King Andrew, Hopkins Kathryn, Plack Christopher J
School of Psychological Sciences, University of Manchester, Manchester Academic Health Science Centre, Manchester, Greater Manchester, M13 9PL, UK.
J Assoc Res Otolaryngol. 2016 Apr;17(2):133-43. doi: 10.1007/s10162-016-0556-x. Epub 2016 Feb 26.
The frequency following response (FFR) arises from the sustained neural activity of a population of neurons that are phase locked to periodic acoustic stimuli. Determining the source of the FFR noninvasively may be useful for understanding the function of phase locking in the auditory pathway to the temporal envelope and fine structure of sounds. The current study compared the FFR recorded with a horizontally aligned (mastoid-to-mastoid) electrode montage and a vertically aligned (forehead-to-neck) electrode montage. Unlike previous studies, envelope and fine structure latencies were derived simultaneously from the same narrowband stimuli to minimize differences in cochlear delay. Stimuli were five amplitude-modulated tones centered at 576 Hz, each with a different modulation rate, resulting in different side-band frequencies across stimulus conditions. Changes in response phase across modulation frequency and side-band frequency (group delay) were used to determine the latency of the FFR reflecting phase locking to the envelope and temporal fine structure, respectively. For the FFR reflecting phase locking to the temporal fine structure, the horizontal montage had a shorter group delay than the vertical montage, suggesting an earlier generation source within the auditory pathway. For the FFR reflecting phase locking to the envelope, group delay was longer than that for the fine structure FFR, and no significant difference in group delay was found between montages. However, it is possible that multiple sources of FFR (including the cochlear microphonic) were recorded by each montage, complicating interpretations of the group delay.
频率跟随反应（FFR）源于一群与周期性听觉刺激锁相的神经元的持续神经活动。无创地确定FFR的来源可能有助于理解听觉通路中锁相对声音的时间包络和精细结构的作用。本研究比较了用水平排列（乳突到乳突）电极蒙太奇和垂直排列（额头到颈部）电极蒙太奇记录的FFR。与以往研究不同的是，包络和精细结构潜伏期是从相同的窄带刺激中同时得出的，以尽量减少耳蜗延迟的差异。刺激是五个以576赫兹为中心的调幅音，每个调幅音有不同的调制率，导致不同刺激条件下有不同的边带频率。调制频率和边带频率的反应相位变化（群延迟）分别用于确定反映对包络和时间精细结构锁相的FFR潜伏期。对于反映对时间精细结构锁相的FFR，水平蒙太奇的群延迟比垂直蒙太奇短，表明在听觉通路中有更早的产生源。对于反映对包络锁相的FFR，群延迟比精细结构FFR的群延迟长，并且在蒙太奇之间未发现群延迟有显著差异。然而，每个蒙太奇可能记录了FFR的多个来源（包括耳蜗微音），这使得群延迟的解释变得复杂。
