A stereotaxic atlas of the forebrain of the bank vole (Clethrionomys glareolus)

In this article part of the forebrain of the bank vole (Clethrionomys glare olus) is presented in stereotaxic coordinates. The stereotaxic procedure wa s performed as follows. With the vote's head mounted in a stereotaxic adapt or, internal reference tracks were made with a 0.5-mm diameter microdialysi s cannula and India ink, 2 mm in front and 2.6 mm behind the skull landmark bregma. Brains were fixed for 72 h in 4% commercial formaldehyde in sodium cacodylate buffer containing 1% CaCl2. To determine shrinkage they were wei ghed before and after fixation. After embedding in paraffin they were secti oned at 25 mu m and stained with Nissl. Photomicrographs were taken from th e brain of one animal while its frontal (antero-posterior) coordinates of f ive neural structures were compared with those of 12 other voles. Variabili ty was also checked in lateral and vertical directions at frontal level -1. 0 mm (relative to bregma). The results show that the distance between the t wo skull landmarks bregma and lambda correlates significantly and negativel y with the antero-posterior position of each of the brain areas. On the bas is of these results an equation is proposed to improve accuracy in locating neural structures that deviate due to biological variability. (C) 1999 Els evier Science Inc.