This subproject is one of many research subprojects utilizing the resources provided by a Center grant funded by NIH/NCRR. The subproject and investigator (PI) may have received primary funding from another NIH source, and thus could be represented in other CRISP entries. The institution listed is for the Center, which is not necessarily the institution for the investigator. Introduction While there appears to be a link between repetition suppression in medial temporal cortex and item memory strength, the factors that mediate this effect are unclear at present. Recognition memory models posit that a key factor impacting item memory strength is the global similarity between a test probe and studied items. Accordingly, in the current experiment, high-resolution functional MRI (fMRI) indexed correlates of graded memory strength in the human brain, focusing on the medial temporal cortex (specifically, perirhinal cortex). Materials and Methods Twenty healthy participants were recruited from Stanford University. 16 high-resolution functional MRI (fMRI) scans using a 3 tesla scanner (spiral in-out sequence, TR=4, TE= 34, 1.89 x 1.89 x 3 mm, 22 slices) were collected. A T2-weighted high- resolution (0.4 x 0.4 x 3 mm) structural image was also collected in the same plane. Anatomically defined regions of interest (ROIs) were used to compare BOLD signal changes due to the conditions of interest. At study, faces were incidentally encoded during performance of a similarity judgment task. At test, a subsequent recognition memory test varied study-test perceptual similarity across three classes of memory probes: studied faces, faces that were morphs between a studied and an unstudied face, and unstudied faces. Subjects responded using a five-point confidence scale, indicating whether they recognized the face as old or new (1= sure new, 5= sure old).
Showing the most recent 10 out of 446 publications
