Table 2.

Reviewed Imaging Studies

	Reference	Subjects	Task	Analysis	Comments
Study 1	Habeck et al., 2005	40 Younga	Letter Sternberg	ORT	Identify a covariance pattern whose expression increased with task load
Study 2	Habeck et al., 2003	17 Youngb	Nonverbal Serial Recognition	ORT	Identify a covariance pattern whose expression increased with task load
Study 3	Zarahn, Rakitin, Abela, Flynn, & Stern, 2007	40 Younga, 18 Oldc	Letter Sternberg	MLM	Compare load-related activation across groups in each task phase
Study 4	Holtzer et al., 2008	25 Youngd, 25 Olde	Shape Sternberg	MLM	Compare load-related activation across groups in each task phase
Study 5	Steffener, Brickman, Rakitin, Gazes, & Stern, 2008	37 Younga, 15 Oldc	Letter Sternberg	MLM and VBM	Determine whether expression of a second network by elder subjects is related to atrophy in the primary network
Study 6	Stern et al., 2005	17 Youngb, 19 Oldd	Nonverbal Serial recognition	ORT	Identify a covariance pattern whose expression increased with task load and was differentially expressed by the young and elderly subjects
Study 7	Stern et al., 2003	19 Young	Nonverbal Serial recognition	GLM	Identify voxels where the change in fMRI response amplitude with task load correlated with CR
Study 8	Scarmeas et al., 2003b	17 Youngb, 19 Oldd	Nonverbal Serial recognition	GLM	Identify voxels where the change in PET signal with task load correlated with CR
Study 9	Stern et al., 2008	40 Younga, 18 Oldc and 24 Youngd, 21 Olde	Letter and Shape Sternberg Task	MLM	Identify a common CR network: a spatial pattern that increased in expression with task load as a function of CR across both tasks.

ORT = Ordinal Trend CVA

MLM=Multivariate Linear Model

GLM= General Linear Model (standard SPM)

VBM= Voxel-based Morphometry

The same superscript letter associated with subject groups indicates that a common data set was used in the different analyses.