Introducing the brain: neuron self-control (Introduction)

by David Turell , Tuesday, December 06, 2022, 18:14 (716 days ago) @ David Turell

They handle the level of their own excitability:

https://medicalxpress.com/news/2022-12-neurons-autonomously.html

"The neurons in the brain can also fine-tune their sensitivity, and even do so autonomously. A new study led by the University of Bonn and the University Hospital Bonn shows how they do this. For this purpose, the participants investigated nerve cell networks that also play a role in vision, hearing and touch. The stimulus first travels to the so-called thalamus, a structure deep in the center of the brain. From there, it is then conducted to the cerebral cortex, where it is further processed.

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"For example, they need to dial down their sensitivity if the incoming stimuli were very strong. "We have now discovered that a specific enzyme called SLK plays a role in this process," says Beck, who is also spokesperson for the Transdisciplinary Research Area "Life and Health" at the University of Bonn. "It enables neurons to individually calibrate their own excitability." Which is somewhat like having no sound engineer: Instead, the microphones would automatically adjust their sensitivity so that the recording is neither too quiet nor overamplified.

"'In this mechanism, special nerve cells play an essential role, the so-called interneurons," explains Dr. Pedro Royero from Beck's research group. He earned his doctorate with this study in the Max Planck International Graduate School and performed most of the experiments. Interneurons send inhibitory action potentials to excited neurons. In a way, they turn the knob that reduces their sensitivity. "The SLK now determines how much this regulator can be adjusted by the interneurons, that is, how strong their inhibitory effect is."

"There are two different types of interneurons. Some are activated directly by incoming impulses from the thalamus. They already inhibit the neurons while these are simultaneously excited by the thalamus. Another type, in contrast, is only switched on by the activity of the neurons in the cerebral cortex—i.e. the very neurons they are supposed to inhibit afterwards. So they are part of a negative feedback loop. "Interestingly, the SLK is not active in this feedback inhibition, but only in the first case," Royero points out.

"The researchers were also able to show that certain genes are activated during sensitivity adjustment. They now want to investigate their role in the process in more detail. This is also interesting because the balance between excitation and inhibition is extremely important for brain function."

Comment: How did neurons do this? Trial and error? No animal can live with that sort of brain. Must be designed all at once for survival.