Abstract
Aiming to investigate whether handedness-related language lateralization is related to the intrinsic resting-state functional connectivity (RSFC) pattern within the language network, the present study integrated the information of functional activations during a semantic task of Chinese characters and FC in resting-state based on functional magnetic resonance imaging (fMRI) data of healthy left handers (LH) and right handers (RH). RSFC was calculated on a voxel-based level between the seed regions chosen from functional activations during the task and the rest of the brain. The results demonstrated that LH had significantly stronger RSFC than RH between the cerebellum and supratentorial areas of the frontal, parietal and temporal lobe, and between the occipital lobe and frontal/parietal lobe. Correlation analysis showed that RSFC values between right MFG and left cerebellum_crus2, between SMA and right cerebellum_crus2, and between the right cerebellum_crus1 and left MFG were negatively correlated with cerebral laterality index in LH and RH groups. Our results highlight key nodes of Chinese language brain network processing in the cerebellum, and suggest that atypical language dominance relates to stronger crossed reciprocal RSFC in the frontal-cerebellar system. The findings provide new insights into the intrinsic FC substrates underlying the atypical language lateralization of LH.
Highlights
Language lateralization has been a subject of intense research[1], and both behavioral and neuroimaging studies have shown that handedness contributes to language lateralization[2]
The group analysis showed that two areas in the frontal lobe, namely the right middle frontal gyrus (MFG) and the inferior frontal gyrus opercular (IFGoper), displayed a significantly higher activity in left handers (LH) than in right handers (RH)
Cerebellar laterality index (LI) values showed activated areas as right dominant in RH, which was contralateral to the activations in the cerebral cortex; whereas in LH, a more bilateral activity pattern was found in the cerebellum compared with RH
Summary
Language lateralization has been a subject of intense research[1], and both behavioral and neuroimaging studies have shown that handedness contributes to language lateralization[2]. Our previous study focused on the analysis of handedness and effective connectivity among brain regions recruited by a Chinese language task. To our knowledge, only a few studies have integrated information of the brain’s intrinsic functional integration during resting-state and language-related task activations to reveal the association of RSFC and language lateralization in Chinese. To define the nodes of the language network, the activated brain regions in healthy LH and RH groups in a Chinese semantic task were selected based on our previous study[9]. The conjoined activated areas of the two groups based on conjunction analysis were defined in our previous study[9] These selected regions were included in the present study and acted as seed regions to calculate the FC between the seeds and the remaining brain voxels in resting-state. Correlation analysis was further performed to examine whether the altered RSFC between the two groups was associated with handedness-related language lateralization during the task performance
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