Moore Sharlen, Kuchibhotla Kishore V
Department of Psychological and Brain Sciences, Krieger School of Arts and Sciences, Johns Hopkins University, Baltimore, MD, USA.
The Solomon H. Snyder Department of Neuroscience, School of Medicine, Johns Hopkins University, Baltimore, MD, USA.
IBRO Neurosci Rep. 2022 May 24;13:9-14. doi: 10.1016/j.ibneur.2022.05.006. eCollection 2022 Dec.
Learning is fundamental to animal survival. Animals must learn to link sensory cues in the environment to actions that lead to reward or avoid punishment. Rapid learning can then be highly adaptive and the difference between life or death. To explore the neural dynamics and circuits that underlie learning, however, has typically required the use of laboratory paradigms with tight control of stimuli, action sets, and outcomes. Learning curves in such reward-based tasks are reported as slow and gradual, with animals often taking hundreds to thousands of trials to reach expert performance. The slow, highly variable, and incremental learning curve remains the largely unchallenged belief in modern systems neuroscience. Here, we provide historical and contemporary evidence that instrumental forms of reward-learning can be dissociated into two parallel processes: knowledge acquisition which is rapid with step-like improvements, and behavioral expression which is slower and more variable. We further propose that this conceptual distinction may allow us to isolate the associative (knowledge-related) and non-associative (performance-related) components that influence learning. We then discuss the implications that this revised understanding of the learning curve has for systems neuroscience.
学习是动物生存的基础。动物必须学会将环境中的感官线索与导致奖励或避免惩罚的行为联系起来。快速学习具有高度适应性，关乎生死存亡。然而，要探究学习背后的神经动力学和神经回路，通常需要使用对刺激、动作集和结果进行严格控制的实验室范式。在这类基于奖励的任务中，学习曲线被认为是缓慢且渐进的，动物通常需要进行数百到数千次试验才能达到专家级表现。这种缓慢、高度可变且渐进的学习曲线在现代系统神经科学中基本上未受到质疑。在此，我们提供历史和当代证据表明，工具性奖励学习形式可分为两个并行过程：知识获取过程迅速，有阶梯式提升；行为表现过程较慢且更具变异性。我们进一步提出，这种概念上的区分可能使我们能够分离出影响学习的联想（与知识相关）和非联想（与表现相关）成分。然后，我们讨论这种对学习曲线的修正理解对系统神经科学的影响。
