Jordan Jake T, Shanley M Regis, Pytte Carolyn L
Biology PhD Program, The Graduate Center, CUNY, New York, NY 11016, U.S.A.
CUNY Neuroscience Collaborative, The Graduate Center, CUNY, New York, NY 11016, U.S.A.
Neuronal Signal. 2019 Mar;3(1):NS20180206. doi: 10.1042/NS20180206. Epub 2019 Feb 27.
Hemispheric lateralization is a fundamental organizing principle of nervous systems across taxonomic groups with bilateral symmetry. The mammalian hippocampus is lateralized anatomically, physiologically, and chemically; however, functional asymmetries are not yet well understood. Imaging studies in humans have implicated the left and right hippocampus in specialized processing. However, it is not clear if lateralized activity occurs in the rodent hippocampus. c-Fos imaging in animals provides a measure of neuronal activity with a resolution at the level of single cells. The aim of the present study was to determine whether lateralized activity-dependent c-Fos expression occurs in the rodent hippocampus. To understand functional lateralization of hippocampal processing, we compared interhemispheric expression of c-Fos in the dentate gyrus (DG), a structure involved in encoding new experiences, in mice that ran on a wheel, encoded a novel object, or remained in home cages. We found that wheel running (WR) induced the greatest amount of DG c-Fos expression in both hemispheres, with no difference between hemispheres. Object exploration (OB) resulted in left-lateralized DG c-Fos expression, whereas control (CON) mice were not lateralized. We then sought to determine whether differential consideration of hemispheres might influence the conclusions of a study by simulating common cell quantitation methods. We found that different approaches led to different conclusions. These data demonstrate lateralization of neuronal activity in the mouse DG corresponding to the experience of the animal and show that differentially considering hemisphere leads to alternative conclusions.
半球偏侧化是具有双侧对称性的分类群中神经系统的一个基本组织原则。哺乳动物的海马体在解剖学、生理学和化学上存在偏侧化；然而，功能不对称性尚未得到充分理解。人类的成像研究表明左右海马体参与特定的加工过程。然而，尚不清楚啮齿动物的海马体是否会出现偏侧化活动。动物体内的c-Fos成像提供了一种在单细胞水平上分辨率的神经元活动测量方法。本研究的目的是确定啮齿动物海马体中是否会出现依赖于活动的偏侧化c-Fos表达。为了理解海马体加工的功能偏侧化，我们比较了在跑步机上跑步、对新物体进行编码或待在笼子里的小鼠齿状回（DG）中c-Fos的半球间表达，齿状回是一个参与编码新体验的结构。我们发现，跑步（WR）在两个半球中诱导的DG c-Fos表达量最大，半球之间没有差异。物体探索（OB）导致DG c-Fos表达出现左侧偏侧化，而对照（CON）小鼠没有出现偏侧化。然后，我们试图通过模拟常见的细胞定量方法来确定对半球的不同考量是否可能影响一项研究的结论。我们发现不同的方法会导致不同的结论。这些数据证明了小鼠DG中神经元活动的偏侧化与动物的经历相对应，并表明对半球的不同考量会导致不同的结论。
