Place cells on a maze encode routes rather than destinations.
Place cells on a maze encode routes rather than destinations.
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DOI：
10.7554/elife.15986
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发表时间：
2016-06-10
期刊：
影响因子：
7.7
通讯作者：
Dudchenko PA
中科院分区：
文献类型：
--
作者：
Grieves RM;Wood ER;Dudchenko PA
当一只啮齿动物在前往不同目的地的途中经过一个给定的位置时，海马神经元的位置细胞会以不同的速度放电。然而，目前尚不清楚这种射击是否代表动物的预定目的地或特定轨迹的执行。为了区分这些可能性，训练Lister Hooded大鼠（n = 8）通过四条部分重叠的路线从起始框导航到三个目标位置。其中两个导致了同一个目标位置。在这两条路线上发射的细胞中，95.8%表现出路线依赖性发射（仅在一条路线上发射），而只有两个细胞（4.2%）表现出目标依赖性发射（在两条路线上发射相似）。此外，依赖于路线的位置单元过度表示了可辨别性较低的路线，并且位置单元通常过度表示了起始位置。这些结果表明，重叠路线上的位置细胞放电反映了动物的路线，而不是它的目标，这种放电可能有助于空间歧视。DOI：http://dx.doi.org/10.7554/eLife.15986.001大脑如何代表外部世界？回答这个问题的一种方法是研究老鼠的大脑，因为啮齿动物大脑的基本结构与其他哺乳动物（如人类）相似。例如，啮齿动物和人类的大脑都含有一种称为海马体的结构，它在导航和空间记忆中起着重要作用。海马体中的位置细胞通过在动物占据特定位置时发射电脉冲来支持这些过程。当老鼠在迷宫中沿着沿着奔跑时，当它接近一个选择点时，它的位置细胞经常会被激活。一个给定的位置细胞通常会在老鼠选择通往一个特定位置的路径之前启动，但不会在选择通往其他位置之前启动。在选择点之前发生的击发被称为“预期击发”。然而，目前还不知道位置细胞的预期放电是否代表了老鼠的最终目的地，或者动物到达那里的具体路线。为了解决这个问题，Grieves等人设计了一个迷宫，其中两条不同的路径从起始走廊通向同一个目标位置。如果位置细胞代表目标位置，它们应该发射大鼠选择的任何路线。然而，如果它们代表了老鼠到达目标的特定路径，它们应该在其中一条路线上开火，而不是两条。Grieves等人发现，几乎所有在起始通道中具有预期活动的位置细胞都在单一路线上发射，而不是在两条路线上发射到共同目标。这表明海马体中的预期放电反映了动物将要采取的路线，而不是其预期的目的地。未来的挑战将是了解海马体编码路线的方式如何与编码预期目标的大脑回路相互作用，以及这些回路的活动如何影响动物的导航能力。DOI：http://dx.doi.org/10.7554/eLife.15986.002网站
Hippocampal place cells fire at different rates when a rodent runs through a given location on its way to different destinations. However, it is unclear whether such firing represents the animal’s intended destination or the execution of a specific trajectory. To distinguish between these possibilities, Lister Hooded rats (n = 8) were trained to navigate from a start box to three goal locations via four partially overlapping routes. Two of these led to the same goal location. Of the cells that fired on these two routes, 95.8% showed route-dependent firing (firing on only one route), whereas only two cells (4.2%) showed goal-dependent firing (firing similarly on both routes). In addition, route-dependent place cells over-represented the less discriminable routes, and place cells in general over-represented the start location. These results indicate that place cell firing on overlapping routes reflects the animal’s route, not its goals, and that this firing may aid spatial discrimination. DOI: http://dx.doi.org/10.7554/eLife.15986.001 How does the brain represent the outside world? One way of answering this question is to study the brains of rats, because the basic plan of a rodent’s brain is similar to that of other mammals, such as humans. For example, the brains of rodents and humans both contain a structure called the hippocampus, which plays important roles in navigation and spatial memory. Cells within the hippocampus called place cells support these processes by firing electrical impulses whenever the animal occupies a specific location. When a rat runs along a corridor in a maze, its place cells often fire as it approaches a choice point. A given place cell will typically fire before the rat chooses a path leading towards one particular location, but not before choices that lead to other locations. The firing that occurs prior to the choice point is termed “prospective firing”. However, it is not known whether the prospective firing of place cells represents the rat’s final destination, or the specific route the animal takes to get there. To address this question, Grieves et al. designed a maze in which two different paths from a starting corridor led to the same goal location. If place cells represent the goal location, they should fire whichever route the rat chooses. However, if they represent the specific path the rat takes to the goal, they should fire on one or the other route, but not both. Grieves et al. found that almost all place cells with prospective activity in the starting corridor fired on a single route, as opposed to firing on both routes to the common goal. This suggests that the prospective firing in the hippocampus reflects the route the animal will take, rather than its intended destination. A future challenge will be to understand how the way the hippocampus codes routes interacts with brain circuits that code for intended goals, and how the activity of these circuits influences the animal’s ability to navigate. DOI: http://dx.doi.org/10.7554/eLife.15986.002