Synesthesia is a neurological condition that involves hyper-connectivity, a high degree of cross-talk between senses. This extreme connection causes individuals with synesthesia to make unusual—and sometimes extremely artistically interesting—associations. For example, in colored sequence synesthesia, individuals associate graphemes—letters or numbers—with specific colors. This tendency seems to be an exaggeration of the tendency that cognitively normal humans have to use metaphor—to connect different imagery in a unique, visually-rich manner.
Multiple studies have confirmed a probable genetic basis of synesthesia using Family Linkage studies, which explore the prevalence of a disorder within a specific lineage. However, finding specific genes linked to the disorder has been extremely challenging due to the highly heterogeneous nature of the condition; over 60 different kinds of synesthesia have been identified.
In a new study, published in a 2011 issue of Behavior Brain Research, a team of researchers has discovered that color-association synesthesia, in particular, seems to be linked to a gene in the region 16q12.2-23.1. However, only two of the families used in the study showed linkage to this region; thus, CSS on its own is likely heterogenous. Thus, the study largely supports previous research, which suggested that synesthesia was likely tied to a complex interaction between many different genes. Still, though, it presents progress on the identification of specific loci.
Understanding synesthesia goes beyond simply understanding one very specific condition; this study, for example, aims “to understand how neural crosstalk arises in a healthy brain, in the hopes of ultimately understanding how this mechanism might be modified in a disease state.” Indeed, the authors suggest that we can use Synesthesia to understand disorders that involve a high degree of cross-talk, such as Autism, Alzheimer’s disease, and Schizophrenia. On the other side, understanding the genetic basis Synesthesia may also help us to more deeply understand other aspects of the human brain; perhaps, by understanding this disorder, we can start to understand a potential genetic basis for the complex processes of human creative thought.
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For a really interesting article on sound-symbolism and a kind of synesthesia-like mechanism in language development, see: