  We investigated how the organization of functional brain networks was related
to cognitive reserve (CR) during a memory task in healthy aging. We obtained
the magnetoencephalographic functional networks of 20 elders with a high or low
CR level to analyse the differences at network features. We reported a negative
correlation between synchronization of the whole network and CR, and observed
differences both at the node and at the network level in: the average shortest
path and the network outreach. Individuals with high CR required functional
networks with lower links to successfully carry out the memory task. These
results may indicate that those individuals with low CR level exhibited a dual
pattern of compensation and network impairment, since their functioning was
more energetically costly to perform the task as the high CR group.
Additionally, we evaluated how the dynamical properties of the different brain
regions were correlated to the network parameters obtaining that entropy was
positively correlated with the strength and clustering coefficient, while
complexity behaved conversely. Consequently, highly connected nodes of the
functional networks showed a more stochastic and less complex signal. We
consider that network approach may be a relevant tool to better understand
brain functioning in aging.
