The BioRobotics Institute, Department of Excellence in Robotics and AI, Scuola Superiore Sant'Anna, 56025, Pisa, Italy.
Dept. of Theoretical Neuroscience, Central Institute of Mental Health, Medical Faculty Mannheim, Heidelberg University, 68159, Mannheim, Germany.
Nat Commun. 2024 Oct 22;15(1):8880. doi: 10.1038/s41467-024-52988-x.
Spatial information is encoded by location-dependent hippocampal place cell firing rates and sub-second, rhythmic entrainment of spike times. These rate and temporal codes have primarily been characterized in low-dimensional environments under limited cognitive demands; but how is coding configured in complex environments when individual place cells signal several locations, individual locations contribute to multiple routes and functional demands vary? Quantifying CA1 population dynamics of male rats during a decision-making task, here we show that the phase of individual place cells' spikes relative to the local theta rhythm shifts to differentiate activity in different place fields. Theta phase coding also disambiguates repeated visits to the same location during different routes, particularly preceding spatial decisions. Using unsupervised detection of cell assemblies alongside theoretical simulation, we show that integrating rate and phase coding mechanisms dynamically recruits units to different assemblies, generating spiking sequences that disambiguate episodes of experience and multiplexing spatial information with cognitive context.
空间信息由位置依赖的海马体位置细胞放电率和亚秒级、有节奏的尖峰时间同步编码。这些速率和时间编码主要在低维环境下，在认知需求有限的情况下进行了描述；但是当单个位置细胞表示多个位置、单个位置对应多个路径以及功能需求不同时，编码是如何配置的呢？在这里，我们通过量化雄性大鼠在决策任务期间 CA1 群体动力学，发现个体位置细胞的尖峰相对于局部 theta 节律的相位发生变化，从而区分不同位置场的活动。theta 相位编码还可以区分不同路径下同一位置的重复访问，特别是在空间决策之前。通过使用无监督的细胞集合检测以及理论模拟，我们发现，动态地整合速率和相位编码机制会将单元分配到不同的集合中，生成尖峰序列，从而区分经历的各个片段，并将空间信息与认知上下文进行多路复用。
