Department of Speech Language and Hearing Sciences, International University of Health and Welfare, Ohtawara, Japan.
Clin Exp Otorhinolaryngol. 2012 Apr;5 Suppl 1(Suppl 1):S6-9. doi: 10.3342/ceo.2012.5.S1.S6. Epub 2012 Apr 30.
Speech perception abilities, which vary widely among cochlear implant (CI) users, are considered to be associated with the integrity of the central auditory pathways from the auditory nerve to the cortex. Therefore, auditory evoked potentials (AEPs) are used to evaluate central auditory processing, which is thought to contribute to speech perception in CI subjects. In AEPs, the P300 component reflects the cognitive ability of subjects to detect and respond to stimuli and has most frequently been used and investigated in CI subjects. Other studies have used mismatched negativity (MMN) to examine central auditory processing. It is important to compare MMN and P300 and examine the auditory processing mechanisms involved in these components. Our study therefore aimed to investigate the relationship between P300 and MMN using both active and passive hearing paradigms in CI and normal hearing (NH) subjects.
Our subjects consisted of 3 CI subjects and 3 NH subjects. An oddball paradigm was used to deliver the stimuli on both components. The frequent stimuli were 1,000-Hz tone bursts, whereas the rare stimuli were 1,500, 2,000, and 4,000-Hz.
As the frequency contrasts increased, the P3 latencies increased in the CI subjects. However, the latency in NH subjects did not change significantly across the frequency contrast conditions. MMNs were identified for both the CI and NH subjects; the latencies in the CI subjects were longer than those in the NH subjects. However, there were no differences in the latencies of either the CI or NH subjects in the 3 frequency contrast tasks.
Our results indicated that different auditory processing pathways are involved in the active and passive hearing conditions based on the P300 and MMN data and that a combination of both responses plays an important role in the comprehension of auditory processing mechanisms in CI subjects.
由于人工耳蜗（CI）使用者的言语感知能力差异很大，因此被认为与从听神经到大脑皮层的中枢听觉通路的完整性有关。因此，听觉诱发电位（AEPs）被用于评估中枢听觉处理，这被认为有助于 CI 受试者的言语感知。在 AEPs 中，P300 成分反映了受试者检测和响应刺激的认知能力，并且在 CI 受试者中最常使用和研究。其他研究使用失匹配负波（MMN）来检查中枢听觉处理。比较 MMN 和 P300 并研究这些成分涉及的听觉处理机制非常重要。因此，我们的研究旨在使用 CI 和正常听力（NH）受试者的主动和被动听力范式来研究 P300 和 MMN 之间的关系。
我们的受试者包括 3 名 CI 受试者和 3 名 NH 受试者。使用奇异性范式在两个成分上传递刺激。常见刺激是 1,000-Hz 短音，而罕见刺激是 1,500、2,000 和 4,000-Hz。
随着频率对比的增加，CI 受试者的 P3 潜伏期增加。然而，NH 受试者的潜伏期在整个频率对比条件下没有显著变化。在 CI 和 NH 受试者中都确定了 MMN；CI 受试者的潜伏期比 NH 受试者长。然而，在 3 个频率对比任务中，CI 或 NH 受试者的潜伏期都没有差异。
我们的结果表明，基于 P300 和 MMN 数据，主动和被动听力条件涉及不同的听觉处理途径，并且两种反应的组合在理解 CI 受试者的听觉处理机制中起着重要作用。
