Goller Aviva I, Otten Leun J, Ward Jamie
University of Sussex, Falmer, Brighton, UK.
J Cogn Neurosci. 2009 Oct;21(10):1869-81. doi: 10.1162/jocn.2009.21134.
In auditory-visual synesthesia, sounds automatically elicit conscious and reliable visual experiences. It is presently unknown whether this reflects early or late processes in the brain. It is also unknown whether adult audiovisual synesthesia resembles auditory-induced visual illusions that can sometimes occur in the general population or whether it resembles the electrophysiological deflection over occipital sites that has been noted in infancy and has been likened to synesthesia. Electrical brain activity was recorded from adult synesthetes and control participants who were played brief tones and required to monitor for an infrequent auditory target. The synesthetes were instructed to attend either to the auditory or to the visual (i.e., synesthetic) dimension of the tone, whereas the controls attended to the auditory dimension alone. There were clear differences between synesthetes and controls that emerged early (100 msec after tone onset). These differences tended to lie in deflections of the auditory-evoked potential (e.g., the auditory N1, P2, and N2) rather than the presence of an additional posterior deflection. The differences occurred irrespective of what the synesthetes attended to (although attention had a late effect). The results suggest that differences between synesthetes and others occur early in time, and that synesthesia is qualitatively different from similar effects found in infants and certain auditory-induced visual illusions in adults. In addition, we report two novel cases of synesthesia in which colors elicit sounds, and vice versa.
在视听联觉中，声音会自动引发有意识且可靠的视觉体验。目前尚不清楚这反映的是大脑中的早期还是晚期过程。同样未知的是，成人的视听联觉是类似于一般人群中有时会出现的听觉诱发视觉错觉，还是类似于婴儿期在枕叶部位记录到的、被比作联觉的电生理偏转。对成年联觉者和对照参与者进行脑电活动记录，向他们播放简短音调，并要求他们监测不常出现的听觉目标。指导联觉者关注音调的听觉维度或视觉（即联觉）维度，而对照者只关注听觉维度。在早期（音调开始后100毫秒），联觉者和对照者之间就出现了明显差异。这些差异往往在于听觉诱发电位的偏转（例如听觉N1、P2和N2），而不是额外的后部偏转的出现。无论联觉者关注什么，差异都会出现（尽管注意力有晚期效应）。结果表明，联觉者与其他人之间的差异在早期就会出现，并且联觉在性质上与婴儿期发现的类似效应以及成人中某些听觉诱发视觉错觉不同。此外，我们报告了两例新的联觉病例，其中颜色会引发声音，反之亦然。
