Recorded at | April 24, 2017 |
---|---|
Event | TED2017 |
Duration (min:sec) | 09:16 |
Video Type | TED Stage Talk |
Words per minute | 223.85 very fast |
Readability (FK) | 73.37 very easy |
Speaker | Greg Gage |
Occupation | neuroscientist |
Description | neuroscientist |
Official TED page for this talk
Synopsis
Neuroscientist Greg Gage takes sophisticated equipment used to study the brain out of graduate-level labs and brings them to middle- and high-school classrooms (and, sometimes, to the TED stage.) Prepare to be amazed as he hooks up the Mimosa pudica, a plant whose leaves close when touched, and the Venus flytrap to an EKG to show us how plants use electrical signals to convey information, prompt movement and even count.
1 | 00:12 | I'm a neuroscientist, | ||
2 | 00:14 | and I'm the co-founder of Backyard Brains, | ||
3 | 00:16 | and our mission is to train the next generation of neuroscientists | ||
4 | 00:20 | by taking graduate-level neuroscience research equipment | ||
5 | 00:23 | and making it available for kids in middle schools and high schools. | ||
6 | 00:27 | And so when we go into the classroom, | ||
7 | 00:29 | one way to get them thinking about the brain, which is very complex, | ||
8 | 00:33 | is to ask them a very simple question about neuroscience, | ||
9 | 00:36 | and that is, "What has a brain?" | ||
10 | 00:39 | When we ask that, | ||
11 | 00:40 | students will instantly tell you that their cat or dog has a brain, | ||
12 | 00:44 | and most will say that a mouse or even a small insect has a brain, | ||
13 | 00:49 | but almost nobody says that a plant or a tree | ||
14 | 00:51 | or a shrub has a brain. | ||
15 | 00:54 | And so when you push -- | ||
16 | 00:56 | because this could actually help describe a little bit | ||
17 | 00:59 | how the brain actually functions -- | ||
18 | 01:01 | so you push and say, | ||
19 | 01:02 | "Well, what is it that makes living things have brains versus not?" | ||
20 | 01:06 | And often they'll come back with the classification | ||
21 | 01:08 | that things that move tend to have brains. | ||
22 | 01:12 | And that's absolutely correct. | ||
23 | 01:14 | Our nervous system evolved because it is electrical. | ||
24 | 01:16 | It's fast, so we can quickly respond to stimuli in the world | ||
25 | 01:19 | and move if we need to. | ||
26 | 01:21 | But you can go back and push back on a student, | ||
27 | 01:24 | and say, "Well, you know, you say that plants don't have brains, | ||
28 | 01:27 | but plants do move." | ||
29 | 01:28 | Anyone who has grown a plant | ||
30 | 01:30 | has noticed that the plant will move | ||
31 | 01:32 | and face the sun. | ||
32 | 01:34 | But they'll say, "But that's a slow movement. | ||
33 | 01:36 | You know, that doesn't count. That could be a chemical process." | ||
34 | 01:39 | But what about fast-moving plants? | ||
35 | 01:42 | Now, in 1760, Arthur Dobbs, the Royal Governor of North Carolina, | ||
36 | 01:47 | made a pretty fascinating discovery. | ||
37 | 01:49 | In the swamps behind his house, | ||
38 | 01:52 | he found a plant that would spring shut | ||
39 | 01:56 | every time a bug would fall in between it. | ||
40 | 01:59 | He called this plant the flytrap, | ||
41 | 02:02 | and within a decade, it made its way over to Europe, | ||
42 | 02:05 | where eventually the great Charles Darwin got to study this plant, | ||
43 | 02:09 | and this plant absolutely blew him away. | ||
44 | 02:11 | He called it the most wonderful plant in the world. | ||
45 | 02:13 | This is a plant that was an evolutionary wonder. | ||
46 | 02:16 | This is a plant that moves quickly, | ||
47 | 02:18 | which is rare, | ||
48 | 02:19 | and it's carnivorous, which is also rare. | ||
49 | 02:21 | And this is in the same plant. | ||
50 | 02:22 | But I'm here today to tell you | ||
51 | 02:24 | that's not even the coolest thing about this plant. | ||
52 | 02:26 | The coolest thing is that the plant can count. | ||
53 | 02:30 | So in order to show that, | ||
54 | 02:31 | we have to get some vocabulary out of the way. | ||
55 | 02:34 | So I'm going to do what we do in the classroom with students. | ||
56 | 02:37 | We're going to do an experiment on electrophysiology, | ||
57 | 02:41 | which is the recording of the body's electrical signal, | ||
58 | 02:44 | either coming from neurons or from muscles. | ||
59 | 02:46 | And I'm putting some electrodes here on my wrists. | ||
60 | 02:49 | As I hook them up, | ||
61 | 02:50 | we're going to be able to see a signal | ||
62 | 02:52 | on the screen here. | ||
63 | 02:54 | And this signal may be familiar to you. | ||
64 | 02:56 | It's called the EKG, or the electrocardiogram. | ||
65 | 02:58 | And this is coming from neurons in my heart | ||
66 | 03:00 | that are firing what's called action potentials, | ||
67 | 03:03 | potential meaning voltage and action meaning it moves quickly up and down, | ||
68 | 03:07 | which causes my heart to fire, | ||
69 | 03:08 | which then causes the signal that you see here. | ||
70 | 03:11 | And so I want you to remember the shape of what we'll be looking at right here, | ||
71 | 03:15 | because this is going to be important. | ||
72 | 03:17 | This is a way that the brain encodes information | ||
73 | 03:19 | in the form of an action potential. | ||
74 | 03:21 | So now let's turn to some plants. | ||
75 | 03:24 | So I'm going to first introduce you to the mimosa, | ||
76 | 03:28 | not the drink, but the Mimosa pudica, | ||
77 | 03:31 | and this is a plant that's found in Central America and South America, | ||
78 | 03:35 | and it has behaviors. | ||
79 | 03:37 | And the first behavior I'm going to show you | ||
80 | 03:39 | is if I touch the leaves here, | ||
81 | 03:41 | you get to see that the leaves tend to curl up. | ||
82 | 03:45 | And then the second behavior is, | ||
83 | 03:47 | if I tap the leaf, | ||
84 | 03:49 | the entire branch seems to fall down. | ||
85 | 03:51 | So why does it do that? | ||
86 | 03:53 | It's not really known to science. | ||
87 | 03:54 | One of the reasons why could be that it scares away insects | ||
88 | 03:58 | or it looks less appealing to herbivores. | ||
89 | 04:00 | But how does it do that? Now, that's interesting. | ||
90 | 04:02 | We can do an experiment to find out. | ||
91 | 04:04 | So what we're going to do now, | ||
92 | 04:06 | just like I recorded the electrical potential from my body, | ||
93 | 04:09 | we're going to record the electrical potential from this plant, this mimosa. | ||
94 | 04:13 | And so what we're going to do is I've got a wire wrapped around the stem, | ||
95 | 04:19 | and I've got the ground electrode where? | ||
96 | 04:22 | In the ground. It's an electrical engineering joke. Alright. | ||
97 | 04:25 | (Laughter) | ||
98 | 04:26 | Alright. So I'm going to go ahead and tap the leaf here, | ||
99 | 04:29 | and I want you to look at the electrical recording | ||
100 | 04:31 | that we're going to see inside the plant. | ||
101 | 04:34 | Whoa. It is so big, I've got to scale it down. | ||
102 | 04:37 | Alright. So what is that? | ||
103 | 04:38 | That is an action potential that is happening inside the plant. | ||
104 | 04:41 | Why was it happening? | ||
105 | 04:43 | Because it wanted to move. Right? | ||
106 | 04:44 | And so when I hit the touch receptors, | ||
107 | 04:47 | it sent a voltage all the way down to the end of the stem, | ||
108 | 04:51 | which caused it to move. | ||
109 | 04:52 | And now, in our arms, we would move our muscles, | ||
110 | 04:54 | but the plant doesn't have muscles. | ||
111 | 04:56 | What it has is water inside the cells | ||
112 | 04:58 | and when the voltage hits it, it opens up, releases the water, | ||
113 | 05:01 | changes the shape of the cells, and the leaf falls. | ||
114 | 05:04 | OK. So here we see an action potential encoding information to move. Alright? | ||
115 | 05:09 | But can it do more? | ||
116 | 05:10 | So let's go to find out. | ||
117 | 05:12 | We're going to go to our good friend, the Venus flytrap here, | ||
118 | 05:15 | and we're going to take a look at what happens inside the leaf | ||
119 | 05:19 | when a fly lands on here. | ||
120 | 05:21 | So I'm going to pretend to be a fly right now. | ||
121 | 05:24 | And now here's my Venus flytrap, | ||
122 | 05:26 | and inside the leaf, you're going to notice | ||
123 | 05:28 | that there are three little hairs here, and those are trigger hairs. | ||
124 | 05:31 | And so when a fly lands -- | ||
125 | 05:32 | I'm going to touch one of the hairs right now. | ||
126 | 05:35 | Ready? One, two, three. | ||
127 | 05:39 | What do we get? We get a beautiful action potential. | ||
128 | 05:41 | However, the flytrap doesn't close. | ||
129 | 05:44 | And to understand why that is, | ||
130 | 05:46 | we need to know a little bit more about the behavior of the flytrap. | ||
131 | 05:49 | Number one is that it takes a long time to open the traps back up -- | ||
132 | 05:52 | you know, about 24 to 48 hours if there's no fly inside of it. | ||
133 | 05:56 | And so it takes a lot of energy. | ||
134 | 05:58 | And two, it doesn't need to eat that many flies throughout the year. | ||
135 | 06:01 | Only a handful. It gets most of its energy from the sun. | ||
136 | 06:04 | It's just trying to replace some nutrients in the ground with flies. | ||
137 | 06:07 | And the third thing is, | ||
138 | 06:09 | it only opens then closes the traps a handful of times | ||
139 | 06:12 | until that trap dies. | ||
140 | 06:14 | So therefore, it wants to make really darn sure | ||
141 | 06:16 | that there's a meal inside of it before the flytrap snaps shut. | ||
142 | 06:21 | So how does it do that? | ||
143 | 06:23 | It counts the number of seconds | ||
144 | 06:25 | between successive touching of those hairs. | ||
145 | 06:29 | And so the idea is that there's a high probability, | ||
146 | 06:31 | if there's a fly inside of there, they're going to be quick together, | ||
147 | 06:35 | and so when it gets the first action potential, | ||
148 | 06:37 | it starts counting, one, two, | ||
149 | 06:38 | and if it gets to 20 and it doesn't fire again, | ||
150 | 06:41 | then it's not going to close, | ||
151 | 06:42 | but if it does it within there, then the flytrap will close. | ||
152 | 06:45 | So we're going to go back now. | ||
153 | 06:46 | I'm going to touch the Venus flytrap again. | ||
154 | 06:48 | I've been talking for more than 20 seconds. | ||
155 | 06:50 | So we can see what happens when I touch the hair a second time. | ||
156 | 06:55 | So what do we get? We get a second action potential, | ||
157 | 06:58 | but again, the leaf doesn't close. | ||
158 | 07:00 | So now if I go back in there | ||
159 | 07:02 | and if I'm a fly moving around, | ||
160 | 07:04 | I'm going to be touching the leaf a few times. | ||
161 | 07:06 | I'm going to go and brush it a few times. | ||
162 | 07:08 | And immediately, | ||
163 | 07:10 | the flytrap closes. | ||
164 | 07:11 | So here we are seeing the flytrap actually doing a computation. | ||
165 | 07:16 | It's determining if there's a fly inside the trap, | ||
166 | 07:18 | and then it closes. | ||
167 | 07:20 | So let's go back to our original question. | ||
168 | 07:23 | Do plants have brains? | ||
169 | 07:25 | Well, the answer is no. | ||
170 | 07:27 | There's no brains in here. | ||
171 | 07:28 | There's no axons, no neurons. | ||
172 | 07:32 | It doesn't get depressed. | ||
173 | 07:33 | It doesn't want to know what the Tigers' score is. | ||
174 | 07:36 | It doesn't have self-actualization problems. | ||
175 | 07:38 | But what it does have is something that's very similar to us, | ||
176 | 07:41 | which is the ability to communicate using electricity. | ||
177 | 07:44 | It just uses slightly different ions than we do, | ||
178 | 07:47 | but it's actually doing the same thing. | ||
179 | 07:49 | So just to show you | ||
180 | 07:51 | the ubiquitous nature of these action potentials, | ||
181 | 07:54 | we saw it in the Venus flytrap, | ||
182 | 07:56 | we've seen an action potential in the mimosa. | ||
183 | 07:59 | We've even seen an action potential in a human. | ||
184 | 08:01 | Now, this is the euro of the brain. | ||
185 | 08:04 | It's the way that all information is passed. | ||
186 | 08:06 | And so what we can do is we can use those action potentials | ||
187 | 08:09 | to pass information | ||
188 | 08:11 | between species of plants. | ||
189 | 08:13 | And so this is our interspecies plant-to-plant communicator, | ||
190 | 08:17 | and what we've done is we've created a brand new experiment | ||
191 | 08:20 | where we're going to record the action potential from a Venus flytrap, | ||
192 | 08:24 | and we're going to send it into the sensitive mimosa. | ||
193 | 08:27 | So I want you to recall what happens | ||
194 | 08:28 | when we touch the leaves of the mimosa. | ||
195 | 08:30 | It has touch receptors that are sending that information | ||
196 | 08:33 | back down in the form of an action potential. | ||
197 | 08:35 | And so what would happen | ||
198 | 08:36 | if we took the action potential from the Venus flytrap | ||
199 | 08:40 | and sent it into all the stems of the mimosa? | ||
200 | 08:44 | We should be able to create the behavior of the mimosas | ||
201 | 08:47 | without actually touching it ourselves. | ||
202 | 08:49 | And so if you'll allow me, | ||
203 | 08:51 | I'm going to go ahead and trigger this mimosa right now | ||
204 | 08:54 | by touching on the hairs of the Venus flytrap. | ||
205 | 08:58 | So we're going to send information about touch from one plant to another. | ||
206 | 09:06 | So there you see it. | ||
207 | 09:08 | So -- | ||
208 | 09:09 | (Applause) | ||
209 | 09:15 | So I hope you learned a little bit, something about plants today, | ||
210 | 09:18 | and not only that. | ||
211 | 09:19 | You learned that plants could be used to help teach neuroscience | ||
212 | 09:23 | and bring along the neurorevolution. | ||
213 | 09:24 | Thank you. | ||
214 | 09:26 | (Applause) |