A detailed map of the brain synapses lifted the veil on the mystery of thinking

Imagine a map with each star in the galaxy. Map so detailed that it listed looks like every star is, what it consists of, what other star is associated with great physical laws of the cosmos. Although we do not yet have such an astronomical map of the heavens, thanks to a monumental study published last week in Neuron, we have a similar map of the brain.

If each neuron were a galaxy, the synapses are small structures, points rassypnye along the snake-like extensions of the neurons — stars. A group of scientists from the University of Edinburgh in the UK built the first detailed map of every synapse in the mouse brain.

A map of the brain: the key to the riddle of thinking

Using genetically modified mice, the scientists literally drove every synapse to light up under a fluorescent light around the brain like the stars in the sky. And, just as stars differ from one another, scientists have discovered that synapses are very diverse, but observed patterns that can support memory and thinking.

“The human brain has more synapses than stars in the galaxy. The brain is the most complex object known to us, and understanding its connections at this level will be an important step forward in the revelation of his mysteries,” says lead author Dr. Seth Grant from the Centre for clinical brain science.

Detailed maps showed a fundamental law of brain activity. With the help of machine learning a team of scientists divided approximately one billion synapses throughout the brain in 37 categories by type. Here’s the key: when sets of neurons receive electrical information, for example, choosing between different solutions to the problem, unique subtypes of synapses scattered among different neurons, unanimously sparking activity.

In other words, the synapses are of different types. And each type can control the thought, decision or memory.

It is not surprising that neuroscientists have responded to the work very positively.

“Wow,” said Ben Sanders of the University of Minnesota.

This “amazing article, catalogservlet diversity and distribution of subtypes of synapses throughout the brain of the mouse,” writes neurogenetic Kevin Mitchell. It “emphasizes the fact that synapses are the key computational elements of the nervous system.”

Connecting connectomes

The interest of scientists in creating “synaptomys” — the first complete catalogue of synapses in the mouse brain came from a much larger project: connectomes.

In short, connectome — all neural connections within you. As the doctor says Sebastian Seung, a connectome is a biological basis of who you are — your memories, personality, your thoughts and reasoning. Catch connectome — and one day scientists will be able to recover through emulation of a whole brain.

And yet, connectome describes only how the neurons are functionally talk to each other. Where in the brain is encoded physically.

Here come in the synapses. Neuroscientists have long known that synapses transmit information between neurons using chemicals and electricity. There were also hints that synapses vary widely depending on the proteins that contain, but this distinction is commonly ignored. Until recently, most scientists believed that the actual calculations are performed in the neural body, the bulbous part of a neuron, from which come the branches.

Until now there was no way to look at the morphology and function of synapses throughout the brain, explain the authors. Usually we were focused on the comparison of these important connection points in the small areas.

“Map synaptomys you can use in order to understand whether the spatial distribution of synapses with the architecture of connectomes”, scientists say.

And if so, future emulators of the brain will find finally a foothold.

Map synaptomys

To build synaptomys mice, the authors developed a plan called SYNMAP. They started with genetically modified mice in which the synapses glowed different colors. Every synapse densely stocked with different proteins, among which PSD-95 and SAP102 — the most famous of the Lord. Don’t be afraid of names. The authors added the glowing proteins that acted as lanterns, illuminating every synapse in the brain.

In General, a first, scientists have altered the biology of the mouse, forcing her synapses to glow under a fluorescent light.

Then they painstakingly cut the brain into pieces, used the microscope for imaging synapses in different brain regions and have compiled the photos together.

The image of the synapses is reminiscent of the untrained eye densely Packed star map — like the one that filmed the “Hubble” recently. Categorization of each synapse goes beyond the abilities (and time) of any human being, so the researchers used new methods of classification by using machine learning and developed an algorithm that parses this data — more than 10 terabytes — automatically, without the need for supervision.

Physical connectome

First, scientists hit “expressive scheme” shining synapses. One marked protein — PSD-95 — seemed to hang out in more remote parts of the brain, where flow is higher cognitive function. Although the areas overlap, the other a glowing protein have preferred more internal areas of the brain.

Upon closer inspection, it turned out that two glowing protein represent different sets of synapses, the authors explained. Each area of the brain has a characteristic “signature synaptomys”. Like fingerprints, which differ in shape and size, different areas of the brain seem to contain synapses, differing in protein composition, size, and strength.

Using a specially designed machine learning algorithm, the researchers classified the synapses of 37 subtypes. Remarkably, the region of the brain associated with higher reasoning abilities and thinking, also contained the most diverse population of synapses, while “region of the brain of reptiles”, was more homogeneous in the maintenance of synapses.

To see whether the diversity of synapses in processing information, the scientists used a computer simulation showing how synapses respond to conventional electric circuits in the hippocampus region of the brain important for learning and memory. The hippocampus is one of the areas that show a striking diversity in the subtypes of synapses.

Importantly, each type of processing the electrical information transmitted in a unique map synaptomys — change the input, change synaptoman.

This suggests that the brain can process multiple electrical information using the one area of the brain, because it involves different synaptomys.

Scientists found similar results when we recorded the electrical circuits of the mouse brain, trying to choose between the three options awards. Various synaptomys lit when the choice was correct or incorrect. Like the map of the inner thinking, synaptomys drew a vivid picture of what they think the mouse making the choice.

Each behavior activates a separate synaptomys. Each of synaptoman is a unique snapshot of the thinking process.

Reprogramming synaptomys

Like computer code, synaptoman, apparently, is the basis of the computing result of the decisions or thoughts. What if we change this code?

Psychiatric illness often have genetic causes that affect proteins in the synapse. Using mice that showed symptoms similar to schizophrenia or autism, scientists have made a map of their synaptol — and found dramatic changes in how structured and combine various subtypes of synapses in the brain.

For example, in response to the normal electrical circuits of the brain, some synaptic maps were manifested weakly, others became abnormally strong in the mutant mice. Mutations can change synaptomys and potentially lead to psychiatric disorders. That is, some psychiatric illness “preprogramming” synaptoman. Stronger or just a new card synaptomys can be the reason that patients with schizophrenia experiencing delusions and hallucinations.

So you — it’s your synaptoman?

Possible. The essence of you — memories, thoughts — seem imprinted in how different synapses are activated in response to the input. Like a fingerprint, synaptomys could be read to decipher what you’re thinking. However, this study is only the beginning. Neuroscientists have yet to analyze the complex relationship between synapses and you.

“This card opens up many new areas of research which should transform our understanding of the behavior and diseases of the brain,” says Grant.

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