Chiu Yu-Chin, Cools Roshan, Aron Adam R
University of California, San Diego.
J Cogn Neurosci. 2014 Aug;26(8):1851-60. doi: 10.1162/jocn_a_00585. Epub 2014 Feb 24.
Everyday life, as well as psychiatric illness, is replete with examples where appetitive and aversive stimuli hijack the will, leading to maladaptive behavior. Yet the mechanisms underlying this phenomenon are not well understood. Here we investigate how motivational cues influence action tendencies in healthy individuals with a novel paradigm. Behaviorally, we observed that an appetitive cue biased go behavior (making a response), whereas an aversive cue biased no-go behavior (withholding a response). We hypothesized that the origin of this behavioral go/no-go bias occurs at the motor system level. To test this, we used single-pulse TMS as a motor system probe (rather than a disruptive tool) to index motivational biasing. We found that the appetitive cue biased the participants to go more by relatively increasing motor system excitability, and that the aversive cue biased participants to no-go more by relatively decreasing motor system excitability. These results show, first, that maladaptive behaviors arise from motivational cues quickly spilling over into the motor system and biasing behavior even before action selection and, second, that this occurs in opposing directions for appetitive and aversive cues.
日常生活以及精神疾病中，充满了诸如奖赏性和厌恶性刺激劫持意志并导致适应不良行为的例子。然而，这种现象背后的机制尚未得到充分理解。在此，我们用一种新范式研究了动机线索如何影响健康个体的行动倾向。在行为层面，我们观察到奖赏性线索使“执行”行为（做出反应）产生偏向，而厌恶性线索使“不执行”行为（抑制反应）产生偏向。我们假设这种行为上的“执行/不执行”偏向起源于运动系统层面。为了验证这一点，我们使用单脉冲经颅磁刺激（TMS）作为运动系统探测器（而非干扰工具）来衡量动机偏向。我们发现，奖赏性线索通过相对增加运动系统兴奋性，使参与者更倾向于“执行”；而厌恶性线索通过相对降低运动系统兴奋性，使参与者更倾向于“不执行”。这些结果表明，首先，适应不良行为源于动机线索在行动选择之前就迅速渗透到运动系统并使行为产生偏向；其次，奖赏性和厌恶性线索的这种影响方向相反。
