Department of Psychology, University of South Carolina, 1512 Pendleton Street, Columbia, SC, 29208, USA.
Department of Communication Sciences and Disorders, University of South Carolina, 1705 College Street, Columbia, SC, 29208, USA.
Exp Brain Res. 2024 Nov;242(11):2509-2530. doi: 10.1007/s00221-024-06921-9. Epub 2024 Sep 21.
Cochlear implants (CIs) are the most successful neural prostheses, enabling individuals with severe to profound hearing loss to access sounds and understand speech. While CI has demonstrated success, speech perception outcomes vary largely among CI listeners, with significantly reduced performance in noise. This review paper summarizes prior findings on speech-evoked cortical activities in adult CI listeners using functional near-infrared spectroscopy (fNIRS) to understand (a) speech-evoked cortical processing in CI listeners compared to normal-hearing (NH) individuals, (b) the relationship between these activities and behavioral speech recognition scores, (c) the extent to which current fNIRS-measured speech-evoked cortical activities in CI listeners account for their differences in speech perception, and (d) challenges in using fNIRS for CI research. Compared to NH listeners, CI listeners had diminished speech-evoked activation in the middle temporal gyrus (MTG) and in the superior temporal gyrus (STG), except one study reporting an opposite pattern for STG. NH listeners exhibited higher inferior frontal gyrus (IFG) activity when listening to CI-simulated speech compared to natural speech. Among CI listeners, higher speech recognition scores correlated with lower speech-evoked activation in the STG, higher activation in the left IFG and left fusiform gyrus, with mixed findings in the MTG. fNIRS shows promise for enhancing our understanding of cortical processing of speech in CI listeners, though findings are mixed. Challenges include test-retest reliability, managing noise, replicating natural conditions, optimizing montage design, and standardizing methods to establish a strong predictive relationship between fNIRS-based cortical activities and speech perception in CI listeners.
人工耳蜗（CI）是最成功的神经假体之一，使重度至极重度听力损失的个体能够听到声音并理解言语。虽然 CI 已经取得了成功，但 CI 使用者的言语感知结果差异很大，在噪声环境下的表现明显下降。这篇综述论文总结了先前使用功能近红外光谱（fNIRS）研究成人 CI 使用者言语诱发皮质活动的发现，以了解：（a）与正常听力（NH）个体相比，CI 使用者的言语诱发皮质处理；（b）这些活动与行为言语识别分数之间的关系；（c）当前 CI 使用者的 fNIRS 测量的言语诱发皮质活动在多大程度上解释了他们在言语感知方面的差异；（d）fNIRS 在 CI 研究中的应用挑战。与 NH 聆听者相比，CI 聆听者的颞中回（MTG）和颞上回（STG）中的言语诱发激活减少，只有一项研究报告了 STG 的相反模式。NH 聆听者在聆听 CI 模拟言语时表现出更高的额下回（IFG）活动，而不是自然言语。在 CI 聆听者中，较高的言语识别分数与 STG 中较低的言语诱发激活、左侧 IFG 和左侧梭状回的较高激活相关，而 MTG 的发现则不一致。fNIRS 有望增强我们对 CI 使用者言语皮质处理的理解，尽管结果不一。挑战包括测试-重测信度、管理噪声、复制自然条件、优化布局设计以及标准化方法，以在 CI 使用者的基于 fNIRS 的皮质活动与言语感知之间建立强有力的预测关系。
