The Lateralization Of Function In Aging Brain

The idea that the two halves of our brain’s cerebral cortex perform different function has been known for centuries. In humans, the left hemisphere has been shown to be involved with functions associated with language such as grammar and vocabulary, while the right hemisphere is associated with non-verbal functions such as visuospatial and sensory tasks. In this study, we are focused on the lateralization of brain.Brain lateralization is a widely studied topic, however there has been little work focused on lateralization of intrinsic networks in the resting brain. In this study, we evaluate intrinsic network lateralization in a functional magnetic resonance imaging (fMRI) dataset in the process of aging. After establishing sample-wide network lateralization properties, we continue with an investigation of age effects on network lateralization. All data was gathered on the same scanner and preprocessed using an automated pipeline. Networks were extracted via group independent component analysis (gICA). Ten resting state networks were analyzed with a focus on lateralization. We calculated homotopic voxelwise measures of laterality in addition to a global lateralization measure, called the laterality cofactor, for each network. As expected, many of the intrinsic brain networks were lateralized. For example, the visual network was right lateralized, auditory network and default mode network were left lateralized. Age was strongly related to lateralization in multiple regions including fusiform gyrus in visual network and thalamus in basal ganglia network. Significant effects of age were found in visual network and frontal networks on the global measure. Thus, we report a lateralization study that finds intrinsic functional brain networks to be highly lateralized, with regions that are strongly related to age locally, and with age a strong factor in lateralization on global measures of laterality.Functional homotopy, the high degree of synchrony in spontaneous activity between geometrically corresponding interhemispheric region, is a fundamental characteristic of the intrinsic functional architecture of the brain. However, despite prominence, the lifespan development of the homotopic resting-state functional connectivity (RSFC) of the human brain is rarely directly examined in functional magnetic resonance imaging studies. Here, we systematically investigated age-related changes in homotopic REST in two group of aging. We observed marked age-related decrease in homotopic REST including middle frontal gyrus, precuneus, supramarginal gyrus and postcentral gyrus. To further explore the lateralization of aging, we investigated the asymmetry features of these regions exhibiting significantly different voxel-mirrored homotopic connectivity. We observed significantly reducing lateralization on supramarginal gyrus and postcentral gyrus.In this paper, two different methods were described to characterize the changes in the brain during normal aging. This study provided a neuroimaging evidence to support that age is an important influencing factor of the lateralization of brain.