Local extracellular K⁺ in cortex regulates norepinephrine levels, network state, and behavioral output

Area of Science:

• Neuroscience
• Neurophysiology
• Behavioral Neuroscience

Background:

• Extracellular potassium concentration ([K+]e) increases with arousal and modulates neurotransmitter release.
• The role of [K+]e in neuromodulator release during behavioral transitions remains unclear.

Purpose of the Study:

• To investigate whether extracellular potassium concentration ([K+]e) influences the release of monoaminergic neuromodulators.
• To determine the impact of manipulating cortical [K+]e on neuromodulator levels and behavioral states, specifically the sleep-wake cycle.

Main Methods:

• Manipulation of extracellular potassium concentration ([K+]e) in the cortex.
• Measurement of local monoaminergic neuromodulator release (norepinephrine, serotonin, dopamine).
• Electroencephalography (EEG) analysis and behavioral assays in mice to assess sleep-wake cycles and behavior.

Main Results:

• Manipulating cortical [K+]e was shown to control the local release of norepinephrine (NE), serotonin, and dopamine.
• Increasing [K+]e boosted local NE levels, while decreasing [K+]e attenuated them.
• Alterations in cortical [K+]e were sufficient to modify the sleep-wake cycle and behavior in mice.

Conclusions:

• Cortical [K+]e dynamics significantly impact local NE levels, challenging the notion that NE is solely regulated by subcortical release.
• Extracellular potassium concentration emerges as a critical, yet underappreciated, regulator of behavioral transitions and cortical NE.
• This study highlights a novel mechanism linking ionic changes to neuromodulation and behavioral state control.