English: The outer cortical surface with proposed regions involved in the neural substrates of grapheme–color synesthesia under the conceptual-mediation model. The anterior temporal lobe (ATL) is indicated in magenta. In our model, the ATL functions as a representational “hub” that processes lexical meaning and associates the lexicon to synesthetic color representation at an abstract, conceptual level. The color-related area of the posterior ventral temporal cortex is indicated in green. This cortical region contains the fusiform gyrus (V4) and the lingual gyrus. In our model, this area serves as a “spoke” that processes the subjective experience of synesthetic color and may not overlap with the neural basis of real color experience. The posterior parietal lobe is indicated in blue. This region mediates the attention-related functions in synesthesia, such as directing voluntary attention to an inducer or binding graphemes with color at a perceptual level, akin to its role in the typical function of binding various visual attributes (color, shape, location, etc.) of an object.