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Nature Neuroscience Heavy: Topological Modeling First Discovers the "Compass" in Mouse's Mind

via:博客园     time:2019/8/16 8:01:11     readed:93

Compile Author: Juno (brainnews creative team), proofreaders: Simon (brainnews newsroom)

As the saying goes, "Looking at the mountains is a mountain, watching the mountains are not mountains, watching mountains or mountains", how does the brain know that it is a mountain?How do neurons transform the original visual signal into a psychological representation of an object?The world is constantly bombarding our senses with all sorts of information, but the way the brain extracts its meaning from this information is still unknown.

An article published in Nature Neuroscience on August 12, 2019 explains the problem. Sabbi Lall, a neuroscientist at the Massachusetts Institute of Technology, discovered a special neural circuit in the brain of a mouse.This loop converts high-dimensional complex signals in the environment into simple abstract objects..The researchers characterized and directly visualized the manifold structure in the mammalian head-direction circuit, revealing that these states form a topologically unique one-dimensional ring.

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Fiete of the McGovern Institute is one of the authors of this article and an associate professor at the Department of Brain and Cognitive Sciences at the Massachusetts Institute of Technology. She mentioned that the external world does not have an orientation marker. The direction of the current head must be The brain extracts, calculates, and evaluates. This process allows us to confirm the emergence of low-dimensional concepts.The essence is that there is an abstract compass in the brain.. Researchers say the compass is a one-dimensional ring that represents the current head's direction relative to the outside world.

Fiete said: “Without this ring, we will be lost in this world.. ”

Previous studies of the Drosophila brain revealed a similar neuronal elliptical ring that represents the direction of the head of the fruit fly, and the researchers suspect that this system may also be present in mammals.

Fiete uses a kind of calledTopological modelingThe method of transforming the activities of a large number of complex neurons into a circular data cloud. Similar to the situation where the specific pattern is not visible, by tracking the sardines, plotting the location of the entire sardine group, and the location of each fish relative to its neighbors, a clear pattern of fish activity will emerge. This model usually forms a ring, a simple shape formed by hundreds of individual fish activities.

Fiete and her colleagues measured the number of hours of neural activity in dozens of neurons in the anterior nucleus of the thalamus when the mouse was free to move in the environment, and the anterior dorsal nucleus of the thalamus (anterodorsal thalamic nucleus).ADNIt is currently considered to play an important role in regional space navigation.They plotted how the neurons in the ADN loop are when the animal's head changes direction.Conducting electrical activities.Eventual discoveryThese data points together form a simple and long-lasting ring cloud.

Moser, director of the Norwegian Cavali System Neuroscience Institute, has not participated in this research, but he is very concerned about it. He believes that the previous data indirectly proves the existence of such a ring organization, but now researchers are likely to use the appropriate The number of cells and a convincing method to prove their existence.

Animal behavior is complex, and the loop integrates the speed of the animal through this one-dimensional compass that encodes the head direction. Without a way to get the overall spatial state, it is impossible to know that this loop of thousands of neurons encodes this aspect of the animal's complex behavior, and it is not known whether it is also involved in coding other behaviors. The topology modeling approach enabled Fiete and colleagues to identify key variables in the loop and then worked on decoding the variable through neural responses.

Even thoughRapid eye movementDuring sleep, there is no bombardment of external information, thisreturnroadStill ableTrack the same one-dimensional ring,asDreaming of the headonceDirectional trajectory.

Further analysis shows that the ringcanThe role of attractors.in caseRelatedThe neurons are off track, they are pulled back into orbit, quicklyCorrection.This feature means that even in the abstract space, the perception of the head direction is reliable and stable over time, which is a key factor in maintaining a stable positioning of the head relative to the outside world.

This study allowed us to get a glimpse of how complex sensory information was refined into simple concepts in the mind and how this expression was automatically corrected to maintain stability. But the meaning of this study is not just the coding of the head direction.akinOrganizational loopsMay exist in other cognitive functions.Neuroscientists at the Norwegian University of Science and Technology, Princeton University, and the Weitzmann Institute have been conducting research, and their work is the basis for future neural decoding research.

The brain deconstructs and represents the complex things in the world in a simple shape. Multi-level analysis can helpResearchersFind those shapes.thereforeThis articlechaptermaybegiveMany new studiesProvide ideas and research methods.With this method, it is possible to get from the brainExtract its exactAbstract representation, maybe even thoughts and dreamsterritory.

Reference materials:

Chaudhuri R, Ger & ccedil; ek B, Pandey B, et al. The intrinsic attractor manifold and population dynamics of a canonical cognitive circuit across waking and sleep [J]. Nature neuroscience, 2019.

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