Luke Robert, De Vos Astrid, Wouters Jan
Research Group Experimental ORL, Department of Neurosciences, KU Leuven - University of Leuven, Belgium.
Research Group Experimental ORL, Department of Neurosciences, KU Leuven - University of Leuven, Belgium; Parenting and Special Education Research Unit, Faculty of Psychology and Educational Sciences, KU Leuven - University of Leuven, Belgium.
Neuroimage. 2017 Feb 15;147:568-576. doi: 10.1016/j.neuroimage.2016.11.023. Epub 2016 Nov 25.
Speech is a complex signal containing a broad variety of acoustic information. For accurate speech reception, the listener must perceive modulations over a range of envelope frequencies. Perception of these modulations is particularly important for cochlear implant (CI) users, as all commercial devices use envelope coding strategies. Prolonged deafness affects the auditory pathway. However, little is known of how cochlear implantation affects the neural processing of modulated stimuli. This study investigates and contrasts the neural processing of envelope rate modulated signals in acoustic and CI listeners. Auditory steady-state responses (ASSRs) are used to study the neural processing of amplitude modulated (AM) signals. A beamforming technique is applied to determine the increase in neural activity relative to a control condition, with particular attention paid to defining the accuracy and precision of this technique relative to other tomographies. In a cohort of 44 acoustic listeners, the location, activity and hemispheric lateralisation of ASSRs is characterised while systematically varying the modulation rate (4, 10, 20, 40 and 80Hz) and stimulation ear (right, left and bilateral). We demonstrate a complex pattern of laterality depending on both modulation rate and stimulation ear that is consistent with, and extends, existing literature. We present a novel extension to the beamforming method which facilitates source analysis of electrically evoked auditory steady-state responses (EASSRs). In a cohort of 5 right implanted unilateral CI users, the neural activity is determined for the 40Hz rate and compared to the acoustic cohort. Results indicate that CI users activate typical thalamic locations for 40Hz stimuli. However, complementary to studies of transient stimuli, the CI population has atypical hemispheric laterality, preferentially activating the contralateral hemisphere.
语音是一种包含广泛声学信息的复杂信号。为了准确接收语音，听者必须感知一系列包络频率上的调制。对于人工耳蜗（CI）使用者来说，感知这些调制尤为重要，因为所有商业设备都采用包络编码策略。长期耳聋会影响听觉通路。然而，关于人工耳蜗植入如何影响调制刺激的神经处理却知之甚少。本研究调查并对比了正常听力者和人工耳蜗使用者对包络速率调制信号的神经处理情况。听觉稳态反应（ASSR）被用于研究调幅（AM）信号的神经处理。应用波束形成技术来确定相对于对照条件下神经活动的增加，特别关注相对于其他断层扫描技术来定义该技术的准确性和精确性。在一组44名正常听力者中，在系统地改变调制率（4、10、20、40和80Hz）和刺激耳（右、左和双侧）的同时，对ASSR的位置、活动和半球侧化进行了表征。我们展示了一种复杂的侧化模式，其取决于调制率和刺激耳，这与现有文献一致并有所扩展。我们提出了一种波束形成方法的新颖扩展，它有助于对电诱发听觉稳态反应（EASSR）进行源分析。在一组5名单侧右耳植入人工耳蜗的使用者中，确定了40Hz频率下的神经活动，并与正常听力者组进行了比较。结果表明，人工耳蜗使用者在40Hz刺激下激活了典型的丘脑位置。然而，与瞬态刺激研究互补的是，人工耳蜗使用者群体具有非典型的半球侧化，优先激活对侧半球。
