Redon Bastien, Hurel Imane, Marsicano Giovanni, Chaouloff Francis
Inserm U1215, Neurocentre Magendie, Team Endocannabinoids & NeuroAdaptation, Bordeaux F33077, France.
Université de Bordeaux, Bordeaux-F33077, France.
Bio Protoc. 2019 Oct 5;9(19):e3381. doi: 10.21769/BioProtoc.3381.
Wheel running, especially in the homecage, has been widely used to study the neurobiology of exercise because animal tends to use it voluntarily. However, as for each reward, its consumption (in the present case, running performance) does not specifically provide information on its incentive value, , the extent to which animals are motivated to run independently from their consumption of that reward. This is a major drawback, especially when focusing on the neurobiology governing the pathological imbalances between exercise and , feeding (obesity, anorexia nervosa). Yet, few studies have shown that operant conditioning wherein wheel-running is used as a reinforcer that can be "consumed" after nose-poking or lever-pressing allows to distinguish motivation from consumption. Thus, nose-poking or lever-pressing under a progressive ratio schedule of reinforcement in animals trained under fixed ratio reinforcement schedules provides, through the so-called breakpoint, an index of running motivation. As compared to wheel-running, numerous studies have used food as a reinforcer, which helped to uncover the neurobiology of feeding. However, to our knowledge, there is no paradigm allowing the assessment of the choice between running and feeding when presented in concurrence, with the possibility to measure the motivation for each reward. Herein, we describe a protocol that first permits to measure the drive for each of these two rewards before it allows to measure the preference for one over the other in a reward choice setting. This paradigm could help to better characterize the neurobiology underlying pathological imbalances between physical activity and feeding, which is the core feature of eating disorders.
轮转运动，尤其是在动物饲养笼中的轮转运动，已被广泛用于研究运动的神经生物学，因为动物倾向于自愿进行此项运动。然而，对于每一种奖励而言，其消耗（在当前情况下即跑步表现）并不能具体提供关于其激励价值的信息，即动物在不依赖该奖励消耗的情况下自主跑步的动机程度。这是一个主要缺点，尤其是在关注调节运动与进食（肥胖、神经性厌食）之间病理失衡的神经生物学时。然而，很少有研究表明，将轮转运动用作一种强化物，在动物进行鼻触或压杆操作后可“消耗”该强化物的操作性条件反射，能够区分动机与消耗。因此，在固定比率强化程序下训练的动物，在渐进比率强化程序下进行鼻触或压杆操作，通过所谓的断点，可提供跑步动机的指标。与轮转运动相比，许多研究使用食物作为强化物，这有助于揭示进食的神经生物学机制。然而，据我们所知，尚无一种范式能够在同时呈现跑步和进食时评估两者之间的选择，并测量对每种奖励的动机。在此，我们描述一种方案，该方案首先允许在奖励选择环境中测量对这两种奖励中每一种的驱动力，然后再测量对其中一种奖励相对于另一种奖励的偏好。这种范式有助于更好地描述身体活动与进食之间病理失衡背后的神经生物学机制，而这正是饮食失调的核心特征。
