Task-dependent representations in rat hippocampal place neurons
Task-dependent representations in rat hippocampal place neurons
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DOI：
10.1152/jn.1997.78.2.597
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发表时间：
1997-08-01
影响因子：
2.5
通讯作者：
Ono, T
中科院分区：
文献类型：
--
作者：
Kobayashi, T;Nishijo, H;Ono, T
研究表明，在导航过程中，海马体的形成对多种信息的灵活编码是空间表征所必需的，这些信息不仅包括视觉和听觉等外部产生的感觉信息，还包括与运动有关的意识形态信息（即内部产生的本体感觉和前庭感觉）以及有关奖励的信息。在本研究中，我们通过记录大鼠的海马体复合体-刺突细胞，研究了不同类型的信息是如何在海马体形成中表现出来的，这些大鼠在一个圆形的开放区域中执行三种类型的位置学习任务，并使用颅内自我刺激作为奖励。在以下三种情况下给予颅内自我刺激奖励：如果大鼠1)进入实验者在开放区域内确定的奖励地点，并且该地点在连续试验中随机变化；2)进入两个特定的位置，一个在位置场内，一个在位置场外（通过位置神经元活动的变化来识别的区域）；或3)进入位置字段外的实验者指定的位置。由于导航过程中的行为轨迹在第二项任务中比在第一项任务中更稳定，因此第二项任务中与运动有关的意识形态信息与获得奖励的关系比在第一项任务中更密切。在记录的43个复杂尖峰细胞中，有37个在第一项任务下显示位置场。在这37个位置神经元中，34个也只在位置场内有显著的奖励相关。虽然位置神经元活动的奖励和位置相关性在第一任务和第二任务之间没有变化，但在第二任务中，与运动行为变量（如运动速度、方向和转弯角度）相关的神经元显著增加。此外，在第三个任务中，31个位置神经元中有6个位于原始位置域之外，转移了位置域。结果表明，大多数位置神经元的关联神经元在特定的情境和环境中灵活地增加了对相关信息的敏感性，一些位置神经元通过位置奖励关联改变了位置场本身。这些结果表明了海马体神经元如何将难以置信的各种感知整合到环境的统一表征中的两种策略：通过灵活使用信息和创造新的表征。
It is suggested that the hippocampal formation is essential to spatial representations by flexible encoding of diverse information during navigation, which includes not only externally generated sensory information such as visual and auditory sensation but also ideothetic information concerning locomotion (i.e., internally generated information such as proprioceptive and vestibular sensation) as well as information concerning reward. In the present study, we investigated how various types of information are represented in the hippocampal formation, by recording hippocampal complex-spike cells from rats that performed three types of place learning tasks in a circular open field with the use of intracranial self-stimulation as reward. The intracranial self-stimulation reward was delivered in the following three contexts: if the rat 1) entered an experimenter-determined reward place within the open field, and this place was randomly varied in sequential trials; 2) entered two specific places, one within and one outside the place field (an area identified by change in activity of a place neuron); or 3) entered an experimenter-specified place outside the place field. Because the behavioral trails during navigation were more constant in the second task than in the first task, ideothetic information concerning locomotion was more relevant to acquiring reward in the second task than in the first task. Of 43 complex-spike cells recorded, 37 displayed place fields under the first task. Of these 37 place neurons, 34 also had significant reward correlates only inside the place field. Although reward and place correlates of the place neuron activity did not change between the first and second tasks, neuronal correlates to behavioral variables for locomotion such as movement speed, direction, and turning angle significantly increased in the second task. Furthermore, 6 of 31 place neurons tested with the third task, in which the reward place was located outside the original place field, shifted place fields. The results indicated that neuronal correlates of most place neurons flexibly increased their sensitivity to relevant information in a given context and environment, and some place neurons changed the place field per se with place reward association. These results suggest two strategies for how hippocampal neurons incorporate an incredible variety of perceptions into a unified representation of the environment: through flexible use of information and the creation of new representations.