Department of Integrative Medical Biology, Physiology Section, Umeå University,SE 90187 Umeå, Sweden.
J Cogn Neurosci. 2012 Oct;24(10):2120-34. doi: 10.1162/jocn_a_00261. Epub 2012 Aug 20.
Although some brain areas preferentially process information from a particular sensory modality, these areas can also respond to other modalities. Here we used fMRI to show that such responsiveness to tactile stimuli depends on the temporal frequency of stimulation. Participants performed a tactile threshold-tracking task where the tip of either their left or right middle finger was stimulated at 3, 20, or 100 Hz. Whole-brain analysis revealed an effect of stimulus frequency in two regions: the auditory cortex and the visual cortex. The BOLD response in the auditory cortex was stronger during stimulation at hearable frequencies (20 and 100 Hz) whereas the response in the visual cortex was suppressed at infrasonic frequencies (3 Hz). Regardless of which hand was stimulated, the frequency-dependent effects were lateralized to the left auditory cortex and the right visual cortex. Furthermore, the frequency-dependent effects in both areas were abolished when the participants performed a visual task while receiving identical tactile stimulation as in the tactile threshold-tracking task. We interpret these findings in the context of the metamodal theory of brain function, which posits that brain areas contribute to sensory processing by performing specific computations regardless of input modality.
尽管一些大脑区域优先处理来自特定感觉模态的信息，但这些区域也可以对其他模态做出反应。在这里，我们使用 fMRI 显示这种对触觉刺激的反应取决于刺激的时间频率。参与者执行触觉阈值跟踪任务，他们的左或右中指指尖以 3、20 或 100 Hz 的频率受到刺激。全脑分析显示在两个区域存在刺激频率的影响：听觉皮层和视觉皮层。听觉皮层在可听频率（20 和 100 Hz）刺激期间的 BOLD 反应更强，而在次声频率（3 Hz）下视觉皮层的反应受到抑制。无论刺激哪只手，频率依赖性效应都偏向左侧听觉皮层和右侧视觉皮层。此外，当参与者在执行与触觉阈值跟踪任务相同的触觉刺激的同时执行视觉任务时，两个区域中的频率依赖性效应都被消除。我们在大脑功能的变模态理论的背景下解释这些发现，该理论假设大脑区域通过执行特定的计算来为感觉处理做出贡献，而不管输入模态如何。
