Vander Werff Kathy R, Nesbitt Kerrie L
Department of Communication Sciences and Disorders, Syracuse University, Syracuse, NY.
Exceptional Education, Oswego County BOCES, Mexico, NY.
J Am Acad Audiol. 2017 May;28(5):373-384. doi: 10.3766/jaaa.15056.
Recent behavioral studies have suggested that individuals with sloping audiograms exhibit localized improvements in frequency discrimination in the frequency region near the drop in hearing. Auditory-evoked potentials may provide evidence of such cortical plasticity and reorganization of frequency maps.
The objective of this study was to evaluate electrophysiological evidence of cortical plasticity related to cortical frequency representation and discrimination abilities in older individuals with high-frequency sensorineural hearing loss (SNHL). It was hypothesized that the P3 response in this group would show evidence of physiological reorganization of frequency maps and enhanced neural representation at the edge of their high-frequency loss due to their restricted SNHL.
The P3 auditory event-related potential in response to small frequency changes was recorded in a repeated measures design using an oddball paradigm that presented upward and downward frequency changes of 2%, 5%, and 20% to three groups of listeners.
P3 recordings from a group of seven older individuals with a restricted sloping hearing loss >1000 or 2000 Hz was compared to two control groups of younger (n = 7) and older (n = 7) individuals with normal hearing/borderline normal hearing through 4000 Hz.
The auditory P3 was recorded using an oddball paradigm (80%/20%) with the standard tone at the highest frequency of normal hearing in the hearing-impaired participants, also known as the edge frequency (EF). EFs were either 1000 or 2000 Hz for all participants. The target tones represented upward and downward frequency changes of 2%, 5%, and 20% from the standard tones of either 1000 or 2000 Hz. Waveforms were recorded using a two-channel clinical-evoked potential system. Latency and amplitude of the P300 peak were analyzed across groups for the three frequency conditions using repeated measures analysis of variance.
The results of this study suggest that the P3 response can be elicited by frequency changes as small as 2-5%. P3 responses at the EF of hearing loss were present and larger in amplitude for more participants with a sloping hearing loss compared to age-matched normal-hearing peers tested at the same frequencies. As a result, the older participants with sloping hearing losses had P3 responses more similar to the younger normal-hearing participants than their age-matched peers with normal hearing.
These preliminary results partially support the idea of enhanced cortical representation of frequency at the EF of localized SNHL in older adults that is not purely due to age.
最近的行为学研究表明，听力图呈斜坡状的个体在听力下降区域附近的频率辨别能力有局部改善。听觉诱发电位可能为这种皮质可塑性和频率图谱重组提供证据。
本研究的目的是评估高频感音神经性听力损失（SNHL）的老年人中与皮质频率表征和辨别能力相关的皮质可塑性的电生理证据。据推测，由于其局限性SNHL，该组中的P3反应将显示频率图谱生理重组的证据，以及在其高频听力损失边缘处神经表征增强。
采用重复测量设计，使用奇偶数范式记录对小频率变化的P3听觉事件相关电位，该范式向三组听众呈现2%、5%和20%的向上和向下频率变化。
将一组7名听力损失呈斜坡状且>1000或2000Hz的老年人的P3记录与两组听力正常/4000Hz以下听力临界正常的年轻（n = 7）和年长（n = 7）个体的对照组进行比较。
使用奇偶数范式（80%/20%）记录听觉P3，听力受损参与者的标准音为正常听力的最高频率，也称为边缘频率（EF）。所有参与者的EF为1000或2000Hz。目标音表示相对于1000或2000Hz标准音的2%、5%和20%的向上和向下频率变化。使用双通道临床诱发电位系统记录波形。使用重复测量方差分析对三组在三种频率条件下的P300峰潜伏期和波幅进行分析。
本研究结果表明，小至2 - 5%的频率变化即可诱发P3反应。与在相同频率下测试的年龄匹配的听力正常同龄人相比，更多听力损失呈斜坡状的参与者在听力损失的EF处出现P3反应且波幅更大。因此，听力损失呈斜坡状的年长参与者的P3反应比其年龄匹配的听力正常同龄人更类似于年轻的听力正常参与者。
这些初步结果部分支持了老年人局部SNHL的EF处频率皮质表征增强这一观点，且这种增强并非完全由年龄所致。
