Cholinergic signals in mouse barrel cortex during active whisker sensing

Area of Science:

• Neuroscience
• Cortical dynamics
• Sensory processing

Background:

• Internal brain states modulate perception, cognition, and learning.
• Neocortical areas show altered neuronal activity patterns during quiet versus active behaviors.
• Active behaviors typically correlate with desynchronized cortical dynamics.

Purpose of the Study:

• To investigate the mechanisms underlying cortical state changes during active behaviors, specifically whisking.
• To determine the role of acetylcholine in mediating whisking-related cortical desynchronization.
• To elucidate the distinct signals contributing to the barrel cortex state during active whisker sensing.

Main Methods:

• Whole-cell recordings in mouse barrel cortex.
• Local pharmacology to manipulate neurotransmitter levels.
• Axonal calcium imaging to monitor neuronal activity.
• Optogenetic stimulation to control neuronal populations.

Main Results:

• Whisking behavior induces prominent cholinergic signals in the barrel cortex.
• Cholinergic input during whisking suppresses spontaneous cortical activity.
• A whisking-related cortical state change persists even after thalamic inactivation, indicating a parallel pathway.

Conclusions:

• The desynchronized state of the barrel cortex during whisking is driven by two opposing signals: thalamic excitation and cholinergic suppression of spontaneous activity.
• Acetylcholine plays a significant role in shaping cortical dynamics during active sensory behaviors.
• Understanding these dual mechanisms is crucial for comprehending sensory perception and learning.