Subdural Implantation of a Soft Electrocorticography Array for Cortical Electrophysiology Recording in Minipigs

Begin with an anesthetized minipig with a bilateral craniotomy over the auditory cortex.

Create slits in the dura mater, the brain's outer covering.

Take a soft electrocorticography array consisting of electrode strips, flexible cables, and a port with connectors.

Insert the strip until the cable edge rests atop the slit, ensuring proper electrode placement on the auditory cortex surface.

Repeat the procedure contralaterally.

Place a titanium bridge over the cables, securing the implant.

Insert the ground wires to establish a recording reference.

Suture the dura mater and replace and secure the bone flaps using titanium bridges.

Attach the footplate and pedestal to the skull. Suture the incision.

Allow the pig to recover and affix a wireless head stage to the pedestal.

The array captures electrical signals generated by cortical neurons, which are transmitted from the head stage to the recording system.

Apply sound stimulation and record the stimulus-induced activity of the auditory neurons.

Place the implant above the dura mater slit, and with small forceps, subdurally insert the device by sliding it sequentially on each edge. Carefully hold the pedestal end of the device, and advance with the implant in order not to create tension hindering the insertion.

Stop the insertion when the connector edge is located on top of the slit. To secure the implant in place, place a titanium bridge over the cable after the edge of the craniotomy or in the anchoring wings, and secure it with one or two titanium screws using the appropriate screwdriver.

Next, suture the dura mater carefully around the implant cable using a 3-0 resorbable suture and a small needle holder. Bring the two dura mater edges together as much as possible without tearing through the thin membrane with the suture wire.

To perform bone flap placement, fix a titanium bridge on the anterior and posterior part of each bone flap using a titanium screw. Screw the end of the titanium bridges to the skull. Next, plan the orientation of the footplate.

To ensure all legs can be screwed into the skull, then secure the footplate by screwing in the titanium screws of the footplate until it is firmly in place. Then, screw the pedestal onto the footplate. Create subcutaneous sutures with a 4-0 non-resorbable suture wire with sutures three millimeters apart. Start away from the pedestal, moving toward it on both sides of the incision. Next, close the dermal layer by suturing the skin using a 6-0 non-resorbable suture wire with sutures five millimeters apart.

Start away from the pedestal, moving toward it on both sides of the incision. Take care to achieve good tissue apposition between the two skin flaps and near the pedestal edge to avoid a void. After plugging the wireless head stage onto the animal, achieved by either holding the animal or distracting it by feeding it with treats, record the awake brain signals. Ensure to place the amplifier antenna and the external speakers close to the pig's cage while recording the signals.