Biduła Szymon P, Króliczak Gregory
Action & Cognition Laboratory, Institute of Psychology, Adam Mickiewicz University, ul. Szamarzewskiego 89, 60-568, Poznan, Poland.
Eur J Neurosci. 2015 May;41(11):1438-47. doi: 10.1111/ejn.12888. Epub 2015 Apr 10.
The control of gesture is one of the most left-lateralized functions, and the insular cortex is one of the most left-biased structures in the human brain. Therefore, we investigated whether structural asymmetries of the insula are linked to the organization of functional activity during gesture planning. We reconstructed and parcellated the insular cortex of 27 participants. First, we tested 15 strongly left-handed individuals because of a higher incidence of atypical organization of functions such as gesture and language in such a population. The inter-hemispheric structural asymmetries were compared with the lateralization of activity for gesture in the supramarginal gyrus (the hotspot of signal increase regardless of the gesturing hand) and Broca's area (the hotspot of signal increase for language production). The more pronounced leftward structural asymmetries were accompanied by greater left-hemisphere dominance for both of the studied functions. Conversely, an atypical, bilateral or rightward functional shift of gesture and language was accompanied by an attenuated leftward asymmetry of the insula. These significant relationships were driven primarily by differences in surface area. Subsequently, by adding 12 right-handed individuals to these analyses we demonstrated that the observed significant associations are generalizable to the population. These results provide the first demonstration of the relationships between structural inter-hemispheric differences of the insula and the cerebral specialization for gesture. They also corroborate the link between insular asymmetries and language lateralization. As such, these outcomes are relevant to the common cerebral specialization for gesture and language.
手势控制是最偏向左侧化的功能之一，而岛叶皮质是人类大脑中最偏向左侧的结构之一。因此，我们研究了岛叶的结构不对称是否与手势规划过程中的功能活动组织有关。我们重建并分割了27名参与者的岛叶皮质。首先，我们测试了15名强左利手个体，因为这类人群中手势和语言等功能的非典型组织发生率较高。将半球间结构不对称与上缘回（无论使用哪只手做手势，都是信号增强的热点区域）和布洛卡区（语言产生时信号增强的热点区域）中手势活动的偏侧化进行比较。在这两种被研究的功能中，更明显的向左结构不对称伴随着更强的左半球优势。相反，手势和语言的非典型、双侧或向右功能转移伴随着岛叶向左不对称的减弱。这些显著关系主要由表面积差异驱动。随后，通过在这些分析中加入12名右利手个体，我们证明了观察到的显著关联在总体人群中具有普遍性。这些结果首次证明了岛叶半球间结构差异与手势脑区特化之间的关系。它们还证实了岛叶不对称与语言偏侧化之间的联系。因此，这些结果与手势和语言共同的脑区特化相关。
