Fig. 2. Histologic localization of a dialysis site. Sagittal section of cat brain stem shows a typical microdialysis site (arrow) localized within the medial pontine reticular formation (mPRF). Inset indicates location of the mPRF on a midsagittal schematic of the cat brain and schematizes a microdialysis probe used to deliver drugs and collect endogenously released acetylcholine. Comparison of histologic sections from all cats to a cat brain stem atlas 32confirmed mPRF dialysis probe placement for all animals used in this study. 7G = genu of facial nerve; 6 = abducens nucleus; 6N = abducens nerve; IC = inferior colliculus; TB = trapezoid body.