Conexões corticais de duas espécies de primatas não humanos neotropicais (Sapajus apella e Alouatta caraya) evidenciados por tractografia de ressonância magnética

Abstract

Sapajus apella and Alouatta caraya are species of New World primates that inhabit South America. Both are distributed in different ecosystems that test their physical and behavioral aptitudes, needing their biological adaptations to conquer these environments such as vocalization and manipulation of tools. Many primates have prefrontal, parietal, temporal, and occipital cortex, all connected with white matter fibers, composed of long associative fibers and with well-defined sensory areas curiously separated from the cortex. Such connections are made by myelinated axons, which travel their paths grouped in order to form bundles or tracts. All these bundles are extremely important, because through them the integrality of the brain functions is succeeded by an exchange of somatosensory, visual, auditory information to plan whether or not to create a motor response for a situation faced. In order to map these different brain tracts, the magnetic resonance tractography technique is used, which uses the signal of diffusion tensor imaging that allows obtaining three-dimensional images. To identify the main cortical tracts of the central nervous system of non-human primates: Sapajus apella and Alouatta caraya using non-contrasted magnetic resonance imaging. Two healthy individuals of each species were chosen, male and female, which were submitted to deep sedation to be collected MRI images for a scan time of approximately 50 minutes. Then, the raw data underwent offline computational post-processing (3D Slicer software) and UKF tractography data rendering Pyhon package; tractography was calculated from DWI data using unscented Kalman filter obtaining a three-dimensional anatomical image. The three-dimensional images generated allow the analysis of brain tracts regarding their topography in the brain and also differentiate them from each other due to the color contrasted image that indicates the direction of the fibers. Thus, corticopontine, corticothalamic and corticospinal tracts are observed in a cranialcaudal direction; in an anteroposterior direction superior and inferior longitudinal fasciculus; in a laterolateral direction posterior commissure fibers. Through the reconstruction of the white matter of the central nervous system of new world primates by diffusion tractography, it is possible to identify details of nerve bundles, fibers and fascicles, proving that the recognition of the neuroanatomy of these structures is feasible by conventional imaging in non-contrasted magnetic resonance.