美国加州大学旧金山分校Loren M. Frank等研究人员合作揭示海马表征与踏步之间的动态同步性。该项研究成果于2023年4月12日在线发表在《自然》杂志上。
研究人员表示，海马是哺乳动物的一种大脑结构，表达空间表征，并对导航至关重要。反过来，导航又错综复杂地依赖于运动；然而，目前的说法表明，海马的空间表征与运动过程的细节之间存在着差异。具体来说，海马被认为主要代表高阶认知和运动变量，如位置、速度和运动方向，而推动动物的肢体运动则主要在皮层下回路中计算和表现，包括脊髓、脑干和小脑。海马的表征是否真的与运动过程的详细结构脱钩仍然是未知的。
为了解决这个问题，研究人员同时监测了海马的空间表征和正在进行的肢体运动的快速时间尺度运动。研究人员发现，自由行动大鼠的前肢踏步周期是有节奏的，在运动过程中的峰值约为8赫兹，与运动过程中海马活动和空间表征的约8赫兹调制相匹配。研究人员还发现，前肢接触地面的时间（步态周期的“植物”时间）与海马的空间表征之间有精确的时间协调。值得注意的是，植物时间与最接近大鼠鼻子实际位置的海马表征相吻合，而在这些植物时间之间，海马表征向可能的未来位置发展。当大鼠接近空间决策时，这种同步性是可以具体检测到的。
总之，这些研究结果揭示了中枢认知表征和外周运动过程之间在几十毫秒的时间尺度上的深刻和动态协调。这种协调与认知需求相关联，迅速参与和脱离，并非常适合支持认知和感觉-运动回路之间的快速信息交流。
附：英文原文
Title: Dynamic synchronization between hippocampal representations and stepping
Author: Joshi, Abhilasha, Denovellis, Eric L., Mankili, Abhijith, Meneksedag, Yagiz, Davidson, Thomas J., Gillespie, Anna K., Guidera, Jennifer A., Roumis, Demetris, Frank, Loren M.
Issue&Volume: 2023-04-12
Abstract: The hippocampus is a mammalian brain structure that expresses spatial representations1 and is crucial for navigation2,3. Navigation, in turn, intricately depends on locomotion; however, current accounts suggest a dissociation between hippocampal spatial representations and the details of locomotor processes. Specifically, the hippocampus is thought to represent mainly higher-order cognitive and locomotor variables such as position, speed and direction of movement4,5,6,7, whereas the limb movements that propel the animal can be computed and represented primarily in subcortical circuits, including the spinal cord, brainstem and cerebellum8,9,10,11. Whether hippocampal representations are actually decoupled from the detailed structure of locomotor processes remains unknown. To address this question, here we simultaneously monitored hippocampal spatial representations and ongoing limb movements underlying locomotion at fast timescales. We found that the forelimb stepping cycle in freely behaving rats is rhythmic and peaks at around 8Hz during movement, matching the approximately 8 Hz modulation of hippocampal activity and spatial representations during locomotion12. We also discovered precisely timed coordination between the time at which the forelimbs touch the ground (‘plant’ times of the stepping cycle) and the hippocampal representation of space. Notably, plant times coincide with hippocampal representations that are closest to the actual position of the nose of the rat, whereas between these plant times, the hippocampal representation progresses towards possible future locations. This synchronization was specifically detectable when rats approached spatial decisions. Together, our results reveal a profound and dynamic coordination on a timescale of tens of milliseconds between central cognitive representations and peripheral motor processes. This coordination engages and disengages rapidly in association with cognitive demands and is well suited to support rapid information exchange between cognitive and sensory–motor circuits.
DOI: 10.1038/s41586-023-05928-6
Source: https://www.nature.com/articles/s41586-023-05928-6
Nature：《自然》，创刊于1869年。隶属于施普林格·自然出版集团，最新IF：69.504
官方网址：http://www.nature.com/
投稿链接：http://www.nature.com/authors/submit_manuscript.html
本期文章：《自然》：Online/在线发表
