The effects of aging on visual memory: evidence for functional reorganization of cortical networks.
Recent evidence suggests that the mature human brain is capable of substantial functional reorganization following injury. The fact that the brain retains a great deal of plasticity raises the possibility that cortical reorganization may occur during normal aging. We examined this issue by using positron emission tomography (PET) to measure the brain activity associated with short-term memory for simple visual attributes in young and old observers. A two-interval forced choice procedure was used to measure spatial frequency discrimination thresholds for sine wave gratings presented at different inter-stimulus intervals (ISI). Memory load was manipulated by varying the duration of the ISI and by presenting an irrelevant masking stimulus in the middle of the ISI. Old and young observers performed the experiment equally well. However, the neural systems correlated with good performance differed for the two age groups. The results support the hypothesis that the functional networks that underlie visual memory undergo reorganization during aging.
Bennett
P J
PJ
Department of Psychology, University of Toronto, Suite 4020, 100 St. George St., Toronto, Ont. M5S 3G3, Canada.
Sekuler
A B
AB
McIntosh
A R
AR
Della-Maggiore
V
V
D000293:Adolescent; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D000375:Aging / Q000502:physiology*; D002560:Cerebrovascular Circulation / Q000502:physiology; D006801:Humans; D008279:Magnetic Resonance Imaging; D008568:Memory / Q000502:physiology*; D008875:Middle Aged; D009473:Neuronal Plasticity / Q000502:physiology; D010470:Perceptual Masking / Q000502:physiology; D011897:Random Allocation; D014055:Tomography, Emission-Computed; D014793:Visual Cortex / Q000033:anatomy & histology* / Q000098:blood supply*; D014796:Visual Perception / Q000502:physiology*