Anomalous Auditory Cortex Activations in Colored Hearing Synaesthetes: An fMRI-Study

作者:Gaschler Markefski Birgit; Szycik Gregor R*; Sinke Christopher; Neufeld Janina; Schneider Udo; Baumgart Frank; Dierks Oliver; Stiegemann Ursula; Scheich Henning; Emrich Hinderk Meiners; Zedler Markus
来源:Seeing and Perceiving, 2011, 24(4): 391-405.
DOI:10.1163/187847511X588061

摘要

Color percept induction in synaesthetes by hearing words was previously shown to involve activation of visual and specifically color processing cortex areas. While this provides a rationale for the origin of the anomalous color percept the question of mechanism of this crossmodal activation remains unclear. We pursued this question with fMRI in color hearing synaesthetes by exposing subjects to words and tones. Brain activations in word condition accompanied by highly reliable color percepts were compared with activations in tone condition with only occasional color percepts and both contrasted to activations in normal subjects under the same stimulus conditions. This revealed that already the tone condition similar to the word condition caused abnormally high activations in various cortical areas even though synaesthetic percepts were more rare. Such tone activations were significantly larger than in normal subjects in visual areas of the right occipital lobe, the fusi form gyros, and the left middle temporal gyros and in auditory areas of the left superior temporal gyms. These auditory areas showed strong word and tone activation alike and not the typically lower tone than word activation in normal subjects. Taken together these results are interpreted in favour of the disinhibited feedback hypothesis as the neurophysiological basis of genuine synaesthesia.