Yoganarasimha D, Knierim James J
Department of Neurobiology & Anatomy, W.M. Keck Center for the Neurobiology of Learning and Memory, University of Texas Medical School at Houston, P.O. Box 20708, Houston, TX 77225, USA.
Exp Brain Res. 2005 Jan;160(3):344-59. doi: 10.1007/s00221-004-2016-9. Epub 2004 Sep 1.
Hippocampal place cells are selectively active when a rat occupies restricted locations in an environment, and head direction cells fire selectively when the rat's head is pointed in a particular direction in allocentric space. Both place cells and head direction cells are usually coupled, and they are controlled by a complex interaction between external landmarks and idiothetic cues. Most studies have investigated this interaction by rotating the landmarks in the environment. In contrast, a recent study translated the apparatus relative to the landmarks in an environment and found that most place cells maintained the same preferred location on the apparatus regardless of the location of the apparatus in the room. Because head direction cells are insensitive to the rat's location in an environment, the distal landmarks may influence the place field firing locations primarily by controlling the bearing of the head direction cell system. To address this question, ensembles of CA1 place cells and head direction cells of the anterior thalamus were recorded simultaneously, as a rectangular or circular track was moved to different locations in a room with distinct visual landmarks. Most place cells maintained their firing fields relative to the track when the track was translated, and head direction cells maintained the same preferred firing direction. When the distal landmarks were rotated around the track, the firing fields of place cells and the preferred directions of head direction cells rotated with the cues. These results suggest that the precise firing locations of place cells are controlled by an interaction between local and idiothetic cues, and the orientation of the CA1 ensemble representation relative to the distal landmarks may be controlled indirectly by the distal landmarks' influence over the bearing of the head direction cell system.
当大鼠处于环境中的特定受限位置时，海马位置细胞会选择性地激活；而当大鼠头部在以环境为中心的空间中指向特定方向时，头部方向细胞会选择性地放电。位置细胞和头部方向细胞通常是耦合的，它们受外部地标与自身运动线索之间复杂相互作用的控制。大多数研究通过在环境中旋转地标来研究这种相互作用。相比之下，最近一项研究将实验装置相对于环境中的地标进行平移，发现大多数位置细胞在装置上保持相同的偏好位置，而不管装置在房间中的位置如何。由于头部方向细胞对大鼠在环境中的位置不敏感，远处的地标可能主要通过控制头部方向细胞系统的方位来影响位置野的放电位置。为了解决这个问题，在一个有明显视觉地标的房间里，当一个矩形或圆形轨道移动到不同位置时，同时记录前丘脑的CA1位置细胞和头部方向细胞的集群活动。当轨道平移时，大多数位置细胞相对于轨道保持其放电野，头部方向细胞保持相同的偏好放电方向。当地远处地标围绕轨道旋转时，位置细胞的放电野和头部方向细胞的偏好方向会随着线索一起旋转。这些结果表明，位置细胞的精确放电位置受局部线索和自身运动线索之间相互作用的控制，并且CA1集群表征相对于远处地标的方向可能通过远处地标对头部方向细胞系统方位的影响而间接受到控制。
