In the past, the usefulness of atlases available for stereotaxy in non-human primates has been limited by the way in which the horizontal zero plane was defined. When using the orbitomeatal plane (the so-called Frankfurt plane) or the Horsley–Clarke reference (10 mm dorsal and parallel to the Frankfurt plane), huge differences have been observed between existing atlases (Shanta et al.
1968; Szabo and Cowan
1984). This especially holds true when trying to calculate stereotaxic coordinates for deep brain structures, as reported elsewhere (Percheron and Lacourly
1973; Dubach et al.
1985). Given the current popularity of ventriculography-assisted surgery as well as other non-invasive imaging methods such as MRI, researchers can now rely on internal landmarks instead of cranial references for accurate primate stereotaxy. In this regard, the bicommissural plane defined as a horizontal plane linking the anterior and posterior commissures (ac–pc line) is the basic reference in modern primate stereotaxy, as is the standard for human neuroimaging (Tailarach et al.
1957; Schaltebrand and Wahren
1977; Morel
2007).
In designing a useful stereotaxic atlas for non-human primate surgery, several requirements must be considered, as summarized by Martin and Bowden (
1996). Among others, these “golden rules” comprises (1) appropriate stereotaxic references for any given point within the brain, (2) complete segmentation for unambiguous representation of the boundaries of the brain nuclei, (3) comprehensive and detailed representation of brain structures and (4) usage of standardized nomenclature. In our experience, two more requirements are desirable: firstly, a modern atlas should be constructed keeping in mind at all times a surgical perspective, and therefore, all coordinates should be referenced to the ac–pc line, as the origin of the bicommisural space being the center of the anterior commissure at the midline. Secondly, we emphasize the need for technical excellence of stained sections (histochemical and immunohistochemical procedures) from which brain cartography is performed. Although existing atlases do not fulfill all these demanding criteria, several atlases do approach the ideal. The Szabo and Cowan atlas (
1984) established the basis for stereotaxic surgery in
Macaca fascicularis many years ago. Later on, this atlas was superseded by the seminal contribution of Martin and Bowden (
1996). The Martin–Bowden atlas was published one year later in a book format by the University of Washington in Seattle (
1997) and then licensed to Elsevier (Martin and Bowden
2000), the latter version included a useful CD-ROM. Unlike the Szabo-Cowan atlas, the Martin and Bowden atlas combined complete brain segmentation and exquisite drawing technique, with the use of a comprehensive nomenclature based on NeuroNames Brain Hierarchy (Bowden and Martin
1995). It is also worth noting that an excellent probabilistic atlas for the basal ganglia in macaques was published some years ago by François et al. (
1996). Finally, three stereotaxic atlases of
Macaca mulatta based on different concepts have been made available: one comprising of full brain segmentation based on coronal sections from Paxinos and his colleagues (2009, 2nd edition, fist edition appeared in 2000), another one containing Nissl-stained sagittal sections of the basal ganglia and thalamus (Ilinsky and Kultas-Ilinsky
2002), and the most recent atlas was designed for MRI-based stereotaxic surgery, including horizontal and coronal sections stained with several cytoarchitectonic and immunohistochemical techniques (Saleem and Logothetis,
2007).