This is the Convergent Science Network podcast. Leading researchers in the domain
of neuroscience, brain theory and technology are interviewed by Paul Verschure and Tony Prescott.
Here's Paul Verschure with the Convergent Science Network podcast together with
my colleague Tony Prescott.
And today we're having a conversation with Giacomo Rizzolatti,
who gave a fantastic talk this morning in our 10th edition of our summer school,
Barcelona Cognition, Brain, and Technology.
So Giacomo, you were building on your long tradition of work on the mirror neuron
system, and the outlook of your talk was to move from a mirror neuron to the
mirror brain. This is really now the ambition, right?
To show the more general relevance of this general idea.
But maybe to really understand the significance of it, it would be very useful
to really try to understand in detail what we exactly mean with a mirror neuron.
So what's the core behavior or what's the core base of evidence that makes you
speak of a mirror neuron?
Well, the basic evidence is still the old one, that we have neurons in the motor
system which fire when the monkey grasps an object, and when the monkey observes
another people doing it.
Note that it should be the action with a similar goal. It's not simply visual motor transformation.
It's exactly you see something and you do something similar. So that's the basis.
Subsequently, in humans, it's very difficult to record single neurons,
but we have a lot of data with fMRI and now more recently with gamma-rhythm
that this mechanism is really diffusive.
It's not only in the premotor cortex.
That's why we think that we have to enlarge the concept. Okay.
So let's first look at the work in the macaque monkey where the core ideas were
sort of fleshed out initially.
So how general is this effect?
So you say, okay, it must be related to the same goal. So that means if I observe
another agent or that's sort of morphologically comparable to myself,
perform a certain task or a certain goal, let's say eat a peanut,
or I perform this action myself being the macaque monkey in the monkey chair.
Dual-fied neurons in specific areas of its cortex that respond to both that
observation of the goal-directed action and the execution of the goal-directed action.
What's the minimum set of neurons that are involved in that?
What do you mean by minimal? Where we know is the parietal lobe,
two areas in parietal lobe, area AAP and PFG.
We know about area F5, and recently it has been discovered in London by Roger
Lemon that corticospinal tract has many neurons with mirror properties,
both starting from area F5, but also from primary motor cords.
So that means we have a parietal premotor motor kind of circuit that would sustain.
I would say there is a pattern, a schema, using the word of Michael Arpib.
Right. There is a motor schema, which is rather diffused. It's four,
five centers which collaborate.
Altogether, they create a motor schema in my brain, and I see the same motor
schema in your brain. Right. I understand it.
But now, so we have sort of parietal premotor motor circuit.
But that's still fairly broad. So how many neurons within that circuit would you really say are now,
identifiable as mirror neurons and how many of how big a fraction will be doing other things?
I don't know. Now we have a method in which we can maybe learn more because
in the past we have a single neuron and it was very hard to make a sample.
But now the technology allows you to record from several points in the same
electrode and to put many electrodes in parallel in the cortex.
So for example, my colleague Bonini, a young assistant professor,
now is recording from many, many neurons.
So we can give you in short time data at the moment.
What's your expectation though? What do you expect? Well, in layer three,
I think it's a large number of neurons have this property. If you go down, they are motor.
So I think there is a laminar distribution. Unfortunately, in the monkey,
is very difficult to record it because part of a five it's laying,
near the sulcus so if you go down with the electrode you change continuously
columns you cannot do a columnar work so easily ok so now we have this basic
circuit we know neurons expecting layer 3 participate in that but how did you really,
stumble into the existence of these neurons was it like a chance discovery or
you were really looking for them you knew where to look and you found them.
No, it was not a priori, how we can think such a strange thing a priori.
So what we are doing, we were studying the motor system, but with a kind of ethological approach.
So looking if there are visual responses, if the visual responses are related
to food or to other objects and so on.
And we first discovered neurons which fire in relation to the presentation of object.
And that was something that we did in collaboration with a Japanese group.
And now these neurons are called canonical neurons.
What they do is just a transformation of object into action.
The surprise was that some of these neurons do not want the object, want the action.
And that's how we discover it. But then what was the specific paradigm?
What was the very first experiment in which a penny dropped,
if you want, that you said, okay, we found it, this is it?
I must say that we observed this phenomenon several times. And I was the guy
who tried to say, be calm.
It could be an artifact because my young colleague said, we have to publish,
send to nature, send to science.
I said, well, let's wait a bit.
And then eventually it appeared in Brain and it had been cited 5,000 times.
But how many experiments does it take for you to be convinced? Three years.
Because we have to record EMG. You know, we are in the motor system.
We are not so obsessive like Roger Lemmon who recorded 25 muscles.
But anyway, we recorded the most important to be sure there is no artifact due to movements. Right.
Now, in the response of these neurons, are there response patterns?
We look at peristimulus histograms or rates of firing. But is there anything
special or unique about the response patterns of these neurons?
Or you can just look at the rate and that's it?
At the beginning, we tried to find something, but at least with the methods
that we have at the time, we haven't found anything.
It seems the intensity most frequently is higher, stronger for action than for observation.
I think when we came on to start talking about the function of the mirror neurons,
you gave a quote, I think, from Mark Jennerod, and that was that a mere visual
perception without involvement of the motor system would only provide a description
of the visible aspects of the movement of the agent,
but it would not give precise information about the intrinsic components of
the observed action, which are critical for understanding.
So what I take from that is that you see the mirror neuron as the path for how
our brains understand what other people are doing.
Now you're touching a very dangerous thing.
Because when you said understanding, you say, what do you mean?
Well, it was a good quote, yeah. No, it's correct. You are correct.
It's me that the people say to me, why you don't use recognizing or why you
don't use another words?
But I think with understanding, we imply that you not only recognize the action,
but you can generalize to say that's grasping.
It's not grasping with the hand or grasping with... It's just grasping.
Instead, the visual area cannot generalize because when you see,
for example, a hand with glass, you cannot generalize to the other hand because it's a visual area.
They just say, this hand and this glass.
So generalization is something which really, I think, requires the motor system.
That's why I prefer understanding in the sense that you can use it for many
purposes, not just describe what is going on in that moment.
And people have taken this idea and they've kind of flown with it to sort of
imagine simulation engines inside our heads heads,
that are able to imagine actions and create them without performing them,
and also when you see a person, you can recreate that inside your head.
How far do you want to push it in that direction?
Well, I like very much the speculation of the philosopher Goldman, Olving Goldman.
He decided to split in the lower level, a mirroring, and a higher level mirroring.
Lower mirroring is what I described.
Higher mirroring is one you cannot understand immediately, and then you try
cognitively to replicate the data, so you make an effort from yourself, from internal.
Instead, mirror neurons tell you immediately what's going on.
But I can be unable to understand, then I think, what I will do in this occasion?
What is the point of view if I move my head?
That's what he called higher-order mirroring. And how would that affect?
So if you observe a novel action that you haven't seen before,
how would your mirror neurons operate in that context?
Would they try and generalize from something they have seen?
I don't know about single action. We did an experiment in which there is a pattern
of action, like make a chord on the guitar.
So what happens is that you learn it by cutting, for example,
these two fingers, then two of these fingers, and then you reorganize.
Reorganization is not made by mirror neurons, but by the prefrontal lobe.
The prefrontal lobe is the head of orchestra who put together this elementary
movement that you took away from the mirror system and organize the new chord, the new movement.
I suppose also the new movement, but I have no data about sequences.
That's a good metaphor because both Paul and I are guitar players.
But Tony is a lot better than me. My mirror neuron system is now active with
the thought of us learning chords from each other.
There yeah so they but what i get you're saying
is that i might not know the chord that you're showing me but
i know how to put my fingers in each of those places and so
i can build up the representation of the whole chord from
these components which i recognize yeah but so okay but now there's there's
a little challenge here i believe and i don't mean this in sort of a metaphysical
way but we could because as you said earlier and also the examples you showed
us there must be a matching of the goals of the act, right?
You make a sort of movement to, let's say, obtain a peanut, right? So there's a goal.
But there's a potential circularity now, because how can the observing monkey,
in this case, from whom you're measuring, how can you be certain about the goal of that other agent?
So I could also say, does it really need to be goal, or is it,
let's say, the directedness of the action itself?
Like there's an action, the action is oriented towards an object,
and it's that relationship that has to match, irrespective of what the goal
might be of the other agent.
Or at best, I just infer the goal of the agent from this perception-action relationship.
So how am I going to bring in goal here? Do we really need it?
Well, I think I infer, but remember that motor neurons in premotor cortex, they code already goal.
So if you admit that one neuron A, fire, give a certain information,
It doesn't matter if it's my will which moves the hand, or when I observe him, I move.
So the output will be the same because the connections are the same.
And so in this moment, the action is recognized.
But if I may, there is one point that you may be marginally touching.
There is a contradiction because to imitation, according to ethologists,
is to repeat exactly the movement.
To reach the goal, I can use different.
That's a point which has been raised by Chibra, and he was right because there is.
A tension between the two concepts.
You could not have both. And I think monkey have only the capacity to reach the goal.
Human have an additional system for imitation, which you can replicate exactly the movement.
That's done in the humans, of course, of the finger in the guitar or play piano or all this stuff.
But in that sense, do you believe that the internal state of the monkey will
then modulate the response of the mirror.
Let's imagine we talk about objects and actions that are ambiguous.
There's an object I can use in two ways, but depending on whether I'm thirsty
or hungry, I would go for pattern A or B.
So if the monkey is hungry, then its mirror neuron system will bias towards
the hunger interpretation.
And if it's thirsty, we go to the thirst interpretation. Is this internal motivational
state now defining the mirror and urn response, or would you think that the
mirror and urn response would be independent of that?
No, I suppose it should be a modulation, but I don't have empirical data to answer you.
There is a group in Germany who noticed that the intensity of response is stronger
if the object that you act upon has significance for the monkey.
So it's much stronger if it's cheap food than if there is something which is
not interesting for many.
So in a sense, there is something in this sense, but it's not really an experiment done.
You described an experiment which cast some light on this question of the motivated
nature of the system, which was where you compared humans with monkeys and with dogs.
And if we observe a human eating or a monkey eating a banana or a dog eating,
in each case, and it was quite remarkable, you said that there's a mirror neuron
response even for the dog eating.
Yeah. And you compared that with the situation where we're looking at communication,
where you're looking at a human speaker.
I think you were looking at a monkey making lip movements, and then you were
looking at the dog barking.
And in the case of the dog barking, there was no mirror neuron response.
So the mirror neuron generalizes to dogs eating, but not to dogs barking.
Now, this is interesting, but I didn't quite grasp why you think that is.
What's the core explanation?
It depends on what you have inside yourself.
You have some motor programs, which include biting, and the dog has the same motor program, biting.
We have a program for talking.
Dog have a program for barking. But we don't have a program for barking.
So barking, we have to understand in a different way.
But I can imagine barking and making kind of barking sounds.
Metaphorically, actually, we even use this. Of course. I often tell Tony, stop barking at me.
Tony says, stop wagging your tail. I can also bark here.
I know what me is supposed to talk about.
But actually, we can push it a bit further. So do you believe that,
imagine it would not be a dog, but it would be, let's say, an animal with whom
we don't share any sort of morphology, like we take a whale, okay?
Do you think that we need some sort of morphological matching with that other organism or not?
At least the dog has still, let's say, the kind of face we might recognize.
We have to put sort of anthropomorphized dogs also very often.
So is that an important modulator of this? If I have a non-anthropomorphic agent
who would express these kinds of actions, would it then break down?
Well, I think the basic should be to have a motor program. Of course,
the motor program of biting is present also in other animals,
like in rodents, but morphologically it's a bit different.
Another difference between those two situations is that in the eating,
you have a cue, which is the food item, which maybe helps your mirror system
see the dog biting as being like biting, whereas in the bark,
there's nothing to cue that that's what the action is.
I wonder if the mirror system activation is a product of this mixture of the
visual cues and sort of recognizing the motivation. That's a very good point
because the mirror neuron is really goal-directed.
But goal must be in animal life, in the monkey life, it's not an abstract gesture.
So goal is an object, it's dark.
So maybe really you're right that the food helped it.
We have to do another experiment. Okay.
But in that sense, you could also argue it's about the invariances,
in the environment and the environment you share with other agents.
So for instance, imagine I would live together with whales.
I might be able to develop mirror and learn responses with whales or them with
me if I learn how to catch herring, let's say.
Would you believe that indeed it's the statistics of the interaction with the
environment and also the consistency of our behaviors as compared to other agents
that would allow you to then learn those mirror responses in this context?
No, I prefer to think that we must share the same motor program from evolution.
As a matter of fact, the problem with rodents, we have such a difficulty to
find mirror neurons in rodents, but because we have no communication with rodents,
rodents look at nothing, go away, that's finished.
With the monkeys, much easier. So, should you believe that the mirror neuron
system is learned on top of behavioral priors?
Or is it a morphological prior because we have hands? Well, that's even more complicated.
No, I think the basis should be to have a motor program. And the motor program improves, increases.
I mean, I play tennis and Federer plays tennis. I think there is a big difference.
So, why? Why? Because he learned much more than me.
Maybe he has more talent and so on. But anyway, of course, all of us can play
tennis after three lectures.
But then it's a big difference between who has been in practice and who has not.
Okay, but now this idea that it's all predicated on shared motor programs,
what's the data you have to support that?
Well, first, because we discovered it in the motor cortex.
Second, because before claiming that also, for example, disgust,
it's mirror neurons, because when you stimulate desire, both in monkeys and humans,
you have feeling of disgust, you can reach vomiting if you want.
And so there is a motor program for that, which goes from insula probably to
other subcortical center. and when arrive input from external person.
Are we going to get to those, that data a little bit?
No, I am very happy about this emotional stuff because it's easier to demonstrate.
But this is really an important point because I could also say look,
the brain is geared towards generating action, that's it.
That's whatever it does under all conditions with or without mirror neurons. Right.
So that would mean that That feature of being dependent on a motor program is
nonspecific to the mirror neurons because everything depends on motor programs.
Motor clover is the basis, yeah. That's true. But then the other thing is you
show also from this data from Roger Lemon,
that there appears to be, at least if you look at mirror neurons in the corticospinal
tract, because that's what he documented, right, at the single cell level,
there seems to be some competition between them because actually some mirror
neurons are suppressing their response.
Is that significant to you, the idea that there might be competition across mirror neuron systems?
You know, when he described it, the moment I thought, well, great.
So we have found a system.
That's his idea. The whole group of London has this idea that it blocks.
So when I see you doing something, I have the activity of the mirror neurons,
but I don't repeat your action. So it should be a blocking mechanism.
And maybe this lemon mechanism is part of it, but I don't One thing is the whole
story, because there are some patients with lesion of the frontal lobe and they are unable to stop.
So let's call it imitation behavior or utilization behavior.
So the doctor put the glasses down and the patient take and put on his nose.
So it means that it is a multiple control.
I think the control of Roger Lemmon is the subtle control. When you're uncertain,
do or not do, then stop it.
But the big control is from prefrontal nerve. Okay, fair enough. Yeah, I get it.
And you touched quite briefly on the ability now with imaging techniques to
look more at the temporal structure or processing in these neurons.
What is it that you think we can find out from this temporal profile?
Well, it's difficult to say what, But certainly time is very important because
you know, for example, in the case of tools that we have data,
the people think the tools, you recognize the action together with your hand movement.
Instead, after that, you first recognize somebody is grasping and then you know that it's tool.
I suppose maybe it's some disease. It could be important that your timing is wrong.
I don't know, I never thought how to demonstrate why time is important,
because just the word, you know, we add time to space, seems great,
so I have never thought of a peculiar, particular case in which time should be important.
Well, we've been thinking about time a lot at this school, you know,
and how timing relates to decisions and actions and so on.
So it was interesting for me, and I think it relates maybe also to this goal-directedness,
because if you can see peaks in this profile and match them maybe to some aha moment, you know, I...
And then also, it might be interesting to look at ambiguous situations.
So, if you're looking at the dog biting, does it take longer to see that?
Why do you have to bring up the dog again, Tony?
No, thank you very much. You are right.
Decide the dog. But what he said, I think it's very important,
is that we are very biased still to a kind of low-level motor system and so on.
But the decision-making and so on. In this case, the time will be much more
important than we can give you now as an example.
But maybe you have this actually, this information, because if you measure from
the sort of parietal frontal system and the motor cortex,
you will see responses develop over time as the monkey is responding, right?
So does it show any kind of temporal structuring of that response?
Can we say we see a clear parietal frontal movement of neural activity,
and then maybe we see again some top-down information going back to the parietal area?
Is that a pattern that you would observe? That's something extremely interesting.
But up to now, we just make very naive experiments.
Just they observe an action. It would be interesting if they think about the
intention, why he's doing that to eat.
So we have to render a bit more complicated.
But first, it was the beginning. The second, my co-worker was Georg Bonk,
who is a visual physiologist.
So he stressed that we have to study first vision.
That's what happened. Right. But now, if we anchor it to intention… Yeah,
that's just what I think.
And you could also imagine that you then could have an experimental paradigm
where the intention is actually changed.
There's an ambiguity in the task, and first it appears to be,
okay, I'm going for this object, but then I actually go for that one.
Go for the microphone or for the cup where are you predicting that kind of intentional
processing that happens where is this intention set in the brain.
Well, my intention or others' intention, because... I guess from the mirror
nerve perspective, first your own, and then the other, right?
Well, for my intention, I think it's very important.
It's the presupplementary motor cortex, RAFF, maybe also the cingulate,
but then area on the mesial cortex.
And it's also for...
Well, you touched a good point. because Tillner in London made an experiment
in which he replicated the readiness potential.
Readiness potential appears when you are ready to do something.
And then he asked people to observe another person and they can predict when
they will do the movement.
And they found readiness potential in the middle part of the brain.
They don't know where because that's surface electrode.
But so, it's true. It's true. It will be an experiment.
Sometimes I forget to mention, but it's very good.
Yes, I think, I mean, I'm imagining that you have multiple motor programs which
can be activated when you start observing an action.
And then these are competing to be the best match to what you're observing.
And that you might see that in the temporal evolution of the activity.
And that at some point you say, aha, he's going to bite the banana.
Rather than shove it up his nose.
Right. And so this would be a good way to get at the intention, maybe.
Yeah, well, that's the idea of Friston, that our neurons actually are Bayesian predictors.
But this is the point, how many actions we can predict. So you have to put some limit.
Instead, my view is when I see an action, It's immediately activated the motor
program corresponding, and so I don't need prediction.
But I am very open. I think it's a very clever idea that mirror systems can act as a predictor.
But there's something tricky in the background there, in my opinion,
because if we talk about motor program and motor schema, it gives this idea
of a very discretized action space.
But given our morphology, given our skeletal muscle system, that space and the
goals we can attain, it's basically an infinite space.
Right so so how
do you really see then this mirror neuron system develop
into its response because i cannot either you have to say it's it's a library
i have a huge set of possible motor programs that are linked to possible sensory
states and goals that feed them and i choose from this long list which computationally
is problematic in my opinion right so we have to think about a more
dynamic solution to that motor space encoding.
So how do you think about the motor space encoding in this context?
Well, when we first discovered this property of motor cortex,
I suggested that we have exactly a vocabulary of motor act, but only for the hand.
So if you think in the monkey, there are not so many.
They can grasp like that, grasp like that, push, and so on.
If you increase and think about all the possible movements, I think it's more
difficult for Friston because the system should predict, I don't know, how many actions.
The only solution could be that context already cut some of them,
and so of infinite they become a limited number.
So I think the context is very important in deciding how many actions.
So if I'm here, I'm not going to swim.
I hope. No, this could actually happen, you know.
So you're saying, okay, there are movement primitives at a relatively high level,
like grasp, push, pinch, and so on. This is not such a huge set.
But I'm not worried about their combinatorics, like reach, push, grasp.
That's not my concern. I'm not going to worry about how I link them together,
because within each of them, there's a goal and an action associated, if you want. Right.
It's actually like a triad, right? There's a sensory state, a goal state,
an action state, and this is now my primitive.
And then this is my mirror primitive.
My mirror primitive is grasping. But if you grasp to reach or to place,
I think there are two primitives put together. It's not one.
Okay. And that's how you assemble. Assemble your motor programs, if you want.
Okay, and so the schema would act predicated on these discrete actions,
like reach, grasp, point, whatever.
My schema, but I suppose there are higher order schema for reach to grasp,
reach to put, reach to throw, and so on.
But then how does it scale to Tony's case, who actually can play guitar?
Well, with guitar, the idea, it's not only mine, Ethologists also think that
you somehow split what you observe in elements.
You store this element and then prefrontal cortex put together this element
in a new sequence, which is completely new. You don't know before.
Okay, fine. But the granularity of now the action states might be very different
from the granularity of the goal states.
Because the goal is I want to play that chord, right? At the level of intention,
I want to say I want to play a G major chord.
But in terms of the action space, the granularity seems at a much lower level of resolution.
Because I look at single digits and how I place them. So how would I bring that
together with that goal of playing the G major chord? Right.
Well, at the beginning, somebody has to teach you. At least you have a particular talent for music.
But typically, I think you see the teacher, which is showing you how to put
the finger, and you replicate.
Okay. But also, I think your goal is also to make the sound.
And when you're observing someone else playing the guitar, you would be listening
for the sound and watching their fingers.
But do you see the problem I'm after? Because first we agree there's some sort of triad.
There's a perceptual state, there's a goal state, there's an action state.
The action states are built on primitives.
And then when I try to match that to the idea of playing a chord,
your goal state is to reproduce a sound, right, or to play the label to G major.
But now the way Giacomo described it is I'm going to assemble the chord from
having a mirroring of single digit movement.
Movement so now i have two levels of description and i have to link the lower
level to the higher level so do you then just say okay i just percolate now
that sound of the g major chord down towards a single digit movement so i have
a hierarchy i have a hierarchical mirror encoding if you want,
yeah or is something else going on that means i have sub goals that say this
finger here well i mean people talk about chunking don't they in this situation
so exactly so you assemble the whole g major caught as a chunk.
So you're Giacomo's lawyer now. Well, no, but you've...
He knows how to play guitar. I told you, I'm not very good at it, you know.
Okay, so the other thing in terms of generality, you did this beautiful experiment
where you actually not only used biological effectors, but also robotic effectors
to see, does Does it generalize to tools?
Does it generalize to, let's say, non-human, but maybe still anthropomorphic effectors?
So how general is it? When does it break down?
What kind of effector can I present to the monkey that's, if you want,
at the threshold of still giving me a mirror response?
No, no, no. We have to distinguish now monkey and humans.
We did experiment with Gurbain and people in Leuven teaching the monkey to use
a tool. What happens is that the circuit which is activated is just grasping.
They know how to use the tool, but there is no human.
They are probably the only creature which have in the parietal lobe an area
which is really specific for tool.
So even when the monkey is very fluent in using a rake, nothing happens in the brain.
I don't know where it is raking, but probably it's together with the drastic movement.
But this is counterintuitive, right? Because monkeys can be pretty proficient tool users.
No, not so good. Like sticks? Not so good as we are.
Maybe not so good as we are, but still. I don't need the lawyer here. Let them play guitar.
They do it just in a different way. They play like Jimi Hendrix at the end of
a concert, right? You just smash them.
So you're saying, but then the human specialization for tool use,
you would see as having, let's say, emerged or having differentiated from the
general motor system as a specialization?
I think so, but not because we have learned. I think it's evolutionary.
It's a prior, yeah, right.
Evolutionary, because it's only on the left side. It's not on the right side. Okay.
In the monkey, there is nothing which is so strongly lateralized.
It's like language, I think. Right.
But do you also see that in this human specialization, is the way it innervates
the periphery unique in any way? or the way it's linked to other neural systems
and the way it works down?
I think anatomically, it's very close to the region where you have movement of the fingers.
Although when you use a tool, it's completely different way because your tool is solid stuff.
For example, if you do an experiment, instead of using a rake,
you take your hand and you use as a rake, you have an activity in the area of tools.
So the tool is not considered a tool, but it's considered an instrument.
Right. So, if we now think about language, I know it's a bit of a jump,
okay, but still, we could think also about language in terms of actions.
We have speech acts, we say words, right?
Now, in a conversation, I might make predictions about the things you're going
to say and what your goals are in saying that.
So do you think as much if you have a tool specialization do you also see language
production as a specialization of a mirror neuron like substrate?
Or you see it as completely disconnected?
Well you know with language we wrote some years ago 15 years ago a paper with Michael Arby which we.
Which we claimed that at least Semantic we understand because it derives from gesture.
Mm-hmm And the idea was that imagine grasping so I understand grasping but I
think the word grasping No, the meaning why it's grasping and on something else.
That's true for Semantic, I don't know anything about syntax syntax Syntax,
I prefer not to speak because it's so complicated.
I don't have any model of neurophysiological model on how we can explain the syntax.
So here I am like Chomsky. Okay. Not for us.
So now the last part of your talk, you showed these really exciting results
that you were obtaining looking at humans who had intracranial recordings.
So these were epilepsy patients with implanted electrodes. Why did you move
in that direction because you were doing fMRI, you have the monkey model.
Why was the intracranial patient for you so relevant and important?
Well, I was really a bit disappointed in the last year with fMRI because I think
fMRI at the beginning was extremely precious at the time when it was the beginning in London,
in Montreal and so on.
Every paper was something new. Then I think they feel almost finished.
The people start to think about where is the gambling area?
Where is the area for love of the mother?
It became not science. And I discovered this recording from humans.
I hoped to record also single neurons like they did in Los Angeles,
Isaac Fried. But up to now, I am happy with the gamma-rhythm because gamma-rhythm
is really very close to, it's much easier to manipulate.
So what did you observe in this patient? So what you did, basically you have
these implanted patients, you have many contacts. Yes.
Over 100 per patient, 16 different electrodes.
Of course, you cannot go at arbitrary locations in the brain because it's not
clinically relevant, right? So there are some constraints.
Of course. But then what you did, which I found really, really very exciting,
is you started to sort of map mirror neuron paradigms to these patients, right?
To look at how are these aspects of the sensory motor coupling or the intention
coupling coded in the brains of these patients.
So what are the main principles that you observe there?
Well, there are two streams in this type of experiment.
One is just based on something which is important for clinical purposes but
has never been studied deeply.
An example, pain.
Most of people are convinced that they are center of pain in the cingulate.
Wrong. You can stimulate cingulate, there is never pain.
So what happens in the pain, what happens in the cingulate, it's probably the
fear that something could happen bad.
So you don't feel pain, but you say, I want to go away.
You know, I am distressed.
That's what happened in the cingulate. So that's something that you can learn by stimulation.
The same is true for.
For the insula. We have data from the monkey, but only the neurosurgeon can
demonstrate that really the anterior insula is for disgust.
And then I can construct my theory because otherwise we'll be only monkey on one side, human.
That's one part of it that we are now working very hard because they have many, many data.
Clinicians do it for critical purposes. They stimulate many,
many points in the brain, and they store it.
The only point to send is to take away and to analyze it. The second is to make an experiment.
And up to now, I must confess he's right, our fantasy was not very big because
we just replicate a tool instead will be much more interesting for time to see
decision taking or uncertainty and so on.
So to go a bit higher in the nervous system functions.
So what you focused on was the insula.
You know, we have also to publish. I have young people with me,
so they cannot wait two years, three years, the tower test is finished.
They say, listen, professor, we have insula.
Why we don't publish it right away? That's the truth.
But also in the monkey, and you sort of confirmed in the human,
you saw, okay, the insula is like, A part of insula, only the rostral part of
the insula. Okay, rostral part of insula.
It's like valence encoded relative to ingestive actions. Exactly. Right?
Excellent definition. Humans and mercado. The same in humans and mercado. Okay.
But now, to what extent should I think about that in mirroring terms?
Because I could also say, well, this is just a higher level representation of a very simple...
Emotional triggered disgust circuit
but I'm not mirroring this to the other why
why can we say now in this case that there is a
mirroring component to it because fmri experiment indicated the same voxel are
activated in both cases right so when you have natural stimulus or when you
observe so it is overlap but between this case it's overlap yeah factory driven
disgust and And a visually observed disgust and other.
Real disgust. I don't know about moral disgust because the people claim that
also that's not my field.
Well, that's something else that we can also talk about maybe a little bit later, right?
Because mirror neurons had quite an impact on the field and many people had
the wildest of imaginations what mirror neurons could do. Too much.
Right. So do you feel that that has also maybe impeded a little the progress,
these over-interpretations?
No, not the progress. But, you know, I am sometimes surprised because,
for example, for many years I have been asking, but maybe mirror neurons are only in the monkey.
But they said, but human envisage is never recorded from humans.
And everybody believes it. The simple, complex, hyper-complex neurons are there.
And look at the hippocampus.
The hippocampus is a wonderful work that they did, O'Keeffe and Moselle, in Rhodes.
And nobody asked. I don't know why, but the mirror triggered something that
we are entering into sociology.
Well, maybe we should push back and say maybe there are no play cells in the human brain.
Yes, but you believe it. Sure we do. You do?
Your study sort of showed that some of the insular neurons would respond for
seeing somebody with an expression of disgust.
Others would respond to the smell, a disgusting odorant.
And then a subset of neurons would respond to both.
So it's that subset that you're describing as the mirror cells in that case?
I know only from fMRI that the same voxels. Okay, the voxels.
So I suppose that in voxels there are mirror neurons, but I have never recorded single neurons.
Okay, but there's a part of the insula which you think is particularly… But
at this point, everybody seems to believe that since it's the same voxel,
it should be a population of neurons which are mirror.
Right. But the point is that it's actually in the images that you showed,
it was quite a small and specific area that had these voxels.
And so there's a small area of ventrila which has mirror neurons, is what you're saying.
Or mirror neurons for disgust. Again, since we know only the voxels,
we don't know how many neurons are there.
It seems to be small areas, you're right. And is that small area,
is it the same small area across subjects?
Again, we have only an average. That's a point which we can now study in humans.
The humans, I mean, with stereo-AG, not with fMRI.
But are you now also bringing these paradigms to your intracranial patients,
the disgust experiment you're going to do, or you are doing already?
No, disgust, no. But fortunately, disgust, I mean, they stimulate the insula
because often they are epileptic.
But they don't go, unfortunately, so far anterior.
It's more in the center of the insula, even the posterior part.
So the data on this is very little.
But the people in France, in Lyon, stimulated the insula several times,
and they have disgust. Right.
But it's more fun to do laughter, I think, is the answer.
Exactly. When you could choose disgust or laughter, which would you choose?
That's a good point, because that's what you show, that the cingulate cortex,
would be more specialized for laughter. Only a small part of it.
Yeah, but how should we really interpret that?
This is so confusing to me. Let's say... Why?
Let me tell you. He's a simple man. I can see his getuping. Yeah, exactly.
So the point is that we find these voxels, so rather localized response contrasts,
right, for disgust in humans, or now for laughter.
So that means now I see a laughing face, I'm responding to that,
and what you showed us, which is really fascinating, you show an increased neural
activation in the cingulate cortex.
What worries me about it is that,
It seems to tell us that of all these possible combinations of internal valence
states and behaviors and goals, you get very localized response.
You have some sort of grandmother cells of, let's say, this coupling of affective
states in a social context, right?
The mirroring of affective states and sort of having grandmother cells that encode them.
And what I find annoying about that is that it also pulls away from your earlier
idea that the mirror neurons are actually a circuit property of a parietal frontal
system, right? So how do you bring these two things together?
Well, I think what happens in the cingulate, it receives input from outside
and it sends information down because in order to laugh.
And you see this laughing was very complicated movement of...
So I think there are many output going down, which trigger center in the...
Especially in the periaqueductal gray, and so it determine.
So really that's the master, but then the whole action, it's very complicated, I think, by many center.
It's not going down to hand and to fascia nervosa.
But then there's another circuit on top of that, that fMRI doesn't allow you
to visualize, because, of course, we're looking at really long time constants, right?
You know, with a point which I have not discussed, but with fMRI there is another point.
Imagine that you have a very weak activation, and the activation could go under
the threshold that you don't detect.
Instead, with this system, you detect. I mean, when we use fMRI,
we use seconds, not milliseconds.
So if you have activation of some milliseconds, and then it vanishes,
you are lost. You said there is no such an activation.
So it's not, I show as similar thing, but it was a bit a trick for a student because it's not true.
It's not completely natural. But it's extremely interesting,
right? Because you also showed in your intracranial patients,
the action sits in high gamma.
So can we be confident that you will see these high gamma events back in your fMRI as well?
Well, there is an experiment done by Christian Kaiser who recorded not intracranially,
but EEG and fMRI simultaneously.
And when you have an activation in correspondence of the motor cortex,
you have the synchronization. So, in other words, it's gamma.
Gamma filtering, but anyway, it's gamma.
But is it significant for you that these events that you pulled out in intracranial
patients was mainly playing out in high gamma?
Or because I asked you earlier about the patterning of the monkey response in
the mirror neurons and you felt, well, there was nothing really special about it.
We had some rate fluctuations that correlated with the task.
But now when you bring it to the human brain, it's for now, okay,
you look at the LFP, you look at the power spectrum, but the main impact is
not at some slowly fluctuating signal.
You look really at the power in the high frequency signal. In the high frequency
and synchronize it with the signal. Right.
Which in some sense is a somewhat different mode of analyzing the data as you
originally did with the macaque monkeys, right? To establish the mirror neurons.
In a sense, it's true. I hope that I will be able to record single neurons in the future.
But at the moment, that's the best I can have. But it's not a criticism because
maybe it's also exciting because maybe why not believe that the human brain
is again using a somewhat more sophisticated coding scheme to build these kinds of circuits, right?
That we go away from simple rates, that we move into a higher dimensional space
of, let's say, frequency, high gamma, phase coupling, or that you don't find
an appealing alternative. No, I think it's very interesting what you're saying.
Because historically, we started with anatomy and with lesion.
We said, here is visual area, here is motor area. We knew nothing.
Then with human vision, Moncasse and so on, we started to know something about the mechanism.
Then fMRI, no mechanism anymore. Again, here is vision, here is motor.
And now we're right. Maybe we are back now.
Learn something about the mechanism, but maybe in a more sophisticated way.
Exactly. That's a single neuron with one tungsten electrode.
That's right, exactly. That may be, you're absolutely right.
That could be something more than time. That's right.
So I think it's a great opportunity that you now opened that door.
And it actually also consists of what we see in our intracranial patients in very different tasks.
You have? You record intracranial? Yeah, we do. And in rate, we don't see very much.
We see a lot in high gamma, in phase coupling. And so we use more virtual reality
tasks, navigations, decision-making, and so on. So it's something else we should talk about.
So when I will come next time, only for scientific purposes,
you will show me. Absolutely. We'll show you everything.
Okay. Listen, I have to go. I know. No, we have to finish up.
I have this girl from Madrid. Okay.
We will make sure you have enough time for the girl from Madrid.
So let's go to the finish line.
We're almost there. The girl from Madrid sounds great. She sounds very excited.
We did not provide as part of this of this arrangement that I have to just declare
that before people get the wrong idea Tony so the I think one of the,
The most striking part of the talk was when you moved from talking about this
activity as describing a response to a movement or a visual perception,
and you began to say, well, this actually is the basis for empathy.
So the human response where we see someone's pain and we share it,
and we share it because we see the expression on their face or we hear their
cry or whatever. So, I mean, that's fascinating.
And I think you've presented some quite compelling arguments as to why we should think that.
And you also said, Dan, that in some cases it appeared that that empathic response
might, well, it is learned or some aspects of it are learned.
And there could be some level of voluntary control, or in some people that it's
not enabled or disabled.
Could you say a bit more about what you think is the variation between people
with respect to this empathic capability and how we can understand it?
It's difficult to give you a scientific answer
in the sense that I don't have a patient or
people which is highly empathic or no
empathic and so I don't know that but if
you think about history and also
also about some experiment because that woman
for example are more empathic that's clear that's London
as I told the student they use only girl never male for that but if you think
on the logic it's more a logic experiment not scientific experiment if you have
a mechanism which renders you empathic towards somebody. And this mechanism is destroyed.
What will be your behavior? You will consider this person, it's not a person anymore.
It's a thing. It's untermenschen. Untermenschen means it's not real.
It's something below in evolution. In evolution.
So at this point, it seems logical that you can behave in a nasty way.
Because, you know, this, I don't know, you probably read or know about the Arendt,
Hannah Arendt, she wrote the book about Eichmann process.
And all the psychiatrists said that Eichmann, it's a good man.
He likes his wife. He likes the children.
He's a good citizen. So well expected, a monster.
Instead, it turned out that it was a really normal person who simply obeyed
the order without thinking about that.
As she said at the beginning that, as a matter of fact, I like a Jewish,
I have some friends, but why obey that?
Well, because I am a person who obeyed the order and I am an important functionary
in the German government or German administration.
So, at a certain point, if you lose the feel that what you're doing is something
against a human being, why not be a good administrator?
Just organize the transport of Jews from one camp to another.
So there will be in some people, or maybe in all of us, the ability to control
the degree of empathy, maybe to shut down some of the system.
Well, that's not my idea, but it's one of my friend philosophers that's really
derived, in Germany especially,
from the philosophy of Hegel, who thinks that we are just something very small.
The important is the state.
The state is really the entity which we have to obey and so on.
If you think of Hegelian philosophy, maybe many Germans really feel that state
is much more important than individual.
So we have to help the right to become important.
That's, again, more speculation, but it makes sense. Because,
for example, in England, you have not this tradition.
It's more empiricist, it's more individualistic, if you read Adam Smith or the
other. In Germany, there is this big tradition of Hegel, which, again,
That's not Miles' film, so they've told me. Think also about the Marxists.
Marxists was considered the left wing of Hegel, the left Hegelism.
And again, the state is the most important thing.
One started killing the people. It was bad. But let's not forget that the Brits,
like the Dutch, had their own big empires where they also killed plenty of people.
So Aaron talked about the banality of evil in the argument in your personal
book. And what's really important about that is that what we consider evil can
be in some sense a normality dependent on the context.
And there might be a more biological route to that, which might also go back to the work by Francois,
for instance, on, let's say, the morality of bonobos and chimpanzees,
where this whole idea of us and them is a very important construct to build
social cohesion in groups, right?
You also define the cohesion of a group by pointing out what is not the group, and that is them.
So in that sense, this idea of being able to either empathize or not empathize
can also play a constructive role in defining groups.
But the thing is, it can become a runaway morality that the other now must be
destroyed to sort of maintain the in-group.
But that's not a bit the question, but if you compare the macaque brain and
the human brain, in your experience, would the human brain have more capability
to overwrite, if you want, these rules of empathy than the macaque brain?
Is that also what makes us so powerful and so dangerous?
You are absolutely right. I heard Tomasello talking about that,
and he said something very similar to what you said. So human brain could be
override an excess of people coming from outside.
So he was very cautious. It's true. We have to consider all immigrants,
all people as ourselves.
But be careful because there is a mechanism.
One mechanism says, which I like very much, that we are empathic towards other people.
But there is also mechanism that when this number grow up.
The idea is that you have to defend your tribe somehow.
But don't forget, empathy is also overrated in some sense, right?
Because even if I face my enemy, it is by virtue of me being empathic to my
enemy that I can defeat him or her, right?
So empathy is just my ability to model the other, not necessarily to sympathize
with the other. Absolutely, absolutely.
That should be clear to everybody because otherwise there is a lot of confusion. Exactly, right. Right.
So then, okay, so you're in this business for a long time. You're in Parma for many years.
We calculated 45 years, right? 40 years.
So you've seen a lot in neuroscience. You also led to a revolution in neuroscience
with all the positive and negative fallout that that brings about, right? Right?
So, given that experience, what is Giacomo's law that we should adhere to to
advance our understanding of the brain and the human condition?
Don't forget about cognitive and system neuroscience.
Because now I think the strong tendency is just to look how it's organized the
visual cortex, the molecular level in a mole, which is blind.
Okay, no more moles. And then my last question is, so Tony likes traveling,
and he likes food as well.
So it'll be a good restaurant. I've never been to Parma.
Exactly. Oh, you must come. We're going to send Tony to Parma five years from
now, but he's going to pay himself.
And because he's going to come and check whether a prediction you're going to
make today was falsified or verified. So, what's the one prediction that you
would like to see sort of tested in that five-year time frame?
Well, the idea that the brain is really have molded inside, say.
It's not empiric system.
Okay. So, Giacomo Rizzolatti, thank you very much for this conversation.
Thank you. It was very pleasant.
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Music.