Recording of Local Field Potential from Both Hemispheres of the Mouse Brain

Prior to surgery, confirm the depth of anesthesia of the mouse by performing a tail or toe pinch with forceps. Next, position the mouse in a stereotaxic apparatus, and fix its head. Apply ointment on both eyes to keep them moist.

Then, shave the head and sterilize the area. Make a small incision of 12 to 15 millimeters in the middle of the shaved area. Using forceps, gently pull the scalp away from the midline. Afterward, separate the skin gently, and remove the residual tissue.

Clean the skull using hydrogen peroxide-coated cotton buds. Under a stereomicroscope, drill two small holes of 1- to 1.5-millimeter radii on both the left and right sides of the skull to allow insertion of the recording microelectrodes into the M2 regions.

Carefully, remove the dura mater with a tungsten needle, then, insert two separate recording microelectrodes filled with 0.5 molar sodium chloride into the holes at an angle of 60 degrees using mechanical micromanipulators.

For LFP recording, slowly lower the left and right glass electrodes to the M2 coordinates. For quality control, test the resistance of each electrode using the differential amplifier. Next, set the recording process at 0.1 Hertz high-pass and 1,000 Hertz low-pass with 1,000 times amplification. Collect the digitized raw LFP data in stable state for at least 60 seconds, with the mouse breathing evenly at two breaths per second under anesthesia.