Figure 2.

Possible instantiation of CR via neural reserve and neural compensation. One study [82] using this model in the context of a working memory task observed decreasing network efficiency with volume loss within the network (path d). However, this decreasing efficiency was mitigated by higher measured CR (path f), consistent with the concept of neural reserve. Neural compensation was also observed via a second network expressed by older but not younger adults when efficiency was sufficiently impaired in the first network. More activation in the compensatory network was associated with diminished task performance (path e), which demonstrates that compensation need not always improve performance but may only maintain it, albeit at a lower level. Higher measured CR moderated the detrimental effect of the compensatory network on performance (path g), which suggests that individuals with higher CR may recruit additional networks not directly captured by task-related activation.