Comparative anatomical and functional measurements across species

Throughout history, comparative brain measurements across species have provided invaluable insight into not only the evolution of brain structure and function, but also insights for health, disease, and medicine. The CNL has dabbled in studies comparing functional and anatomical measurements across species. The CNL will continue to do so through collaborations and data sharing. For example, we have recently started a collaboration with Bill Hopkins at Emory to examine the fusiform gyrus (FG) in non-human hominoids. This is important because widely studied species such as marmosets and macaques do not have an FG. Thus, from a comparative anatomy standpoint, a natural starting point for understanding the evolution of the structure of the FG is to study non-human hominoids (see image).

The medial surface of a chimpanzee (Troglodytes niger) from Retzius (1906). While Retzius only labeled the collateral sulcus (co, right), we preliminarily identified what is likely the mid-fusiform sulcus (black arrow) and the lingual sulcus (asterisk). Future morphological analyses of cortical folding from neuroimaging datasets of chimpanzees in the coming years will support or refute these preliminary observations. Image adapted from Weiner and Zilles, 2016.

From a cognitive neuroanatomy standpoint, an interesting theoretical question that we keep in the back of our minds is: if the anatomical substrate is different among species, but the topological layout of cortical systems is similar among species, are the neurons within those systems actually performing the same computations? For example, the brains of marmosets and humans are vastly different, yet their face processing systems are topologically very similar. Thus, thinking of ways to computationally model the emergence of cortical networks in vastly different brains is a topic for future work.

Inflated cortical surface of a marmoset (from Hung et al., 2015) and a human. Warm colors indicate face-selective regions for each species. Dotted circular outline indicates the location of area MT in marmosets and the hMT+ complex in humans. Human data are from our lab. Note that despite vastly different brain size, appearance, and the fact humans have more gyri and sulci, as well as other neuroanatomical structures, compared to marmosets, the face networks of the two species are each topologically distributed in similar ways. Image adapted from Weiner and Grill-Spector, 2015.

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