  The human brain is liable to undergo substantial alterations, anatomically
and functionally with aging. Cognitive brain aging can either be healthy or
degenerative in nature. Such degeneration of cognitive ability can lead to
disorders such as Alzheimer's disease, dementia, schizophrenia, and multiple
sclerosis. Furthermore, the brain network goes through various changes during
healthy aging, and it is an active area of research. In this study, we have
investigated the rs-functional connectivity of participants (in the age group
of 7-89 years) using a publicly available HCP dataset. We have also explored
how different brain networks are clustered using K-means clustering methods
which have been further validated by the t-SNE algorithm. The changes in
overall resting-state brain functional connectivity with changes in brain
developmental stages have also been explored using BrainNet Viewer. Then,
specifically within-cluster network and between-cluster network changes with
increasing age have been studied using linear regression which ultimately shows
a pattern of increase/decrease in the mean segregation of brain networks with
healthy aging. Brain networks like Default Mode Network, Cingulo opercular
Network, Sensory Motor Network, and Cerebellum Network have shown decreased
segregation whereas Frontal Parietal Network and Occipital Network show
increased segregation with healthy aging. Our results strongly suggest that the
brain has four brain developmental stages and brain networks reorganize their
functional connectivity during these brain developmental stages.

Signal Processing