Zimmerman Michael P, Kissinger Samuel T, Edens Paige, Towers Renee C, Nareddula Sanghamitra, Nadew Yididiya Y, Quinn Christopher J, Chubykin Alexander A
Department of Biological Sciences, Purdue Institute for Integrative Neuroscience, Purdue University, 915 Mitch Daniels Blvd., West Lafayette, IN 47907, USA; Department of Biomedical Engineering, Purdue University, 206 S. Martin Jischke Dr., West Lafayette, IN 47907, USA.
Department of Biological Sciences, Purdue Institute for Integrative Neuroscience, Purdue University, 915 Mitch Daniels Blvd., West Lafayette, IN 47907, USA.
Curr Biol. 2025 Jan 6;35(1):87-99.e6. doi: 10.1016/j.cub.2024.11.015. Epub 2024 Dec 9.
Visual experience gives rise to persistent theta oscillations in the mouse primary visual cortex (V1) that are specific to the familiar stimulus. Our recent work demonstrated the presence of these oscillations in higher visual areas (HVAs), where they are synchronized with V1 in a context-dependent manner. However, it remains unclear where these unique oscillatory dynamics originate. To investigate this, we conducted paired extracellular electrophysiological recordings in two visual thalamic nuclei (dorsal lateral geniculate nucleus [dLGN] and lateral posterior nucleus [LP]), the retrosplenial cortex (RSC), and the hippocampus (HPC). Oscillatory activity was not found in either of the thalamic nuclei, but a sparse ensemble of oscillating neurons was observed in both the RSC and HPC, similar to V1. To infer functional connectivity changes between the brain regions, we performed directed information analysis, which indicated a trend toward decreased connectivity in all V1-paired regions, with a consistent increase in V1 → V1 connections, suggesting that the oscillations appear to initiate independently within V1. Lastly, complete NMDA lesioning of the HPC did not abolish theta oscillations in V1 that emerge with familiarity. Altogether, these results suggest that (1) theta oscillations do not originate in the thalamus; (2) RSC exhibits theta oscillations, which may follow V1 given the temporal delay present; and (3) the HPC had a sparse group of neurons, with theta oscillations matching V1; however, lesioning suggests that these oscillations emerge independent of each other. Overall, our findings pave the way for future studies to determine the mechanisms by which diverse inputs and outputs shape this memory-related oscillatory activity in the brain.
视觉体验会在小鼠初级视觉皮层（V1）中引发持续的theta振荡，这种振荡特定于熟悉的刺激。我们最近的研究表明，在高级视觉区域（HVAs）也存在这些振荡，并且它们在特定情境下与V1同步。然而，这些独特的振荡动力学起源于何处仍不清楚。为了探究这一点，我们在两个视觉丘脑核团（背外侧膝状体核 [dLGN] 和外侧后核 [LP]）、 retrosplenial皮层（RSC）和海马体（HPC）中进行了细胞外配对电生理记录。在两个丘脑核团中均未发现振荡活动，但在RSC和HPC中均观察到了稀疏的振荡神经元集群，这与V1相似。为了推断脑区之间的功能连接变化，我们进行了定向信息分析，结果表明所有与V1配对的区域中连接性均有下降趋势，而V1→V1连接则持续增加，这表明振荡似乎在V1内独立起始。最后，对HPC进行完全的NMDA损伤并没有消除因熟悉度而在V1中出现的theta振荡。总之，这些结果表明：（1）theta振荡并非起源于丘脑；（2）RSC表现出theta振荡，考虑到存在的时间延迟，其可能跟随V1；（3）HPC有一组稀疏的神经元，其theta振荡与V1匹配；然而，损伤表明这些振荡彼此独立出现。总体而言，我们的发现为未来研究确定各种输入和输出塑造大脑中这种与记忆相关的振荡活动的机制铺平了道路。
