Cambridge Hearing Group, MRC Cognition & Brain Sciences Unit, University of Cambridge, Cambridge, England.
Department of Otolaryngology, University of California at Irvine, Irvine, CA, USA.
J Assoc Res Otolaryngol. 2022 Aug;23(4):513-534. doi: 10.1007/s10162-022-00851-5. Epub 2022 Jun 13.
We describe a scalp-recorded measure of tonotopic selectivity, the "cortical onset response" (COR) and compare the results between humans and cats. The COR results, in turn, were compared with psychophysical masked-detection thresholds obtained using similar stimuli and obtained from both species. The COR consisted of averaged responses elicited by 50-ms tone-burst probes presented at 1-s intervals against a continuous noise masker. The noise masker had a bandwidth of 1 or 1/8th octave, geometrically centred on 4000 Hz for humans and on 8000 Hz for cats. The probe frequency was either - 0.5, - 0.25, 0, 0.25 or 0.5 octaves re the masker centre frequency. The COR was larger for probe frequencies more distant from the centre frequency of the masker, and this effect was greater for the 1/8th-octave than for the 1-octave masker. This pattern broadly reflected the masked excitation patterns obtained psychophysically with similar stimuli in both species. However, the positive signal-to-noise ratio used to obtain reliable COR measures meant that some aspects of the data differed from those obtained psychophysically, in a way that could be partly explained by the upward spread of the probe's excitation pattern. Our psychophysical measurements also showed that the auditory filter width obtained at 8000 Hz using notched-noise maskers was slightly wider in cat than previous measures from humans. We argue that although conclusions from COR measures differ in some ways from conclusions based on psychophysics, the COR measures provide an objective, noninvasive, valid measure of tonotopic selectivity that does not require training and that may be applied to acoustic and cochlear-implant experiments in humans and laboratory animals.
我们描述了一种基于头皮记录的音位选择性测量方法，即“皮质起始反应”（COR），并比较了人类和猫之间的结果。反过来，将 COR 结果与使用类似刺激物并从两种物种获得的心理物理掩蔽检测阈值进行了比较。COR 由在 1 秒间隔内呈现的 50 毫秒音爆探针引起的平均反应组成，这些探针在连续噪声掩蔽器的背景下呈现。噪声掩蔽器的带宽为 1 或 1/8 倍频程，对于人类来说，几何中心位于 4000 Hz，对于猫来说，几何中心位于 8000 Hz。探针频率要么比掩蔽器中心频率低-0.5、-0.25、0、0.25 或 0.5 倍频程，要么比掩蔽器中心频率高。对于距离掩蔽器中心频率更远的探针频率，COR 更大，对于 1/8 倍频程的掩蔽器，这种效果比 1 倍频程的掩蔽器更大。这种模式广泛反映了在两种物种中使用类似刺激物进行心理物理测量获得的掩蔽激发模式。然而，为了获得可靠的 COR 测量值而使用的正信噪比意味着数据的某些方面与心理物理测量值不同，这种情况在一定程度上可以通过探针的激发模式向上扩展来解释。我们的心理物理测量还表明，使用缺口噪声掩蔽器在 8000 Hz 获得的听觉滤波器宽度在猫中比以前在人类中获得的测量值稍宽。我们认为，尽管 COR 测量值的结论在某些方面与基于心理物理学的结论不同，但 COR 测量值提供了一种客观、非侵入性、有效的音位选择性测量值，不需要训练，并且可以应用于人类和实验室动物的声学和耳蜗植入实验。
