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Sarah / @RealScientists @realscientists
, 31 tweets, 11 min read Read on Twitter
Nothing is on fire, tea is forthcoming AND NOW IT'S TIME TO TALK BRAINS.
For today, we're going to be going over how the brain processes bits of information, and how it puts it together into coherent thoughts and responses. This is, broadly, cognitive neuroscience!
There are two general categories: bottom-up processes, which react to stuff; and top-down processes, which generate stuff.

This reaction is bottom-up:
Also, we're going to use Marvel characters. BECAUSE BRAIN DAY IS THE BEST DAY.
First up is bottom-up processing! Here, we start with the sensory cortices, which pick up information from the environment. Meet the sensory cortices!
These are the eyes and ears of your brain. Literally. They are connected to the eyes and ears via the optic and auditory nerves. (There are also areas for touch/smell/taste connected to the skin/nose/tongue).
If you hear a sound (maybe...A DASTARDLY SPACESHIP NOISE?), your ears send that information to the relevant auditory cortex. The info is then passed up to regions in the parietal lobe, which bind everything together.
Parietal regions are like mission control - they take in the raw sensory information and assemble it into something that we can make sense of. Say hello to PARIETAL MISSION CONTROL:
This is how we hear in 3-D - the information from both ears is combined as a single concept (or percept) which allows us to localize the sound. Your parietal system:
Knowing WHERE the sound is is very important as our ears can hear in 360 degrees, but our eyes can't ( know...)
From that information, you make a decision whether to approach or avoid the source of the sound. This isn't always conscious - think about jumping when you hear a sudden loud noise. Or are poked with pointy things.
Deciding what to do next brings in a different team. Here, aspects of memory and emotion show up. Say hello to The Limbic System!
The limbic system does lots of cool stuff related to memory and emotions; namely remembering what did and did not work in the past, and using that information to collect new information and keep us alive. The limbic system:
So if you remember "hey, that sounded like the last space ship that tried to blow us up", you might want to GTFO. Or, you know, try to smash it.
If it's a *new* noise, you have to decide what to do based on information you THINK is relevant based on past experiences, and here's where we get into top-down processing.
You have information and need to decide what to do with it. Exploring something new could bring even more valuable information (in the brain, information is like infinity stones. Also NO INFINITY WAR SPOILERS, PLEASENTHANKS).
New information could also destroy your entire planet. The fun never stops!
Deciding to approach or avoid requires computation comparing the risks/rewards of each approach.
Meanwhile, the sensory team is still monitoring the situation and feeding that sweet, sweet information up to central control.
When you decide what to do, you're going to need to actually do the thing. Meet the planning and execution team!
Regions in the frontal lobes oversee planning based on the material sent up by mission control in the parietal regions.
If the plan involves moving in any way, engage thrusters (motor cortices) and get to work.
If it requires guessing and learning, your frontal and limbic areas will coordinate to update your risk/reward calculation to make sure things aren't going sideways.
If you're making a moral decision, these folks show up (these folks being regions in the pre-frontal cortex)
Moral decisions are a bit more tricky. Risk, in this case, is less obvious. Instead of bodily harm, you risk guilt/shame/loss of status/etc.
Interestingly, similar calculations run between these regions and the limbic system, rewarding or punishing with satisfaction or guilt depending on the decision.
And this happens back and forth countless times each day! Your brain is always perceiving stuff and will direct your attention in the case of important or novel stimuli.
...even when you're not paying attention to anything. This is the Default Mode Network, and it keeps you ready.
This is one example of how bottom-up/top-down processing work together, but another is music!
And that was AVENGERS: AGE OF NEURON. How about you? What are your casting suggestions for other brain areas?
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