits your windshield,
Dialogue: 0,0:03:53.08,0:03:55.48,Default,,0000,0000,0000,,it's basically the power muscle that you're looking at.
Dialogue: 0,0:03:55.48,0:03:57.63,Default,,0000,0000,0000,,But attached to the base of the wing
Dialogue: 0,0:03:57.63,0:04:00.27,Default,,0000,0000,0000,,is a set of little, tiny control muscles
Dialogue: 0,0:04:00.27,0:04:03.57,Default,,0000,0000,0000,,that are not very powerful at all, but they're very fast,
Dialogue: 0,0:04:03.57,0:04:06.78,Default,,0000,0000,0000,,and they're able to reconfigure the hinge of the wing
Dialogue: 0,0:04:06.78,0:04:08.54,Default,,0000,0000,0000,,on a stroke-by-stroke basis,
Dialogue: 0,0:04:08.54,0:04:11.68,Default,,0000,0000,0000,,and this is what enables the fly to change its wing
Dialogue: 0,0:04:11.68,0:04:14.65,Default,,0000,0000,0000,,and generate the changes in aerodynamic forces
Dialogue: 0,0:04:14.65,0:04:17.22,Default,,0000,0000,0000,,which change its flight trajectory.
Dialogue: 0,0:04:17.22,0:04:20.79,Default,,0000,0000,0000,,And of course, the role of the nervous system is to control all this.
Dialogue: 0,0:04:20.79,0:04:22.30,Default,,0000,0000,0000,,So let's look at the controller.
Dialogue: 0,0:04:22.30,0:04:24.95,Default,,0000,0000,0000,,Now flies excel in the sorts of sensors
Dialogue: 0,0:04:24.95,0:04:27.23,Default,,0000,0000,0000,,that they carry to this problem.
Dialogue: 0,0:04:27.23,0:04:31.36,Default,,0000,0000,0000,,They have antennae that sense odors and detect wind detection.
Dialogue: 0,0:04:31.36,0:04:33.03,Default,,0000,0000,0000,,They have a sophisticated eye which is
Dialogue: 0,0:04:33.03,0:04:35.49,Default,,0000,0000,0000,,the fastest visual system on the planet.
Dialogue: 0,0:04:35.49,0:04:37.52,Default,,0000,0000,0000,,They have another set of eyes on the top of their head.
Dialogue: 0,0:04:37.52,0:04:39.58,Default,,0000,0000,0000,,We have no idea what they do.
Dialogue: 0,0:04:39.58,0:04:42.53,Default,,0000,0000,0000,,They have sensors on their wing.
Dialogue: 0,0:04:42.53,0:04:46.29,Default,,0000,0000,0000,,Their wing is covered with sensors, including sensors
Dialogue: 0,0:04:46.29,0:04:48.34,Default,,0000,0000,0000,,that sense deformation of the wing.
Dialogue: 0,0:04:48.34,0:04:50.44,Default,,0000,0000,0000,,They can even taste with their wings.
Dialogue: 0,0:04:50.44,0:04:53.00,Default,,0000,0000,0000,,One of the most sophisticated sensors a fly has
Dialogue: 0,0:04:53.00,0:04:54.81,Default,,0000,0000,0000,,is a structure called the halteres.
Dialogue: 0,0:04:54.81,0:04:56.69,Default,,0000,0000,0000,,The halteres are actually gyroscopes.
Dialogue: 0,0:04:56.69,0:05:01.14,Default,,0000,0000,0000,,These devices beat back and forth about 200 hertz during flight,
Dialogue: 0,0:05:01.14,0:05:03.81,Default,,0000,0000,0000,,and the animal can use them to sense its body rotation
Dialogue: 0,0:05:03.81,0:05:07.78,Default,,0000,0000,0000,,and initiate very, very fast corrective maneuvers.
Dialogue: 0,0:05:07.78,0:05:10.10,Default,,0000,0000,0000,,But all of this sensory information has to be processed
Dialogue: 0,0:05:10.10,0:05:13.82,Default,,0000,0000,0000,,by a brain, and yes, indeed, flies have a brain,
Dialogue: 0,0:05:13.82,0:05:16.98,Default,,0000,0000,0000,,a brain of about 100,000 neurons.
Dialogue: 0,0:05:16.98,0:05:19.18,Default,,0000,0000,0000,,Now several people at this conference
Dialogue: 0,0:05:19.18,0:05:23.98,Default,,0000,0000,0000,,have already suggested that fruit flies could serve neuroscience
Dialogue: 0,0:05:23.98,0:05:27.23,Default,,0000,0000,0000,,because they're a simple model of brain function.
Dialogue: 0,0:05:27.23,0:05:29.31,Default,,0000,0000,0000,,And the basic punchline of my talk is,
Dialogue: 0,0:05:29.31,0:05:31.97,Default,,0000,0000,0000,,I'd like to turn that over on its head.
Dialogue: 0,0:05:31.97,0:05:34.60,Default,,0000,0000,0000,,I don't think they're a simple model of anything.
Dialogue: 0,0:05:34.60,0:05:37.07,Default,,0000,0000,0000,,And I think that flies are a great model.
Dialogue: 0,0:05:37.07,0:05:39.59,Default,,0000,0000,0000,,They're a great model for flies.
Dialogue: 0,0:05:39.59,0:05:42.07,Default,,0000,0000,0000,,(Laughter)
Dialogue: 0,0:05:42.07,0:05:45.07,Default,,0000,0000,0000,,And let's explore this notion of simplicity.
Dialogue: 0,0:05:45.07,0:05:47.50,Default,,0000,0000,0000,,So I think, unfortunately, a lot of neuroscientists,
Dialogue: 0,0:05:47.50,0:05:49.34,Default,,0000,0000,0000,,we're all somewhat narcissistic.
Dialogue: 0,0:05:49.34,0:05:52.77,Default,,0000,0000,0000,,When we think of brain, we of course imagine our own brain.
Dialogue: 0,0:05:52.77,0:05:54.73,Default,,0000,0000,0000,,But remember that this kind of brain,
Dialogue: 0,0:05:54.73,0:05:56.50,Default,,0000,0000,0000,,which is much, much smaller
Dialogue: 0,0:05:56.50,0:05:59.17,Default,,0000,0000,0000,,— instead of 100 billion neurons, it has 100,000 neurons —
Dialogue: 0,0:05:59.17,0:06:02.06,Default,,0000,0000,0000,,but this is the most common form of brain on the planet
Dialogue: 0,0:06:02.06,0:06:04.96,Default,,0000,0000,0000,,and has been for 400 million years.
Dialogue: 0,0:06:04.96,0:06:07.25,Default,,0000,0000,0000,,And is it fair to say that it's simple?
Dialogue: 0,0:06:07.25,0:06:09.34,Default,,0000,0000,0000,,Well, it's simple in the sense that it has fewer neurons,
Dialogue: 0,0:06:09.34,0:06:11.10,Default,,0000,0000,0000,,but is that a fair metric?
Dialogue: 0,0:06:11.10,0:06:13.37,Default,,0000,0000,0000,,And I would propose it's not a fair metric.
Dialogue: 0,0:06:13.37,0:06:16.47,Default,,0000,0000,0000,,So let's sort of think about this. I think we have to compare --
Dialogue: 0,0:06:16.47,0:06:18.03,Default,,0000,0000,0000,,(Laughter) —
Dialogue: 0,0:06:18.03,0:06:23.15,Default,,0000,0000,0000,,we have to compare the size of the brain
Dialogue: 0,0:06:23.15,0:06:25.18,Default,,0000,0000,0000,,with what the brain can do.
Dialogue: 0,0:06:25.18,0:06:28.06,Default,,0000,0000,0000,,So I propose we have a Trump number,
Dialogue: 0,0:06:28.06,0:06:30.93,Default,,0000,0000,0000,,and the Trump number is the ratio of this man's
Dialogue: 0,0:06:30.93,0:06:34.61,Default,,0000,0000,0000,,behavioral repertoire to the number of neurons in his brain.
Dialogue: 0,0:06:34.61,0:06:37.28,Default,,0000,0000,0000,,We'll calculate the Trump number for the fruit fly.
Dialogue: 0,0:06:37.28,0:06:39.96,Default,,0000,0000,0000,,Now, how many people here think the Trump number
Dialogue: 0,0:06:39.96,0:06:42.45,Default,,0000,0000,0000,,is higher for the fruit fly?
Dialogue: 0,0:06:42.45,0:06:44.88,Default,,0000,0000,0000,,(Applause)
Dialogue: 0,0:06:44.88,0:06:48.31,Default,,0000,0000,0000,,It's a very smart, smart audience.
Dialogue: 0,0:06:48.31,0:06:51.64,Default,,0000,0000,0000,,Yes, the inequality goes in this direction, or I would posit it.
Dialogue: 0,0:06:51.64,0:06:54.02,Default,,0000,0000,0000,,Now I realize that it is a little bit absurd
Dialogue: 0,0:06:54.02,0:06:57.58,Default,,0000,0000,0000,,to compare the behavioral repertoire of a human to a fly.
Dialogue: 0,0:06:57.58,0:07:01.72,Default,,0000,0000,0000,,But let's take another animal just as an example. Here's a mouse.
Dialogue: 0,0:07:01.72,0:07:06.02,Default,,0000,0000,0000,,A mouse has about 1,000 times as many neurons as a fly.
Dialogue: 0,0:07:06.02,0:07:08.05,Default,,0000,0000,0000,,I used to study mice. When I studied mice,
Dialogue: 0,0:07:08.05,0:07:10.89,Default,,0000,0000,0000,,I used to talk really slowly.
Dialogue: 0,0:07:10.89,0:07:13.46,Default,,0000,0000,0000,,And then something happened when I started to work on flies.
Dialogue: 0,0:07:13.46,0:07:15.88,Default,,0000,0000,0000,,(Laughter)
Dialogue: 0,0:07:15.88,0:07:19.34,Default,,0000,0000,0000,,And I think if you compare the natural history of flies and mice,
Dialogue: 0,0:07:19.34,0:07:22.65,Default,,0000,0000,0000,,it's really comparable. They have to forage for food.
Dialogue: 0,0:07:22.65,0:07:25.10,Default,,0000,0000,0000,,They have to engage in courtship.
Dialogue: 0,0:07:25.10,0:07:28.57,Default,,0000,0000,0000,,They have sex. They hide from predators.
Dialogue: 0,0:07:28.57,0:07:30.55,Default,,0000,0000,0000,,They do a lot of the similar things.
Dialogue: 0,0:07:30.55,0:07:32.26,Default,,0000,0000,0000,,But I would argue that flies do more.
Dialogue: 0,0:07:32.26,0:07:35.64,Default,,0000,0000,0000,,So for example, I'm going to show you a sequence,
Dialogue: 0,0:07:35.64,0:07:39.85,Default,,0000,0000,0000,,and I have to say, some of my funding comes from the military,
Dialogue: 0,0:07:39.85,0:07:41.92,Default,,0000,0000,0000,,so I'm showing this classified sequence
Dialogue: 0,0:07:41.92,0:07:46.01,Default,,0000,0000,0000,,and you cannot discuss it outside of this room. Okay?
Dialogue: 0,0:07:46.01,0:07:47.92,Default,,0000,0000,0000,,So I want you to look at the payload
Dialogue: 0,0:07:47.92,0:07:50.95,Default,,0000,0000,0000,,at the tail of the fruit fly.
Dialogue: 0,0:07:50.95,0:07:53.05,Default,,0000,0000,0000,,Watch it very closely,
Dialogue: 0,0:07:53.05,0:07:57.34,Default,,0000,0000,0000,,and you'll see why my six-year-old son
Dialogue: 0,0:07:57.34,0:08:02.07,Default,,0000,0000,0000,,now wants to be a neuroscientist.
Dialogue: 0,0:08:02.07,0:08:03.25,Default,,0000,0000,0000,,Wait for it.
Dialogue: 0,0:08:03.25,0:08:04.82,Default,,0000,0000,0000,,Pshhew.
Dialogue: 0,0:08:04.82,0:08:07.90,Default,,0000,0000,0000,,So at least you'll admit that if fruit flies are not as clever as mice,
Dialogue: 0,0:08:07.90,0:08:12.82,Default,,0000,0000,0000,,they're at least as clever as pigeons. (Laughter)
Dialogue: 0,0:08:12.82,0:08:16.79,Default,,0000,0000,0000,,Now, I want to get across that it's not just a matter of numbers
Dialogue: 0,0:08:16.79,0:08:19.39,Default,,0000,0000,0000,,but also the challenge for a fly to compute
Dialogue: 0,0:08:19.39,0:08:22.24,Default,,0000,0000,0000,,everything its brain has to compute with such tiny neurons.
Dialogue: 0,0:08:22.24,0:08:25.22,Default,,0000,0000,0000,,So this is a beautiful image of a visual interneuron from a mouse
Dialogue: 0,0:08:25.22,0:08:27.99,Default,,0000,0000,0000,,that came from Jeff Lichtman's lab,
Dialogue: 0,0:08:27.99,0:08:31.24,Default,,0000,0000,0000,,and you can see the wonderful images of brains
Dialogue: 0,0:08:31.24,0:08:34.43,Default,,0000,0000,0000,,that he showed in his talk.
Dialogue: 0,0:08:34.43,0:08:36.80,Default,,0000,0000,0000,,But up in the corner, in the right corner, you'll see,
Dialogue: 0,0:08:36.80,0:08:40.91,Default,,0000,0000,0000,,at the same scale, a visual interneuron from a fly.
Dialogue: 0,0:08:40.91,0:08:42.75,Default,,0000,0000,0000,,And I'll expand this up.
Dialogue: 0,0:08:42.75,0:08:44.92,Default,,0000,0000,0000,,And it's a beautifully complex neuron.
Dialogue: 0,0:08:44.92,0:08:48.41,Default,,0000,0000,0000,,It's just very, very tiny, and there's lots of biophysical challenges
Dialogue: 0,0:08:48.41,0:08:52.03,Default,,0000,0000,0000,,with trying to compute information with tiny, tiny neurons.
Dialogue: 0,0:08:52.03,0:08:55.57,Default,,0000,0000,0000,,How small can neurons get? Well, look at this interesting insect.
Dialogue: 0,0:08:55.57,0:08:57.78,Default,,0000,0000,0000,,It looks sort of like a fly. It has wings, it has eyes,
Dialogue: 0,0:08:57.78,0:09:00.58,Default,,0000,0000,0000,,it has antennae, its legs, complicated life history,
Dialogue: 0,0:09:00.58,0:09:03.67,Default,,0000,0000,0000,,it's a parasite, it has to fly around and find caterpillars
Dialogue: 0,0:09:03.67,0:09:05.06,Default,,0000,0000,0000,,to parasatize,
Dialogue: 0,0:09:05.06,0:09:09.17,Default,,0000,0000,0000,,but not only is its brain the size of a salt grain,
Dialogue: 0,0:09:09.17,0:09:11.14,Default,,0000,0000,0000,,which is comparable for a fruit fly,
Dialogue: 0,0:09:11.14,0:09:14.07,Default,,0000,0000,0000,,it is the size of a salt grain.
Dialogue: 0,0:09:14.07,0:09:17.70,Default,,0000,0000,0000,,So here's some other organisms at the similar scale.
Dialogue: 0,0:09:17.70,0:09:21.83,Default,,0000,0000,0000,,This animal is the size of a paramecium and an amoeba,
Dialogue: 0,0:09:21.83,0:09:25.71,Default,,0000,0000,0000,,and it has a brain of 7,000 neurons that's so small --
Dialogue: 0,0:09:25.71,0:09:28.17,Default,,0000,0000,0000,,you know these things called cell bodies you've been hearing about,
Dialogue: 0,0:09:28.17,0:09:29.82,Default,,0000,0000,0000,,where the nucleus of the neuron is?
Dialogue: 0,0:09:29.82,0:09:33.28,Default,,0000,0000,0000,,This animal gets rid of them because they take up too much space.
Dialogue: 0,0:09:33.28,0:09:35.75,Default,,0000,0000,0000,,So this is a session on frontiers in neuroscience.
Dialogue: 0,0:09:35.75,0:09:41.11,Default,,0000,0000,0000,,I would posit that one frontier in neuroscience is to figure out how the brain of that thing works.
Dialogue: 0,0:09:41.11,0:09:46.74,Default,,0000,0000,0000,,But let's think about this. How can you make a small number of neurons do a lot?
Dialogue: 0,0:09:46.74,0:09:49.27,Default,,0000,0000,0000,,And I think, from an engineering perspective,
Dialogue: 0,0:09:49.27,0:09:50.100,Default,,0000,0000,0000,,you think of multiplexing.
Dialogue: 0,0:09:50.100,0:09:53.70,Default,,0000,0000,0000,,You can take a hardware and have that hardware
Dialogue: 0,0:09:53.70,0:09:55.31,Default,,0000,0000,0000,,do different things at different times,
Dialogue: 0,0:09:55.31,0:09:58.31,Default,,0000,0000,0000,,or have different parts of the hardware doing different things.
Dialogue: 0,0:09:58.31,0:10:01.58,Default,,0000,0000,0000,,And these are the two concepts I'd like to explore.
Dialogue: 0,0:10:01.58,0:10:03.24,Default,,0000,0000,0000,,And they're not concepts that I've come up with,
Dialogue: 0,0:10:03.24,0:10:07.78,Default,,0000,0000,0000,,but concepts that have been proposed by others in the past.
Dialogue: 0,0:10:07.78,0:10:10.86,Default,,0000,0000,0000,,And one idea comes from lessons from chewing crabs.
Dialogue: 0,0:10:10.86,0:10:12.72,Default,,0000,0000,0000,,And I don't mean chewing the crabs.
Dialogue: 0,0:10:12.72,0:10:16.32,Default,,0000,0000,0000,,I grew up in Baltimore, and I chew crabs very, very well.
Dialogue: 0,0:10:16.32,0:10:19.18,Default,,0000,0000,0000,,But I'm talking about the crabs actually doing the chewing.
Dialogue: 0,0:10:19.18,0:10:21.21,Default,,0000,0000,0000,,Crab chewing is actually really fascinating.
Dialogue: 0,0:10:21.21,0:10:24.47,Default,,0000,0000,0000,,Crabs have this complicated structure under their carapace
Dialogue: 0,0:10:24.47,0:10:25.78,Default,,0000,0000,0000,,called the gastric mill
Dialogue: 0,0:10:25.78,0:10:28.21,Default,,0000,0000,0000,,that grinds their food in a variety of different ways.
Dialogue: 0,0:10:28.21,0:10:33.47,Default,,0000,0000,0000,,And here's an endoscopic movie of this structure.
Dialogue: 0,0:10:33.47,0:10:36.03,Default,,0000,0000,0000,,The amazing thing about this is that it's controlled
Dialogue: 0,0:10:36.03,0:10:39.46,Default,,0000,0000,0000,,by a really tiny set of neurons, about two dozen neurons
Dialogue: 0,0:10:39.46,0:10:44.42,Default,,0000,0000,0000,,that can produce a vast variety of different motor patterns,
Dialogue: 0,0:10:44.42,0:10:48.77,Default,,0000,0000,0000,,and the reason it can do this is that this little tiny ganglion
Dialogue: 0,0:10:48.77,0:10:52.95,Default,,0000,0000,0000,,in the crab is actually inundated by many, many neuromodulators.
Dialogue: 0,0:10:52.95,0:10:55.09,Default,,0000,0000,0000,,You heard about neuromodulators earlier.
Dialogue: 0,0:10:55.09,0:10:57.32,Default,,0000,0000,0000,,There are more neuromodulators
Dialogue: 0,0:10:57.32,0:11:02.80,Default,,0000,0000,0000,,that alter, that innervate this structure than actually neurons in the structure,
Dialogue: 0,0:11:02.80,0:11:07.04,Default,,0000,0000,0000,,and they're able to generate a complicated set of patterns.
Dialogue: 0,0:11:07.04,0:11:10.49,Default,,0000,0000,0000,,And this is the work by Eve Marder and her many colleagues
Dialogue: 0,0:11:10.49,0:11:12.78,Default,,0000,0000,0000,,who've been studying this fascinating system
Dialogue: 0,0:11:12.78,0:11:14.93,Default,,0000,0000,0000,,that show how a smaller cluster of neurons
Dialogue: 0,0:11:14.93,0:11:16.76,Default,,0000,0000,0000,,can do many, many, many things
Dialogue: 0,0:11:16.76,0:11:21.61,Default,,0000,0000,0000,,because of neuromodulation that can take place on a moment-by-moment basis.
Dialogue: 0,0:11:21.61,0:11:24.05,Default,,0000,0000,0000,,So this is basically multiplexing in time.
Dialogue: 0,0:11:24.05,0:11:26.84,Default,,0000,0000,0000,,Imagine a network of neurons with one neuromodulator.
Dialogue: 0,0:11:26.84,0:11:30.32,Default,,0000,0000,0000,,You select one set of cells to perform one sort of behavior,
Dialogue: 0,0:11:30.32,0:11:32.93,Default,,0000,0000,0000,,another neuromodulator, another set of cells,
Dialogue: 0,0:11:32.93,0:11:34.65,Default,,0000,0000,0000,,a different pattern, and you can imagine
Dialogue: 0,0:11:34.65,0:11:38.52,Default,,0000,0000,0000,,you could extrapolate to a very, very complicated system.
Dialogue: 0,0:11:38.52,0:11:40.62,Default,,0000,0000,0000,,Is there any evidence that flies do this?
Dialogue: 0,0:11:40.62,0:11:43.99,Default,,0000,0000,0000,,Well, for many years in my laboratory and other laboratories around the world,
Dialogue: 0,0:11:43.99,0:11:46.64,Default,,0000,0000,0000,,we've been studying fly behaviors in little flight simulators.
Dialogue: 0,0:11:46.64,0:11:48.35,Default,,0000,0000,0000,,You can tether a fly to a little stick.
Dialogue: 0,0:11:48.35,0:11:50.85,Default,,0000,0000,0000,,You can measure the aerodynamic forces it's creating.
Dialogue: 0,0:11:50.85,0:11:53.40,Default,,0000,0000,0000,,You can let the fly play a little video game
Dialogue: 0,0:11:53.40,0:11:57.27,Default,,0000,0000,0000,,by letting it fly around in a visual display.
Dialogue: 0,0:11:57.27,0:11:59.61,Default,,0000,0000,0000,,So let me show you a little tiny sequence of this.
Dialogue: 0,0:11:59.61,0:12:00.84,Default,,0000,0000,0000,,Here's a fly
Dialogue: 0,0:12:00.84,0:12:04.27,Default,,0000,0000,0000,,and a large infrared view of the fly in the flight simulator,
Dialogue: 0,0:12:04.27,0:12:06.23,Default,,0000,0000,0000,,and this is a game the flies love to play.
Dialogue: 0,0:12:06.23,0:12:08.67,Default,,0000,0000,0000,,You allow them to steer towards the little stripe,
Dialogue: 0,0:12:08.67,0:12:11.49,Default,,0000,0000,0000,,and they'll just steer towards that stripe forever.
Dialogue: 0,0:12:11.49,0:12:15.05,Default,,0000,0000,0000,,It's part of their visual guidance system.
Dialogue: 0,0:12:15.05,0:12:17.39,Default,,0000,0000,0000,,But very, very recently, it's been possible
Dialogue: 0,0:12:17.39,0:12:22.33,Default,,0000,0000,0000,,to modify these sorts of behavioral arenas for physiologies.
Dialogue: 0,0:12:22.33,0:12:24.82,Default,,0000,0000,0000,,So this is the preparation that one of my former post-docs,
Dialogue: 0,0:12:24.82,0:12:27.26,Default,,0000,0000,0000,,Gaby Maimon, who's now at Rockefeller, developed,
Dialogue: 0,0:12:27.26,0:12:28.95,Default,,0000,0000,0000,,and it's basically a flight simulator
Dialogue: 0,0:12:28.95,0:12:32.03,Default,,0000,0000,0000,,but under conditions where you actually can stick an electrode
Dialogue: 0,0:12:32.03,0:12:34.29,Default,,0000,0000,0000,,in the brain of the fly and record
Dialogue: 0,0:12:34.29,0:12:37.95,Default,,0000,0000,0000,,from a genetically identified neuron in the fly's brain.
Dialogue: 0,0:12:37.95,0:12:40.24,Default,,0000,0000,0000,,And this is what one of these experiments looks like.
Dialogue: 0,0:12:40.24,0:12:43.22,Default,,0000,0000,0000,,It was a sequence taken from another post-doc in the lab,
Dialogue: 0,0:12:43.22,0:12:44.41,Default,,0000,0000,0000,,Bettina Schnell.
Dialogue: 0,0:12:44.41,0:12:47.81,Default,,0000,0000,0000,,The green trace at the bottom is the membrane potential
Dialogue: 0,0:12:47.81,0:12:49.84,Default,,0000,0000,0000,,of a neuron in the fly's brain,
Dialogue: 0,0:12:49.84,0:12:52.78,Default,,0000,0000,0000,,and you'll see the fly start to fly, and the fly is actually
Dialogue: 0,0:12:52.78,0:12:56.06,Default,,0000,0000,0000,,controlling the rotation of that visual pattern itself
Dialogue: 0,0:12:56.06,0:12:57.54,Default,,0000,0000,0000,,by its own wing motion,
Dialogue: 0,0:12:57.54,0:12:59.65,Default,,0000,0000,0000,,and you can see this visual interneuron
Dialogue: 0,0:12:59.65,0:13:03.55,Default,,0000,0000,0000,,respond to the pattern of wing motion as the fly flies.
Dialogue: 0,0:13:03.55,0:13:05.93,Default,,0000,0000,0000,,So for the first time we've actually been able to record
Dialogue: 0,0:13:05.93,0:13:08.84,Default,,0000,0000,0000,,from neurons in the fly's brain while the fly
Dialogue: 0,0:13:08.84,0:13:13.31,Default,,0000,0000,0000,,is performing sophisticated behaviors such as flight.
Dialogue: 0,0:13:13.31,0:13:15.16,Default,,0000,0000,0000,,And one of the lessons we've been learning
Dialogue: 0,0:13:15.16,0:13:17.58,Default,,0000,0000,0000,,is that the physiology of cells that we've been studying
Dialogue: 0,0:13:17.58,0:13:20.00,Default,,0000,0000,0000,,for many years in quiescent flies
Dialogue: 0,0:13:20.00,0:13:22.65,Default,,0000,0000,0000,,is not the same as the physiology of those cells
Dialogue: 0,0:13:22.65,0:13:25.39,Default,,0000,0000,0000,,when the flies actually engage in active behaviors
Dialogue: 0,0:13:25.39,0:13:27.92,Default,,0000,0000,0000,,like flying and walking and so forth.
Dialogue: 0,0:13:27.92,0:13:30.85,Default,,0000,0000,0000,,And why is the physiology different?
Dialogue: 0,0:13:30.85,0:13:32.91,Default,,0000,0000,0000,,Well it turns out it's these neuromodulators,
Dialogue: 0,0:13:32.91,0:13:36.86,Default,,0000,0000,0000,,just like the neuromodulators in that little tiny ganglion in the crabs.
Dialogue: 0,0:13:36.86,0:13:39.41,Default,,0000,0000,0000,,So here's a picture of the octopamine system.
Dialogue: 0,0:13:39.41,0:13:41.16,Default,,0000,0000,0000,,Octopamine is a neuromodulator
Dialogue: 0,0:13:41.16,0:13:45.50,Default,,0000,0000,0000,,that seems to play an important role in flight and other behaviors.
Dialogue: 0,0:13:45.50,0:13:47.97,Default,,0000,0000,0000,,But this is just one of many neuromodulators
Dialogue: 0,0:13:47.97,0:13:49.04,Default,,0000,0000,0000,,that's in the fly's brain.
Dialogue: 0,0:13:49.04,0:13:51.71,Default,,0000,0000,0000,,So I really think that, as we learn more,
Dialogue: 0,0:13:51.71,0:13:54.23,Default,,0000,0000,0000,,it's going to turn out that the whole fly brain
Dialogue: 0,0:13:54.23,0:13:57.32,Default,,0000,0000,0000,,is just like a large version of this stomatogastric ganglion,
Dialogue: 0,0:13:57.32,0:14:01.68,Default,,0000,0000,0000,,and that's one of the reasons why it can do so much with so few neurons.
Dialogue: 0,0:14:01.68,0:14:04.47,Default,,0000,0000,0000,,Now, another idea, another way of multiplexing
Dialogue: 0,0:14:04.47,0:14:06.13,Default,,0000,0000,0000,,is multiplexing in space,
Dialogue: 0,0:14:06.13,0:14:07.82,Default,,0000,0000,0000,,having different parts of a neuron
Dialogue: 0,0:14:07.82,0:14:09.94,Default,,0000,0000,0000,,do different things at the same time.
Dialogue: 0,0:14:09.94,0:14:11.78,Default,,0000,0000,0000,,So here's two sort of canonical neurons
Dialogue: 0,0:14:11.78,0:14:14.06,Default,,0000,0000,0000,,from a vertebrate and an invertebrate,
Dialogue: 0,0:14:14.06,0:14:17.31,Default,,0000,0000,0000,,a human pyramidal neuron from Ramon y Cajal,
Dialogue: 0,0:14:17.31,0:14:21.31,Default,,0000,0000,0000,,and another cell to the right, a non-spiking interneuron,
Dialogue: 0,0:14:21.31,0:14:25.46,Default,,0000,0000,0000,,and this is the work of Alan Watson and Malcolm Burrows many years ago,
Dialogue: 0,0:14:25.46,0:14:28.54,Default,,0000,0000,0000,,and Malcolm Burrows came up with a pretty interesting idea
Dialogue: 0,0:14:28.54,0:14:31.42,Default,,0000,0000,0000,,based on the fact that this neuron from a locust
Dialogue: 0,0:14:31.42,0:14:33.38,Default,,0000,0000,0000,,does not fire action potentials.
Dialogue: 0,0:14:33.38,0:14:35.12,Default,,0000,0000,0000,,It's a non-spiking cell.
Dialogue: 0,0:14:35.12,0:14:37.90,Default,,0000,0000,0000,,So a typical cell, like the neurons in our brain,
Dialogue: 0,0:14:37.90,0:14:40.66,Default,,0000,0000,0000,,has a region called the dendrites that receives input,
Dialogue: 0,0:14:40.66,0:14:43.24,Default,,0000,0000,0000,,and that input sums together
Dialogue: 0,0:14:43.24,0:14:45.54,Default,,0000,0000,0000,,and will produce action potentials
Dialogue: 0,0:14:45.54,0:14:47.87,Default,,0000,0000,0000,,that run down the axon and then activate
Dialogue: 0,0:14:47.87,0:14:50.17,Default,,0000,0000,0000,,all the output regions of the neuron.
Dialogue: 0,0:14:50.17,0:14:53.04,Default,,0000,0000,0000,,But non-spiking neurons are actually quite complicated
Dialogue: 0,0:14:53.04,0:14:56.16,Default,,0000,0000,0000,,because they can have input synapses and output synapses
Dialogue: 0,0:14:56.16,0:14:59.82,Default,,0000,0000,0000,,all interdigitated, and there's no single action potential
Dialogue: 0,0:14:59.82,0:15:02.94,Default,,0000,0000,0000,,that drives all the outputs at the same time.
Dialogue: 0,0:15:02.94,0:15:06.85,Default,,0000,0000,0000,,So there's a possibility that you have computational compartments
Dialogue: 0,0:15:06.85,0:15:10.83,Default,,0000,0000,0000,,that allow the different parts of the neuron
Dialogue: 0,0:15:10.83,0:15:13.39,Default,,0000,0000,0000,,to do different things at the same time.
Dialogue: 0,0:15:13.39,0:15:18.06,Default,,0000,0000,0000,,So these basic concepts of multitasking in time
Dialogue: 0,0:15:18.06,0:15:20.42,Default,,0000,0000,0000,,and multitasking in space,
Dialogue: 0,0:15:20.42,0:15:23.25,Default,,0000,0000,0000,,I think these are things that are true in our brains as well,
Dialogue: 0,0:15:23.25,0:15:25.83,Default,,0000,0000,0000,,but I think the insects are the true masters of this.
Dialogue: 0,0:15:25.83,0:15:28.95,Default,,0000,0000,0000,,So I hope you think of insects a little bit differently next time,
Dialogue: 0,0:15:28.95,0:15:31.88,Default,,0000,0000,0000,,and as I say up here, please think before you swat.
Dialogue: 0,0:15:31.88,0:15:34.84,Default,,0000,0000,0000,,(Applause)