Abstract

One important topic of debate in synesthesia literature is whether the brains of synesthetes differ structurally from the brains of non-synesthetes. Specifically, is the 'connection' from one experience to another experience, served by increased anatomical connections in the brain? DTI is a relatively novel methodological approach that allows us to measure and compare white matter properties in vivo in the human brain. In this chapter, we will describe this methodology, discuss what can be concluded based on DTI results, and show what DTI research has taught us so far about the neurobiological mechanisms underlying synesthesia. DTI results show that synesthetes indeed have hyperconnectivity as compared with non-synesthetes. Furthermore, this hyperconnectivity is obtained in brain areas functionally related to the inducer and the concurrent experience, as well as in 'higher-level' or associative brain areas.