Guterman Y, Josiassen R C, Bashore T R
Medical College of Pennsylvania, Eastern Pennsylvania Psychiatric Institute, Philadelphia 19129.
Int J Psychophysiol. 1992 Mar;12(2):197-209. doi: 10.1016/0167-8760(92)90011-y.
To determine if attentional factors influence the suppression of the auditory P50 in a conditioning-testing paradigm, known as the 'sensory gating' effect, we tested 10 healthy young adults in four experimental conditions. The first condition was the traditional passive conditioning-testing paradigm in which a pair of identical auditory clicks is administered at an interstimulus interval fixed at 500 ms. The effect of interest is a reduction of P50 amplitude in response to the second stimulus. In the next condition, the second stimulus could be one of two possible frequencies and subjects were required to count one and to ignore the other. The third and fourth experimental conditions involved a motor response. In the third condition, subjects were required to make a unimanual button press to the occurrence of the second stimulus. In the fourth condition, subjects were required to discriminate among two possible second stimuli, and make a unimanual button press to the occurrence of the designated stimulus. Subjects also completed four matched blocks of single stimulus (i.e., unpaired) presentations to provide a baseline for assessing the effect of the warning stimulus on the evoked response. We found, in agreement with previous results, that passive exposure to the paired stimuli produced a suppression of P50 amplitude to the second stimulus. However, we also found that suppression of P50 amplitude was not evident when subjects selectively counted the designated stimuli, and was reduced in magnitude when a simple motor response was required and when a selective motor response was based on stimulus discrimination. In addition, we observed that the amplitude of the P50 was larger with unpaired single stimuli than it was either with the first or second stimulus of a pair, regardless of processing demands. Furthermore, variations in processing demands did not affect P50 amplitude when a single stimulus was presented. This pattern of results suggests that the 'sensory gating' effect is not a simple 'hard-wired' inhibitory phenomenon. Rather, it may be one manifestation of an attention regulation process that is activated by a warning stimulus and has either inhibitory or excitatory effects on neural transmission, determined by variations in processing demands. Presentation of a warning stimulus may have an additional, unselective suppressing effect, operating independently of this attention regulating process.
为了确定在一种被称为“感觉门控”效应的条件测试范式中，注意力因素是否会影响听觉P50的抑制，我们在四种实验条件下对10名健康的年轻成年人进行了测试。第一种条件是传统的被动条件测试范式，其中以固定为500毫秒的刺激间隔给予一对相同的听觉咔哒声。感兴趣的效应是对第二个刺激的P50振幅降低。在下一种条件下，第二个刺激可以是两种可能频率之一，受试者被要求数其中一个并忽略另一个。第三和第四种实验条件涉及运动反应。在第三种条件下，要求受试者在第二个刺激出现时进行单手按键。在第四种条件下，要求受试者区分两种可能的第二个刺激，并在指定刺激出现时进行单手按键。受试者还完成了四个匹配的单刺激（即未配对）呈现块，以提供评估警告刺激对诱发反应影响的基线。我们发现，与先前的结果一致，被动暴露于配对刺激会导致对第二个刺激的P50振幅受到抑制。然而，我们还发现，当受试者选择性地数指定刺激时，P50振幅的抑制并不明显，并且当需要简单运动反应以及当选择性运动反应基于刺激辨别时，抑制程度会降低。此外，我们观察到，无论处理要求如何，未配对单刺激时的P50振幅都比配对刺激中的第一个或第二个刺激时的P50振幅更大。此外，当呈现单个刺激时，处理要求的变化不会影响P50振幅。这种结果模式表明，“感觉门控”效应不是一种简单的“硬连线”抑制现象。相反，它可能是一种注意力调节过程的表现，该过程由警告刺激激活，并且对神经传递具有抑制或兴奋作用，这取决于处理要求的变化。警告刺激的呈现可能具有额外的、非选择性的抑制作用，独立于这种注意力调节过程起作用。
