Hippocampal place cells construct reward related sequences through unexplored space.
Hippocampal place cells construct reward related sequences through unexplored space.
复制标题
海马位置细胞通过未探索的空间构建奖励相关序列。
DOI：
10.7554/elife.06063
复制
发表时间：
2015-06-26
期刊：
影响因子：
7.7
通讯作者：
Spiers HJ
中科院分区：
文献类型：
--
作者：
Ólafsdóttir HF;Barry C;Saleem AB;Hassabis D;Spiers HJ
海马功能的主导理论提出，位置细胞表征是在动物第一次遇到新环境时形成的，随后在离线状态下重播，以支持巩固和未来的行为。在这里，我们报告说，查看交付的食物到一个未访问的部分的环境导致离线预激活的位置细胞序列对应的空间。这种“预演”在没有奖励但在其他方面类似的环境中是没有观察到的。这些结果表明，海马表示一个可见的，但未探索的环境可以形成，如果环境是动机相关的动物。我们假设，这种目标偏向的预演可能会支持在新的环境中为未来的经验做准备。http://dx.doi.org/10.7554/eLife.06063.001当动物探索一个区域时，大脑中被称为海马体的部分会创建一个空间的心理地图。当动物处于一个位置时，一些被称为“位置细胞”的神经元会被激活。如果动物移动到一个新的地方，其他地方的细胞就会被激活。每次动物回到那个地方，同一个地方的细胞就会被激活。因此，当动物移动时，一种特定于位置的放电模式出现了，科学家可以通过记录细胞的活动来观察，并可用于重建动物的位置。在探索了一个空间之后，海马体可能会在睡眠期间重现新的特定于位置的活动模式。通过这样做，大脑巩固了回访空间的记忆。最近的证据表明，这些心理排练或对空间的内部模拟甚至可能在探索新空间之前就开始开始。现在，Alflafsdóttir、巴里等人报告说，动物的大脑是否会模拟第一次访问一个新的空间取决于动物是否期待奖励。在实验中，老鼠被允许沿着T形轨道跑到交叉口。动物们可以看到每一只手臂，但不能进入它们。然后将食物放在一个无法接触的臂中。Ellafsdóttir、巴里等人记录了动物在赛道上和之后休息期间大脑中位置细胞的放电。然后让老鼠爬到无法接近的手臂上，再次记录它们的大脑活动。在老鼠第一次看到无法接近的手臂后的休息期，位置细胞模式被预先激活，后来形成了往返于含食物手臂的心理地图。然而，在老鼠探索那个区域之前，位置细胞模式并没有被激活，它将成为另一个不可接近的手臂的心理地图。因此，Jellafsdóttir、巴里等人认为，奖赏的感知会影响休息时模拟的位置细胞模式。这些发现的一个含义是，大脑优先模拟过去或未来的经验，这些经验被认为是功能上重要的，比如那些与奖励有关的经验。未来的一个挑战将是确定这种与目标相关的未访问空间模拟是否可以预测以及是否需要成功导航到目标等行为。DOI：http://dx.doi.org/10.7554/eLife.06063.002网站
Dominant theories of hippocampal function propose that place cell representations are formed during an animal's first encounter with a novel environment and are subsequently replayed during off-line states to support consolidation and future behaviour. Here we report that viewing the delivery of food to an unvisited portion of an environment leads to off-line pre-activation of place cells sequences corresponding to that space. Such ‘preplay’ was not observed for an unrewarded but otherwise similar portion of the environment. These results suggest that a hippocampal representation of a visible, yet unexplored environment can be formed if the environment is of motivational relevance to the animal. We hypothesise such goal-biased preplay may support preparation for future experiences in novel environments. DOI: http://dx.doi.org/10.7554/eLife.06063.001 As an animal explores an area, part of the brain called the hippocampus creates a mental map of the space. When the animal is in one location, a few neurons called ‘place cells’ will fire. If the animal moves to a new spot, other place cells fire instead. Each time the animal returns to that spot, the same place cells will fire. Thus, as the animal moves, a place-specific pattern of firing emerges that scientists can view by recording the cells' activity and which can be used to reconstruct the animal's position. After exploring a space, the hippocampus may replay the new place-specific pattern of activity during sleep. By doing so, the brain consolidates the memory of the space for return visits. Recent evidence now suggests that these mental rehearsals—or internal simulations of the space—may begin even before a new space has been explored. Now, Ólafsdóttir, Barry et al. report that whether an animal's brain simulates a first visit to a new space depends on whether the animal anticipates a reward. In the experiments, rats were allowed to run up to the junction in a T-shaped track. The animals could see into each of the arms, but not enter them. Food was then placed in one of the inaccessible arms. Ólafsdóttir, Barry et al. recorded the firing of place cells in the brain of the animals when they were on the track and during a rest period afterwards. The rats were then allowed onto the inaccessible arms, and again their brain activity was recorded. In the rest period after the rats first viewed the inaccessible arms, the place cell pattern that would later form the mental map of a journey to and from the food-containing arm was pre-activated. However, the place cell pattern that would become the mental map of the other inaccessible arm was not activated before the rat explored that area. Therefore, Ólafsdóttir, Barry et al. suggest that the perception of reward influences which place cell pattern is simulated during rest. An implication of these findings is that the brain preferentially simulates past or future experiences that are deemed to be functionally significant, such as those associated with reward. A future challenge will be to determine whether this goal-related simulation of unvisited spaces predicts and is needed for behaviour such as successful navigation to a goal. DOI: http://dx.doi.org/10.7554/eLife.06063.002