Physiological, Neural and Cognitive Bases of Age-Related Working Memory Change
In these studies, pencil-and-paper and computerized test data and MRI structural and functional images will be obtained. The tasks used will be the delayed response, perceptual speed, and digit symbol substitution tasks. Each trial in the delayed response task consists of three periods: encoding, delay, and response. During the encoding period, participants will study letters from the English alphabet, Korean symbols, or pictures. The participants will be asked to remember the stimuli in the order presented or to reorder the stimuli, for example, alphabetize the letters or order the symbols by size. During the delay period, participants will just remember the stimuli. Finally, during the response period, participants will indicate whether a different set of stimuli, for example, a set of letters, matches the original or reordered set. On each trial in the perceptual speed task, participants will judge whether sets of stimuli, for example, letter pairs or line drawings, are similar or not. Finally, two versions of the digit symbol substitution task will be used, computerized and paper and pencil versions. On each trial of the computerized task, participants view a digit-symbol key containing sets of digit-symbol pairs. At the same time, a single digit-symbol probe will appear below the key, and participants will indicate if the probe matches one in the key or not. In the paper and pencil version, participants will be given a sheet of paper with a digit-symbol key across the top. Below the key will be rows of pairs of boxes with symbols in the top row and nothing in the bottom row. Participants will enter the digit that corresponds with each symbol in the empty bottom row. Participation will involve two lab visits, the second of which will involve collecting the MRI data. During the first lab visit, not to last more than 1.5 hours, they will complete all of the tasks described above. During the second lab visit, not to last more than 1 hour, they will complete shortened versions of the computerized tasks while the MRI data are collected. During the FMRI session, participants will also complete three tasks to differentiate fMRI signal changes due to neural activity versus vascular reactivity. Participants will complete these 3 tasks in 3 separate scanning runs within the FMRI session: (1) rest while breathing room air, (2) rest during expirational breath-holding, and (3) periodic bilateral finger-tapping. During the resting scan, participants will rest with their eyes closed for 3 minutes. For the expirational breath-hold task, participants will be trained to perform the task before entering the scanner. Participants will complete three breath-hold trials, lasting 20 seconds each separated by 80 seconds of normal respiration. Blood-oxygen saturation will be continuously monitored using a pulse oximeter. For the finger-tapping trials, participants will successively touch each finger to its respective thumb in a self-paced manner. Participants will complete four finger-tapping trials, 20 seconds of finger-tapping alternated with 20 seconds of rest. Even with the addition of these tasks, the participants will not be in the scanner more than 1 hour in the scanner, and the session will not last more than 1.5 hours. Participants will be paid $10 per half-hour to participate in this research in the behavioral portion of the study (i.e., the first lab visit) and $50 to participate in the FMRI portion (i.e., the second visi
Participants will be selected in an unbiased fashion with regard to sex and race. Participants (ages 18-75) will be recruited from UT Southwestern Medical Center, UT Dallas, and the greater metroplex area.