Thread by @rockatscientist

FINDING THAT CONNECTION

You’re watching two neurons that I saw under the microscope sensing one another + connecting.

There are 86 billion neurons in the brain - how do they know how to connect to other neurons?

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#WomenInSTEM @ScienceAU @UTAS_ #science @elonmusk

They use these webbed hand-like structures called “growth cones” that you can see in this video. The finger like projections (called “filopodia”) actively reach out to sense the environment around it.

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When we are developing in utero, you’ll find these “growth cones,” at the tip of every single growing neuron, actively searching their way between cells, trying to find the right spot to connect to. When they make their connection, they become resorbed and disappear.

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Considering there are trillions of cells in the body, finding the correct one is no small feat! This wiring is super precise - and it needs to be: eg. you wouldn’t want a motor neuron connecting to a tastebud. We can accurately predict where certain neurons will connect

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What you are seeing here represents the process that happens in development in utero. Growth cones are also redeployed after injury (eg. Spinal cord injury). But the process doesn’t work very well after injury - reconnection attempts often fail, which is why recovery is poor
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I know - it’s heartbreaking that the video ends right when we get to the exciting part, but see the black wavering line in the bottom right? That’s what they would have looked like after connecting.

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When people see this video they often ask, is this what happens when we learn new things? Unfortunately not.

Growth cones aren’t responsible for the special connections between neurons that form in learning and memory (those are known as synapses).

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Synapses are *much* smaller and appear as thousands of tiny bumps along the length of the part of a neuron called a dendrite.

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This is a video I took of a neuron in a culture dish that I was just about to toss out. I looked at it under the microscope and saw that something interesting was about to happen, so set up a recording.

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This video has been sped up - it’s the growth that occurred over the space of ~20 min

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This video belongs to me, Dr Lila Landowski. I am very happy for you to use it for teaching purposes, but please acknowledge me accordingly. I am tired of seeing my video pop up without attribution, so I’ve made this version with a watermark: youtube.com/shorts/Rvmvt7g…

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It’s been 3 years since I first shared this gem on social media! But the video itself is one I recorded a decade ago.

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Ps. It’s actually more than two neurons connecting, really - those “two” that you can see, are actually comprised of a few neurons that have bundled up, tracking along together. They’re hugged together so tightly they look like one

A better love story than Twilight 😂 🥰
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