Effects of Deep Brain Stimulation on Hippocampal Neuronal Activity in a Rat Model

Take an anesthetized rat secured in a stereotactic frame and sterilize the exposed scalp. Then, drape the animal, exposing the surgical site.

Make a midline incision and retract the skin to expose the skull. Clean the incision site.

Identify the bregma, then mark two points on both sides of the skull to target the brain region that directly communicates with the hippocampal neurons.

Drill small holes at the marked sites and remove the bone debris.

Mount a dual-electrode assembly onto the electrode holder.

Insert the electrodes deep into the brain through the holes, reaching the target region.

Apply deep brain stimulation, or DBS, using high-frequency electrical pulses.

These pulses change neuronal activity and signal transmission, enhancing communication with the hippocampal neurons.

In response, neurons in the hippocampus release factors that support their survival and improve connections with other neurons.

These factors also help create conditions that allow new neurons to form.

This demonstrates the therapeutic potential of DBS in treating brain disorders.

Make an incision in the scalp sagittally to reveal the skull. Using a pair of retractors, secure the incised scalp to expose the skull. Then with sterile swabs dipped in ethanol, clean the incised region to expose the sutures clearly. Locate the bregma and use a black marker to mark it.

To guide the position of the bur holes, make two more marks at approximately 1.5 millimeters Mediolaterally on both sides from the sagittal suture and 1.6 millimeters posterior to the coronal suture. Now to make the two bur holes, use ethanol to disinfect the tip of the drill.

Using a drill held at a 45 degree angle, drill the bur holes frequently switching between the two holes to avoid excessive heat at the center of either bur hole. Continue drilling until the dura is exposed. Using a needle with its tip bent in the shape of an L, remove any broken pieces of bone that would obstruct the insertion of the electrode.

Take care to avoid damaging the underlying dura and or brain tissue while removing bone fragments. Fix the dual electrode assembly to the rotating handle of the stereotactic frame and fix the handle at a 90 degree angle. Using the adjustments in the stereotactic frame position the left electrode exactly above the bregma.

Using the stereotactic adjustments for mediolateral positioning precisely move the left electrode 1.5 millimeters to the left side of bregma, such that now there are two electrodes perfectly aligned along the coronal suture, but spaced apart 1.5 millimeters mediolaterally from the bregma.

Then with the anterior posterior stereotactic adjustments, move the electrodes 1.6 millimeters posterior to the coronal suture. Then with the dorsal ventral adjustments, lower the electrodes to first check if the bur holes have been made in the right location, such that the electrodes can be inserted with ease without touching the rough edges of the bur holes. If so, insert the electrodes to a depth for 5.2 millimeters from the surface of the skull.

Connect the electrodes via leads to a stimulator set at 130 hertz, 2.5 volts and 90 microsecond pulse width. Deliver high frequency stimulation for a desired period of time. Performing unilateral or bilateral stimulation.