Meyer Heidi C, Putney Rachel B, Bucci David J
Department of Psychological and Brain Sciences, Dartmouth College, Hanover, NH 03755, USA.
Neuropharmacology. 2015 Feb;89:360-7. doi: 10.1016/j.neuropharm.2014.10.025.
Prior research has established that stimulating nicotinic acetylcholine receptors can facilitate learning and memory. However, most studies have focused on learning to emit a particular behavior, while little is known about the effects of nicotine on learning to withhold a behavioral response. The present study consisted of a dose response analysis of the effects of nicotine on negative occasion setting, a form of learned inhibition. In this paradigm, rats received one type of training trial in which presentation of a tone by itself was followed immediately by food reward. During the other type of trials, the tone was preceded by presentation of a light and no food was delivered after the tone. Rats gradually learned to approach the cup in anticipation of receiving food reward during presentations of the tone alone, but withheld that behavior when the tone was preceded by the light. Nicotine (0.35 mg/kg) facilitated negative occasion setting by reducing the number of sessions needed to learn the discrimination between trial types and by reducing the rate of responding on non-reinforced trials. Nicotine also increased the orienting response to the light, suggesting that nicotine may have affected the ability to withhold food cup behavior on non-reinforced trials by increasing attention to the light. In contrast to the effects of nicotine, rats treated with mecamylamine (0.125, 0.5, or 2 mg/kg) needed more training sessions to discriminate between reinforced and non-reinforced trials compared to saline-treated rats. The findings indicate that nicotinic acetylcholine receptors may be active during negative occasion setting and that nicotine can potentiate learned inhibition.
先前的研究已经证实，刺激烟碱型乙酰胆碱受体会促进学习和记忆。然而，大多数研究都集中在学习发出特定行为上，而关于尼古丁对学习抑制行为反应的影响却知之甚少。本研究包括对尼古丁对负性情境设定（一种习得性抑制形式）影响的剂量反应分析。在这个范式中，大鼠接受一种类型的训练试验，即单独呈现一个音调后立即给予食物奖励。在另一种类型的试验中，音调之前会呈现一道光，音调之后不给予食物。大鼠逐渐学会在单独呈现音调时预期会得到食物奖励而接近杯子，但当音调之前有光时则抑制该行为。尼古丁（0.35毫克/千克）通过减少学习区分试验类型所需的训练次数以及减少无强化试验中的反应率，促进了负性情境设定。尼古丁还增加了对光的定向反应，这表明尼古丁可能通过增加对光的注意力，影响了在无强化试验中抑制接近食物杯行为的能力。与尼古丁的作用相反，与生理盐水处理的大鼠相比，用美加明（0.125、0.5或2毫克/千克）处理的大鼠需要更多的训练次数来区分强化和无强化试验。这些发现表明，烟碱型乙酰胆碱受体可能在负性情境设定过程中发挥作用，并且尼古丁可以增强习得性抑制。
