Cortical Cells Identified as Initiators of Sleep Rhythms, Challenging Prior Assumptions

Cortex's Role in Sleep Re-evaluated

Traditional sleep research has largely considered the cerebral cortex a passive recipient of sleep-inducing signals originating from deeper brain regions. The slow rhythms characteristic of deep sleep are visible in the cortex, but their initiation was previously attributed to subcortical areas.

Discovery of Sst-Chodl Neurons

A recent study published in Nature by Geoffrey Terral and Renata Batista-Brito from the Albert Einstein College of Medicine identified a specific population of cortical cells that can initiate these sleep rhythms. These cells, named Sst-Chodl neurons after two active genes, constitute approximately one percent of the cortex's inhibitory neurons.

The research demonstrated that activating these Sst-Chodl neurons in mice was sufficient to induce sleep in the animals. This indicates that the cortex is not merely observing sleep rhythms but can actively initiate them, a finding that alters previous understandings of sleep mechanisms.

Challenges in Identification

Long-range inhibitory neurons marked by the activity of these genes have been known from studies in monkeys, but manipulating them proved difficult. Targeting a single gene would activate a broad range of different neurons, making specific manipulation challenging. The research team spent years developing a strategy to specifically label cells where both Sst and Chodl genes were active, enabling their targeted study.