Cornwell Brian R, Johnson Linda L, Holroyd Tom, Carver Frederick W, Grillon Christian
Mood and Anxiety Disorders Program, National Institute of Mental Health, Bethesda, Maryland 20892, USA.
J Neurosci. 2008 Jun 4;28(23):5983-90. doi: 10.1523/JNEUROSCI.5001-07.2008.
The hippocampus and parahippocampal cortices exhibit theta oscillations during spatial navigation in animals and humans, and in the former are thought to mediate spatial memory formation. Functional specificity of human hippocampal theta, however, is unclear. Neuromagnetic activity was recorded with a whole-head 275-channel magnetoencephalographic (MEG) system as healthy participants navigated to a hidden platform in a virtual reality Morris water maze. MEG data were analyzed for underlying oscillatory sources in the 4-8 Hz band using a spatial filtering technique (i.e., synthetic aperture magnetometry). Source analyses revealed greater theta activity in the left anterior hippocampus and parahippocampal cortices during goal-directed navigation relative to aimless movements in a sensorimotor control condition. Additional analyses showed that left anterior hippocampal activity was predominantly observed during the first one-half of training, pointing to a role for this region in early learning. Moreover, posterior hippocampal theta was highly correlated with navigation performance, with the former accounting for 76% of the variance of the latter. Our findings suggest human spatial learning is dependent on hippocampal and parahippocampal theta oscillations, extending to humans a significant body of research demonstrating such a pivotal role for hippocampal theta in animal navigation.
在动物和人类进行空间导航时，海马体和海马旁皮质会出现theta振荡，并且在前者中被认为介导空间记忆的形成。然而，人类海马体theta的功能特异性尚不清楚。当健康参与者在虚拟现实莫里斯水迷宫中导航到一个隐藏平台时，使用全头275通道脑磁图（MEG）系统记录神经磁活动。使用空间滤波技术（即合成孔径磁力测定法）分析MEG数据中4-8Hz频段的潜在振荡源。源分析显示，相对于感觉运动控制条件下的无目的运动，在目标导向导航期间，左前海马体和海马旁皮质中的theta活动更强。进一步分析表明，左前海马体活动主要在训练的前半段观察到，表明该区域在早期学习中发挥作用。此外，后海马体theta与导航性能高度相关，前者占后者方差的76%。我们的研究结果表明，人类空间学习依赖于海马体和海马旁皮质的theta振荡，这将大量证明海马体theta在动物导航中起关键作用的研究扩展到了人类。
