Wada Makoto, Takano Kouji, Ide Masakazu, Sano Yoshitake, Shinoda Yo, Furuichi Teiichi, Kansaku Kenji
Developmental Disorders Section, Department of Rehabilitation for Brain Functions, Research Institute of National Rehabilitation Center for Persons with Disabilities, Tokorozawa, Japan.
Systems Neuroscience Section, Department of Rehabilitation for Brain Functions, Research Institute of National Rehabilitation Center for Persons with Disabilities, Tokorozawa, Japan.
Front Behav Neurosci. 2021 Jun 10;15:680206. doi: 10.3389/fnbeh.2021.680206. eCollection 2021.
Rubber hand illusion (RHI), a kind of body ownership illusion, is sometimes atypical in individuals with autism spectrum disorder; however, the brain regions associated with the illusion are still unclear. We previously reported that mice responded as if their own tails were being touched when rubber tails were grasped following synchronous stroking to rubber tails and their tails (a "rubber tail illusion", RTI), which is a task based on the human RHI; furthermore, we reported that the RTI response was diminished in knockout (-KO) mice that exhibit autistic-like phenotypes. Importance of the posterior parietal cortex in the formation of illusory perception has previously been reported in human imaging studies. However, the local neural circuits and cell properties associated with this process are not clear. Therefore, we aimed to elucidate the neural basis of the RTI response and its impairment by investigating the c-Fos expression in both wild-type (WT) and -KO mice during the task since the c-Fos expression occurred soon after the neural activation. Immediately following the delivery of the synchronous stroking to both rubber tails and actual tails, the mice were perfused. Subsequently, whole brains were cryo-sectioned, and each section was immunostained with anti-c-Fos antibody; finally, c-Fos positive cell densities among the groups were compared. The c-Fos expression in the posterior parietal cortex was significantly lower in the -KO mice than in the WT mice. Additionally, we compared the c-Fos expression in the WT mice between synchronous and asynchronous conditions and found that the c-Fos-positive cell densities were significantly higher in the claustrum and primary somatosensory cortex of the WT mice exposed to the synchronous condition than those exposed to the asynchronous condition. Hence, the results suggest that decreased c-Fos expression in the posterior parietal cortex may be related to impaired multisensory integrations in -KO mice.
橡胶手错觉（RHI）是一种身体所有权错觉，在自闭症谱系障碍个体中有时表现异常；然而，与这种错觉相关的脑区仍不清楚。我们之前报道，在对橡胶尾巴和小鼠自身尾巴进行同步抚摸后握住橡胶尾巴时，小鼠会表现得好像自己的尾巴被触摸了一样（一种“橡胶尾巴错觉”，RTI），这是一项基于人类RHI的任务；此外，我们还报道，在表现出自闭症样表型的基因敲除（-KO）小鼠中，RTI反应减弱。此前在人类成像研究中已报道后顶叶皮质在虚幻感知形成中的重要性。然而，与此过程相关的局部神经回路和细胞特性尚不清楚。因此，我们旨在通过研究野生型（WT）和-KO小鼠在任务过程中的c-Fos表达来阐明RTI反应及其受损的神经基础，因为c-Fos表达在神经激活后很快就会出现。在对橡胶尾巴和实际尾巴进行同步抚摸后，立即对小鼠进行灌注。随后，将全脑进行冷冻切片，并用抗c-Fos抗体对每个切片进行免疫染色；最后，比较各组之间的c-Fos阳性细胞密度。-KO小鼠后顶叶皮质中的c-Fos表达明显低于WT小鼠。此外，我们比较了WT小鼠在同步和异步条件下的c-Fos表达，发现暴露于同步条件下的WT小鼠的屏状核和初级体感皮质中的c-Fos阳性细胞密度明显高于暴露于异步条件下的小鼠。因此，结果表明后顶叶皮质中c-Fos表达的降低可能与-KO小鼠多感觉整合受损有关。
