Zou D, Aitake M, Hori E, Umeno K, Fukuda M, Ono T, Nishijo H
System Emotional Science, Graduate School of Medicine and Pharmaceutical Sciences, University of Toyama, Sugitani, Toyama, Japan.
Hippocampus. 2009 Apr;19(4):350-9. doi: 10.1002/hipo.20524.
It has been suggested that sensory mismatch induces motion sickness, but its neural mechanisms remain unclear. To investigate this issue, theta waves in the hippocampal formation (HF) were studied during sensory mismatch by backward translocation in awake rats. A monopolar electrode was implanted into the dentate gyrus in the HF, from which local field potentials were recorded. The rats were placed on a treadmill affixed to a motion stage translocated along a figure 8-shaped track. The rats were trained to run forward on the treadmill at the same speed as that of forward translocation of the motion stage (a forward condition) before the experimental (recording) sessions. In the experimental sessions, the rats were initially tested in the forward condition, and then tested in a backward (mismatch) condition, in which the motion stage was turned around by 180 degrees before translocation. That is, the rats were moved backward by translocation of the stage although the rats ran forward on the treadmill. The theta (6-9 Hz) power was significantly increased in the backward condition compared with the forward condition. However, the theta power gradually decreased by repeated testing in the backward condition. Furthermore, backward translocation of the stage without locomotion did not increase theta power. These results suggest that the HF might function as a comparator to detect sensory mismatch, and that alteration in HF theta activity might induce motion sickness.
有人提出感觉不匹配会诱发晕动病，但其神经机制仍不清楚。为了研究这个问题，在清醒大鼠中通过向后移位造成感觉不匹配期间，对海马结构（HF）中的θ波进行了研究。将一个单极电极植入HF的齿状回，从那里记录局部场电位。将大鼠放置在固定于沿着8字形轨道移位的运动平台上的跑步机上。在实验（记录）阶段之前，训练大鼠在跑步机上以与运动平台向前移位相同的速度向前奔跑（向前条件）。在实验阶段，大鼠最初在向前条件下进行测试，然后在向后（不匹配）条件下进行测试，即在移位前将运动平台旋转180度。也就是说，尽管大鼠在跑步机上向前奔跑，但通过平台移位使大鼠向后移动。与向前条件相比，向后条件下的θ（6 - 9赫兹）功率显著增加。然而，在向后条件下通过重复测试，θ功率逐渐降低。此外，在没有运动的情况下平台向后移位并不会增加θ功率。这些结果表明，HF可能起到检测感觉不匹配的比较器的作用，并且HF中θ活动的改变可能诱发晕动病。
