Department of Experimental Psychology, University of Oxford Oxford, UK.
Front Hum Neurosci. 2014 Feb 20;8:89. doi: 10.3389/fnhum.2014.00089. eCollection 2014.
The neurochemical mechanisms that contribute to synaesthesia are poorly understood, but multiple models implicate serotonin and GABA in the development of this condition. Here we used psychophysical tasks to test the predictions that synaesthetes would display behavioral performance consistent with reduced GABA and elevated serotonin in primary visual cortex. Controls and synaesthetes completed the orientation-specific surround suppression (OSSS) and tilt-after effect (TAE) tasks, previously shown to relate to GABA and serotonin levels, respectively. Controls and synaesthetes did not differ in the performance parameter previously associated with GABA or in the magnitude of the TAE. However, synaesthetes did display lower contrast difference thresholds in the OSSS task than controls when no surround (NS) was present. These results are inconsistent with the hypothesized roles of GABA and serotonin in this condition, but provide preliminary evidence that synaesthetes exhibit enhanced contrast discrimination.
神经化学机制导致联觉的原因尚不清楚，但多种模型表明，血清素和 GABA 参与了这种情况的发展。在这里，我们使用心理物理任务来测试以下预测：联觉者将表现出与初级视觉皮层中 GABA 减少和血清素升高一致的行为表现。对照组和联觉者分别完成了定向特化环绕抑制（OSSS）和倾斜后效应（TAE）任务，这两个任务之前被证明分别与 GABA 和血清素水平相关。对照组和联觉者在与 GABA 或 TAE 幅度相关的先前表现参数上没有差异。然而，当没有环绕（NS）时，联觉者在 OSSS 任务中表现出比对照组更低的对比度差异阈值。这些结果与该条件下 GABA 和血清素的假设作用不一致，但提供了初步证据表明联觉者表现出增强的对比度辨别能力。
