Hsieh Ming H, Swerdlow Neal R, Braff David L
Department of Psychiatry, National Taiwan University Hospital, Taipei, Taiwan.
Biol Psychiatry. 2006 Mar 15;59(6):555-9. doi: 10.1016/j.biopsych.2005.07.032. Epub 2005 Sep 19.
Both prepulse inhibition (PPI) and prepulse facilitation (PPF) deficits have been reported in schizophrenia patients, but the use of different experimental parameters across laboratories makes direct comparisons of results difficult. We assessed the effects of different parameters on PPI and PPF in normal subjects.
Eyeblink startle was measured in 14 healthy male subjects, using 115 dB[A] white noise startle pulses and 86 dB[A] prepulses. Analyses compared the effects of: 1) background noise level (ambient 54 vs. 70 dB[A]) on PPI and PPF, 2) prepulse duration (discrete 20 msec vs. continuous) on PPF, 3) prepulse frequency (1000 Hz vs. white noise) on PPI and PPF, and 4) prepulse interval (2000 vs. 4500 msec) on PPF.
Compared to an experimentally delivered 70 dB[A] background, ambient 54 dB[A] background led to significantly more PPI (with discrete white noise prepulses), and more PPF (with continuous prepulses). Continuous and longer (4500 msec) prepulses induced more PPF than did discrete and shorter (2000 msec) prepulses.
Paradigmatic differences appear likely to be responsible for divergent findings in studies of PPI and PPF in normal and schizophrenia subjects. The present study should guide investigators in the selection of parameters for assessing PPI and PPF in studies of normal subjects and schizophrenia patients. Attention to the 4 factors of 1) background noise, 2) prepulse duration, 3) frequency, and 4) interval will facilitate comparability of results across different laboratories, especially when using PPI/PPF in schizophrenia research as neural substrate probes, as biomarkers, and as endophenotypes.
已有报道称精神分裂症患者存在前脉冲抑制（PPI）和前脉冲易化（PPF）缺陷，但各实验室使用的实验参数不同，使得结果难以直接比较。我们评估了不同参数对正常受试者PPI和PPF的影响。
对14名健康男性受试者进行眨眼惊吓测量，使用115 dB[A]的白噪声惊吓脉冲和86 dB[A]的前脉冲。分析比较了以下因素的影响：1）背景噪声水平（环境噪声54 dB[A]与70 dB[A]）对PPI和PPF的影响；2）前脉冲持续时间（离散20毫秒与连续）对PPF的影响；3）前脉冲频率（1000赫兹与白噪声）对PPI和PPF的影响；4）前脉冲间隔（2000毫秒与4500毫秒）对PPF的影响。
与实验施加的70 dB[A]背景相比，环境噪声54 dB[A]背景导致（使用离散白噪声前脉冲时）PPI显著增加，（使用连续前脉冲时）PPF增加。连续且较长（4500毫秒）的前脉冲比离散且较短（2000毫秒）的前脉冲诱导出更多的PPF。
范式差异可能是导致正常受试者和精神分裂症患者PPI和PPF研究结果不一致的原因。本研究应为研究人员在选择评估正常受试者和精神分裂症患者PPI和PPF的参数时提供指导。关注1）背景噪声、2）前脉冲持续时间、3）频率和4）间隔这四个因素将有助于不同实验室之间结果的可比性，特别是在将PPI/PPF用于精神分裂症研究作为神经基质探针、生物标志物和内表型时。
