5 projects that made me fall in love with neuroscience.
And how they shatter the mind/body divide.
(CW: animal experimentation, including a cat)
I have some news for you.
You don’t control your body.
“Au contraire!”, you say, “I refute this with my actions! We duel at dawn!”
Hold your violence and indulge my incendiary statement for just a moment. If you please, prove me wrong by voluntarily slowing down your heartbeat.
Or wiggle your ears. Or independently raise your eyebrows.
While you were making funny faces, were you even thinking about the fact that you were breathing? Who decided to keep doing that?
Our available movements are a relatively narrow preset list of options. We have the muscles (and some of us practice and gain access to some of them), but most of our body is just chugs silently beneath or awareness or control.
“But I am in control! Look, I can walk around!”
That’s not a huge accomplishment. Even literally newborn babies can walk:
Think about that: you’ve just been popped from nonexistence, the world is bright and loud and confusing, everything is upsetting, but you’re able to just sorta naturally move these two meat-limbs in succession in a crude but clearly recognizable gait.
Since you don’t have to be preternaturally brilliant to figure this out, it’s pretty clear that you’ve been set up for success.. At the very least, part of the credit is owed to places other than your noggin.
Actually, it even turns out walking doesn’t require your brain at all. You might’ve heard about chickens running around without their heads, but to be a little less graphic, here’s a de-cerebrate cat on a treadmill:
All of the actual work is being done by areas of your brain and spine that are outside of that highfalutin prefrontal cortex of yours. You think walking is easy? That’s just because you’re not the one having to actively think about how to do it.
Face it: you’re just an emotional monkey sitting at the helm of a ship yelling commands down at crewmen to make the vessel go. You don’t even know how the inner workings of the ship works — or in most cases that they even exist until something goes wrong.
If you’ve ever tried learning dance (or something similar), you know the feeling of utter awkwardness of attempting a new kind movement. As soon as you stray from the path of your pre-set motions, it feels like you forget how to move. It feels weird and unnatural for months until your body learns what to do and you don’t have to manually constantly be thinking about it.
So! With that introduction, lemme show you some of the *KICKASS SCIENCE* that is being done to puzzle out the inner workings of these meat puppets that we’re steering through the universe.
~ Neuroscience that BLOWS MY FLIPPING MIND ~
1. We can shut down your ability to move (with magnets, of course)
Long gone are the days of pseudo-scientists waving magnets around claiming intangible health benefits. Now, we just wave really strong magnets around to get people to poke themselves in the face. It’s both more grounded in reality and immediately gratifying to watch.
This wand trick happens to work because the motor cortex (involved in is a band along the very top of the brain, so it’s easier to reach with the magnetic pulse. We don’t completely know how it works; it seems to just temporarily scramble the activity of the neurons, like getting a burst of static on your TV. It’s not like we can, like, mind-control you to do more complicated and realistic behaviors.
2. We can turn complicated behaviors on and off with light (and a few viruses)
But mind-controlling mice is another matter. Humans generally make a fuss when you start doing much more than waving wands around the outsides of their heads. That’s where animal models come in — by infecting neurons with a special virus, we can get them to express proteins that activate in response to being physically hit with light. It sort of makes a switch on those neurons that we can then flip on and off.
Depending on which neurons are infected by the virus, mice will run around in circles, attack, freeze in place, or gorge themselves:
I’m using words like mind-control, but it would be more accurate to say that we found a few preexisting switches for these behaviors. For all of the fancy viruses and brain surgery and fiber-optic cables, optogenetics is still a relatively crude tool. It’s like we just have a big ON/OFF button that we can mash. Compared to the nuanced native language of the brain, we’re a bull in the china shop.
If only there was some way to examine what’s actually going on a little more directly…
3. We can take brains right out and watch them behave in a dish.
Let’s turn that situation with the cat around: rather than having a body behave without a brain, is it possible to have a brain behave without a body? What would that even mean?
Coincidentally, I happen to have a bit of video with my own research that shows just that situation with a frog brain (taken from Crescent Loom’s Kickstarter video):
This still boggles my mind. It’s like we’re able to rev up this tiny little motor inside the frog brain and it putts along despite its body missing.
Imagine the Titanic sinking, but somewhere in the bowels of the ship there’s a room where an accountant. We slip some spreadsheets under the door and they’ll happily keep doing their job while ignoring the chaos that is the rest of the ship. Or the fact that there is very little ship remaining at all.
The fact that you can just switch on an (attempted) behavior in isolated brain raise a lot of philosophical questions that can keep you up at night. What would it feel like to be that frog brain? What are the other parts of my brain thinking when I’m not paying attention? Where does my consciousness live?
Onward!
4. We can make neuron maps of specific behaviors
With my frogs up there, we turned the vocal circuit on by applying a dose of pure serotonin — not something that usually happens naturally. But some circuits can instead be turned on just as reliably by just blowing on them. Here, a puff of air is all it takes to trigger a locust to flap its wings:
By recording from its neurons while it’s trying to fly, we’ve managed to puzzle out precisely which ones are active during flight and how they’re connected. The end result is a chart that looks suspiciously like an electrical circuit diagram.
Making drawings of how neurons are connected isn’t a new kid on the block: here’s a illustration of the cells in the mammalian retina by Ramón y Cajal from the flipping-year-1800.
If you wanna learn some solid science on these circuits, the Eve Marder has a great series of introductory videos.
This happens to be my favorite thing in the world. The idea of being able to break down our brains into these mechanistic maps has captivated me. It drives home the fact that we are physical beings that can be charted and understood — and perhaps eventually engineered.
5. We can grow our own neurons — and then put ’em in robotic bodies.
Whoops, did I say eventually? I meant to say we’re doing it now. RIGHT NOW. This project was published in Science just last year.
These are real neurons inside of and controlling an artificial body. It swims and can respond to light. The line between real and syntheticlife is starting to get a tad blurry.
Fun bonus fact: these aren’t yet ready to be released in the wild due to a lack of immune system. They swim just fine, but their neurons are totally vulnerable to germs. Truth in fiction.
But this isn’t the first time biological neurons have been used to drive something. Here’s honest-to-god the closest thing I’ve ever seen to the Matrix.
There’s a fondness in his voice as he talks about teaching his plates of very real and very alive rat neurons to fly a virtual plane. When you play god, I guess you can’t help but feel affectation for the life you create.
Here’s one more:
“Whether or not we can ever get to conscious cultured networks is a question that I would say that we’ve already answered: yes. We have culture dishes receiving input from the environment and they’re responding to it in complicated ways. So they’re conscious of their environment in some very rudimentary fashion.”
Wrap-up
Are you as excited as I am? Maybe a little overwhelmed? Wish that you could get a better handle on all of this and play a little god yourself?
As you may have gathered from my not-too-subtle links, I felt limited without a way to visualize these neural circuits and wanted something a little more hands-on, so I decided to make a neuroscience video game! It’s called Crescent Loom, and it could use some love on Kickstarter.
The basic idea is to put together the bones, muscles, and senses of a creature and then connect up its neurons in order to get it to swim. I’m pulling a page out of Spore’s playbook and saving player creations to populate an ecosystem for people to explore.
My dream is to let Crescent Loom naturally teach the basic dynamics of neurons and circuits. I want to see a thriving world of creatures growing and being modified as people learn better ways to make creatures swim and prey on eachother. It’d mean a lot to me if you checked it out!
“What I cannot create, I do not understand.”
— Richard Feynman
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Note: I’ve used an upbeat voice throughout this piece, but please don’t interpret that as irreverence for the animals used in this research. I take their welfare very seriously, and my enthusiasm stems from wonder at the knowledge their sacrifice bestows. I can only truly speak for myself, but if you have concerns and want to have a conversation about it, I’m happy to discuss it on a private forum.
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