Zou Dan, Nishimaru Hiroshi, Matsumoto Jumpei, Takamura Yusaku, Ono Taketoshi, Nishijo Hisao
System Emotional Science, Graduate School of Medicine and Pharmaceutical Sciences, University of ToyamaToyama, Japan.
Department of Pathophysiology, Shenyang Medical CollegeShenyang, China.
Front Pharmacol. 2017 Aug 23;8:581. doi: 10.3389/fphar.2017.00581. eCollection 2017.
The hippocampal formation (HF) is implicated in a comparator that detects sensory conflict (mismatch) among convergent inputs. This suggests that new place cells encoding the new configuration with sensory mismatch develop after the HF learns to accept the new configuration as a match. To investigate this issue, HF CA1 place cell activity in rats was analyzed after the adaptation of the rats to the same sensory mismatch condition. The rats were placed on a treadmill on a stage that was translocated in a figure 8-shaped pathway. We recorded HF neuronal activities under three conditions; (1) an initial control session, in which both the stage and the treadmill moved forward, (2) a backward (mismatch) session, in which the stage was translocated backward while the rats locomoted forward on the treadmill, and (3) the second control session. Of the 161 HF neurons, 56 place-differential activities were recorded from the HF CA1 subfield. These place-differential activities were categorized into four types; forward-related, backward-related, both-translocation-related, and session-dependent. Forward-related activities showed predominant spatial firings in the forward sessions, while backward-related activities showed predominant spatial firings in the backward sessions. Both-translocation-related activities showed consistent spatial firings in both the forward and backward conditions. On the other hand, session-dependent activities showed different spatial firings across the sessions. Detailed analyses of the place fields indicated that mean place field sizes were larger in the forward-related, backward-related, and both-translocation-related activities than in the session-dependent activities. Furthermore, firing rate distributions in the place fields were negatively skewed and asymmetric, which is similar to place field changes that occur after repeated experience. These results demonstrate that the HF encodes a naturally impossible new configuration of sensory inputs after adaptation, suggesting that the HF is capable of updating its stored memory to accept a new configuration as a match by repeated experience.
海马结构（HF）参与了一个比较器，该比较器可检测汇聚输入之间的感觉冲突（不匹配）。这表明，在HF学会将新配置视为匹配之后，编码具有感觉不匹配的新配置的新位置细胞才会发育。为了研究这个问题，在大鼠适应相同的感觉不匹配条件后，分析了大鼠HF CA1区位置细胞的活动。将大鼠放置在一个在8字形路径中移动的平台上的跑步机上。我们在三种条件下记录了HF神经元的活动：（1）初始对照阶段，此时平台和跑步机都向前移动；（2）向后（不匹配）阶段，此时平台向后移动，而大鼠在跑步机上向前移动；（3）第二个对照阶段。在161个HF神经元中，从HF CA1亚区记录到了56种位置差异活动。这些位置差异活动被分为四种类型：向前相关型、向后相关型、双向移动相关型和阶段依赖型。向前相关型活动在向前阶段表现出主要的空间放电，而后向相关型活动在向后阶段表现出主要的空间放电。双向移动相关型活动在向前和向后条件下均表现出一致的空间放电。另一方面，阶段依赖型活动在不同阶段表现出不同的空间放电。对位置野的详细分析表明，向前相关型、向后相关型和双向移动相关型活动的平均位置野大小比阶段依赖型活动更大。此外，位置野中的放电率分布呈负偏态且不对称，这与反复经历后发生的位置野变化相似。这些结果表明，HF在适应后编码了一种自然不可能的感觉输入新配置，这表明HF能够通过反复经历更新其存储的记忆，以将新配置视为匹配。
