Representative examples of NeuN immunohistochemistry of a complete auditory cortex lesion or sham-operated control section. Rats were anesthetized with halothane and placed in a Kopf stereotaxic apparatus. The skin overlying the skull was disinfected, an incision made, and small burr holes drilled through the skull bone to allow penetration of the injector (Hamilton 1 µl syringe). Bilateral excitotoxic lesions (two per side) were produced by injections of 0.25 µl ibotenic acid (10 µg/µl in 0.1 M sodium phosphate buffer, pH: 7.4; ab120041). The rate of infusion was 0.05 µl/min. The injector was lowered in the brain and left in place 3 min before and 5 min after each injection.