A craniotomy was made, the dura was retracted to expose the cortex and the needle was lowered to the desired location under microscopic guidance.
The dura was excised above the injection site using a 30-gauge needle.
Due to the angle of entry, the majority of recordings were made beneath intact dura, with generally good stability.
The dura was resected and the cortex was aspirated down to white matter.
The dura mater overlying both regions of exposed central nervous tissue was cut and warm mineral oil applied to prevent drying.
The dura mater was removed above the auditory cortex and at a position vertically above the auditory thalamus.
The dura mater was sewn back and regrew over the electrode array.
After removing the dura, the chamber was filled with silicone oil and sealed with a round glass coverslip.
