Campeau S, Davis M
Department of Psychiatry and Psychology, Yale University School of Medicine, New Haven, Connecticut, USA.
Psychopharmacology (Berl). 1995 Feb;117(3):267-74. doi: 10.1007/BF02246101.
The amplitude of the acoustic startle reflex can be reduced reliably when preceded at short intervals by a weak stimulus (prepulse) which itself does not elicit startle. The magnitude of this prepulse inhibition effect is attenuated by several dopamine agonists, such as apomorphine, especially when there is a relatively small difference between the intensity of the prepulse and the intensity of the background noise over which the prepulse is superimposed. One goal of the present experiment was to test the generality of this disruptive effect of apomorphine on prepulse inhibition by using either an auditory prepulse that included both a change in intensity and a change in frequency relative to the background noise or a visual prepulse stimulus. Apomorphine reduced auditory prepulse inhibition when induced by a small change in stimulus intensity, but not when induced by a change in both intensity and frequency. Apomorphine consistently reduced visual prepulse inhibition with a complete blockade at 100-ms test interval. However, it did not fully block the usual reduction in startle onset latency or even attenuate the increase in startle amplitude when a visual prepulse was presented 5, 10 or 15 ms before the startle stimulus. Consistent with conclusions from other laboratories using auditory prepulse inhibition, these data suggest that apomorphine did not prevent the animal from detecting prepulse presentation under conditions where the drug completely blocked prepulse inhibition. Moreover, they indicate that the blockade of prepulse inhibition by apomorphine was independent of prepulse modality, adding generality to the original finding. Visual prepulse inhibition may be a useful alternative procedure for evaluating the effects of drugs on this attentional process.
当在短时间间隔之前出现一个本身不会引发惊吓反应的弱刺激（预脉冲）时，听觉惊吓反射的幅度可以可靠地降低。几种多巴胺激动剂，如阿扑吗啡，会减弱这种预脉冲抑制效应的大小，尤其是当预脉冲强度与叠加预脉冲的背景噪声强度之间的差异相对较小时。本实验的一个目的是通过使用相对于背景噪声强度和频率都有变化的听觉预脉冲或视觉预脉冲刺激，来测试阿扑吗啡对预脉冲抑制的这种干扰效应的普遍性。当由刺激强度的小变化诱发时，阿扑吗啡会降低听觉预脉冲抑制，但当由强度和频率的变化共同诱发时则不会。阿扑吗啡在100毫秒测试间隔时会持续降低视觉预脉冲抑制，并完全阻断。然而，当在惊吓刺激前5、10或15毫秒呈现视觉预脉冲时，它并没有完全阻断惊吓起始潜伏期通常的缩短，甚至没有减弱惊吓幅度的增加。与其他使用听觉预脉冲抑制的实验室得出的结论一致，这些数据表明，在药物完全阻断预脉冲抑制的情况下，阿扑吗啡并没有阻止动物检测到预脉冲的呈现。此外，它们表明阿扑吗啡对预脉冲抑制的阻断与预脉冲模态无关，这扩展了最初的发现。视觉预脉冲抑制可能是评估药物对这一注意力过程影响的一种有用的替代方法。
