WEBVTT 00:00:03.557 --> 00:00:10.517 This is the Convergent Science Network podcast. Leading researchers in the domain 00:00:10.517 --> 00:00:16.757 of neuroscience, brain theory and technology are interviewed by Paul Verschoor and Tony Prescott. 00:00:17.637 --> 00:00:21.897 It's Paul Verschoor with the Convergent Science Network podcast together with 00:00:21.897 --> 00:00:23.397 my colleague Tony Prescott. 00:00:23.457 --> 00:00:28.597 And we're here at the BCBT Summer School 2015 in Barcelona. And we're talking 00:00:28.597 --> 00:00:34.437 to Benny Hochner, who gave a talk this morning about his work on an amazing animal, the octopus. 00:00:36.997 --> 00:00:43.097 So, Benny, of course, we're very familiar with the octopus in different restaurants 00:00:43.097 --> 00:00:45.617 and so on, because of culinary experience. 00:00:46.137 --> 00:00:49.917 But why is an octopus so interesting also from a scientific perspective? 00:00:53.517 --> 00:00:59.937 Okay. Octopus is interesting from a scientific point of view for several reasons. 00:01:01.037 --> 00:01:04.457 First, it's the best example 00:01:04.457 --> 00:01:08.097 for invertebrate or animal that 00:01:08.097 --> 00:01:15.297 uses a soft body for doing motor or action with a very sophisticated control 00:01:15.297 --> 00:01:24.837 mechanism of this very complex computational task of controlling movement in flexible structure. 00:01:25.417 --> 00:01:34.397 And the second reason to the interest in the octopus is because octopus is considered 00:01:34.397 --> 00:01:39.297 to be the most intelligent invertebrate. 00:01:40.077 --> 00:01:47.677 And therefore, it's very interesting from a comparative viewpoint to see what has evolved. 00:01:48.677 --> 00:01:55.757 Independently in the octopus that enabled this high, what we can call cognitive 00:01:55.757 --> 00:01:58.717 capabilities of this animal. 00:01:58.717 --> 00:02:02.037 And by such a comparative approach, 00:02:02.317 --> 00:02:13.737 we may find the universal common mechanism which are important to the evolution 00:02:13.737 --> 00:02:21.557 of animal with cognitive capability and complex behavior. 00:02:22.557 --> 00:02:25.737 Okay. So one thing you emphasize is complex behavior. 00:02:26.037 --> 00:02:31.457 Yeah. So, what kind of behavior should we be thinking about for the octopus? 00:02:31.497 --> 00:02:34.557 What's the most complex behavior an octopus is capable of? 00:02:36.317 --> 00:02:40.977 This is a tough question for a human being. 00:02:41.057 --> 00:02:44.917 I think you should ask the octopus what is very different. No, 00:02:44.957 --> 00:02:49.617 but given that you are the ambassador of the octopus in this room, we're forced to ask you. 00:02:51.997 --> 00:02:52.477 So... 00:02:54.592 --> 00:03:02.832 If we speak about, for example, from a point of view of motor control in an 00:03:02.832 --> 00:03:07.332 animal which doesn't have any hard skeletal structure, 00:03:07.492 --> 00:03:19.652 that is able to do so much different forms of behavior, From swimming, to crawling, 00:03:19.972 --> 00:03:32.452 to walking, to hiding, to go through very narrow holes, to extend an arm into a target. 00:03:33.072 --> 00:03:40.552 This is a very, very, the repertoire of behavior is very amazing. 00:03:40.552 --> 00:03:47.132 And this is a predator animal with a very good visual system, 00:03:47.472 --> 00:03:53.832 and it's very sensitive to what's going on in the environment. 00:03:54.052 --> 00:04:08.092 And then it can organize its attack behavior and all of it with this flexible body. 00:04:09.672 --> 00:04:14.512 Another reason I think which I got from your talk as to why octopus is so interesting 00:04:14.512 --> 00:04:19.672 scientifically is that from the point of view of mammals or vertebrates, 00:04:19.732 --> 00:04:23.592 which is what we are, octopus is really quite an alien species. 00:04:24.232 --> 00:04:28.792 So we only share a common ancestor if you go a very long way back. 00:04:29.332 --> 00:04:36.232 So the interest in octopus is partly around how it has come up with sometimes 00:04:36.232 --> 00:04:42.452 convergent solutions to the problems it faces, where it faces similar problems to vertebrates, 00:04:42.512 --> 00:04:45.332 and in other ways, perhaps divergent solutions. 00:04:45.772 --> 00:04:53.412 Would you agree with that? Yeah, I think this is exactly what we find in our research. 00:04:53.672 --> 00:05:03.432 And interestingly, we study both motor control and learning memory in this animal. 00:05:03.792 --> 00:05:08.132 So on one side, because of this flexibility of the body and soft body. 00:05:09.158 --> 00:05:13.638 We find a very unique solution, evolution solution. 00:05:14.718 --> 00:05:21.258 To this big problem of controlling the flexible body, while on the other side, 00:05:21.318 --> 00:05:26.998 in learning memory, we find in the brain an area which is very similar to our hippocampus, 00:05:27.618 --> 00:05:36.418 not only by structure, but also, for example, by its very robust long-term potentiation, 00:05:36.418 --> 00:05:38.998 activity-dependent long-term potentiation, 00:05:39.338 --> 00:05:45.358 which is probably a common mechanism to mediate changes in the nervous system, 00:05:45.478 --> 00:05:51.678 which is the basis for long-term learning and memory. 00:05:52.038 --> 00:05:55.458 So there may be some convergence in these more cognitive functions. 00:05:55.718 --> 00:05:59.538 Yes. But the divergence that you're seeing in motor control, 00:05:59.778 --> 00:06:05.138 some of that you then put down to the very different morphology of the octopus, 00:06:05.138 --> 00:06:11.518 purpose, that it has no internal skeleton, it's just made of soft parts, and that then, 00:06:12.298 --> 00:06:16.158 enforces a different way of solving the problem of controlling limbs? 00:06:16.718 --> 00:06:21.618 I think yes, because it creates two main problems that I would define. 00:06:21.938 --> 00:06:27.878 One is that a soft structure has infinitely large degrees of freedom. 00:06:29.180 --> 00:06:36.140 That the animal has, the control system has to control while doing a certain task. 00:06:36.940 --> 00:06:42.100 For example, in our arm, we have only seven degrees of freedom, 00:06:42.300 --> 00:06:49.440 which is relatively easy to solve, and this is due to the skeletal structure of our arm. 00:06:49.800 --> 00:06:57.640 When you have an arm without any rigid steltron, any joint, this can do any 00:06:57.640 --> 00:07:01.100 movement into any direction, elongate, bend, 00:07:01.520 --> 00:07:07.380 shortening, twisting, and the octopus uses this kind of movement. 00:07:07.520 --> 00:07:18.900 So it has to evolve a completely different approach to solve this complexity and how to use it. 00:07:20.600 --> 00:07:25.280 To produce a goal-directed, for example, a goal-directed movement. 00:07:26.140 --> 00:07:30.420 Just to push you on that, I mean, although I have only seven joints in my arm, 00:07:30.520 --> 00:07:33.480 I still have many ways of reaching to a given point in space. 00:07:33.740 --> 00:07:38.680 So I have the same problem of redundancy of degrees of freedom, 00:07:38.800 --> 00:07:43.360 not to the same extent as the octopus, but I still have to reduce the degrees 00:07:43.360 --> 00:07:45.880 of freedom and I do that by exploiting synergies. 00:07:46.080 --> 00:07:49.700 And isn't there some convergence, Maybe in the way that the octopus is also 00:07:49.700 --> 00:07:50.760 finding things. I think this is right. 00:07:51.920 --> 00:07:58.680 Also, what we find in the octopus is that in certain kinds of behavior, 00:07:59.100 --> 00:08:06.120 and this is, I think, a great achievement of the octopus, it can use all its degrees of freedom. 00:08:06.340 --> 00:08:11.620 For example, if the arm is as if it behaves by itself when it's searching the 00:08:11.620 --> 00:08:17.640 surrounding and looking for and saving as a probe, then it can let the arm loose 00:08:17.640 --> 00:08:21.300 and do whatever it likes according to the to some uh. 00:08:23.670 --> 00:08:28.870 Motor primitives that are embedded in the arm itself, while when goal-directed 00:08:28.870 --> 00:08:37.310 movement, the octopus has to use a way to reduce the number of degrees of freedom to only very few. 00:08:37.570 --> 00:08:42.490 So for example, if the octopus reached to a target, use only three degrees of freedom. 00:08:43.010 --> 00:08:51.810 One which took, sorry, which control the propagation of a bend in the arm toward 00:08:51.810 --> 00:08:57.990 the target, and the two others just to control the direction of the arm in space. 00:08:58.850 --> 00:09:06.190 Similarly, when the octopus gets food with one of its suckers along the arm, 00:09:06.290 --> 00:09:12.990 and it wants to bring the food to the mouse, it creates an articulated structure from its arm. 00:09:13.150 --> 00:09:18.270 He reshapes its arm into an articulated structure, and then it can bring the 00:09:18.270 --> 00:09:25.590 food to its mouse very accurately, similarly in the ways that we are doing this behavior. 00:09:26.670 --> 00:09:34.210 But in our case, it's embedded in our skeletal structure, while in the octopus, 00:09:34.410 --> 00:09:37.290 it's basically embedded in the motor program. 00:09:38.350 --> 00:09:46.570 He uses a certain way to reshape its arm into an articular structure, 00:09:46.570 --> 00:09:47.810 structure, which is a dynamic, 00:09:48.030 --> 00:09:53.290 can be dynamically adjusted to the site where the octopus got the target and 00:09:53.290 --> 00:09:57.230 bring the target accurately to the mouse. 00:09:57.430 --> 00:10:03.570 But you use the same mechanism, the same strategy of doing accurate point-to-point movement. 00:10:03.610 --> 00:10:09.690 Now before we delve into your own research on the behavior and the control of 00:10:09.690 --> 00:10:11.370 these arms by a neocupist. 00:10:12.730 --> 00:10:18.250 So is it actually even useful to still talk about degrees of freedom in this case? 00:10:18.750 --> 00:10:24.930 Should we just forget about that because it's practically an infinite set of 00:10:24.930 --> 00:10:26.790 control points it can work with? 00:10:27.990 --> 00:10:31.810 To what extent is it really helpful to talk about degrees of freedom from that 00:10:31.810 --> 00:10:38.630 perspective? I think it's good from the point of view that you set to yourself 00:10:38.630 --> 00:10:41.790 the problem, what the problems the octopus has to deal with. 00:10:43.270 --> 00:10:49.110 And what he has to deal with is to control many degrees of freedom. 00:10:49.110 --> 00:10:54.190 I don't think the octopus knows about this many degrees of freedom because it's 00:10:54.190 --> 00:10:58.970 embedded in his evolution and his structure and self-organization of his nervous 00:10:58.970 --> 00:11:01.730 system to be able to use this. 00:11:03.290 --> 00:11:10.210 Uh, many degrees of freedom and to collapse them in only few degrees of freedom 00:11:10.210 --> 00:11:15.870 by doing stereotypical movement, which suit this kind of flexible structure. 00:11:17.390 --> 00:11:25.770 And it's also, um, constrained by how, how complex the motor, 00:11:25.810 --> 00:11:28.090 the motor command can be to the muscle. 00:11:28.090 --> 00:11:34.410 For example, a simple motor command to a muscular hydrosat like the octopus 00:11:34.410 --> 00:11:42.410 arm, where the arm is organizing longitudinal and transversal orientation of muscle fiber, 00:11:42.630 --> 00:11:48.550 the activation of both muscles together, to the same extent, creates stiffening. 00:11:49.330 --> 00:11:55.090 So, this is a very simple motor program. The brain has just to give the motor 00:11:55.090 --> 00:11:58.810 neurons in the arm command to have the same output. 00:11:59.370 --> 00:12:05.610 And this is enough to create the stiffening. And then you can use a rather simple, 00:12:05.670 --> 00:12:11.250 I think, motor program to propagate this stiffening along the arm. 00:12:11.410 --> 00:12:14.830 And this can create the reaching movement very simply, 00:12:14.850 --> 00:12:17.910 not only by the degree of 00:12:17.910 --> 00:12:20.850 freedom they need to be controlled in to produce the movement 00:12:20.850 --> 00:12:24.130 but but also a very simple motor 00:12:24.130 --> 00:12:27.950 program to activate the the the 00:12:27.950 --> 00:12:31.010 reaching but before you look at the motor program 00:12:31.010 --> 00:12:35.210 what is what is interesting about the octopus among many things it's like a 00:12:35.210 --> 00:12:39.190 mollusk that that escaped from its shell i mean in phylogenetically it sits 00:12:39.190 --> 00:12:44.250 in this family with a phylum of mollusks and right its Its closest neighbors 00:12:44.250 --> 00:12:49.450 in that phylum are actually really simple animals that live in a shell. Right. 00:12:49.890 --> 00:12:52.390 So, what are the... 00:12:53.837 --> 00:12:59.597 What are the differences between the octopus and the other animals in that phylum? 00:12:59.697 --> 00:13:03.797 Like if you look at the nervous system of a mollusk and an octopus, 00:13:04.137 --> 00:13:04.977 what are the differences? 00:13:05.397 --> 00:13:10.737 First of all, there is a big difference in the size of the nervous system. 00:13:11.097 --> 00:13:20.717 The octopus nervous system contains half a billion neurons, while a garden snail 00:13:20.717 --> 00:13:25.217 may have a few tens of thousands of neurons. 00:13:25.617 --> 00:13:29.157 So there is a big difference in cell number. 00:13:29.657 --> 00:13:35.257 And also what we see is that there is a huge difference in the way the nervous 00:13:35.257 --> 00:13:38.237 system is organized in the body. 00:13:40.577 --> 00:13:45.577 Both in the simple animal and in the octopus, the nervous system is organized 00:13:45.577 --> 00:13:51.597 to maximize the efficiency of the nervous system controlling different parts of the body. 00:13:51.777 --> 00:13:57.697 So for example, in the octopus, the majority of nerve cells are situated already 00:13:57.697 --> 00:14:01.037 in the peripheral nervous system of the arm. 00:14:01.677 --> 00:14:06.057 This fits what we are finding in the behavior in our physiological studies, 00:14:06.097 --> 00:14:13.377 that many of of the motor program are generated at the level of the neuromuscular system of the arm. 00:14:13.537 --> 00:14:20.037 So basically, the central brain, which contains only 50 million neurons, 00:14:21.934 --> 00:14:27.334 actually need to process information and set command to the peripheral nervous 00:14:27.334 --> 00:14:32.954 system how to produce stereotypical arm movement. 00:14:33.734 --> 00:14:36.514 Now, the main difference really is that. 00:14:38.634 --> 00:14:45.934 Lower invertebrate mollusks depend on their protection on their shell. 00:14:46.154 --> 00:14:52.414 The shell is a very nice protection. I should mention that mollusks have another 00:14:52.414 --> 00:14:57.834 way of protecting themselves, and they are a very rich source for all kinds of toxins. 00:14:58.214 --> 00:15:02.194 So they are a very efficient, let's say, 00:15:02.374 --> 00:15:12.314 factory of biochemicals or things that can help us in studying the nervous system 00:15:12.314 --> 00:15:18.734 because they block ion channels and receptors and so forth. 00:15:19.854 --> 00:15:25.054 So they used this kind of defense mechanism. 00:15:26.294 --> 00:15:33.294 And the octopus lost his protecting shell and became to be a freely moving animal, 00:15:33.494 --> 00:15:40.054 a predator, that depends very much on its visual system. 00:15:40.054 --> 00:15:45.054 Them and losing the shell, 00:15:45.294 --> 00:15:51.294 enable the animal, the heavy shell, enable the animal to become such a freely 00:15:51.294 --> 00:15:53.934 moving and really during the 00:15:53.934 --> 00:16:00.274 revolutions they actually compete with fishes at the time of evolution. 00:16:00.974 --> 00:16:05.614 But is there anything conserved there? If we go from mollusks to snail to octopus, 00:16:05.914 --> 00:16:11.154 is there anything conserved when we think go up into complexity? 00:16:11.994 --> 00:16:17.694 I think this is a very good question. I used to work on. 00:16:20.274 --> 00:16:27.874 Plesia californica, together with Professor Eric Kandel, on the basic mechanism 00:16:27.874 --> 00:16:30.374 of learning memory in this animal. 00:16:30.634 --> 00:16:35.674 So for me particularly, it's very interesting to see if the simple, 00:16:36.634 --> 00:16:40.994 mechanisms that exist in the aplysia for 00:16:40.994 --> 00:16:43.934 mediating simple form of learning and memory 00:16:43.934 --> 00:16:47.334 in the reflex of the 00:16:47.334 --> 00:16:55.494 defense reflex of this animal are conserved or completely different mechanisms 00:16:55.494 --> 00:17:05.914 that is converging with our brain has been evolved in the octopus. and what we find that. 00:17:07.233 --> 00:17:14.893 No. In the octopus, there are still mechanisms which are more likely to what 00:17:14.893 --> 00:17:17.793 takes place in other mollusks. 00:17:18.333 --> 00:17:27.293 But interestingly, they have been modified a lot in order to establish a new cellular mechanism. 00:17:27.293 --> 00:17:35.153 So I mentioned before the mechanism of activity-dependent long-term potentiation, 00:17:35.333 --> 00:17:41.493 which I think it's the universal cellular mechanism for mediating learning memory. 00:17:41.493 --> 00:17:47.773 Memory, but the molecular mechanism that mediates this long-term potentiation 00:17:47.773 --> 00:18:00.913 in the octopus brain is mediated by a mechanism which is conserved from other mollusks, 00:18:01.033 --> 00:18:01.933 but it was 00:18:02.093 --> 00:18:11.133 modified to do this kind of long-term potentiation as a cellular process. 00:18:12.233 --> 00:18:17.873 But doesn't, in some sense, it makes the octopus a strange exception in its 00:18:17.873 --> 00:18:22.053 phylum, but also a bit annoying because also as you described in your talk, 00:18:22.133 --> 00:18:25.273 you looked at the evolution of the eye. 00:18:26.313 --> 00:18:30.293 The octopus eye, eye which shares many properties with the human eye which 00:18:30.293 --> 00:18:33.413 is is is sort of suggesting that the 00:18:33.413 --> 00:18:37.433 common ancestor is is way beyond uh 00:18:37.433 --> 00:18:45.573 a very very early in in phylogeny so um doesn't that really mean that that from 00:18:45.573 --> 00:18:50.733 a genetic perspective uh also these very simple organisms are actually carrying 00:18:50.733 --> 00:18:54.513 a lot of additional information that they share with us, 00:18:54.573 --> 00:18:59.153 way beyond just the basics of cellular mechanisms and so on. 00:18:59.353 --> 00:19:03.453 Yeah, I think this is completely true. And I think it fits. 00:19:03.993 --> 00:19:09.633 First of all, with the idea that what we find is, you know, the number of genes 00:19:09.633 --> 00:19:15.193 in our, or in octopus, is not that many. 00:19:15.193 --> 00:19:25.653 Actually, probably there are rather basic building blocks of genes that the 00:19:25.653 --> 00:19:30.053 first living creature already had when it developed. 00:19:30.433 --> 00:19:41.293 So now for analyzing a light, you have molecules that can be shared by plants, 00:19:41.653 --> 00:19:53.133 by animals, and by eyes and by other creatures that are using light to do all 00:19:53.133 --> 00:19:57.753 kinds of camera photosynthesis and things like this, 00:19:57.853 --> 00:20:01.633 and they are built to the world. 00:20:05.514 --> 00:20:12.094 To collect light? To collect photons? No, to... 00:20:13.594 --> 00:20:14.994 Transform? Transform. 00:20:16.754 --> 00:20:21.374 Converge? Transform light into... Electrical signals. Yeah. 00:20:22.654 --> 00:20:26.854 Transduce, maybe. Transduce. Transduce. Transform. 00:20:27.854 --> 00:20:31.574 Anyway. Transduction. It's called the transduction mechanism. 00:20:32.274 --> 00:20:40.194 Okay. okay so now we have a bit an idea about the octopus it's really a very 00:20:40.194 --> 00:20:44.934 strange almost an alien species that sort of got plunked into a phylogeny but 00:20:44.934 --> 00:20:50.354 still it shares properties with even with us now it controls this very strange body, 00:20:51.114 --> 00:20:52.714 it has eight arms, 00:20:53.674 --> 00:20:59.574 controlled by complex ganglia that again talk to a central brain what do we 00:20:59.574 --> 00:21:05.054 know about this ganglia what do the ganglia do that are linked to a single arm? 00:21:05.234 --> 00:21:09.334 The ganglia in the arm or the ganglia in the brain? 00:21:09.794 --> 00:21:13.714 No, the ganglia in the arm. So I want to start at the periphery. Yeah. 00:21:14.854 --> 00:21:22.134 Actually we don't know much about the ganglia in the arm, about the function of the arm. 00:21:22.234 --> 00:21:29.714 We know that there are motor neurons which are innervating about 400,000 motor 00:21:29.714 --> 00:21:33.554 neurons on in each arms that are innovating very every. 00:21:36.617 --> 00:21:45.577 Every hundred micron, the muscles that run along the arm, and each muscle is 00:21:45.577 --> 00:21:51.557 innervated by three types of motor neurons that have different properties. 00:21:51.877 --> 00:21:56.817 But we don't know exactly what's going on in the arm in terms of the computational 00:21:56.817 --> 00:22:01.037 properties of this structure, the reflexive behavior. 00:22:01.037 --> 00:22:04.677 We know that there is some input from 00:22:04.677 --> 00:22:08.357 proprioceptive into the central nervous 00:22:08.357 --> 00:22:11.357 system of the arm but we don't know exactly what how 00:22:11.357 --> 00:22:14.857 it's activated the for example the the reflex 00:22:14.857 --> 00:22:22.097 of the suckers or the or the bending or any other function of the of the arm 00:22:22.097 --> 00:22:33.017 we know better due to many not not our work but the the people in Wells and J.Z. 00:22:33.017 --> 00:22:36.957 Young and other people that work mainly in Napoli, 00:22:37.117 --> 00:22:43.957 they studied the structure of the central brain and they found very interestingly 00:22:43.957 --> 00:22:45.977 that the brain is organized still, 00:22:46.077 --> 00:22:52.337 it's very very centralized, but it's still composed of lobes, 00:22:52.457 --> 00:22:53.077 of ganglia. 00:22:54.037 --> 00:23:02.637 And by stimulating and by lesioning, they could assign a more or less specific 00:23:02.637 --> 00:23:06.177 function for different lobes. 00:23:06.477 --> 00:23:14.097 And this is what makes us interested in this central brain, because we think 00:23:14.097 --> 00:23:18.377 that the separation between the periphery and the central processes, 00:23:18.777 --> 00:23:25.257 the central brain seems to be dealing more with cognitive function. 00:23:25.957 --> 00:23:32.177 We think it's an ideal preparation to study these processes because it's separated 00:23:32.177 --> 00:23:36.597 from the input and the output structure. 00:23:37.557 --> 00:23:43.437 And in vertebrate brains, you might look at sort of the spinal cord as being 00:23:43.437 --> 00:23:48.897 doing a lot of this motor sensory stuff and processing things locally. 00:23:49.737 --> 00:23:56.257 And then brainstem perhaps doing some more of that and then midbrain and forebrain 00:23:56.257 --> 00:23:58.457 doing these more higher executive functions. 00:23:58.737 --> 00:24:02.937 Yeah. Sort of deciding what are targets for movement and then executing movements. 00:24:03.257 --> 00:24:08.957 I mean, does that kind of way of thinking about the decomposition of the nervous 00:24:08.957 --> 00:24:10.577 system work at all for Octopus? 00:24:10.577 --> 00:24:19.777 I think yes, but actually you can look at the nervous system of the arm, 00:24:19.817 --> 00:24:24.157 the arm nerve cord, as a spinal cord. 00:24:25.653 --> 00:24:30.133 But it's much more elaborated than, for example, our spinal cord, 00:24:30.273 --> 00:24:39.293 because of the special separation of labor between the central nervous system and the peripheral one. 00:24:39.973 --> 00:24:44.253 The peripheral one has a lot of function of its own, and therefore, 00:24:44.533 --> 00:24:51.273 although we treat it as a peripheral nervous system, it's very elaborated in 00:24:51.273 --> 00:24:56.053 its organization because its function, both in processing sensory information, 00:24:57.153 --> 00:25:00.033 and activating motor program. 00:25:01.433 --> 00:25:03.353 Is very rich. 00:25:04.653 --> 00:25:09.233 But if you take the head off a chicken or you decorticate a cat, 00:25:09.313 --> 00:25:13.133 they can still generate rhythmic motions, run on a treadmill, 00:25:13.953 --> 00:25:16.113 these sorts of things. So is there a parallel there? 00:25:16.453 --> 00:25:20.413 So I understand that the arm can do a lot of autonomous behavior. 00:25:20.973 --> 00:25:28.413 Yeah, so for example, For example, the central brain is divided into two parts, 00:25:28.573 --> 00:25:33.913 one which is above the oesophagus, which is called the supraesophageal part 00:25:33.913 --> 00:25:38.033 of the brain, and there is a lower part which is the subesophageal part. 00:25:38.393 --> 00:25:46.073 So the subesophageal part is really like the brainstem is more like dealing 00:25:46.073 --> 00:25:50.073 with the vegetative function of the body, 00:25:50.333 --> 00:25:53.433 like breathing and other very, 00:25:54.493 --> 00:25:56.013 basic reflex. 00:25:56.333 --> 00:26:01.933 And the upper part of the brain, the superesophageal part, is more... 00:26:02.913 --> 00:26:08.373 Here is where the learning memory centers are organized, and the higher motor 00:26:08.373 --> 00:26:09.713 control center is organized. 00:26:10.233 --> 00:26:19.673 And so if you can create a decerebrated octopus by removing only this part of 00:26:19.673 --> 00:26:22.253 the brain. And then you find that there is some. 00:26:23.808 --> 00:26:27.708 Reflexes that are coordinated between the arms. 00:26:28.348 --> 00:26:34.408 For example, if you take such a dis-erebrated octopus and you hold one of its 00:26:34.408 --> 00:26:42.108 arms, you will find that the rest of the arm is coming to help the taken arm. 00:26:42.348 --> 00:26:52.048 So there is a lot of coordination taken also at the lower level of the central nervous system. 00:26:52.048 --> 00:27:03.248 And this area has this very basic surviving properties of the central nervous system. 00:27:03.568 --> 00:27:10.568 So I think you're right that it's organized in more or less similar hierarchy 00:27:10.568 --> 00:27:17.608 of responsibility, let's say, of the animal behavior. 00:27:18.788 --> 00:27:23.948 So then so we could call these reflexes of the octopus this would be a typical 00:27:23.948 --> 00:27:29.208 defensive reflex one arm gets stuck and you pull the other arms towards it right 00:27:29.208 --> 00:27:35.328 but now if we go further down and let's say now we, 00:27:35.908 --> 00:27:41.568 also we just sever an arm what can a single arm still do? 00:27:42.568 --> 00:27:48.028 Arm can do a lot especially if you if you you. 00:27:50.220 --> 00:27:53.460 Encourage it to do something like, like, you know, like, uh, 00:27:53.660 --> 00:27:59.380 like bringing a piece of food into the sucker, uh, the arm can continue to survive 00:27:59.380 --> 00:28:05.200 about half an hour in, uh, in a isolated, in, in, in normal seawater. 00:28:05.520 --> 00:28:11.820 And the, and the, and the, um, and the arm will grab the food and will behave as, 00:28:11.860 --> 00:28:25.860 as, as really it's bringing it, maybe even bringing it back to the place where the mouse is. 00:28:26.300 --> 00:28:34.160 Actually, in 1971, there was a paper in Nature by Jennifer Altman, 00:28:34.380 --> 00:28:38.980 who described that the octopus can bring food, 00:28:38.980 --> 00:28:42.100 an isolated arm can bring food toward 00:28:42.100 --> 00:28:45.060 the mouse by moving it along the 00:28:45.060 --> 00:28:47.960 suckers and if you put an acid or 00:28:47.960 --> 00:28:51.160 something on this food and put it on the arm again it will 00:28:51.160 --> 00:28:58.560 move it outward so when we started we we already had some ideas that there is 00:28:58.560 --> 00:29:09.260 a lot of autonomy in the behavior of the of the arm itself so but now you What you also showed is that, 00:29:09.360 --> 00:29:15.420 so there is some sense of, let's say, hierarchical organization of this motor system. 00:29:16.240 --> 00:29:20.080 But then if you go look for, let's say, the organization of, 00:29:20.100 --> 00:29:23.420 let's say, the control signals of that in the central brain, 00:29:23.740 --> 00:29:26.920 it looks surprisingly, let's say, disorganized. 00:29:27.340 --> 00:29:30.600 So you don't find a somatotopic map, right? 00:29:30.760 --> 00:29:34.180 You don't find that, let's say, arms are represented in some coherent, 00:29:34.300 --> 00:29:38.200 at least so far, no one has found that. Yeah. So how do you interpret that? 00:29:40.220 --> 00:29:49.200 I think this fits the idea that in order to control a flexible structure, 00:29:49.580 --> 00:30:00.740 you cannot use what we use to define as a conventional mechanism by representing the body, 00:30:00.860 --> 00:30:05.340 the body part in the brain, and use it as an input to a system that will, 00:30:05.420 --> 00:30:11.820 together with the sensory information that is also represented in a somatotopic way, 00:30:12.560 --> 00:30:15.780 will integrate into initiation of command. 00:30:17.335 --> 00:30:23.675 And this is because it's very hard to envisage a way that such, 00:30:23.895 --> 00:30:32.495 let's say, 300 suckers along the arm will be, and each arm, an eight arm, 00:30:32.635 --> 00:30:37.215 will be represented in a specific location in the brain. 00:30:37.315 --> 00:30:41.535 I think it's a lot of information. So, the octopus, 00:30:41.655 --> 00:30:48.715 I think, solved this problem by that in the brain what is represented is what 00:30:48.715 --> 00:30:55.415 kind of behavior the higher motor center should induce as a response to some 00:30:55.415 --> 00:30:58.615 specific input, sensory input. 00:30:58.915 --> 00:31:04.555 So the brain is organized in what we think, we have to test it yet, 00:31:04.695 --> 00:31:08.535 in a more of motor or program organization. 00:31:09.655 --> 00:31:14.635 But it is in some sense doing something a little bit like conventional sort 00:31:14.635 --> 00:31:19.715 of inverse kinematics so that in order to solve this problem of reaching to a point in space, 00:31:20.035 --> 00:31:25.015 it has to, as you explained, reduce the degrees of freedom in the arm and make 00:31:25.015 --> 00:31:31.515 it to a number of relatively rigid parts with joints in between them. 00:31:31.655 --> 00:31:36.455 And then you can imagine that the brain is doing some inverse kinematics in 00:31:36.455 --> 00:31:41.655 order to work out how to control that reduced degree of freedom system to reach a point. 00:31:42.035 --> 00:31:44.375 Yeah. So, yeah. 00:31:45.295 --> 00:31:49.315 So, this is what is happening in the system. 00:31:49.655 --> 00:31:54.375 Yeah. But in that case, wouldn't you expect something sort of convergent about 00:31:54.375 --> 00:31:58.595 the control of these high-level structures compared to, for instance, 00:31:59.015 --> 00:32:01.215 the mammalian motor cortex? 00:32:01.975 --> 00:32:06.455 Isn't the control of my arm solving something of a similar problem if I'm reaching 00:32:06.455 --> 00:32:08.575 to a point in space guided by a vision? 00:32:12.055 --> 00:32:19.615 Reaching is different than what we are doing. Right. 00:32:20.155 --> 00:32:25.355 So the motor program, the behavior is completely different than what we are 00:32:25.355 --> 00:32:30.315 doing, and this is taking advantage of the flexibility of the arm. 00:32:30.595 --> 00:32:38.395 Because reaching to a target by propagating a wave wave of activation and bends 00:32:38.395 --> 00:32:41.495 that propagate through the arms, it's something that we cannot do. 00:32:41.875 --> 00:32:47.235 Right. But the command to induce this kind of behavior might be very simple. 00:32:47.535 --> 00:33:00.155 It just has to activate this wave of stiffening muscles that will push the arm toward the target. 00:33:01.546 --> 00:33:06.066 But if it would be so easy, I'm sure I would have been able to fully understand 00:33:06.066 --> 00:33:08.446 it. And there's still something missing in that picture, right? 00:33:08.626 --> 00:33:14.086 So, for instance, what is then also strange, if there's no smetotopy to the 00:33:14.086 --> 00:33:16.726 organization of the motor neurons, 00:33:17.526 --> 00:33:23.326 you could still maybe expect that in terms of the haptic information that the 00:33:23.326 --> 00:33:27.486 central brain receives from the different arms, that since this would express 00:33:27.486 --> 00:33:29.306 some topological organization, 00:33:30.106 --> 00:33:33.466 might be reflected in a topological map of the body. 00:33:33.566 --> 00:33:38.326 But since you haven't found it, does that maybe imply that the sensory information 00:33:38.326 --> 00:33:40.226 never reaches the central brain? 00:33:40.746 --> 00:33:45.386 Is that possible? That the central brain only knows something about what let's 00:33:45.386 --> 00:33:50.046 say the ganglia tell it at sort of a very abstract level about the arm, 00:33:50.106 --> 00:33:51.346 like, oh, the arm is still there. 00:33:51.486 --> 00:33:55.666 Yeah. But it doesn't receive more detailed information from all the suckers, for instance. 00:33:55.886 --> 00:34:04.046 So I think to answer your question, I think there are some behavioral experiments 00:34:04.046 --> 00:34:10.666 that have been done by Wells in Napoli, 00:34:11.306 --> 00:34:15.426 and they show that, for example, octopus, you can train octopus very nicely 00:34:15.426 --> 00:34:18.066 to do tactile discrimination. 00:34:18.966 --> 00:34:27.686 But you cannot train an octopus to do with one arm one task and with the other arm, different task. 00:34:28.226 --> 00:34:33.206 The training, the learning is general to the entire arm. 00:34:33.926 --> 00:34:39.506 To all arm? To all arm. So if I learn a tactile discrimination with arm number 00:34:39.506 --> 00:34:42.446 one, I can also do it with arm number three? It will be generalized to all other 00:34:42.446 --> 00:34:44.586 arms. So that would mean central brain is involved. 00:34:45.466 --> 00:34:52.426 Yes, of course, it's involved in the learning, but it's not involved in the specific arm. 00:34:53.846 --> 00:35:00.906 But still, no one has found some sort of somatotopic map of that in the central brain? No. 00:35:02.716 --> 00:35:09.136 Not yet. And similarly, for example, is with motor command. 00:35:09.916 --> 00:35:16.016 When octopus extend arm or several arm together, it never extend one arm in 00:35:16.016 --> 00:35:22.396 a higher speed and the other one with a smaller one, with a slower speed. 00:35:22.396 --> 00:35:30.816 It always will have the same speed as if a real, a single program has been evolved. 00:35:31.096 --> 00:35:36.796 And maybe there is a gating mechanism that determine at the lower level which 00:35:36.796 --> 00:35:41.776 arm will be activated by this motor program. 00:35:42.756 --> 00:35:50.236 But now, about the sensory representation of let's say touch, 00:35:50.376 --> 00:35:52.316 haptic information that comes from these arms, 00:35:52.536 --> 00:35:58.016 people have looked for that and also found the same kind of broad distribution 00:35:58.016 --> 00:36:03.096 in the central brain, or people have just not really looked for it yet in detail? 00:36:05.956 --> 00:36:12.736 What I have showed today is that when we record from the central brain, 00:36:12.836 --> 00:36:15.116 from the higher motor center, 00:36:15.416 --> 00:36:26.676 we find that there is no specific representation of specific area in the body in the center brain. 00:36:26.876 --> 00:36:29.236 But wait, I thought that was with respect to motor action. 00:36:29.476 --> 00:36:32.376 What you showed us is for different movements, right? 00:36:32.796 --> 00:36:44.336 No, but what we have shown also is that if you record from this side in the, 00:36:45.116 --> 00:36:50.916 in the higher motor center in the brain, and you stimulate tactically different 00:36:50.916 --> 00:36:54.076 parts of the body, you can get. 00:36:55.965 --> 00:36:59.545 Response from different area in the body. 00:37:00.145 --> 00:37:04.365 So if you get the response from one arm, you will get from the other arm and 00:37:04.365 --> 00:37:08.085 even from the mantle or from the sacral. 00:37:08.505 --> 00:37:16.625 So there is no, it seems that the conventional representation doesn't exist in between. 00:37:16.705 --> 00:37:23.365 It still might be that this information is presented in different units that 00:37:23.365 --> 00:37:27.845 are activated by by uh but you you would at this point in time given what you know say, 00:37:28.785 --> 00:37:31.945 both the direct to the somatosensory processing and 00:37:31.945 --> 00:37:38.065 motor control there is no no somatotopic exactly yeah organization yeah all 00:37:38.065 --> 00:37:42.345 right so and that can also lead you to this point that that you pushed rather 00:37:42.345 --> 00:37:48.245 strongly in your presentation that the octopus is able to generate these complex 00:37:48.245 --> 00:37:51.465 complex behaviors without a map of its body. 00:37:53.005 --> 00:37:58.565 So now I could argue with that by saying, well, one, you just haven't found it yet. 00:37:58.645 --> 00:38:02.705 And the organization is such that it is not easy to interpret. 00:38:02.865 --> 00:38:04.005 So there's still a body representation. 00:38:04.565 --> 00:38:08.965 Yeah. Because in some sense, you do see that the central brain is involved in controlling the body. 00:38:09.085 --> 00:38:13.285 We have this generalization that you also just described, right? 00:38:13.325 --> 00:38:15.545 I can learn from one arm and execute with the other arm. 00:38:15.625 --> 00:38:20.085 Yeah. Wouldn't that actually imply that there must be something like a body 00:38:20.085 --> 00:38:22.505 representation somewhere and you just haven't found it yet? 00:38:22.725 --> 00:38:26.465 Yeah, it very well can be. 00:38:26.665 --> 00:38:34.345 But what I showed that at least two movements that I analyzed, 00:38:34.645 --> 00:38:36.125 which is the reaching movement, 00:38:37.145 --> 00:38:43.745 and the fetching movement, we can explain the motor program that generate this movement, 00:38:46.472 --> 00:38:50.372 on the action of the peripheral nervous system. 00:38:52.712 --> 00:38:56.732 Neuromuscular system itself. So, for example, in reaching movement, 00:38:56.952 --> 00:39:03.672 we have shown that you can generate a perfectly well extension movement in amputated 00:39:03.672 --> 00:39:07.192 arm by stimulating the arm nerve cord. 00:39:08.092 --> 00:39:13.232 So it means that at least irrespective of central representation, 00:39:13.232 --> 00:39:16.412 representation it is possible to generate such movement 00:39:16.412 --> 00:39:20.192 in amputated arm it means that the program are embedded 00:39:20.192 --> 00:39:23.172 in the well not necessarily 00:39:23.172 --> 00:39:27.252 right because as we discussed earlier there might be hierarchical structuring 00:39:27.252 --> 00:39:31.812 right so if you decorticate me i might still be able to make let's say walking 00:39:31.812 --> 00:39:37.032 like rhythmic movements with my legs and that does not imply that the bit you 00:39:37.032 --> 00:39:41.012 just removed from my brain is not representing my body or controlling it or 00:39:41.012 --> 00:39:42.012 whatever just means i have 00:39:42.092 --> 00:39:45.832 lower level reflexes that give structure to the behaviors I generate. 00:39:46.752 --> 00:39:50.192 So, so isn't that then the same case here? Because we can look at, 00:39:50.232 --> 00:39:53.332 let's say, let's look at the reaching actions. 00:39:53.472 --> 00:39:58.652 So my argument would be, well, maybe the reaching is really like a very simple reflex. 00:39:58.772 --> 00:40:03.772 It's a very important reflex for this animal that is basically used as, 00:40:03.792 --> 00:40:06.972 as a movement primitive by higher level systems. Right. 00:40:07.332 --> 00:40:10.812 So what you really show, and this is true, it is, it is definitely a reflex 00:40:10.812 --> 00:40:16.632 that sits it's very close to the organization of a single arm because a single 00:40:16.632 --> 00:40:20.092 arm can almost generate a reaching movement. 00:40:20.352 --> 00:40:25.932 So how do reaching movements exactly come about? How does this work in the octopus arm? 00:40:26.372 --> 00:40:31.932 So without the central brain, right? Yes. So what we think happens is that by 00:40:31.932 --> 00:40:34.152 stimulating locally at the base of the arm, 00:40:34.312 --> 00:40:42.552 we generate motor programs that propagate along the arm and activate both the 00:40:42.552 --> 00:40:46.832 transversal and longitudinal muscle and create a stiffening wave, 00:40:47.072 --> 00:40:51.052 which pushes actually passively at the bend forward. 00:40:51.952 --> 00:40:57.112 And this has similar kinematics to what we see in a freely behaving animal. 00:40:57.532 --> 00:41:03.572 So what we think is that maybe this movement or the command for this movement 00:41:03.572 --> 00:41:06.032 are stored in the central brain. 00:41:06.832 --> 00:41:10.452 So the way to activate this movement is stored in the higher motor center. 00:41:11.917 --> 00:41:17.577 And it's based, and therefore we say that maybe in the central nervous system 00:41:17.577 --> 00:41:26.837 what is decoded is the motor program rather than information based on the different part of the muscle. 00:41:26.857 --> 00:41:29.137 So what you're saying is, look, I have the longitudinal muscle, 00:41:29.397 --> 00:41:35.137 I have the transversal muscle, and then we have, again, a muscle sheet around that at the outside. 00:41:35.137 --> 00:41:44.217 If I drive those from inside, so from proximal to distal in sort of, 00:41:44.217 --> 00:41:47.717 it doesn't need to be a wave actually, it's a single wave front that moves to the edge. 00:41:48.537 --> 00:41:54.697 And by activating all these muscles, I create stiffness of this hydrostat, this arm. 00:41:54.997 --> 00:42:01.257 And I just have that instruction and just has to move distally through my arm. 00:42:01.497 --> 00:42:09.137 This is roughly the idea. What the brain has to do is to scale this movement, 00:42:09.217 --> 00:42:13.357 because we know that octopus can extend its arm in different speed. 00:42:13.997 --> 00:42:18.597 And this probably is done via a central command. 00:42:19.497 --> 00:42:25.517 But the propagating signal then passes through a number of neural stages. 00:42:25.517 --> 00:42:32.717 So how many neurons, so how many synapses do I cross to go from proximal to 00:42:32.717 --> 00:42:34.277 distal? Many, many, many. 00:42:34.537 --> 00:42:42.937 There are 400,000 motor neurons in each arm. 00:42:43.797 --> 00:42:47.597 And they are organized very closely one to each other. 00:42:47.597 --> 00:42:55.377 And the nerve roots that go from the nervous system to the arm leave the root, 00:42:55.497 --> 00:42:59.817 leave the central nervous system of the arm every 100 micrometer. 00:43:00.277 --> 00:43:11.637 So there is a very, very refined innervation of the muscle structure by the neural system. 00:43:12.537 --> 00:43:20.477 But what's also interesting is when we study the properties of the neuromuscular connection, 00:43:20.897 --> 00:43:27.997 we find that this connection is unlikely in all other invertebrates. 00:43:28.097 --> 00:43:30.417 It doesn't have any short-term plasticity. 00:43:30.797 --> 00:43:36.297 So it seems more that the neural activity actually determines I mean, 00:43:36.317 --> 00:43:40.537 in a more or less linear way, what will be the motor action? 00:43:40.897 --> 00:43:46.077 And this fit, what we find is that octopus probably use a feed-forward program 00:43:46.077 --> 00:43:49.937 to activate this kind of, for example, the reaching movement. 00:43:50.397 --> 00:43:55.297 Okay, but then in the case of reaching, do these motor neurons have any kind 00:43:55.297 --> 00:43:56.277 of spontaneous activity? 00:43:56.717 --> 00:44:02.037 Or they must be driven by, let's say, a command neuron that sits at the base of the arm? 00:44:03.860 --> 00:44:11.360 I think when, probably these motor neurons also are active during local movement of the arm. 00:44:11.460 --> 00:44:18.680 There is searching, there is bending, there is a lot of movement that goes on in the amputated arm. 00:44:19.140 --> 00:44:25.440 So this kind of movements also are controlled by the motor neuron of the arm. 00:44:25.700 --> 00:44:30.640 But then I assume assumes that this is coordinated by a local circuit, 00:44:30.900 --> 00:44:35.400 which is embedded in the local ganglia. 00:44:35.700 --> 00:44:43.740 Each ganglia is located next to one of the 300 circles that are running along the arm. 00:44:44.100 --> 00:44:51.520 When a central command is coming through the axonal track, which runs above the ganglia structure, 00:44:51.940 --> 00:45:01.040 it's probably activate all of the motor neurons which are needed to produce 00:45:01.040 --> 00:45:04.040 this brain directed movement. 00:45:04.480 --> 00:45:08.660 So the central brain accents cruise all the way through the arm to the end? Yeah. 00:45:08.840 --> 00:45:19.100 Okay. So there is a good radiation, but I think there is a lot of… for example, one of the possibility, 00:45:19.520 --> 00:45:26.820 and I think one student asked this question during my talk, is how the octopus 00:45:26.820 --> 00:45:30.600 generates this band at different locations along the arm. 00:45:30.740 --> 00:45:35.560 So we had the idea that what might exist in this system is a labeled line, 00:45:35.720 --> 00:45:39.680 where neurons from the brain are going to a specific site. 00:45:40.500 --> 00:45:46.940 Along the arm, and the octopus determines where, not only to activate the movement, but also where. 00:45:46.940 --> 00:45:52.980 But we didn't find yet any indication for such label line theory. 00:45:53.140 --> 00:45:55.900 But that's for the fetching behavior, right? 00:45:55.940 --> 00:46:02.060 So now, if we just look at the reaching… No, this is for the reaching, actually. Okay. 00:46:02.920 --> 00:46:07.440 What I'm speaking about. Okay. In the fetching movement, we are less…, 00:46:10.300 --> 00:46:15.180 Let's say our ideas are not that concrete because we don't know exactly what's 00:46:15.180 --> 00:46:18.960 going on. So let's wait for, let's first figure out the reaching. 00:46:20.080 --> 00:46:26.300 But now a typical thing, at least as a non-expert, you see in these octopus 00:46:26.300 --> 00:46:31.620 movies, also the ones you showed, is sort of this wavy wiggling of the arms. 00:46:31.760 --> 00:46:37.060 So that would suggest that there is also some sort of pattern generator behind that. 00:46:37.220 --> 00:46:41.860 So do these motor neurons in the arm have pattern generator-like properties? Yes. 00:46:45.910 --> 00:46:54.950 I think pattern generator is a valid term to use in this case, 00:46:55.250 --> 00:47:03.190 but I'm not sure, for example, I don't think that it's based on rhythmical pattern generating. 00:47:03.690 --> 00:47:07.970 So you can generate patterns that will induce, for example, arm reaching. 00:47:08.790 --> 00:47:13.670 So this is pattern, generating patterns which is producing the behavior. 00:47:13.670 --> 00:47:19.910 But it's not in the general sense when we speak on central pattern generator, 00:47:20.410 --> 00:47:29.230 where we create a rhythmical movement mainly to control locomotion and coordination between arms. 00:47:30.270 --> 00:47:36.410 This, I think it's less likely, but… So it's more like a variable, 00:47:36.590 --> 00:47:38.070 a more variable pattern generator. 00:47:38.070 --> 00:47:42.850 But are you saying it's maybe not so dependent on single cells and more dependent 00:47:42.850 --> 00:47:45.530 on networks of cells? Is that really the implication? 00:47:45.910 --> 00:47:50.490 Yeah, I think it's very dependent on network connection in the arm. 00:47:51.230 --> 00:47:56.110 But now, what you talked to earlier, which is important here, 00:47:56.230 --> 00:48:00.890 is that, okay, when we talk about reaching, we sort of have a wave of stiffening 00:48:00.890 --> 00:48:01.930 running through this arm. 00:48:01.930 --> 00:48:06.790 Arm, if we now go to a next level of behavior, which is more complex, 00:48:06.870 --> 00:48:13.610 which is fetching, what you showed is if an object touches the arm at some point, 00:48:13.770 --> 00:48:18.850 this leads to, and it wants to now fetch this object to bring it to the mouth, 00:48:18.930 --> 00:48:21.110 or however you call that in the Octopus. 00:48:22.610 --> 00:48:27.990 Now, you see a very specific reconfiguration of the arm. Right. 00:48:28.190 --> 00:48:31.470 That it creates even virtual joints in the arm. 00:48:31.930 --> 00:48:40.190 So, how does that work? So, we correlate this behavior with a recording, EMG recording. 00:48:40.450 --> 00:48:44.050 It's a very complex behavior, but we managed to do it. 00:48:44.350 --> 00:48:52.430 And what we discovered that probably the touching of the food in one of the 00:48:52.430 --> 00:48:58.050 sacchar activate a two-wave of propagation of muscle contraction, 00:48:58.050 --> 00:49:06.550 One which is coming from the base of the arm and one which goes from the more 00:49:06.550 --> 00:49:13.890 or less place where the arm touches the food and they are propagating in the 00:49:13.890 --> 00:49:17.110 same more or less the same speed one toward the other. 00:49:18.364 --> 00:49:23.844 And in such a form that where the point where they are colliding, 00:49:24.024 --> 00:49:31.004 this will set the site where the virtual elbow, if you like, would be created. 00:49:31.004 --> 00:49:39.464 And then in a kind of motor programs that we don't understand yet, 00:49:39.664 --> 00:49:46.524 there is a rotation of these elbows that brings the food to the mouse exactly 00:49:46.524 --> 00:49:51.764 as we do when we take something with our hand and bring it to the mouse. 00:49:51.764 --> 00:49:54.784 But this configuration, reconfiguration looks very complex, right? 00:49:54.804 --> 00:49:58.584 Because it means I have to stiffen the part that becomes a segment. 00:49:58.904 --> 00:50:05.384 Yeah. I have to then release a small part that becomes my virtual elbow. 00:50:05.664 --> 00:50:08.944 Yeah. However, I also have to give that a directionality. Yeah. 00:50:09.044 --> 00:50:13.724 It cannot be, let's say, flexible in all directions. Yeah. It's a constrained flexibility. 00:50:14.144 --> 00:50:19.104 Yeah. So how is that done? No, the arm has some structure that goes from the 00:50:19.104 --> 00:50:20.424 dorsal to the ventral part. 00:50:20.424 --> 00:50:26.504 So, you can imagine that all movements are done in the same planarity, 00:50:26.664 --> 00:50:30.344 where the soccer is pointing downward. 00:50:32.504 --> 00:50:36.604 So maybe, you know, that such a bend in the arm, 00:50:36.784 --> 00:50:41.884 which serves as the elbow, and we don't know yet, and this is one of the experiments 00:50:41.884 --> 00:50:46.404 that we would like to do, if simply two-way, because of the structure, 00:50:46.504 --> 00:50:47.644 of the muscular structure, 00:50:47.844 --> 00:50:52.884 it will be enough that two waves of activation will collide with each other 00:50:52.884 --> 00:50:55.544 due to the structure of the muscular system, 00:50:56.452 --> 00:51:00.372 a band, a rotation will be created at this point. 00:51:00.792 --> 00:51:10.932 Otherwise, it may need a more specific activation of dorsal versus ventral part of the musculature. 00:51:11.212 --> 00:51:14.712 But why would the collision of these two waves give me a joint? 00:51:14.952 --> 00:51:18.292 I mean, then you would expect that dependent on the width of your wave. 00:51:19.172 --> 00:51:25.172 Your joint would be a variable size. size, and also that you won't have such 00:51:25.172 --> 00:51:26.772 a very discrete transition. 00:51:27.112 --> 00:51:30.992 Yeah. Well, if you look at the behavior, it seems very well circumscribed where 00:51:30.992 --> 00:51:33.932 you insert that joint, no? Yeah, I think you're right. 00:51:34.292 --> 00:51:40.272 And therefore, I think the only way is to test it by an experiment to see if 00:51:40.272 --> 00:51:45.652 first, maybe it's created by two waves of muscle activation. 00:51:45.752 --> 00:51:51.192 So what we have to do is to stimulate the arm from two sides and see if we can 00:51:51.192 --> 00:52:00.072 control controlled the point where the bend will be initiated, or it won't happen. 00:52:00.492 --> 00:52:08.612 And then we may look for a mechanism whereby more specific activation of the muscle, 00:52:08.752 --> 00:52:14.912 meaning that the dorsal muscle will stiffen while the ventral part will shorten 00:52:14.912 --> 00:52:17.952 in order to create this bend. 00:52:17.952 --> 00:52:24.732 But what you also showed is that dependent on the distance from the item, 00:52:24.852 --> 00:52:29.332 from the stimulus that touches the arm to the base of the arm, 00:52:29.372 --> 00:52:30.232 dependent on the distance, 00:52:30.412 --> 00:52:34.672 the length of the segments will vary. This is one thing you showed. 00:52:35.172 --> 00:52:41.232 But then is the number of virtual joints I generate always the same? Like I think it's two. 00:52:41.652 --> 00:52:46.812 In your examples, it was always two. Two, yes, with one distal one, 00:52:47.012 --> 00:52:51.812 which serves as a hand, but the two are exactly the same. 00:52:52.012 --> 00:53:00.372 And this virtual segment are created in accordance with the site. 00:53:01.773 --> 00:53:08.593 Where the foot is was taken so this is a dynamical uh uh way of constructing an an elbow, 00:53:09.213 --> 00:53:16.613 in accordance with with what uh with what uh with where the food is uh has been 00:53:16.613 --> 00:53:22.993 uh uh catched and and this is of course a dynamical structure completely different, 00:53:23.873 --> 00:53:28.073 from that's already important no because it means it will never generate three 00:53:28.073 --> 00:53:36.393 joints or one joint No, it's dictated by a very specific motor program, this structure. 00:53:36.693 --> 00:53:42.433 But does it also already tell you some critical properties of the wave-like 00:53:42.433 --> 00:53:44.313 response that you depend on? 00:53:45.133 --> 00:53:49.813 Because that means this wave has a certain length, a certain boundary on its length. 00:53:49.813 --> 00:53:55.553 It cannot extend beyond, let's say, what the segment length dictates, 00:53:55.573 --> 00:54:01.373 and it can never get shorter than that the interference pattern gives rise to more than two joints. 00:54:03.373 --> 00:54:06.853 So doesn't this wave-like response that you built your argument on, 00:54:07.053 --> 00:54:12.873 doesn't the number of segments we get and the intersegment distance tell you 00:54:12.873 --> 00:54:18.993 something about the phase of that or the period of that wave? 00:54:22.393 --> 00:54:25.453 Because you talk about two colliding waves that give you joints. 00:54:25.593 --> 00:54:29.193 Yes. So if you already know that these joints must be at some minimum distance, 00:54:29.553 --> 00:54:32.493 it tells you something about the period and the phase of these two waves. 00:54:32.633 --> 00:54:38.553 Yeah, but the time and the period, it depends on what determines them is the 00:54:38.553 --> 00:54:40.053 site where the food was grabbed. 00:54:40.933 --> 00:54:48.553 So the time and the distance is actually the variable which determines the size 00:54:48.553 --> 00:54:50.293 of the the articulated structure. 00:54:50.833 --> 00:54:55.113 And this depended on where the octopus got the target. 00:54:55.293 --> 00:55:02.013 Right. So now we see that actually locally, such an arm already has a lot of capabilities, right? 00:55:02.073 --> 00:55:07.693 In terms of its articulation, controlling these unspecified numbers of degrees of freedom. 00:55:07.733 --> 00:55:13.353 And actually when it has to act, it freezes the degrees of freedom and reduces them into few. Right. 00:55:14.793 --> 00:55:18.533 Maybe, I guess, four, right? Because of the base of the arm. 00:55:18.613 --> 00:55:22.773 I think it's three. Well, I was thinking maybe the wiggly tip might count. I don't know. 00:55:23.413 --> 00:55:25.793 Okay. Yeah, but three, let's say. 00:55:26.673 --> 00:55:31.533 So, this is interesting. Basically, what Octopus is doing with its hydrostat 00:55:31.533 --> 00:55:35.593 is given the contact, it just freezes its degrees of freedom. Right. Right? 00:55:36.433 --> 00:55:39.713 But the point is that with that, it can build multiple configurations, 00:55:39.893 --> 00:55:43.133 which then can solve the task. This is the beauty, because this is also what 00:55:43.133 --> 00:55:50.033 people want to simulate in a flexible robot. Sure. This... 00:55:51.232 --> 00:55:54.472 New special space of controlling the 00:55:54.472 --> 00:55:57.472 structure controlling the the the shape 00:55:57.472 --> 00:56:01.052 shape of the of the robot right reshaping it's 00:56:01.052 --> 00:56:06.972 a very robust mechanism to you to build a flexible robot right yeah i want i 00:56:06.972 --> 00:56:10.312 want to get to that but first i want to understand something else better now 00:56:10.312 --> 00:56:14.992 we have an idea about what arms can do we have an idea about how reflex systems 00:56:14.992 --> 00:56:18.872 can drive this arm for especially reaching. 00:56:19.152 --> 00:56:22.172 And now we talk about those fetching as a reflex-driven response. 00:56:23.032 --> 00:56:27.272 But we also have here this octopus with these huge eyes that are really highly 00:56:27.272 --> 00:56:29.812 developed. The eyes are linked to the central brain. 00:56:30.192 --> 00:56:34.572 And with the eyes, it will detect prey. And then given the prey detection, 00:56:34.832 --> 00:56:40.212 the central brain will decide to reach for that prey and catch it, right? 00:56:40.272 --> 00:56:46.252 So now, how do you see then the central brain interface Interface to the arms 00:56:46.252 --> 00:56:47.752 and the arm control systems. 00:56:48.112 --> 00:56:53.332 You mean in goal direction? In reaching movement. To make it goal directed. Exactly right. 00:56:54.612 --> 00:56:59.972 We didn't study it, but I think what important part of it would be the base of the arm. 00:57:00.352 --> 00:57:06.452 We don't know even the muscular organization, if it has some specific structure or not. 00:57:06.872 --> 00:57:12.252 We know that along the arm, the muscular organization is exactly the same. 00:57:12.252 --> 00:57:16.372 It's very similar, despite this tapering toward the end. 00:57:16.872 --> 00:57:24.012 So, we assume that there is some system which is directing the base of the arm 00:57:24.012 --> 00:57:26.552 in the direction of the target. 00:57:26.692 --> 00:57:30.332 So, when the arm is stretched, it reaches the target. 00:57:30.852 --> 00:57:37.692 It might be also that the octopus are using feedback control to correct this movement. 00:57:37.692 --> 00:57:44.492 But in some experiments that we did where we trained the octopus to reach to 00:57:44.492 --> 00:57:49.332 a target, and after the arms start to move, we move the target. 00:57:50.890 --> 00:57:53.990 We see that the movement continues as a ballistic behavior. 00:57:54.830 --> 00:57:59.930 This means that it's really a feed-forward kind of movement that the octopus 00:57:59.930 --> 00:58:04.070 cannot readjust it after it has been initiated. 00:58:04.510 --> 00:58:08.950 But maybe also because it moves in a medium, it would be really difficult to 00:58:08.950 --> 00:58:10.130 control it differently, right? 00:58:10.350 --> 00:58:14.150 Yeah. No, but what is nice, because the octopus is so fast learning, 00:58:15.090 --> 00:58:19.210 that it's very difficult to do this experiment because it very fastly understands 00:58:19.210 --> 00:58:23.150 that the movement is going to be moved. 00:58:23.510 --> 00:58:28.910 So it takes it into account when you start the movement and can extend its arm 00:58:28.910 --> 00:58:34.870 to where it knows or assumes that the target will be ended. 00:58:35.250 --> 00:58:38.650 So how accurate is it then in these goal-oriented reaching movements? 00:58:38.970 --> 00:58:44.890 It's not very accurate in the reaching. But you have to remember that the arm is very flexible. 00:58:44.890 --> 00:58:53.670 So even if it reaches the target close enough, we can do then a wiggle or something 00:58:53.670 --> 00:58:58.190 and to get the target by moving it a little bit. 00:58:58.190 --> 00:59:02.970 Okay, so the central brain just has to do a pretty rough target setting. 00:59:03.130 --> 00:59:04.770 Yeah. It doesn't need to be very precise. 00:59:05.110 --> 00:59:07.790 Yes. So that would be with an accuracy of centimeters? 00:59:08.790 --> 00:59:11.670 Yes, I think a few centimeters. Okay. 00:59:11.910 --> 00:59:18.930 So you mentioned also when we looked at octopus motor control, 00:59:19.750 --> 00:59:22.950 that it is also an example of what people call morphological computation, 00:59:23.290 --> 00:59:28.990 for how properties of the body itself contribute to solving the control problem. 00:59:29.290 --> 00:59:31.650 So how do you see that link exactly? 00:59:32.050 --> 00:59:36.610 I think the examples that we see for this kind of computational control is really 00:59:36.610 --> 00:59:41.710 what we just spoke about, and this is the fetching movement. Thank you for watching! 00:59:42.437 --> 00:59:49.137 So I think that the idea is that the site of the elbow is controlled by propagating 00:59:49.137 --> 00:59:51.217 wave on the structure itself. 00:59:51.717 --> 00:59:56.977 And this is what the colliding point is determined the site of the elbow. 00:59:57.537 --> 01:00:03.837 It's a sort of computational, which depends on the morphology of the structure. 01:00:04.437 --> 01:00:08.297 But wait, is that fair to say? Because you could also argue it's essentially 01:00:08.297 --> 01:00:10.757 a neural process that gives you your wave. 01:00:10.757 --> 01:00:13.677 And it's it's it's interaction between the 01:00:13.677 --> 01:00:16.697 neural dynamics right let's say target induced 01:00:16.697 --> 01:00:22.297 waves and base induced waves that sets up the muscular response right and that 01:00:22.297 --> 01:00:27.017 then gives you the this is completely completely true but taking the advantage 01:00:27.017 --> 01:00:33.037 that the nervous system is in parallel with the physical structure you can use 01:00:33.037 --> 01:00:36.537 the propagation of the activity in the nervous system, 01:00:36.957 --> 01:00:45.137 which is parallel to the physical structure of the arm, as a way to compute 01:00:45.137 --> 01:00:47.277 where to build the structure. 01:00:47.517 --> 01:00:52.017 So the structure of the arm is an important component. 01:00:52.237 --> 01:00:56.057 The morphology of the arm itself, right. But it would place you a little bit 01:00:56.057 --> 01:01:00.877 in a different camp than the more extreme view that some people have expressed, 01:01:01.137 --> 01:01:06.157 that in some sense it can be pure morphology, or only the body that gives you 01:01:06.157 --> 01:01:12.637 an adaptive behavior in your proposed it would still depend on nervous system intervention. 01:01:12.977 --> 01:01:16.977 Yeah. Right? So in that sense it's not like an extreme... Yeah, but... 01:01:17.817 --> 01:01:23.097 So for example, if you want maybe the sucker of the arm is built... 01:01:23.817 --> 01:01:33.357 It can work without a sensory signal. It can, you know, attach to a surface by a simple physical... 01:01:36.696 --> 01:01:41.076 Vacuum mechanism which doesn't need any. 01:01:43.496 --> 01:01:52.376 Control. And actually what seems that the octopus have a special mechanism to 01:01:52.376 --> 01:01:55.436 release the sucker instead of attaching. 01:01:55.676 --> 01:02:02.716 Maybe attaching is occurring spontaneously but releasing the structure is more... 01:02:03.316 --> 01:02:08.696 Okay, yeah, that's a good example, really, where morphology is directly implementing a function. 01:02:08.776 --> 01:02:11.816 I would agree with you. But you were also mentioning, for instance, 01:02:11.836 --> 01:02:15.056 Rod Brooks saying that the best robot has no control. Yeah. 01:02:15.616 --> 01:02:21.456 I'm not sure the octopus would then be such a great robot if this is our definition. 01:02:23.076 --> 01:02:34.056 There's still control. Yeah. Yeah, but I think that the flexible arm and that 01:02:34.056 --> 01:02:38.336 is equipped, it's very important. 01:02:38.496 --> 01:02:42.856 The sacchar is a very important part of this structure. 01:02:43.216 --> 01:02:49.216 If there were no sacchar distributed along the arm, the behavior would have 01:02:49.216 --> 01:02:54.256 been completely different. So, because you can imagine that now the sacral fingers 01:02:54.256 --> 01:02:56.976 distributed all along the arm. 01:02:57.116 --> 01:03:07.156 And this allow using such flexible motor program to generate the behavior. 01:03:09.462 --> 01:03:14.302 I think in the Woodley-Brooke idea, building this kind of arm, 01:03:14.462 --> 01:03:19.442 which is flexible, but including many types of passive soccer, 01:03:19.742 --> 01:03:24.422 is a good idea to start in building a flexible robot. 01:03:24.582 --> 01:03:31.862 Right. And put the control on these physical capabilities of the arm. 01:03:32.862 --> 01:03:36.682 Right. But it's interesting that often people don't put their money where their mouth is, right? 01:03:36.722 --> 01:03:41.322 Because with Rod Brooks, for instance, he is actually running a company selling 01:03:41.322 --> 01:03:45.882 robots now, Baxter, a configurable industrial robot for fine manipulation. 01:03:46.342 --> 01:03:51.482 And it definitely has control structures in it. And it actually uses very little 01:03:51.482 --> 01:03:54.242 of morphological computation to be a successful product. 01:03:54.422 --> 01:04:00.082 So it would be nice when people live up to their own sermons in that respect, 01:04:00.422 --> 01:04:07.222 right? So, Benny... But I think it's a good constraint in simplifying the control. 01:04:07.562 --> 01:04:15.782 I don't think it can replace control, but it may make control much simpler. 01:04:16.082 --> 01:04:20.302 Absolutely. I agree with you. This is a good point, yes, absolutely. 01:04:21.802 --> 01:04:25.322 So, Benny, you've been studying the octopus now for how long? 01:04:25.362 --> 01:04:26.482 How many years? 20 years. 01:04:27.362 --> 01:04:32.642 Okay, so So, and you learned a lot about behavior, the nervous system of the 01:04:32.642 --> 01:04:34.782 octopus, so many things we have to discover. 01:04:35.402 --> 01:04:40.362 So, if we want to now take your experience on board in how we started the brain, 01:04:40.462 --> 01:04:41.462 what would be Benny's law? 01:04:44.582 --> 01:04:46.002 I think that…. 01:04:49.738 --> 01:04:56.858 And it's very dangerous to try to understand the brain without the body. 01:04:58.538 --> 01:05:03.338 And when people want to understand how behavior is generated and controlled, 01:05:05.178 --> 01:05:12.958 they can study the brain in isolation just in order to find the properties of 01:05:12.958 --> 01:05:18.218 the component of the central brain. 01:05:18.218 --> 01:05:23.058 But to understand how these properties are organized, 01:05:23.558 --> 01:05:28.418 maybe self-organized, in order to control the behavior, 01:05:28.918 --> 01:05:38.538 you must, part of your study, do when the animal is activating the body and 01:05:38.538 --> 01:05:40.318 better even in behavior. 01:05:40.318 --> 01:05:45.118 And I think the idea of in vivo recording and doing experiments that involve 01:05:45.118 --> 01:05:52.598 monitoring the action of the brain while doing actual behavior is more and more 01:05:52.598 --> 01:05:59.138 common now in our days. Right. Yeah. 01:05:59.838 --> 01:06:04.338 So in some sense, from this embodiment perspective, you also have been looking 01:06:04.338 --> 01:06:06.518 at this emerging field of soft robotics. 01:06:06.518 --> 01:06:13.218 And do you think soft robotics has really taken on board enough of the insights 01:06:13.218 --> 01:06:15.238 and lessons from the study of Octopus yes. 01:06:18.951 --> 01:06:23.611 I think the main problem in soft robotics is the material. 01:06:25.311 --> 01:06:28.231 There is no material like musculoskeletal system. 01:06:28.791 --> 01:06:35.371 So effective, so robust, so high strain. 01:06:35.731 --> 01:06:41.751 And this is what limits the soft robotics at this stage, I think. 01:06:42.171 --> 01:06:45.491 But I think there is a lot of progression in this area. 01:06:45.491 --> 01:06:54.611 At this point, what people do is that they combine different ideas taken from 01:06:54.611 --> 01:06:57.671 the octopus, for example. 01:06:57.971 --> 01:07:05.611 So it's not only constant volume constraint, but it can be the controlling of 01:07:05.611 --> 01:07:12.651 stiffness, it can be particle jamming, other ideas about that. 01:07:12.751 --> 01:07:20.991 If you think about it, it may come from biology and be implemented in the system. 01:07:21.631 --> 01:07:25.591 I think also from the control point of view, 01:07:25.731 --> 01:07:30.651 the idea of distributing the control between the central and peripheral and 01:07:30.651 --> 01:07:34.791 to leave much of the control and even more complex part of it, 01:07:34.871 --> 01:07:40.711 like even learning a memory, learning at the level of the arm, 01:07:40.871 --> 01:07:47.371 are ideas that comes from such studies that we are doing in the octopus. 01:07:47.791 --> 01:07:51.351 Right. So then, last question. Five years from now, we're going to come visit 01:07:51.351 --> 01:07:57.291 you in Jerusalem, and we're going to check whether a prediction you make today 01:07:57.291 --> 01:07:59.011 has actually been verified or not. 01:07:59.011 --> 01:08:04.291 So, what's the most important prediction or hypothesis you would like to see 01:08:04.291 --> 01:08:06.951 verified in that timeframe of five years? 01:08:09.477 --> 01:08:15.017 So, as I mentioned, we have two projects. 01:08:15.277 --> 01:08:19.457 Now we are more into the learning memory mechanism. 01:08:20.077 --> 01:08:25.957 And we are studying what is the mechanism of learning memory in the octopus. 01:08:25.957 --> 01:08:35.377 Octopus, and we may discover a new solution to the problem of how the nervous 01:08:35.377 --> 01:08:38.997 system stores information. 01:08:40.637 --> 01:08:44.757 And I believe that there are many ways, and the octopus is a very good example, 01:08:45.117 --> 01:08:48.817 there are many independent ways to build a complex brain. train. 01:08:49.957 --> 01:08:57.397 But at the end, they will point to what is the universal importance in networks 01:08:57.397 --> 01:09:00.037 that can mediate learning and memory. 01:09:01.017 --> 01:09:07.517 And I hope that we will learn enough on the mechanism of motor control of the 01:09:07.517 --> 01:09:15.157 octopus that it will be really more feasible to implement in the soft robotic. 01:09:16.357 --> 01:09:24.617 Hopefully, while we are doing our biological research, the search into attenuator 01:09:24.617 --> 01:09:29.097 material will progress as well. Right. 01:09:29.277 --> 01:09:31.737 Okay. Benny Hochman, thank you very much for this conversation. 01:09:32.137 --> 01:09:34.357 Thank you. Hochner. Hochner, sorry. 01:09:37.277 --> 01:09:42.917 The CSN podcast was produced by the Convergent Science Network of Biometrics 01:09:42.917 --> 01:09:49.297 and Biohybrid Systems, a project funded by the European 7th Research Framework Program. 01:09:50.857 --> 01:09:56.177 For more interviews, recorded lectures, or upcoming conferences in the field 01:09:56.177 --> 01:10:02.417 of biometrics and biohybrid systems, go to csnnetwork.eu. 01:10:03.120 --> 01:10:10.960 Music.