Fig. 2.

Atlas coordinate system and stereotaxic reference system. Upper panel landmarks bregma, lambda and occipital crest (encircled) on the skull of a Mongolian gerbil in a top view. They are defined by the intersection of lines (dotted lines) approximating the course of the bone sutures. Lower panel montage of CT skull image and MR brain image at a parasagittal distance of 1 mm in standard orientation of the atlas. The solid line corresponds to the horizontal plane through lambda and occipital crest, which is parallel to the plane through the highest points of cerebrum and cerebellum (dotted line)