Vagus nerve stimulation induces widespread cortical and behavioral activation

Area of Science:

• Neuroscience
• Neuromodulation
• Systems Neuroscience

Background:

• Vagus nerve stimulation (VNS) treats neurological conditions, but its mechanisms remain unclear.
• Evidence suggests VNS modulates cortical state and plasticity via neuromodulatory systems.
• Understanding VNS's neural effects is crucial for optimizing therapeutic applications.

Purpose of the Study:

• To investigate the neural mechanisms underlying VNS-induced arousal and cortical activation.
• To compare behavioral and cortical responses to VNS in a mouse model.
• To elucidate the role of neuromodulatory pathways in VNS effects.

Main Methods:

• Used a mouse model with widefield and two-photon calcium imaging (GCaMP6s).
• Performed electrophysiological recordings to assess cortical activity and arousal-linked behaviors.
• Utilized vagus nerve transection to confirm VNS specificity.

Main Results:

• VNS induced dose-dependent increases in arousal behaviors (pupil dilation, movement) and widespread cortical excitatory activity.
• Cholinergic and noradrenergic cortical axons were strongly activated by VNS.
• VNS-evoked cortical activation persisted under light anesthesia, independent of overt motor activity.

Conclusions:

• VNS activates subcortical structures, leading to widespread cortical activation and increased arousal.
• Cholinergic and noradrenergic pathways play a significant role in VNS-mediated cortical modulation.
• Results support a model where VNS enhances cortical function through neuromodulation.