Montreal Neurological Institute, McGill University, Montreal, QC H3A 2B4, Canada; Centre for Research on Brain, Language and Music, Montreal, QC H3G 2A8, Canada; International Laboratory for Brain, Music and Sound Research, Montreal, QC H2V 2S9, Canada.
Montreal Neurological Institute, McGill University, Montreal, QC H3A 2B4, Canada; Centre for Research on Brain, Language and Music, Montreal, QC H3G 2A8, Canada; Institute of Psychology, Carl von Ossietzky University, Oldenburg 26111, Germany.
Neuroimage. 2021 Jun;233:117915. doi: 10.1016/j.neuroimage.2021.117915. Epub 2021 Feb 27.
A body of literature has demonstrated that the right auditory cortex (AC) plays a dominant role in fine pitch processing. However, our understanding is relatively limited about whether this asymmetry extends to perceptual learning of pitch. There is also a lack of causal evidence regarding the role of the right AC in pitch learning. We addressed these points with anodal transcranial direct current stimulation (tDCS), adapting a previous behavioral study in which anodal tDCS over the right AC was shown to block improvement of a microtonal pitch pattern learning task over 3 days. To address the physiological changes associated with tDCS, we recorded MEG data simultaneously with tDCS on the first day, and measured behavioral thresholds on the following two consecutive days. We tested three groups of participants who received anodal tDCS over their right or left AC, or sham tDCS, and measured the N1m auditory evoked response before, during, and after tDCS. Our data show that anodal tDCS of the right AC disrupted pitch discrimination learning up to two days after its application, whereas learning was unaffected by left-AC or sham tDCS. Although tDCS reduced the amplitude of the N1m ipsilaterally to the stimulated hemisphere on both left and right, only right AC N1m amplitude reductions were associated with the degree to which pitch learning was disrupted. This brain-behavior relationship confirms a causal link between right AC physiological responses and fine pitch processing, and provides neurophysiological insight concerning the mechanisms of action of tDCS on the auditory system.
已有大量文献表明，右听觉皮层（AC）在精细音高处理中起主导作用。然而，我们对于这种不对称性是否延伸到音高的感知学习还知之甚少。对于右 AC 在音高学习中的作用，也缺乏因果证据。我们使用经颅直流电刺激（tDCS）来解决这些问题，该方法改编自之前的一项行为研究，该研究表明，右 AC 的阳极 tDCS 可阻止微音高模式学习任务在 3 天内的改善。为了研究与 tDCS 相关的生理变化，我们在第一天同时记录 MEG 数据，并在接下来的两天连续测量行为阈值。我们测试了三组接受右或左 AC 阳极 tDCS 或假 tDCS 的参与者，并在 tDCS 之前、期间和之后测量 N1m 听觉诱发电应。我们的数据表明，右 AC 的阳极 tDCS 会破坏音高辨别学习，最长可持续至其应用后的两天，而左 AC 或假 tDCS 则不会影响学习。尽管 tDCS 降低了刺激半球同侧的 N1m 振幅，但只有右 AC 的 N1m 振幅降低与音高学习的破坏程度有关。这种大脑-行为关系证实了右 AC 生理反应与精细音高处理之间的因果关系，并为 tDCS 对听觉系统的作用机制提供了神经生理学见解。
