A reliable system of ventricular coordinates for the cartography and stereotaxy of the amygdala (and anterior hippocampus) in macaques

Abstract

The most reliable stereotactic methods in primates resort to ventricular as opposed to bony landmarks. The usual CA-CP system did not appear satisfactory for stereotaxy of the amygdala and anterior hippocampus. Variation studies on ventriculograms and reconstructions from histological material were done to find more reliable systems. The most precise system of coordinates for cartography and stereotaxy of the amygdala is based on the `amygdalar notch', a ventricular diverticulum forming the angle between the inferior and anterior borders of the temporal horn of the lateral ventricle, located beneath the inferior border of the amygdala. The AN point, the vertex of the notch in the sagittal direction, is a reliable ventricular landmark in the antero-posterior and infero-superior directions. The medial vertex of the diverticulum, ANm, is a ventricular landmark in the medio-lateral direction. The `AN system of coordinates' is a reliable system for amygdalar stereotaxy. Stereotaxy of the anterior hippocampus would benefit from other ventricular landmarks. The most lateral point of the main body (HiL) is a landmark for the medio-lateral dimension. Ventriculography and ventricular landmarks should always be used for stereotaxy in primate species.