Department of Communication Disorders, Ariel University, Israel.
Department of Communication Disorders, Ariel University, Israel.
Neuropsychologia. 2024 Sep 9;202:108959. doi: 10.1016/j.neuropsychologia.2024.108959. Epub 2024 Jul 17.
Imaging and neurocognitive studies have searched for the brain areas involved in speech perception, specifically when speech is accompanied by noise, attempting to identify the underlying neural mechanism(s). Transcranial direct current stimulation (tDCS), a noninvasive, painless cortical neuromodulation technique, has been used to either excite or inhibit brain activity in order to better understand the neural mechanism underlying speech perception in noise. In the present study, anodal (excitatory) and cathodal (inhibitory) stimulations were performed on 48 participants, either over the left Inferior Frontal Gyrus (IFG), which includes Broca's area (n = 10 anodal, and n = 10 cathodal) or over the left Superior Temporal Gyrus (STG), which includes Wernicke's area (n = 13 anodal, n = 15 cathodal). Speech perception was measured using a sentence recognition task accompanied by white noise with a signal-to-noise ratio of -10 dB. Speech perception performance was measured four times: at baseline, after each of the two sessions of stimulation (one active and one sham session, the order of which was randomized between participants), and at a two-week follow-up session. Groups receiving anodal and cathodal stimulation over the left IFG did not show an effect of stimulation type. For groups receiving left STG stimulation, anodal stimulation resulted in higher scores, regardless of whether it was given before or after sham stimulation. However, cathodal stimulation showed an effect only when active stimulation was applied following sham stimulation. These results showed that tDCS had a direct effect on improving speech perception only over left STG. Furthermore, while anodal stimulation was effective in whatever order it was given, cathodal stimulation was effective only following sham stimulation, thereby allowing some amount of training. These findings carry both theoretical and clinical implications for the relationship between the DMN's left IFG and left STG areas during speech perception accompanied by background noise.
影像学和神经认知研究一直在寻找参与言语感知的大脑区域，特别是当言语伴随着噪音时，试图确定潜在的神经机制。经颅直流电刺激 (tDCS) 是一种非侵入性、无痛的皮质神经调节技术，已被用于兴奋或抑制大脑活动，以更好地理解言语感知在噪声中的神经机制。在本研究中，对 48 名参与者进行了左额下回（IFG）的阳极（兴奋）和阴极（抑制）刺激，包括布罗卡区（n = 10 个阳极，n = 10 个阴极）或左颞上回（STG）的刺激，包括韦尼克区（n = 13 个阳极，n = 15 个阴极）。言语感知通过伴随噪声的句子识别任务进行测量，信噪比为-10dB。言语感知性能在四个时间点进行测量：基线时、两次刺激（一次主动刺激和一次假刺激，参与者之间的顺序随机）之后以及两周的随访时。接受左 IFG 刺激的阳极和阴极刺激组未显示刺激类型的影响。对于接受左 STG 刺激的组，无论阳极刺激是在假刺激之前还是之后给予，阳极刺激都导致更高的分数。然而，只有在假刺激后给予主动刺激时，阴极刺激才显示出效果。这些结果表明，tDCS 仅对左 STG 上的言语感知具有直接影响。此外，虽然阳极刺激在任何顺序下都是有效的，但只有在假刺激后给予阴极刺激才有效，从而允许一定程度的训练。这些发现对 DMN 的左 IFG 和左 STG 区域在伴有背景噪声的言语感知中的关系具有理论和临床意义。
