[An improved method for isolating a section of the rat neocortex].

Neocortical island chronically isolated from surrounding cortical and subcortical structures with preserved pial blood supply has long been a model for research into the mechanisms of cortex functioning. To fully cut the cortex we improved the type of knife by using a retractable tungsten wire. The tip of a syringe needle was bent and cut away all but the beginning of the bend. In anesthetized rats the somatosensory cortex was exposed, the guide needle was lowered down to the desired depth into the cortex avoiding blood vessels. The wire then was pulled out through the curved needle tip until the tip of the wire touched the pia mater. The device was then raised, lowered, rotated to achieve complete separation of the cortical island from the surrounding tissues. The wire was retracted into the needle before withdrawal of the device. Analysis of neocortical slices 8 weeks later showed lesions of the white matter and transcortical cuts.