Following experiments rats were anesthetized with a lethal dose of sodium urethane (2 g kg−1, i.p.). A tungsten electrode was inserted into the location where recordings had been made because the carbon-fiber electrode causes little damage to brain tissue (Peters et al., 2004). To create an electrolytic lesion a constant current of 500 μA was applied twice for 5 s through the tungsten electrode. Rats were then transcardially perfused with 300 ml of saline followed by 300 ml of a 10% formalin solution. Brains were dissected out, cryoprotected and coronally sectioned at 40 μm on a cryostat. Brain sections were mounted on slides, stained with thionin, coverslipped, and viewed with bright field microscopy.
