MRI study on asymmetry of cortical thickness in adult cerebral cortex

Abstract

Objective To explore the lateralization difference of cerebral cortex thickness in adult cerebral cortex. Methods A prospective study was conducted. From September 2017 to December 2018, 360 healthy right-handed Han volunteers aged from 21 to 80 were recruited in CT Magnetic Resonance Room of Shouguang People's Hospital. They were divided into three age groups: the young group (21-40 years old), the middle-aged group (41-60 years old) and the old group (61-80 years old). Raw brain 3.0 T MRI data were obtained and analyzed by FreeSurfer brain imaging software. The cortex thickness of the gyrus of interest in each gyrus of the left and right hemispheres was obtained. The cortical thickness of left and right cerebral hemispheres in different age groups was observed. Observe whether there was laterality in cortex thickness of each gyrus among different age groups, calculate asymmetry index for brain areas with laterality, and count the number and degree of brain areas with laterality. Results In the young group, the cortical thickness of the whole brain and left and right hemispheres were (2.506±0.027)mm, (2.508±0.015)mm and(2.504±0.015)mm, respectively. In the middle-aged group, they were(2.372±0.012)mm, (2.372±0.007)mm and (2.373±0.008)mm, respectively. In the old group, they were(2.264±0.021)mm, (2.264±0.015)mm and(2.263±0.014)mm, respectively. In the same age group, there was no significant difference in cortical thickness between left and right hemispheres (all P values>0.05). In different age groups, the cortical thickness of the whole brain and left and right cerebral hemispheres decreased with the increase of age, and the difference was statistically significant (F=64.907, 34.843, 34.863, all P values<0.01). The laterality and lateralization index of cerebral cortex thickness were different in young, middle-aged and old groups. In the three groups, the lateralization area was retained(such as lateral occipital gyrus, lingual gyrus, posterior cingulate gyrus, entorhinal cortex, etc), increased (such as trigone of inferior frontal gyrus, anterior central gyrus, inferior temporal gyrus, temporal pole, etc)and decreased(such as superior frontal gyrus, inferior frontal gyrus, middle orbital frontal gyrus, cuneiform leaf, anterior cingulate gyrus, etc). The number of lateralized brain areas in the middle-aged group was more than that in the young group and the old group, showing an inverted U pattern. The cortical thickness of some brain regions was laterally distributed in three age groups, but the degree of laterality was different. The lateral occipital gyrus and lingual gyrus showed a large-small-large pattern, while the posterior cingulate gyrus and entorhinal cortex showed a small-large-small pattern. Conclusions The thickness of the left and right hemispheres of the brain is asymmetric. The laterality and degree of the thickness of the cerebral cortex show different patterns with the change of age. It provides a new perspective for cognition of neurobehavioral and neurophysiological diseases. Key words: Cerebral cortex; Cortical thickness; Magnetic resonance imaging; Lateralization