The role of brain neurotransmitters in the control of behaviour

众所周知，行为可以通过奖励(例如，食物、水、远离危险的安全、性)来改变，但对潜在的大脑机制知之甚少。奖励产生激励性学习，即通过预测奖励的刺激获得更强的引出方法和其他反应的能力。这种形式的学习是由大脑神经递质多巴胺调节的，当收到奖励时，多巴胺就会释放出来。在接受奖励的动物或人类的大脑中，释放的多巴胺占据着受体--就像锁上的钥匙一样装入受体--影响脑神经细胞内的化学信息，即神经元。这些化学信息是刺激学习的成长过程和其他化学变化的原因。多巴胺受体有几种类型，形成两个家族，即D1样和D2样受体。以前的工作已经确定了由D1样受体激活的化学信使在激励学习中的重要作用。最近，D2样受体被发现影响另一组不同的化学信使，但人们对它们在激励学习中可能扮演的角色知之甚少。拟议的实验调查了D2样受体连接的化学信使在激励学习中的可能作用。老鼠将在一项任务中接受训练，在这项任务中，它们通常会表现出对以前获得奖励的地方的偏好。我的学生学员和我将使用已知的影响D2样受体激活的化学信使的药物，并将它们注射到大鼠的身体或大脑中。如果这些药物剂量依赖地损害与奖励相关的激励学习，结果将在学习机制中牵涉到D2样受体信号。*当动物或人类遇到新的地方或事物时，它们最初很有趣，通常会进行探索，但如果没有生物上重要的事情发生，这些地方或事物很快就会失去吸引力，变得习以为常。像激励性学习一样，这也是一种学习形式；在这种情况下，预测不会有回报的刺激失去了引发接近和其他反应的能力。我把这种学习称为逆向激励学习。人们对大脑中调节反向激励学习的化学机制知之甚少，但似乎与多巴胺的减少有关。由我的实验室的本科生和研究生实习生进行的拟议研究将评估D1样和D2样受体在反向激励学习中的可能作用。*解开大脑中与奖励相关的激励学习和反向激励学习背后的化学信使通路，将有助于更好地理解动物和人类大脑的工作原理。通过了解我们如何了解我们的环境，我们将能够更有效地通过优化利用基本机制来适应环境。**

It is widely known that behavior can be modified by rewards (e.g., food, water, safety from danger, sex) but much less is known about the underlying brain mechanisms. Rewards produce incentive learning, i.e., the acquisition, by stimuli that predict reward, of an increased ability to elicit approach and other responses. This form of learning is mediated by the brain neurotransmitter dopamine that is released when reward is received. In the brain of the animal or human that received the reward, released dopamine occupies receptors - fitting into them like a key in a lock - that influence chemical messages inside brain nerve cells, i.e., neurons. These chemical messages are responsible for the growth processes and other chemical changes that underlie incentive learning. Dopamine receptors are of several types, forming two families known as D1- and D2-like receptors. Previous work has identified an important role in incentive learning for the chemical messengers activated by D1-like receptors. More recently, D2-like receptors have been found to influence a different set of chemical messengers but little is known about their possible role in incentive learning. The proposed experiments investigate the possible role of D2-like receptor-linked chemical messengers in incentive learning. Rats will be trained in a task where they normally demonstrate a preference for a place where they have previously received reward. My student trainees and I will use drugs that are known to influence the chemical messengers activated by D2-like receptors and inject them into the body or into the brain of the rats. If these drugs dose-dependently impair reward-related incentive learning, results will implicate D2-like receptor signaling in the mechanisms underlying that learning.****When animals or humans encounter novel places or things, they are initially interesting and often explore but if nothing biologically important happens, these places or things quickly lose their attractiveness and become habituated. Like incentive learning, this is also a form of learning; in this case stimuli that predict no reward lose their ability to elicit approach and other responses. I have termed this for of learning as inverse incentive learning. Very little is known about the chemical mechanisms in the brain that mediate inverse incentive learning but decreases in dopamine seem to be involved. Proposed studies carried out by undergrad and grad student trainees in my lab will evaluate the possible role of D1- and D2-like receptors in inverse incentive learning. ****Unraveling the chemical messenger pathways in the brain that underlie reward-related incentive learning and inverse incentive learning will lead to a better understanding of the working of the brains of animals and humans. By understanding how we learn about our environment we will be better able to adapt more effectively by optimizing utilization of the underlying mechanisms. **