Do cuttlefish wear their thoughts on their skin? I mean to the extent that their perception of the world
could be described as their thought? Yeah, that's true.
They look at you in a way that other animals don't look at you. They're just so expressive.
There was a possibility of using a trick to indirectly
sample a very large number of neurons by proxy basically.
A human has about 200 different ways that we can use our muscles to move.
With this kit we can record in an adult cuttlefish probably millions.
Cuttlefish, they've solved the problems. Their solution is there.
There's stuff to be learned just by understanding them.
So cuttlefish are cephalopods and they actually invented this method of hiding which involved the hijacking
of a part of their musculature into an organ in their skin to generate a controllable display.
And the amazing thing about this controllable display is that it's controlled by the nervous system,
meaning that they can change their external appearance extremely fast.
Within a couple of hundred milliseconds, they can completely change their external appearance.
You see behind the house of a snail, there is one. There's always this little animal sitting here.
I should find a name, Johnny or so. And a bigger one likes to hide under this rock, there in the corner.
The way in which the system is organised is such that the output of the system is a set of pixels.
Those are little bags of pigments that are controlled by a radial set of muscles.
And so the diameter of this pixel is controlled by the rate and amount of contraction of these muscles
which itself is under the control of up to three motor neurons. Those motor neurons themselves are located
in the brain of the animal, but they are the last layer of the output of this system.
So they represent the output of this complex computational system that doesn't match in between
an image that the animal sees and what it produces on its skin.
There it goes! So these cameras are zoomed in on small patches of this animal's skin,
overlapping so we tile the entire body. In the skin there's thousands of specialised pigment cells
called chromatophores, and each chromatophore receives direct input from motor neurons
projecting from the brain. So these cameras are picking up the expansion and contraction
of these pigment cells and then use this to infer the activity of motor neurons, and use that to infer
the activity of premotor neurons and sort of walk deeper into the brain.
When we - systems neuroscientists - try and figure out what the neural correlates of perception are,
we have to design very complicated experiments, behavioural experiments, usually involving learning,
of which the results have to be relatively simple. Do you recognise this or do you not recognise this?
Can you do a simple discrimination task?
In this case, you have a behavioural description of the output which is complete.
The animal on its skin tells you its perception of the external world.
Indeed what we are seeing is the output of the system and we know the input as well.
We control the visual inputs coming in. We have this really high-resolution behavioural measurement
and we want to infer something about the black box that is the cuttlefish brain with this input/output mapping.
That's the big goal here.
Cuttlefish as cephalopods are doing an operation which we as humans,
engineers, computer scientists, find extremely difficult to do. What are the features that one needs
to extract so as to reproduce something that will fool another animal, okay?
In the attempts that machine vision people have had to train networks, to do that very simple matching,
you needs hundreds of thousands of training trials.
And the fascinating thing about these animals is that they're born with the ability to immediately do
a camouflage that's effective, which implies that in their brain they have the solution to this problem,
and that if that solution is encoded in their nervous system and their genes,
it must be a relatively simple solution. So that's what we're getting at or we're trying to get at.
I think if we want to learn what is really fundamental about how brains work in general,
we'd want to compare across the most different examples as possible.
Our common ancestor was a small marine worm that lived about 600 million years ago
that had most likely a very, very simple nervous system so it's all independent, so if we find some
common features about how brains work or how behaviour works in these animals,
and how it works in vertebrates like ourselves, we can really say that we've learned something
fundamental about how these things work in general.
We can't really say that if we only study one sort of evolutionary instantiation.
You want to study it because it's so different, not in spite of it.