If you’re happening upon our blog for the first time, the big question on your mind might be: Why do we study brains? And if you checked out out Team of Researchers, you know that many of us are comparative neuroanatomists. So, why study brains and, more specifically, why is it informative to compare brains to one another?
As comparative neuroanatomists, we compare and contrast the brains of different animals (Fig. 1) to try to make sense of the rules that may govern how brains change. We may look at the brains of closely related species (i.e., within a given taxonomic group) or we may broadly compare across divergent taxa. Essentially we are asking two fundamental (and simple sounding) questions: 1. How are brains similar between species? and 2. How are brains different? Although these questions sound very straightforward, they’re not always easy to answer.
Firstly, there are a lot of similarities in the brain that are common across all vertebrates. This means that there are major structures that make up your brain that can be identified in nearly all other vertebrates, including other mammals, birds, and fishes, such as the ‘cerebrum’ (also called the telencephalon), cerebellum, and optic tectum (Figure 2). And there are also fundamental constraints that dictate how big brains can get and the relationship between brain and body growth. Similarly, we can investigate the relationship between different brain structures and brain size and test whether there are rules that govern brain structure change across different animals. In a paper by several members of our team, we showed startling similarities between the relationship between brain structure size and brain size from sharks all the way through to primates (Yopak et al., 2010).
Within these common developmental rules, there is still quite a lot of natural variation in the brain – even within a single taxonomic group – and this variation often reflects the functional requirements of an animal’s nervous system and therefore gives important insights into ecology and evolution. Because we know the regions of the brain that receive input from certain sensory systems or are responsible for coordinating higher cognitive function, examining variation in the size of these structures can have important functional implications. Across many vertebrates groups, studies have shown that differences in brain size as well as the relative development of major brain parts are often closely linked to an animal’s ecology or to specialized behavior patterns. From looking at the relative size and shape of the brain region and pathways responsible for olfaction (smell) (Figure 3), for example, we can make predictions about the animals that may be olfactory specialists.
It’s one thing to tell you that brains are both similar and different, but we’re hoping to take our collective knowledge and move from words into 3D objects that our students can pick up and explore. Our next blog post is going to talk you through how we acquire and properly prepare nervous system tissue, on its journey to becoming a geometrically accurate, 3D printable object. Stay tuned….
1. Yopak KE (2012): Neuroecology in Cartilaginous Fishes: The Functional Implications of Brain Scaling. J Fish Biol 80:1968-2023. (read here)
2. Yopak KE, Lisney TJ, Darlington RB, Collin SP, Montgomery JC, Finlay BL (2010): A conserved pattern of brain scaling from sharks to primates. Proceedings of the National Academy of Sciences 107:12946-12951. (read here)
3. Yopak KE, Lisney TJ, Collin SP (2015): Not all sharks are “swimming noses”: Variation in olfactory bulb size in cartilaginous fishes. Brain Structure and Function 220:1127–1143 (read here)