Age-related changes in the topological architecture of the brain during hand grip.

Neuroanatomical changes in the aging brain are widely distributed rather than focal. We investigated age-related changes in large-scale functional brain networks by applying graph theory to functional magnetic resonance imaging data acquired during a simple grip task with either dominant or nondominant hand. We measured the effect of age on efficiency of information transfer within a series of hierarchical functional networks composed of the whole brain or component parts of the whole brain. Global efficiency was maintained with aging during dominant hand use, primarily due to increased efficiency in parietal-occipital-cerebellar-related networks. During nondominant hand use, global efficiency, as well as efficiency within ipsilateral hemisphere and between hemispheres declined with age. This was attributable largely to frontal-temporal-limbic-cerebellar-related networks. Increased efficiency with age was seen in networks involving parietal-occipital regions, but unlike for dominant hand use, this topological reconfiguration could not maintain the level of global efficiency. Here, graph theoretical approaches have demonstrated both compensatory and noncompensatory changes in topological configuration of large-scale networks during aging depending on the task.