Beuk Jonathan, Beninger Richard J, Mechefske Elysia, Paré Martin
Centre for Neuroscience Studies, Queen's University, Kingston, Ontario K7L 3N6, Canada.
Centre for Neuroscience Studies, Queen's University, Kingston, Ontario K7L 3N6, Canada; Department of Psychology, Queen's University, Kingston, Ontario K7L 3N6, Canada.
Neuroscience. 2016 Nov 19;337:200-217. doi: 10.1016/j.neuroscience.2016.09.009. Epub 2016 Sep 16.
Humans and non-human primates are known to lengthen their response time (RT) to a go signal when they occasionally must cancel their responses following a stop signal in a countermanding task as well as to adjust their RT adaptively on a trial-by-trial basis. Less is clear regarding the adaptive RT adjustments in the countermanding performance of rodents. To investigate this question, male Wistar rats (N=12) were trained with food reward to press a lever directly below an illuminated light (go signal), but to countermand the lever press subsequent to a tone (stop signal) presented infrequently (25% of trials) at variable delays. Rats were then tested in a standard responding task (0% stop trials) or a countermanding task with a 10-s or 1-s TO interval following errors. Rats exhibited significant RT lengthening in the countermanding task, compared with the standard responding task, and RT shortening following consecutive correct go trials. They also show RT lengthening following both error trials in the standard responding task and unrewarded, non-canceled stop trials in the countermanding task. RT lengthening following erroneous stop trials was observed in sessions with a 10-s TO interval, but not with a 1-s TO interval. Analyses of RT distributions suggest that RT lengthening results largely from reduced sensitivity to the go signal, but also from reduced readiness. These findings indicate that rats exert control in the countermanding task by lengthening RT in anticipation of stop trials to avoid long, unrewarded TO intervals.
众所周知，在一项反指令任务中，当人类和非人类灵长类动物偶尔必须在停止信号后取消其反应时，它们对启动信号的反应时间（RT）会延长，并且会在逐次试验的基础上适应性地调整其反应时间。关于啮齿动物在反指令表现中的适应性反应时间调整，目前尚不清楚。为了研究这个问题，对12只雄性Wistar大鼠进行训练，用食物奖励让它们按压照明灯光（启动信号）正下方的杠杆，但在偶尔出现（25%的试验）且延迟可变的音调（停止信号）后取消杠杆按压。然后让大鼠在标准反应任务（0%停止试验）或在错误后有10秒或1秒超时（TO）间隔的反指令任务中进行测试。与标准反应任务相比，大鼠在反指令任务中表现出显著的反应时间延长，并且在连续正确的启动试验后反应时间缩短。它们在标准反应任务中的错误试验以及反指令任务中未得到奖励、未取消的停止试验后也表现出反应时间延长。在有10秒超时间隔的试验中观察到错误停止试验后反应时间延长，但在有1秒超时间隔的试验中未观察到。对反应时间分布的分析表明，反应时间延长主要是由于对启动信号的敏感性降低，但也由于准备状态降低。这些发现表明，大鼠在反指令任务中通过在预期停止试验时延长反应时间来进行控制，以避免长时间的、未得到奖励的超时间隔。
