Is default network activity a sensitive and specific biomarker of memory in multiple sclerosis?
Maintenance of DN activity during sustained attention was supported as a sensitive and specific neurophysiologic biomarker of episodic memory functioning in MS, even when controlling for neuroanatomical changes (brain atrophy).
These results are in line with reports that the rate of dentate gyrus cell proliferation is acutely down-regulated by stress, but the development of helpless behavior does not correlate with this process. Further studies will have to clarify if during learned helpless behavior neurogenesis is impaired by altered differentiation or survival of cells.