İlhan Barkın, Kurt Saliha, Bolay Yavuz, Ungan Pekcan
Department of Biophysics, Necmettin Erbakan University Faculty of Medicine, Konya, Türkiye.
Department of Audiometry, Selçuk University Vocational School of Health Services, Konya, Türkiye.
Eur J Neurosci. 2025 Jan;61(1):e16644. doi: 10.1111/ejn.16644. Epub 2024 Dec 16.
'Opponent channels model' (OCM) is the widely accepted model for cortical representation of sound lateralization. Stimulus-specific 'release from adaptation' (RFA) in cortical responses has been used in previous studies to test the predictions of this model. However, these attempts were shown to be prone to confounds of spurious responses such as those to auditory motion and sound onset. The present study aims to determine whether a multiple-adaptor RFA algorithm could be employed for relatively confound-free quantification of the population response of lateralization-specific auditory cortical neurons, and provide useful data for estimation of the OCM hemifield tuning curves. Two experiments were conducted on 12 volunteers with normal hearing. In Exp.1, quadruple tone pips of either low or high frequency were presented as adaptor, followed by a single tone pip of either frequency as probe. In Exp.2, tone pips were replaced with dichotic click train pips with left-leading and right-leading interaural time difference (ITD). Frequency- and ITD-specific RFA in cortical responses N1 and P2 was quantified using global field magnitude difference between ERPs to mismatched and matched adaptor-probe pairs. RFA level measured was lower for ITD mismatch than frequency mismatch. Nonetheless, it allowed measurement of ITD-specific cortical neurons' population response, without any spurious response confound. We proposed a method for extraction of ITD-specific response magnitude from the N1 response to a lateralized sound. Using it, one can reliably measure the activity of lateralization-specific cortical neurons, i.e. elicited by moderate ITD changes. This allows estimation of hemifield tuning curves in OCM using ERP data.
“拮抗通路模型”（OCM）是目前被广泛接受的用于声音定位皮质表征的模型。在以往的研究中，已利用皮质反应中特定刺激的“适应解除”（RFA）来检验该模型的预测。然而，这些尝试被证明容易受到诸如对听觉运动和声音起始等虚假反应的混淆影响。本研究旨在确定多重适应器RFA算法是否可用于相对无混淆地量化特定定位听觉皮质神经元的群体反应，并为估计OCM半视野调谐曲线提供有用数据。对12名听力正常的志愿者进行了两项实验。在实验1中，呈现低频或高频的四重音短声作为适应器，随后呈现单一频率的音短声作为探测音。在实验2中，用具有左耳领先和右耳领先耳间时间差（ITD）的双耳点击序列短声取代音短声。使用对不匹配和匹配的适应器 - 探测音对的ERP之间的全局场强差异，对皮质反应N1和P2中频率和ITD特异性的RFA进行量化。测量的ITD不匹配的RFA水平低于频率不匹配的情况。尽管如此，它允许测量ITD特异性皮质神经元的群体反应，而没有任何虚假反应的混淆。我们提出了一种从对侧化声音的N1反应中提取ITD特异性反应幅度的方法。使用该方法，可以可靠地测量特定定位皮质神经元的活动，即由适度的ITD变化引起的活动。这使得利用ERP数据估计OCM中的半视野调谐曲线成为可能。
