Department of Psychological and Brain Sciences, Boston University, Boston, MA, USA.
Department of Neuroscience, Tufts University School of Medicine, Boston, MA, USA.
Adv Neurobiol. 2024;38:13-28. doi: 10.1007/978-3-031-62983-9_2.
Animals utilize a repertoire of behavioral responses during everyday experiences. During a potentially dangerous encounter, defensive actions such as "fight, flight, or freeze" are selected for survival. The successful use of behavior is determined by a series of real-time computations combining an animal's internal (i.e., body) and external (i.e., environment) state. Brain-wide neural pathways are engaged throughout this process to detect stimuli, integrate information, and command behavioral output. The hippocampus, in particular, plays a role in the encoding and storing of the episodic information surrounding these encounters as putative "engram" or experience-modified cellular ensembles. Recalling a negative experience then reactivates a dedicated engram ensemble and elicits a behavioral response. How hippocampus-based engrams modulate brain-wide states and an animal's internal/external milieu to influence behavior is an exciting area of investigation for contemporary neuroscience. In this chapter, we provide an overview of recent technological advancements that allow researchers to tag, manipulate, and visualize putative engram ensembles, with an overarching goal of casually connecting their brain-wide underpinnings to behavior. We then discuss how hippocampal fear engrams alter behavior in a manner that is contingent on an environment's physical features as well as how they influence brain-wide patterns of cellular activity. Overall, we propose here that studies on memory engrams offer an exciting avenue for contemporary neuroscience to casually link the activity of cells to cognition and behavior while also offering testable theoretical and experimental frameworks for how the brain organizes experience.
动物在日常体验中会利用一系列行为反应。在潜在危险的情况下，会选择“战斗、逃跑或冻结”等防御行为来求生。行为的成功运用取决于一系列实时计算，这些计算将动物的内部（即身体）和外部（即环境）状态结合起来。在这个过程中，大脑中的广泛神经通路被激活，以检测刺激、整合信息并指挥行为输出。特别是海马体在编码和存储这些遭遇的情景信息方面发挥了作用，这些信息被认为是“记忆痕迹”或经验修饰的细胞集合。回忆起一段负面经历会重新激活特定的记忆痕迹集合，并引发行为反应。海马体记忆痕迹如何调节大脑状态和动物的内外环境以影响行为，是当代神经科学的一个令人兴奋的研究领域。在本章中，我们提供了最近技术进步的概述，这些进步使研究人员能够标记、操作和可视化假定的记忆痕迹集合，其总体目标是将其与大脑广泛的基础联系起来，以影响行为。然后，我们讨论了海马体恐惧记忆痕迹如何以依赖环境物理特征的方式改变行为，以及它们如何影响大脑广泛的细胞活动模式。总的来说，我们在这里提出，记忆痕迹的研究为当代神经科学提供了一个令人兴奋的途径，可以随意将细胞的活动与认知和行为联系起来，同时为大脑如何组织经验提供了可测试的理论和实验框架。
