Researchers identify a class of neurons that are most active
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Typically, pyramidal cells and GABAergic interneurons in the brain are activated simultaneously. A team of neuroscientists recently identified a unique class of neurons that do not fire at the same time as all principal neurons, cells, and interneurons. Interestingly, the team found that these specific neurons are most active during the DOWN state of non-REM (NREM) sleep when all other neuron types are silent.

"By collecting sleep recordings in deep layers of the cortex, we observed that spikes of some rare neurons occasionally occurred during the so-called 'DOWN state' epochs of sleep. No neuron was supposed to do such thing, as a DOWN state is known (and identified by) by its complete neuronal silence (lack of spikes)" said the author.

In their study, scientists identified a class of neurons that appear to be most active when all other neurons (i.e., excitatory pyramidal and inhibitory neurons) are silent, in the DOWN state, during NREM stages of sleep. In their follow-up experiments, they showed that these neurons are neuroglia-form cells found in the deeper layers of the neocortex, which specifically express genes known as ID2 and Nkx2.1.

When they examined this class of neurons more in-depth, they observed that they had an entirely antagonistic relationship with all other known types of neurons in all wakefulness states. This suggests that these neurons could have a unique function that sets them apart from all other cells in the brain.

In addition to identifying this class of neurons that is particularly active in DOWN states of NREM sleep, researchers showed that their artificial activation interferes with the sleep-assisted enhancement of memory. New works examining these neurons could help to better understand their functions, perhaps unveiling their role in very specific physiological processes.

Scientific Reports