A Stereotaxic Template Atlas of the Macaque Brain for Digital Imaging and Quantitative Neuroanatomy

Abstract

A stereotaxic brain atlas of the longtailed macaque (Macaca fascicularis) is presented in a format suitable for use as a template atlas of the macaque brain. It includes most of the brain segmented to show the boundaries of landmark structures such that every point in the brain can be represented by a unique set of coordinates in three-dimensional space and ascribed unambiguously to one and only one primary structure. More than 400 structures are represented, including 360 volumetric structures, which constitute the substance of the brain, and 50 superficial features. To facilitate use with ventriculography, magnetic resonance imaging, and other noninvasive imaging techniques, the stereotaxic space is referenced to internal landmarks, viz., the anterior commissure and posterior commissure; the center of the anterior commissure at the midline is the origin of the stereotaxic axes. Reference of stereotaxis to this bicommissural space facilitates structural comparison with human brain atlases, which are commonly referenced to the biocommissural line. It also facilitates comparison of brains of different nonhuman primate species by providing a template brain against which to compare size and internal variability. Thirty-three coronal sections at 1-mm intervals from the spinomedullary junction to the rostral extreme of the caudate nucleus show most structures of the hindbrain, midbrain, and subcortical forebrain. Separately, four side views and 16 coronal sections show cortical structures. Structures are represented by outlines of their boundaries and labeled according to NeuroNames, a systematic English nomenclature of human and nonhuman primate neuroanatomy. Abbreviations are based on a protocol designed to facilitate cross-species comparisons. Instructions are provided for: (1) locating sites from the Template Atlas in the conventional stereotaxic space of an experimental animal, (2) locating sites identified by conventional stereotaxis in the Template Atlas, and (3) using the Template Atlas to collate, compare, and display image information (e.g., labeled cells, recording sites, stimulation sites, lesions) from multiple animals.