A special interneuron network in the human brain

A human neural network mapped from different parts of the cerebral cortex. A comparison of connectomics with mice revealed a significant expansion of the human interneuron network. Credits: Loomba, Helmstaedter, MPI for Brain Research

Analysis of the human brain is a central goal of neuroscience. However, for methodological reasons, research has focused primarily on model organisms, especially mice. Neuroscientists are now using tissue from neurosurgical interventions to gain new insights into human neural circuits. Three-dimensional electron microscopy data reveal a new extended network of human interneurons compared to mice. The discovery of this prominent network component in the human cortex facilitates a more detailed analysis of its function in health and illness.

At first glance, the mouse and human brains are surprisingly similar.The neurons that make up our brain have very similar shapes and properties, the molecular mechanisms of electrical excitation are highly conserved, and many biophysical phenomena found in other species are present. Human brain.. “So, primarily the fact that our brain is 1,000 times larger and contains 1000 times more nerve cells allows us to play chess and write books for children. Interview with Moritz Helmstetter, director of the Maxplank Brain Research Institute (Frankfurt), who led the new study published in the journal on June 23. Chemistry..

Dense network mapping in the human cortex reveals large interneuron-to-interneuron networks that are rarely present in mice. This new neuronal network has the potential to constitute an important evolutionary invention in the human cortex. Credits: Loomba, Helmstaedter, MPI for Brain Research

By analyzing Neuron network Helmstaedter and his team, in mice, monkeys, and humans, map their complete structure on biopsy of brain tissue, the so-called Connectome, a new neuron in which the human cortical network is essentially absent in mice. I discovered that I have evolved the network type.This neuronal network relies on abundant connections between Inhibitory interneurons..

Using a biopsy from a neurosurgical intervention performed by neurosurgeon Hanno Sebastian Meyer and his team at Technische Universit√§t M√ľnchen, researchers applied a three-dimensional electron microscope to about human brain samples. Mapped 1 million synapses. Their data revealed an unexpected bias in humans that interneurons (rich in humans) connect to each other, but innervation (synaptic connections) to major neurons remained largely the same. “This suggests an almost 10-fold expansion of the network from interneurons to interneurons,” said Sahil Loomba, one of the lead authors of the study.

“Interneurons make about one-quarter to one-third of the cortex Nerve cell It works in a very unique way: they are very active, but not to activate other neurons, but to silence them. Like kindergarten caretakers and museum guards, their very painstaking and extremely energy-consuming activity is to keep others peaceful and quiet.This is a human brain Developed! “

Silence of Thought: A special interneuron network in the human brain

Neural network from mouse, macaque, and human cortex. Connectome comparisons using a three-dimensional electron microscope in a brain biopsy reveal a novel network between human interneurons that is rarely present in mice. Credits: Loomba, Helmstaedter, MPI for Brain Research

But what does this mean? Theoretical studies have suggested that such a network of silencers can extend the amount of time recent events can be retained in a neuronal network: expanding working memory. “In fact, longer than that is very plausible Working memory It helps you deal with more complex tasks and expand your inference capabilities, “Helmstaedter said. This new discovery suggests the first clear network innovation in humans and deserves further research. And it must be studied in the context of neuropsychiatric disorders. And last but not least, none of today’s major AI techniques use such interneuron networks. ”

Network formation method: Graphing the developing brain

For more information:
Sahil Loomba et al, Connectome Comparison of Mouse and Human Cortex, Chemistry (2022). DOI: 10.1126 / science.abo0924

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Max Planck Society

Quote: Silence of Thought: A special interneuron network of the human brain (June 23, 2022) is available at Obtained June 23, 2022

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A special interneuron network in the human brain

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