Investigating Auditory Neuronal Responses in an Awake Mouse in the Presence of an Inhibitory Neurotransmitter Blocker

Secure an awake mouse in a stereotactic frame, with a silver wire inserted into its dura and an opening exposing a brain region that processes auditory stimuli.

Fill a drug solution into a multibarrel glass pipette fitted with a tungsten electrode and attach it to the stereotactic frame holder.

Insert uncoated silver wires into the barrels, ensuring one end contacts the solution while the other connects to a device controlling drug release.

Connect the positive and ground terminals of the recording wires to the tungsten electrode and the silver wire contacting the dura, respectively.

Place the multibarrel electrode on the brain surface and apply auditory stimuli.

Record the neuronal activity.

Next, apply a positive current to release the drug.

The drug enters the brain and blocks specific receptors, preventing inhibitory neurotransmitter binding and increasing neuronal excitability.

Finally, apply the auditory stimuli again and identify the increased neuronal response post-drug treatment.

In this procedure, place the animal's body into a custom-made, foam-cushioned restrainer. Secure the head-post to a holder attached to the stereotaxic frame. This is a good time to give the animal a liquid reward. Next, cover the animal's body with a cotton blanket, and loosely fasten it using a plastic hemi-cylinder and adhesive tape.

Use a syringe with a flexible tip to fill the barrels with the chosen drugs. Using the micromanipulator, place the multi-barrel electrode on its holder. Next, place an uncoated silver wire inside each barrel so one end contacts the solution and the other end is accessible. Then connect those ends to the microiontophoresis device.

After that connect the positive terminal to the end of the tungsten electrode and the ground terminal to the silver wire that contacts the dura. Subsequently, move the multi-barrel electrode until the tip contacts the surface of the brain. Apply warm sterile saline to prevent the desiccation of the brain tissue. At that point, apply retention current to avoid drug leakage from the barrel tip while looking for single-unit activity. Record neural activity and iontophoretic application of gabazine.