Age-related differences in neuromagnetic brain activity underlying concurrent sound perception
Age-related differences in neuromagnetic brain activity underlying concurrent sound perception
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DOI：
10.1523/jneurosci.5433-06.2007
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发表时间：
2007-02-07
影响因子：
5.3
通讯作者：
McDonald, Kelly L.
中科院分区：
文献类型：
--
作者：
Alain, Claude;McDonald, Kelly L.
分析并发听觉事件的缺陷被认为是导致老年人在不利的听力条件下理解语音的困难的原因（例如，鸡尾酒会）。为了探讨年龄对声音分离的影响，我们使用脑磁图测量了听觉诱发场（AEFs），同时向年轻人，中年人和老年人提供复杂的声音，这些声音要么是所有谐波都协调一致，要么是三次谐波失调了原始值的4或16%。在录音过程中，参与者被要求忽略刺激，并观看他们选择的静音字幕电影。对于每个参与者，AEFs建模与一对偶极子在上级颞平面，和年龄和失调的影响进行了检查的幅度和潜伏期的源波形。失调的刺激产生了早期的积极性（60-100 ms），对象相关的负性（ORN）（140-180 ms），重叠的N1和P2波，和一个积极的位移，达到峰值后230 ms（P230）的声音开始。早期失调相关的增强在所有三个年龄组中是相似的，而随后的调制（ORN和P230）在老年人中减少。听觉皮层活动的这些年龄差异与听到两种声音的可能性降低有关，这是失调的函数。结果表明，不和谐是迅速和自动注册在所有三个年龄组，但并发的声音的感知随着年龄的增长而下降。
Deficits in parsing concurrent auditory events are believed to contribute to older adults' difficulties in understanding speech in adverse listening conditions (e.g., cocktail party). To explore the level at which aging impairs sound segregation, we measured auditory evoked fields (AEFs) using magnetoencephalography while young, middle-aged, and older adults were presented with complex sounds that either had all of their harmonics in tune or had the third harmonic mistuned by 4 or 16% of its original value. During the recording, participants were asked to ignore the stimuli and watch a muted subtitled movie of their choice. For each participant, the AEFs were modeled with a pair of dipoles in the superior temporal plane, and the effects of age and mistuning were examined on the amplitude and latency of the resulting source waveforms. Mistuned stimuli generated an early positivity (60-100 ms), an object-related negativity (ORN) (140-180 ms) that overlapped the N1 and P2 waves, and a positive displacement that peaked at similar to 230 ms (P230) after sound onset. The early mistuning-related enhancement was similar in all three age groups, whereas the subsequent modulations (ORN and P230) were reduced in older adults. These age differences in auditory cortical activity were associated with a reduced likelihood of hearing two sounds as a function of mistuning. The results reveal that inharmonicity is rapidly and automatically registered in all three age groups but that the perception of concurrent sounds declines with age.