Human Envelope Following Responses to Amplitude Modulation: Effects of Aging and Modulation Depth
Human Envelope Following Responses to Amplitude Modulation: Effects of Aging and Modulation Depth
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DOI：
10.1097/aud.0000000000000324
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发表时间：
2016-09-01
期刊：
影响因子：
3.7
通讯作者：
Zeng, Fan-Gang
中科院分区：
文献类型：
--
作者：
Dimitrijevic, Andrew;Alsamri, Jamal;Zeng, Fan-Gang
目的：记录单耳调幅宽带噪声载波的包络跟随响应（EFR），其中调幅（AM）深度随时间缓慢变化，并将这些客观电生理测量与年轻正常听力和老年受试者的主观行为阈值进行比较。设计：参与者：三组受试者包括一个年轻正常听力组（YNH 18至28岁;纯音平均值= 5 dB HL），第一老年组（“01”; 41至62岁;纯音平均值= 19 dB HL），第二老年组（“02”; 67至82岁;纯音平均值= 35 dB HL）。电生理学：在条件1中，白色噪声载波的AM深度（41 Hz）从2%到100%（5%/s）连续变化。EFR作为AM深度的函数进行分析。在条件2中，以41 Hz的速率记录固定AM深度（100%、75%、50%和25%）的听觉稳态反应。心理物理学：使用3 AFC（替代强制选择）程序跟踪在41 Hz下检测AM（AM检测）所需的AM深度。最小AM深度能够引起一个统计上可检测的EFR被定义为生理AM检测threshold.Results：在所有年龄，固定AM深度听觉稳态反应和扫AM EFR产生类似的反应幅度。行为和生理AM检测阈值之间存在统计学显著相关性（r = 0.48）。老年受试者的行为AM检测阈值略高于年轻受试者（不显着）。AM检测阈值与年龄无关。所有组均显示S形EFR振幅与AM深度函数，但函数的形状在组间不同。02组在比正常听力组更低的调制深度下达到EFR振幅平台水平，并且具有更窄的神经动态范围。在听力正常的年轻人组中，EFR相位与AM深度没有差异，而在老年人组中，EFR相位随着AM深度的增加而一致下降。相位变化（或相位斜率）的程度显着相关的纯音阈值在4 KHz.Conclusions：EFR可以记录使用扫描调制深度或离散AM深度技术。扫描记录可以在阈上强度下提供额外的有价值的信息，包括平台水平、斜率和动态范围。与年轻受试者相比，老年受试者的神经动态范围减小，这表明衰老影响听觉系统对AM深度的细微差异进行编码的能力。相位斜率差异可能与低频和高频对EFR的贡献差异有关。行为-生理AM深度阈值的关系是显着的，但可能太弱，是临床上有用的，在目前的个别科目谁没有遭受明显的时间处理缺陷。
Objective: To record envelope following responses (EFRs) to monaural amplitude-modulated broadband noise carriers in which amplitude modulation (AM) depth was slowly changed over time and to compare these objective electrophysiological measures to subjective behavioral thresholds in young normal hearing and older subjects.Design: Participants: three groups of subjects included a young normal-hearing group (YNH 18 to 28 years; pure-tone average = 5 dB HL), a first older group ("01"; 41 to 62 years; pure-tone average = 19 dB HL), and a second older group ("02"; 67 to 82 years; pure-tone average = 35 dB HL). Electrophysiology: In condition 1, the AM depth (41 Hz) of a white noise carrier, was continuously varied from 2% to 100% (5%/s). EFRs were analyzed as a function of the AM depth. In condition 2, auditory steady-state responses were recorded to fixed AM depths (100%, 75%, 50%, and 25%) at a rate of 41 Hz. Psychophysics: A 3 AFC (alternative forced choice) procedure was used to track the AM depth needed to detect AM at 41 Hz (AM detection). The minimum AM depth capable of eliciting a statistically detectable EFR was defined as the physiological AM detection threshold.Results: Across all ages, the fixed AM depth auditory steady-state response and swept AM EFR yielded similar response amplitudes. Statistically significant correlations (r = 0.48) were observed between behavioral and physiological AM detection thresholds. Older subjects had slightly higher (not significant) behavioral AM detection thresholds than younger subjects. AM detection thresholds did not correlate with age. All groups showed a sigmoidal EFR amplitude versus AM depth function but the shape of the function differed across groups. The 02 group reached EFR amplitude plateau levels at lower modulation depths than the normal-hearing group and had a narrower neural dynamic range. In the young normal-hearing group, the EFR phase did not differ with AM depth, whereas in the older group, EFR phase showed a consistent decrease with increasing AM depth. The degree of phase change (or phase slope) was significantly correlated to the pure-tone threshold at 4 kHz.Conclusions: EFRs can be recorded using either the swept modulation depth or the discrete AM depth techniques. Sweep recordings may provide additional valuable information at suprathreshold intensities including the plateau level, slope, and dynamic range. Older subjects had a reduced neural dynamic range compared with younger subjects suggesting that aging affects the ability of the auditory system to encode subtle differences in the depth of AM. The phase-slope differences are likely related to differences in low and high-frequency contributions to EFR. The behavioral-physiological AM depth threshold relationship was significant but likely too weak to be clinically useful in the present individual subjects who did not suffer from apparent temporal processing deficits.