Inoue Koutarou, Fukazawa Yugo, Ogura Akihiko, Inokuchi Kaoru
Mitsubishi Kagaku Institute of Life Sciences (MITILS), 11 Minamiooya, Machida, Tokyo 194-8511, Japan.
Neurosci Res. 2005 Apr;51(4):417-25. doi: 10.1016/j.neures.2004.12.012. Epub 2005 Jan 15.
The hippocampus is involved in the encoding, storage, and retrieval of memory. Here, we have developed a novel mapping method for detecting the distribution of neural activity of the entire population of pyramidal cells in the hippocampal CA1 and subiculum regions, where expression profiles of Arc mRNA were used as an indicator of neural activity. The spherical pyramidal cell layer of the intact hippocampus was flattened into a two-dimensional plane, which was then serially sectioned in parallel with the plane to make tangential sections. Tangential sections were hybridized with an Arc cRNA probe and Arc signals from serial tangential sections were stacked and displayed on a two-dimensional plane, allowing one to easily visualize the neural activity of all pyramidal cells. We applied this method to the hippocampus of rats that had experienced contextual fear conditioning, which requires hippocampal function. We observed a net shift of Arc signals from dorsal to ventral CA1/subiculum with an interval prolongation to reconditioning after the initial conditioning. The reconditioning-revealed shift may reflect a reorganization process, which takes place during the period between initial conditioning and reconditioning, in the CA1/subiculum neural network that represents the neural storage and/or retrieval of the contextual fear conditioning.
海马体参与记忆的编码、存储和提取。在此，我们开发了一种新颖的映射方法，用于检测海马体CA1区和下托区锥体细胞全群体的神经活动分布，其中Arc mRNA的表达谱被用作神经活动的指标。完整海马体的球形锥体细胞层被平铺成二维平面，然后与该平面平行进行连续切片以制作切线切片。切线切片与Arc cRNA探针杂交，来自连续切线切片的Arc信号被叠加并显示在二维平面上，从而使人们能够轻松地可视化所有锥体细胞的神经活动。我们将此方法应用于经历过情境恐惧条件反射（这需要海马体功能）的大鼠的海马体。我们观察到，在初次条件反射后进行重新条件反射时，Arc信号从背侧CA1/下托向腹侧出现净移位，且间隔延长。重新条件反射所揭示的移位可能反映了一种重组过程，该过程发生在初次条件反射和重新条件反射之间的时间段内，存在于代表情境恐惧条件反射的神经存储和/或提取的CA1/下托神经网络中。
