Regional Homogeneity Of The Resting-state Brain Activity Study On Healthy Adults' Intelligence

Objective:Resting-state functional magnetic resonance imaging (rs-fMRI) were performed on healthy adults, to detect brain areas whose Regional Homogeneity (ReHo) related to individual intelligence difference. The method of ReHo focuses on synchronization of focal low frequence fluctuation of rs-fMRI signals.Subjects and Methods:Fifty-nine healthy right-handed subjects (29 males and 30 females; mean age=24.6 years, SD=3.5 years, range=18.5-33.3 years) were included in this study. In the present study, the FSIQ score was used to assess individual intelligence by using the Chinese Revised Wechsler Adult Intelligence Scale (WAIS-RC).3.0-Tesla MR scanner (Magnetom Trio, Siemens, Erlangen, Germany) was used to obtain rs-fMRI data. During the fMRI scan, all subjects were explicitly instructed to keep their eyes closed, relax, move as little as possible and think of nothing. Functional images were collected using a gradient echo echo planar imaging (GRE-EPI) sequence sensitive to BOLD contrast. The acquisition parameters are as follows: TR/TE=2000/30ms, FOV=220mm×220mm, Matrix=64×64, Flip angle=90°, thickness=3mm, interslices gap=1mm, slices=32. For each subject the rs-fMRI scan lasted for 9 min and 270 volumes were obtained.The rs-fMRI data were processed with the software of AFNI, Matlab, SPM2 and REST. During the pre-processing steps, the rs-fMRI data were realigned, normalized, spatially smoothed, linear regressed, and band-pass filtered. Individual ReHo maps were generated by calculating KCC within a gray matter mask in a voxel-wise way by the REST software. Considering the possible influence of sex and age on the correlation analysis between the ReHo and FSIQ, we performed partial correlation analysis adjusted for sex and age to assess the correlations between the FSIQ scores and the ReHo of the brain across all subjects in a voxel-wise manner. Statistical parameter mapping was overlapped onto MNI standard template. The coordinate and size of each significant cluster were recorded.Results:Fifty-nine subjects were recruited in this study after the affected factors (head motion, behavioral performance and machine noise) were ruled out.The FSIQ scores were positively correlated with the ReHo values of the bilateral middle frontal, inferior parietal lobules, parahippocampal and inferior temporal gyri, the right thalamus, superior frontal and fusiform gyrus and the left superior parietal lobule. There were no brain areas whose ReHo values were negatively correlated with intelligence scores.Conclusion:1,There were some brain areas whose ReHo values were positively correlated with intelligence scores in healthy adults in resting-state.2,In resting-state the ReHo values of the bilateral middle frontal, inferior parietal lobules, parahippocampal and inferior temporal gyri, the right thalamus, superior frontal and fusiform gyrus and the left superior parietal lobule showed strong positive correlation with FSIQ in healthy adults. The regions whose ReHo values were positively correlated with FSIQ were largely overlapped with the brain areas of the P-FIT model. This implies neural substrate for intelligence is not highly localized but a more distributed network of brain regions, especially the frontal, parietal and temporal lobes.