Neuroscience: unveiling the brain of Saimiri collinsi (Squirrel Monkey)

Abstract

Behavioral intelligence among non-human primates is a somewhat puzzling area to study, since it is closely linked to the morphology of the central nervous system. However, this morphology is still unknown to science in the case of Saimiri collinsi. As a means of assisting future studies on the social behavior of this species, we analyzed the brains of six adult females from the National Primate Center / Pará, which were sent to the Animal Morphological Research Laboratory at the Federal Rural University of Amazônia after death by natural causes. The animals were fixed in formaldehyde solution (10%) and dissected. The brains were covered externally by the dura mater, with long cerebral hemispheres, although there was a complete absence of gyri. The internal structures which form a part of the telencephalon, diencephalon, midbrain, hindbrain and myelencephalon were identified, with the exception of the mammillary bodies. This condition, when linked to the lissencephaly found in these individuals raises questions about the real learning abilities of this species.

Comparative anatomy of the encephalon of new world primates with emphasis for the Sapajus sp

“…Among all primates, the neotropical ones are scarcely studied, except for the genus Sapajus (bearded capuchins), which, remarkably and unexpectedly, exhibit characteristics such as memory, cognition, social behavior, and tool use similar to chimpanzees [ 9 , 13 – 28 ] a big brain in relation to their body mass [ 11 , 20 ]; and high motor development [ 29 , 30 ]. Additionally, there is some research on the brain of Saimiri collinsi [ 31 ], Sapajus apella (formerly Cebus apella ) [ 11 , 32 ] and Callithrix sp. [ 33 ], but the studies did not include a detailed comparative anatomy or investigate the correlations with behavior and evolution.…”