Department of Psychology and Neuroscience Program, University of Michigan, 530 Church Street, 4030 East Hall, Ann Arbor, MI, 48109, USA.
Eur J Neurosci. 2017 Dec;46(11):2768-2781. doi: 10.1111/ejn.13741. Epub 2017 Nov 6.
Discrete Pavlovian reward cues acquire more potent incentive motivational properties (incentive salience) in some animals (sign-trackers; STs) compared to others (goal-trackers; GTs). Conversely, GTs appear to be better than STs in processing more complex contextual cues, perhaps reflecting their relatively greater bias for goal-directed cue processing. Here, we investigated the activity of two major prefrontal neuromodulatory input systems, dopamine (DA) and acetylcholine (ACh), in response to a discrete Pavlovian cue that was previously paired with cocaine administration in STs and GTs. Rats underwent Pavlovian training in which light cue presentations were either paired or unpaired with an intravenous cocaine infusion. Following a 10-day abstinence period, prefrontal dialysates were collected in STs and GTs during cue presentations in the absence of cocaine. In STs, the cue previously paired with cocaine significantly increased prefrontal DA levels. DA levels remained elevated over baseline across multiple cue presentation blocks, and DA levels and approaches to the cue were significantly correlated. In STs, ACh levels were unaffected by cue presentations. In contrast, in GTs, presentations of the cocaine cue increased prefrontal ACh, but not DA, levels. GTs oriented towards the cue at rates similar to STs, but they did not approach it and elevated ACh levels did not correlate with conditioned orientation. The results indicate a double dissociation between the role of prefrontal DA and ACh in STs and GTs, and suggest that these phenotypes will be useful for studying the role of neuromodulator systems in mediating opponent behavioural-cognitive styles.
离散的巴甫洛夫奖励线索在某些动物（标记跟踪者；ST）中比在其他动物（目标跟踪者；GT）中获得更强的激励动机属性（激励显著性）。相反，GT 似乎比 ST 更擅长处理更复杂的上下文线索，这可能反映了它们相对更强的目标导向线索处理偏向。在这里，我们研究了两种主要的前额叶神经调制输入系统，多巴胺（DA）和乙酰胆碱（ACh），对离散的巴甫洛夫线索的反应，该线索以前在 ST 和 GT 中与可卡因给药配对。大鼠接受了巴甫洛夫式训练，其中光线索呈现与静脉内可卡因输注配对或不配对。在 10 天的禁欲期后，在没有可卡因的情况下，在 ST 和 GT 中收集前额叶透析物，在 cue 呈现期间。在 ST 中，与可卡因配对的 cue 显著增加了前额叶 DA 水平。DA 水平在多个 cue 呈现块中一直高于基线，并且 DA 水平和 cue 的接近度呈显著相关。在 ST 中，cue 的呈现对 ACh 水平没有影响。相比之下，在 GT 中，可卡因 cue 的呈现增加了前额叶 ACh，但没有增加 DA 水平。GT 以类似于 ST 的速度朝向 cue，但它们没有接近它，并且升高的 ACh 水平与条件取向没有相关性。结果表明，前额叶 DA 和 ACh 在 ST 和 GT 中的作用存在双重分离，并表明这些表型将有助于研究神经调制系统在调节对手性行为-认知风格中的作用。
