Neocortical long-range inhibition promotes cortical synchrony and sleep

Area of Science:

• Neuroscience
• Cell Biology
• Sleep Science

Background:

• Behavioral states like sleep and wake correlate with cortical rhythmic activity.
• GABAergic inhibitory neurons are implicated in cortical state modulation.
• Mechanisms coordinating synchronized neocortical networks during different arousal states remain unclear.

Purpose of the Study:

• Investigate the role of specific inhibitory neurons in regulating cortical states and behavior.
• Identify neuronal populations active during low arousal states.
• Determine if specific inhibitory neurons can induce sleep-like states and behaviors.

Main Methods:

• In vivo electrophysiology and calcium imaging in mice.
• Optogenetic manipulation of neuronal activity.
• Behavioral state analysis.

Main Results:

• Somatostatin and chondrolectin co-expressing cells (Sst-Chodl cells) are selectively active during low arousal states and silent during high arousal.
• Sst-Chodl cells possess long-range axons projecting across neocortical areas.
• Activation of Sst-Chodl cells promotes synchronized cortical states (low frequency rhythms, increased spike co-firing) and induces sleep behavior.

Conclusions:

• Sst-Chodl cells are a crucial circuit component for regulating behavioral states.
• These long-range inhibitory neurons can induce both sleep-like cortical states and sleep behavior.
• Findings challenge the notion that sleep is exclusively driven by subcortical mechanisms.