Acetylcholine role in the reward system and individual approach style.

早在巴甫洛夫最初的条件反射实验中，狗在听到与食物即将到来有关的蜂鸣器的声音时就开始分泌唾液，研究人员注意到一些动物试图按蜂鸣器以获得食物。在其他物种中也可以观察到同样的行为。在老鼠身上，在动物接受食物之前，给它们一个没有功能的杠杆，会导致一些动物按下杠杆，这种行为被称为“信号追踪”。其他动物会选择食物分配（目标跟踪），或者在这两种行为之间交替进行。这些个体的行为方式与其他表现型相关：信号追踪动物的注意力控制能力差，有成瘾倾向，药物复发的可能性更大。在包括人类在内的其他物种中也可以观察到这些个体的行为方式，在这些物种中，信号追踪与肥胖有关。参与信号追踪的动物在神经系统上存在一些差异，尤其是它们的多巴胺能奖励系统（D2和D3受体，DAT）。虽然乙酰胆碱是一种功能与注意力有关的神经递质，但这种神经递质对多巴胺能系统有一定的控制作用，可能参与了信号跟踪行为。只有少数研究考察了乙酰胆碱在个人风格行为中的作用。由于已知的信号追踪大鼠表现出依赖于乙酰胆碱的注意力缺陷，我们怀疑乙酰胆碱系统的控制较弱。乙酰胆碱在很大程度上被忽视了；它的研究是一个基本的兴趣，因为它被认为是控制奖励因素。

As early as Pavlov's original conditioning experiments in which dogs began to salivate to the sound of a buzzer that had been associated with the imminent arrival of food researchers noticed that some animals attempted to ring the buzzer in order to obtain food. The same behaviour can be observed in other species. In rats, a non-functional lever presented to the animal before receiving food will cause some animals to press the lever, a behaviour known as "sign tracking". Other animals go for the food distributor (goal tracking), or alternate between these two behaviors. These individual approach styles correlate with other phenotypesthe sign tracker animals have poor attention control, a propensity to addiction and a greater probability of drug relapse. These individual styles of behaviour are observed in other species, including humans, in which sign tracking is linked to obesity. Animals who engage in sign tracking have several neurological differences, in particular to their dopaminergic reward system (D2 and D3 receptors, DAT). Although acetylcholine is a neurotransmitter whose function is related to attention, this neurotransmitter exerts some control on the dopaminergic system and may be involved in sign-tracking behaviour. Only a few studies have examined the role of acetylcholine in the individual style behaviour. Since sign tracker rats are known to show attentional deficits that are acetylcholine dependent, we suspect a weaker control by the acetylcholine system. Acetylcholine is largely overlooked; its study is a fundamental interest since it is known to control factors of reward. My innovative research program aims at better understanding the role of acetylcholine in reward valuation and individual differences in approach style. To define the acetylcholine role in the individual approach style, three specific objectives are proposed. 1- We will identify the role of the differents parts of the cholinergic system on the individual approach style by lesioning 3 different acetylcholine areas of the brain (top-down attention, bottom-up attention and reward system). 2- We will evaluate the electrophysiological (ERP) differences according to the individual approach style. 3- We will quantify the neuroanatomical differences from the sign tracker and goal tracker animals, in the three regions aforementioned in objective 1. Overall, these findings will provide new knowledge about the origins of the individual approach style and are especially important since these animals also show deficits in attention, vulnerability to drug dependence and greater susceptibility to relapse. The role of acetylcholine in the individual approach style is a great new vista leading to a better understanding of addiction, attention control and their comorbidity.