Unruly neurons set the stage for synaesthesia

摘要

The mysterious mechanisms that lie behind synaesthesia could be explained by hyperactive neurons. In grapheme-colour synaesthesia an individual's sense of numbers or letters is associated with colours. Devin Terhune at the University of Oxford studied the brains of six people with this kind of synaesthesia using a non-invasive technique called transcranial magnetic stimulation. He found that neurons in the primary visual cortex were more active than expected. Suspecting that these hyperactive neurons played a role in synaesthesia, Terhune used transcranial direct current stimulation to damp down their activity. Surprisingly, this actually intensified the synaesthetic experience (Current Biology, DOI: 10.1016/j.cub.2011.10.032).