Department of Physiology and Pharmacology, Hotchkiss Brain Institute, University of Calgary, Faculty of Medicine, Calgary, Alberta, Canada.
PLoS One. 2012;7(9):e45123. doi: 10.1371/journal.pone.0045123. Epub 2012 Sep 11.
Prepulse inhibition (PPI) depicts the effects of a weak sound preceding strong acoustic stimulus on acoustic startle response (ASR). Previous studies suggest that PPI is influenced by physical parameters of prepulse sound such as intensity and preceding time. The present study characterizes the impact of prepulse tone frequency on PPI.
Seven female C57BL mice were used in the present study. ASR was induced by a 100 dB SPL white noise burst. After assessing the effect of background sounds (white noise and pure tones) on ASR, PPI was tested by using prepulse pure tones with the background tone of either 10 or 18 kHz. The inhibitory effect was assessed by measuring and analyzing the changes in the first peak-to-peak magnitude, root mean square value, duration and latency of the ASR as the function of frequency difference between prepulse and background tones.
Our data showed that ASR magnitude with pure tone background varied with tone frequency and was smaller than that with white noise background. Prepulse tone systematically reduced ASR as the function of the difference in frequency between prepulse and background tone. The 0.5 kHz difference appeared to be a prerequisite for inducing substantial ASR inhibition. The frequency dependence of PPI was similar under either a 10 or 18 kHz background tone.
PPI is sensitive to frequency information of the prepulse sound. However, the critical factor is not tone frequency itself, but the frequency difference between the prepulse and background tones.
前脉冲抑制（PPI）描述了弱声音在前强声刺激对声惊跳反应（ASR）的影响。先前的研究表明，PPI 受到 prepulse 声音的物理参数的影响，如强度和前置时间。本研究描述了 prepulse 音调频率对 PPI 的影响。
本研究使用了 7 只雌性 C57BL 小鼠。ASR 由 100 dB SPL 白噪声爆发引起。在评估背景声音（白噪声和纯音）对 ASR 的影响后，使用背景音为 10 或 18 kHz 的 prepulse 纯音测试 PPI。通过测量和分析 ASR 的第一峰峰值幅度、均方根值、持续时间和潜伏期随 prepulse 和背景音频率差的变化来评估抑制效果。
我们的数据表明，具有纯音背景的 ASR 幅度随音调频率而变化，且小于具有白噪声背景的幅度。 prepulse 音调系统地降低了 ASR，作为 prepulse 和背景音之间频率差的函数。 0.5 kHz 的差异似乎是引起显著 ASR 抑制的前提条件。在 10 或 18 kHz 的背景音下，PPI 的频率依赖性相似。
PPI 对 prepulse 声音的频率信息敏感。然而，关键因素不是音调频率本身，而是 prepulse 和背景音之间的频率差。
