Changes Of The Functional And Structural Connectivities Between Basal Ganglia And Cerebral Cortex Across The Lifespan

The aging of the population is one of the critical problems in today’s society.The memory decline,as well as executive and cognitive function impairment caused by the aging,seriously impact the living condition of the old.The basal ganglia,the sub-cortical structure of the human brain,plays an important role in regulating brain information transmission,and its functional activities are impacted by age.However,the underlying mechanism of basal ganglia in lifespan remains unclear.A number of functional magnetic resonance imaging(f MRI)studies have found that brain functional networks such as default mode network and sensorimotor network decrease with age.These lifespan studies are mostly based on resting state or task state,and few studies are based on the natural stimulation(such as movie-watching)which includes abundant information and is close to daily life.Therefore,this study explored the lifespan changes of functional connectivity between basal ganglia and cortex based on f MRI data collected from 18-87 years old healthy adults during movie-watching state.Furthermore,by combining cognitive behavioral data,structural MRI and diffusion tensor imaging data,changes of structural connections between basal ganglia and cortex in brain aging were explored,which may be promising to provide important information for the early diagnosis and brain aging intervention.The main research contents are as follows:First,we analyzed the lifespan changes of functional connectivity on the basal ganglia-cortical network.Basal ganglia is the main subcortical central region involving in motor and cognitive regulation,and plays an important role in the execution and regulation of various brain function.In this study,f MRI data during movie-watching state was collected to estimate the functional connectivity between the basal ganglia and the whole brain.Then,a general linear model was used to analyze the relationships between the basal ganglia-cortical functional connectivities and age.The relationships between cognitive behavioral scores and basal ganglia-cortical functional connectivities were also investigated.It was found that with the increase of age,the functional connectivities within the basal ganglia and between the basal ganglia and the primary network were decreased;and the functional connectivities between the basal ganglia and the advanced network and cerebellar network were both increased and decreased.In the cognitive behavior analysis,it was found that with the increase of fluid intelligence scores,the functional connectivities within the basal ganglia,between the basal ganglia and the primary network,and between the caudate and the advanced networks were increased.The functional connectivities between the bilateral putamen\thalamus and the advanced networks were reduced.Furthermore,we found that the functional connectivities between the basal ganglia and the cerebellar network were both increased and decreased.We inferred that these increased functional connectivities might be explained by the important compensatory role of basal ganglia in the aging process,which to some extent compensated for the functional decline caused by aging.Then,we analyzed the lifespan changes of structural connectivity on basal ganglia-cortical network.The lifespan changes of morphological characteristics on basal ganglia region with age were investigated using structural MRI data.Next,the basal ganglia region was taken as the region of interest,and the basal ganglia-cortical structural connectivity networks were constructed by applying the deterministic tracing method to diffusion tensor imaging data.Finally,a general linear model was used to explore the relationships between age,cognitive behavior scores and structural connectivities.Results showed that the volumes of gray matter in the basal ganglia decreased with age;the structural connectivities within the basal ganglia were both increased and decreased with age;and the structural connectivities between the basal ganglia and the cortical networks decreased with age(fractional anisotropy reduced).In the cognitive behavior analysis,it was found that the fluid intelligence scores wese negatively correlated with the mean diffusivity between networks,and positively correlated with the fractional anisotropy value.These results suggested that early myelin sheath shedding and late myelin sheth formation might occur in brain microstructures during aging,which might be a complementary and collaborative relationship with functional changes.In summary,the functional and structural connectivities between the basal ganglia and cortex might play an important compensatory role in normal brain aging,and there perhaps was a complementary and collaborative relationship between brain function and structure.These findings provided an important information for us to further understanding the brain aging mechanisms in the real world.