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
Leibniz Institute for Neurobiology, Magdeburg, Germany.
Seeing Perceiving. 2011;24(4):391-405. doi: 10.1163/187847511X588061.
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 fusiform gyrus, and the left middle temporal gyrus and in auditory areas of the left superior temporal gyrus. 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.
先前的研究表明，通过听单词在联觉者中诱发颜色感知涉及视觉及特定颜色处理皮层区域的激活。虽然这为异常颜色感知的起源提供了一种解释，但这种跨模态激活的机制问题仍不清楚。我们通过功能磁共振成像（fMRI）对颜色听觉联觉者进行研究，让受试者接触单词和音调，以探究这个问题。将伴有高度可靠颜色感知的单词条件下的大脑激活与仅有偶尔颜色感知的音调条件下的激活进行比较，并将两者与相同刺激条件下正常受试者的激活进行对比。结果显示，即使联觉感知较为罕见，但与单词条件相似的音调条件已经在各个皮层区域引起了异常高的激活。在右枕叶、梭状回、左颞中回的视觉区域以及左颞上回的听觉区域，这种音调激活明显大于正常受试者。这些听觉区域对单词和音调的激活都很强，而不像正常受试者那样音调激活通常低于单词激活。综合这些结果，它们支持去抑制反馈假说，认为这是真正联觉的神经生理基础。
