A stereotaxic atlas of the rat brain

Includes bibliographical references (pages 91-96)The first stereotaxic brain atlas was published by Horsley and Clarke in an article describing the stereotaxic apparatus that they had designed (1908). Since that time numerous stereotaxic brain atlases have been published covering many different laboratory animals. As most brain surgery is performed using the vertical approach, atlases generally depict the coronal or sagittal plane though preparations involving such areas as the limbic system could be more clearly designed using the horizontal perspective. Presently there are no horizontal stereotaxic brain atlases for the rat. Furthermore, none of the available atlases include any means of correcting for the fixation deformed tissue used in the preparation of the atlas drawings and scales.\ud The rat brain atlas developed in this thesis, sections tissue in the horizontal plane as well as analyzing and quantifying the tissue deformations. After fixation, the distances were measured between the marking rod tracts which had been stereotaxically made at fixed positions in the brains of live, Long-Evans strain rats. The tissue distortion was shown to be less than 11% across any plane, structure or level and, while no corrections were made for this in the atlas plates, included in the text are the reduced statistical data necessary to apply a correction factor if desired. The atlas also employs two stereotaxic coordinate systems. The atlas is made up of photographic enlargements of the actual unstained tissue augmented with the anatomical outlines of structures and fiber tracts on clear acetate overlays. This atlas was designed to supply the horizontal dimension for stereotaxic surgery in the rat brain and to include the necessary statistical data to correct for the distortions encountered in the tissue diagrams