Department of Neurology, Beth Israel Deaconess Medical Center and Harvard Medical School, Boston, MA 02215,USA.
Neuroimage. 2013 Jul 1;74:359-66. doi: 10.1016/j.neuroimage.2013.02.024. Epub 2013 Feb 21.
Synesthesia, a condition in which a stimulus in one sensory modality consistently and automatically triggers concurrent percepts in another modality, provides a window into the neural correlates of cross-modal associations. While research on grapheme-color synesthesia has provided evidence for both hyperconnectivity-hyperbinding and disinhibited feedback as potential underlying mechanisms, less research has explored the neuroanatomical basis of other forms of synesthesia. In the current study we investigated the white matter correlates of colored-music synesthesia. As these synesthetes report seeing colors upon hearing musical sounds, we hypothesized that they might show unique patterns of connectivity between visual and auditory association areas. We used diffusion tensor imaging to trace the white matter tracts in temporal and occipital lobe regions in 10 synesthetes and 10 matched non-synesthete controls. Results showed that synesthetes possessed hemispheric patterns of fractional anisotropy, an index of white matter integrity, in the inferior fronto-occipital fasciculus (IFOF), a major white matter pathway that connects visual and auditory association areas to frontal regions. Specifically, white matter integrity within the right IFOF was significantly greater in synesthetes than controls. Furthermore, white matter integrity in synesthetes was correlated with scores on audiovisual tests of the Synesthesia Battery, especially in white matter underlying the right fusiform gyrus. Our findings provide the first evidence of a white matter substrate of colored-music synesthesia, and suggest that enhanced white matter connectivity is involved in enhanced cross-modal associations.
联觉是一种状态，其中一种感觉模式的刺激会持续自动引发另一种感觉模式的感知。它为跨感觉模式关联的神经相关性提供了一个窗口。虽然关于图形-颜色联觉的研究为超连接-超绑定和去抑制反馈作为潜在的潜在机制提供了证据，但对其他形式的联觉的神经解剖学基础的研究较少。在目前的研究中，我们调查了彩色音乐联觉的白质相关性。由于这些联觉者在听到音乐声音时会报告看到颜色，我们假设他们可能在视觉和听觉联合区域之间显示出独特的连接模式。我们使用弥散张量成像来追踪 10 名联觉者和 10 名匹配的非联觉者控制颞叶和枕叶区域的白质束。结果表明，联觉者在连接视觉和听觉联合区域到额叶区域的主要白质通路下额枕束（IFOF）中具有各向异性分数（FA）的半球模式，这是白质完整性的指标。具体来说，联觉者的右侧 IFOF 内的白质完整性明显大于对照组。此外，联觉者的白质完整性与联觉电池的视听测试得分相关，尤其是与右侧梭状回下的白质相关。我们的发现提供了彩色音乐联觉的白质基质的第一个证据，并表明增强的白质连接性参与了增强的跨感觉模式关联。
