Vagus Nerve Stimulation in a Rat Model to Reduce Freezing Behavior

Begin with a rat implanted with a headcap connected to a stimulation cuff positioned around the vagus nerve.

Place the rat in a sound-attenuated box containing a conditioning chamber with a steel grid floor. First, expose the rat to sound alone to confirm that it does not exhibit a fear response.

Then, deliver the sound with a mild footshock to induce fear conditioning in the rat.

The sound and shock activate fear response pathways in the brain's amygdala, causing the rat to freeze.

Re-expose the habituated rat to the sound without a footshock. This causes the rat to freeze. Record the freezing time to establish a baseline.

Connect the headcap to the stimulation system and return the rat to the chamber.

Initiate vagus nerve stimulation or VNS and present the sound without a footshock.

VNS activates the vagus nerve, stimulating the prefrontal cortex and suppressing amygdala-driven fear signals.

A reduction in freezing time after nerve stimulation demonstrates its neurotherapeutic potential.

Set up the operant conditioning box under video camera surveillance. On the first day of behavioral training, present the tone five times for 30 seconds to demonstrate there is no innate fear of the tone.