Vincent Bergeron (University of Ottawa)
A primary goal of cognitive neuroscience is to identify stable relationships between brain structures and cognitive functions using, for example, functional neuroimaging techniques. Aside from the many technical, theoretical, and methodological issues that accompany this kind of research, an important empirical challenge has begun to receive widespread attention. There is mounting evidence that a great many brain structures are recruited by different tasks across different cognitive domains (Anderson 2010; Poldrack 2006), which suggests that a given brain structure can typically participate in multiple different functions depending on the cognitive context.
One possible reason for the failure to observe systematic mappings between brain structures and cognitive functions is that a given brain structure, or network of brain structures, might do something different (i.e. perform a different set of operations) for each, or at least some, of the different types of cognitive functions it participates in (Anderson 2014). Another possible reason is that our cognitive ontologies—i.e. our current descriptions of cognitive processes and their components—are either incorrect or too coarse (Price and Friston 2005). Thus the basic contribution of a brain structure might be the same for the different types of cognitive functions it participates in—with the possibility of systematic structure-function mappings—but an adequate description of this basic contribution might not correspond to anything in the vocabulary of our current theories about the structure of the mind. My aim in this paper is to explore this second possibility.
The human brain shares many of its anatomical and functional features with that of other species, and we can expect that for any human cognitive function, (at least) some component(s) of it could be found in the cognitive repertoire of another species (de Wall and Ferrari 2010). What is less clear, however, is how best to exploit this evolutionary continuity in order to identify the components of the human neurocognitive architecture that we share with other species and that have remained stable across extended evolutionary periods. Here, I argue that a useful way to think about these shared components is to think of them as cognitive homologies. In contrast with the well-known concept of structural homology in biology—defined as the same structure in different animals regardless of form and function, where sameness is defined by common phylogenetic origin—the proposed notion of cognitive homology focuses on the functional properties of homologous brain structures that tend to remain stable across extended evolutionary periods. I then argue, using recent findings from the cognitive neurosciences, that cognitive homologies are good candidates for stable structure-function mappings which, in turn, can be used for the construction of new cognitive ontologies.
