Cortex-wide Changes in Extracellular Potassium Ions Parallel Brain State Transitions in Awake Behaving Mice

Area of Science:

• Neuroscience
• Computational Neuroscience
• Systems Neuroscience

Background:

• Brain state fluctuations significantly impact sensory processing.
• The underlying mechanisms governing state-dependent neural activity are not fully understood.
• Extracellular potassium ([K+]o) is a key ion influencing neuronal excitability.

Purpose of the Study:

• To investigate the role of extracellular potassium ([K+]o) concentration dynamics during brain state transitions.
• To determine how changes in [K+]o affect sensory and motor processing.
• To elucidate the relationship between brain states, [K+]o, and neural activity modulation.

Main Methods:

• Tracked cortical extracellular potassium ([K+]o) concentrations during awake state transitions in mice.
• Manipulated [K+]o levels in cortical slices and in vivo during visual processing and motor tasks.
• Measured visually evoked responses and neuronal spiking activity in response to motor execution.

Main Results:

• A significant increase in cortical [K+]o (0.6-1.0 mM) preceded locomotion onset by 1 second.
• Emulating this [K+]o increase in slices caused neuronal depolarization and enhanced input-output transformation.
• Locomotion-induced [K+]o increases enhanced visual response gain and improved motor performance.

Conclusions:

• Cortical extracellular potassium ([K+]o) increases in a state-dependent manner, particularly during transitions to locomotion.
• These [K+]o increases dynamically modulate both sensory and motor processing by altering neural activity.
• Extracellular potassium concentration is a critical factor linking brain states to neural function.