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Researchers identify key sources of signals that encode past experiences in the brain

Researchers have identified areas of the brain as the primary source of signals that encode past experiences in the neocortex.

The brain encodes the information collected by our senses. However, in order to perceive and interact with the environment, these sensory signals must be interpreted in the context of past experiences stored in the brain and the individual’s current purpose. A team led by Dr. Johannes Letskus, a professor of medicine at the University of Freiburg and a research group leader at the Max Planck Institute for Brain Research in Frankfurt am Main, has identified an important source of this experience-the so-called top dependent. Down information.Scientists published their results in the journal Science..

The neocortex is the largest and most powerful region of the human brain. All of its important cognitive functions are made possible by the convergence of two different streams of information: a “bottom-up” stream that represents a signal from the environment and a “top-down” stream that sends internally generated information about the past. .. Experience and current purpose. The question of how and where this internally generated information is processed accurately has yet to be investigated, says Letzkus. This allowed him and his team to search for sources of these top-down signals. Scientists have succeeded in identifying the area of ​​the thalamus, a region of the brain embedded deep in the forebrain, as an important candidate region for such inside information.

Based on this, Dr. M. Belén Pardi, a postdoc in the Letzkus lab, has developed a strategy to measure the response of individual thalamic synapses in the neocortex of mice before and after the learning paradigm.

“Unrelated neutral stimuli were encoded by the small, transient responses of this pathway, but learning strongly facilitated their activity, making the signal faster and more persistent.” Explains Paldi.

We were really convinced when we compared the strength of the memory we acquired with the changes in thalamic activity. This reveals a strong positive correlation indicating that thalamic input significantly encodes the association of stimulus-learned behaviors.

Dr. Johannes Letskus, Professor of Medicine, Freiburg University and Research Group Leader, Maxplank Brain Institute in Frankfurt am Main

In further experiments and computer modeling with Dr. Henning Sprekeler’s team at the Berlin Institute of Technology, researchers discovered an unknown mechanism that could fine-tune this information and identified a special type of neuron in the outermost layer. Did. The neocortex that dynamically controls the flow of these top-down signals. This confirms scientists’ assumptions that the projection of the thalamus onto the sensory neocortex serves as an important source of information about previous experiences associated with sensory stimuli. “Such top-down signals are confusing in many brain disorders such as autism and schizophrenia,” explains Letskus. “Our hope is that this result will also enable a deeper understanding of the maladaptated changes that underlie these difficult situations.”

This work was supported by the German Research Foundation, the European Research Council, the Max Planck Society, and the Human Frontier Science Program.


Albert-Ludwigs-Universität Freiburg

Researchers identify key sources of signals that encode past experiences in the brain

Source link Researchers identify key sources of signals that encode past experiences in the brain

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