The “old unsure of pairing” response was to be used when the test word was recognized as having been studied but the studied image was not recollected. Prior to starting each session, participants received written and verbal task instructions. On day 1, participants performed the encoding task on LD pairs. Approximately 24 hr later, they returned to the laboratory and completed the encoding task for SD pairs. After a short

break, participants were positioned in the MRI for the restudy phase. During LY294002 purchase this session, participants studied, in a pseudorandomly intermixed list, the previously encoded LD and SD pairs, as well as a new set (SS) of 60 word-scene and 60 word-object pairs that they had not previously studied (single session condition). The restudy phase was broken into six blocks, each including 60 trials. After this restudy session, participants engaged in a simple http://www.selleckchem.com/products/Rapamycin.html one-back task for which they received instructions prior to beginning the first session on day 2. The fMRI data from this one-back task were later used in the creation of object-

and scene-sensitive ROIs (the localizer task). Before exiting the scanner, an anatomical image of each subject’s brain was obtained. Subjects were then given a short break and returned to the laboratory to complete an immediate memory test on half of all the items from the LD, SD, and SS lists. Instructions were given prior to beginning the first test session. Approximately 24 hr after the MRI session, participants returned to laboratory to complete a final memory test on the remaining untested studied words and new words. Studied pairs were these divided into two test lists as in Litman and Davachi (2008). This was done to avoid contamination of 24 hr memory test performance by the additional learning opportunity afforded by an extra test session

on the same items. High-resolution T1-weighted anatomical images and BOLD, T2∗-weighted echoplanar functional images (TR = 2 s, TE = 30 ms, FOV = 192 mm, flip angle 70°) were acquired using a 3T Siemens Allegra MRI system with a whole head coil. Each volume comprised 36 slices oriented parallel to the AC-PC line (thickness 3 mm, 0.6 mm interslice gap, 3 mm3 voxels) acquired in an interleaved sequence. The first six volumes of each session were discarded to allow equilibration of tissue magnetization. Four hundred and twenty six volumes were acquired during each restudy phase scan and 172 volumes were acquired during each localizer scan. Statistical parametric mapping (SPM8, Wellcome Department of Imaging Neuroscience), run under MATLAB R2010a (MathWorks), was used for fMRI data analysis. Functional imaging time series were subjected to slice timing correction, reorientation, realignment to the first volume of each session, and coregistration with the anatomical image. These time series were then concatenated across runs for the restudy and localizer runs separately.