Neuronal Culture: How do brain cells communicate?

If you listen carefully, can you hear your brain cells talking to each other?

In our lab, we eavesdrop on these neuronal conversations. We know that neurons talk to each other in much the same way that we do. Here in the bottom left corner you can see two brain cells doing what any two cultured neurons do these days—hanging out, and discussing the social media they’re growing up in.

But whilst we converse across the cyberspace, brain cells talk to each other across these junctions known as synapses. You can see one illuminated here on the right. During a neuronal conversation, the presynaptic neuron illustrated in green, talks to the red postsynaptic neuron on the opposite side of the synapse. This neuronal conversation is conducted in the language of these grey neurotransmitter molecules that diffuse across the synapse. Their meaning is decoded by these purple receptors that transmit the information to the inside of the neuron. Message received loud and clear.

But in the busy metropolitan environment of the brain, everyone has something to say. A single neuron cannot listen to all the conversations in its noisy surroundings.  We know that when a postsynaptic neuron is not listening, these purple receptor molecules do not decode and transmit the information carried by the neurotransmitter. For people with Autism, this happens too much. We want to know why.

Perhaps I’m not a great listener myself. So during my PhD project, I’m not listening to these neuronal conversations. Instead, I’m watching them in action. I am looking down a microscope at these synapses and studying what the receptors are doing when neurons are talking (or ignoring) each other.

The problem with studying synapses is that they are very, very small. I would have to split hairs many thousands of times to provide an accurate representation of their incredibly small size. If these chattering neurons are like two trees in the far off distance, then their synapses are the leaves that are just too small to see. So let’s get closer.

Unfortunately, neuronal synapses are so small that we need some kind of super powers to see them, even with a microscope. Thankfully, I’m lucky enough to have access to a new type of microscope with super resolution powers that can see the leaves for the trees.

Stretching across the screen in white is a close up image of just a tiny part of a neuron. At this level of detail, we can now see these synapses that form between this green presynaptic neuron and its red postsynaptic, conversational partner. So despite their small size, we can clearly see these synaptic exchanges in progress.

I hope that by watching neuronal conversations, we will see the secrets in the brain.