Giroud Nathalie, Lemke Ulrike, Reich Philip, Matthes Katarina L, Meyer Martin
Research Unit for Neuroplasticity and Learning in the Healthy Aging Brain, Department of Psychology, University of Zurich, Andreasstrasse 15/2, CH-8050 Zurich, Switzerland; University Research Priority Program "Dynamics of Healthy Aging", Department of Psychology, University of Zurich, Andreasstrasse 15/2, CH-8050 Zurich, Switzerland.
Science & Technology, Phonak AG, Laubisrütistrasse 28, CH-8712 Stäfa, Switzerland.
Hear Res. 2017 Sep;353:162-175. doi: 10.1016/j.heares.2017.06.012. Epub 2017 Jun 29.
The present study investigates behavioral and electrophysiological auditory and cognitive-related plasticity in three groups of healthy older adults (60-77 years). Group 1 was moderately hearing-impaired, experienced hearing aid users, and fitted with new hearing aids using non-linear frequency compression (NLFC on); Group 2, also moderately hearing-impaired, used the same type of hearing aids but NLFC was switched off during the entire period of study duration (NLFC off); Group 3 represented individuals with age-appropriate hearing (NHO) as controls, who were not different in IQ, gender, or age from Group 1 and 2. At five measurement time points (M1-M5) across three months, a series of active oddball tasks were administered while EEG was recorded. The stimuli comprised syllables consisting of naturally high-pitched fricatives (/sh/, /s/, and /f/), which are hard to distinguish for individuals with presbycusis. By applying a data-driven microstate approach to obtain global field power (GFP) as a measure of processing effort, the modulations of perceptual (P50, N1, P2) and cognitive-related (N2b, P3b) auditory evoked potentials were calculated and subsequently related to behavioral changes (accuracy and reaction time) across time. All groups improved their performance across time, but NHO showed consistently higher accuracy and faster reaction times than the hearing-impaired groups, especially under difficult conditions. Electrophysiological results complemented this finding by demonstrating longer latencies in the P50 and the N1 peak in hearing aid users. Furthermore, the GFP of cognitive-related evoked potentials decreased from M1 to M2 in the NHO group, while a comparable decrease in the hearing-impaired group was only evident at M5. After twelve weeks of hearing aid use of eight hours each day, we found a significantly lower GFP in the P3b of the group with NLFC on as compared to the group with NLFC off. These findings suggest higher processing effort, as evidenced by higher GFP, in hearing-impaired individuals when compared to those with normal hearing, although the hearing-impaired show a decrease of processing effort after repeated stimulus exposure. In addition, our findings indicate that the acclimatization to a new hearing aid algorithm may take several weeks.
本研究调查了三组健康老年人（60 - 77岁）在行为和电生理方面与听觉及认知相关的可塑性。第一组为中度听力受损者，是有使用助听器经验的人，并佩戴采用非线性频率压缩（NLFC开启）的新助听器；第二组同样是中度听力受损者，使用相同类型的助听器，但在整个研究期间NLFC处于关闭状态（NLFC关闭）；第三组作为对照组，是听力正常的同龄人（NHO），其智商、性别或年龄与第一组和第二组无差异。在三个月内的五个测量时间点（M1 - M5），在记录脑电图（EEG）的同时进行了一系列主动Oddball任务。刺激包括由自然高音摩擦音（/sh/、/s/和/f/）组成的音节，这些对于患有老年性耳聋的个体来说很难区分。通过应用数据驱动的微状态方法来获得全局场功率（GFP）作为处理努力程度的指标，计算了感知性（P50、N1、P2）和认知相关（N2b、P3b）听觉诱发电位的调制情况，并随后将其与不同时间的行为变化（准确性和反应时间）相关联。所有组随着时间推移表现均有所改善，但NHO组始终比听力受损组具有更高的准确性和更快的反应时间，尤其是在困难条件下。电生理结果通过证明助听器使用者P50和N1峰的潜伏期更长来补充这一发现。此外，认知相关诱发电位的GFP在NHO组从M1到M2下降，而听力受损组中类似的下降仅在M5时明显。在每天使用八小时助听器十二周后，我们发现NLFC开启组的P3b中GFP显著低于NLFC关闭组。这些发现表明，与听力正常者相比，听力受损个体的处理努力程度更高，这由更高的GFP所证明，尽管听力受损者在反复接触刺激后处理努力程度有所下降。此外，我们的发现表明，适应新的助听器算法可能需要几周时间。
