Park Jinsick, Lee Hojong, Kim Taekyung, Park Ga Young, Lee Eun Mi, Baek Seunghee, Ku Jeonghun, Kim In Young, Kim Sun I, Jang Dong Pyo, Kang Joong Koo
Department of Biomedical Engineering, Hanyang University, Seoul, Korea.
Hippocampus. 2014 Nov;24(11):1341-52. doi: 10.1002/hipo.22315. Epub 2014 Jun 25.
The hippocampus plays a key role in the encoding and retrieval of information related to novel environments during spatial navigation. However, the neural basis for these processes in the human hippocampus remains unknown because it is difficult to directly measure neural signals in the human hippocampus. This study investigated hippocampal neural oscillations involved in encoding novel environments during spatial navigation in a virtual environment. Seven epileptic patients with implanted intracranial hippocampal depth electrodes performed three sessions of virtual environment navigation. Each session consisted of a navigation task and a location-recall task. The navigation task consisted of eight blocks, and in each block, the participant navigated to the location of four different objects and was instructed to remember the location of the objects. After the eight blocks were completed, a location-recall task was performed for each of the four objects. Intracranial electroencephalography data were monitored during the navigation tasks. Theta (5-8 Hz) and delta (1-4 Hz) oscillations were lower in the first block (novel environment) than in the eighth block (familiar environment) of the navigation task, and significantly increased from block one to block eight. By contrast, low-gamma (31-50 Hz) oscillations were higher in the first block than in the eighth block of the navigation task, and significantly decreased from block one to block eight. Comparison of sessions with high recall performance (low error between identified and actual object location) and low recall performance revealed that high-gamma (51-100 Hz) oscillations significantly decreased from block one to block eight only in sessions with high recall performance. These findings suggest that delta, theta, and low-gamma oscillations were associated with encoding of environmental novelty and high-gamma oscillations were important for the successful encoding of environmental novelty.
海马体在空间导航过程中对与新环境相关信息的编码和检索起着关键作用。然而，人类海马体中这些过程的神经基础仍然未知，因为很难直接测量人类海马体中的神经信号。本研究调查了在虚拟环境中空间导航期间参与新环境编码的海马体神经振荡。七名植入了颅内海马深度电极的癫痫患者进行了三次虚拟环境导航实验。每次实验包括一个导航任务和一个位置回忆任务。导航任务由八个区块组成，在每个区块中，参与者导航到四个不同物体的位置，并被要求记住物体的位置。在完成八个区块后，对四个物体中的每一个进行位置回忆任务。在导航任务期间监测颅内脑电图数据。在导航任务的第一个区块（新环境）中，θ波（5 - 8赫兹）和δ波（1 - 4赫兹）振荡低于第八个区块（熟悉环境），并且从第一个区块到第八个区块显著增加。相比之下，在导航任务的第一个区块中，低伽马波（31 - 50赫兹）振荡高于第八个区块，并且从第一个区块到第八个区块显著降低。对具有高回忆表现（识别的物体位置与实际物体位置之间误差低）和低回忆表现的实验进行比较发现，仅在具有高回忆表现的实验中，高伽马波（51 - 100赫兹）振荡从第一个区块到第八个区块显著降低。这些发现表明，δ波、θ波和低伽马波振荡与环境新奇性的编码相关，而高伽马波振荡对于环境新奇性的成功编码很重要。
