That aging affects the memory system is fairly obvious. What isn’t as obvious is why, where, or how this effect is taking place. A decrease in short-term memory could be due to a loss of specificity and function, or it could be due to a decrease in attention, or even a general slowing of cognition that naturally happens as the brain ages. By comparing responses of young adults and elderly subjects performing the same experimental task, scientists can draw a clearer picture of how the brain might be changing over time.
In her talk, Dr. Gutchess presented some of her work with functional magnetic resonance imaging, or fMRI, as a way to study the changes in brain function due to aging. In general, there is a loss of specificity in older adults, meaning their cortex responds more generally to a task. For example, in recall tasks, a young brain would usually show only right-hemisphere activation, while an older brain often shows both left and right. Dr. Gutchess discussed an experiment using an adaptation paradigm in which subjects were shown the same image over and over again. Activation decreases in both young and old as the repetitions increased, as they are adapting to the image. When there was a change in the image, different activation patterns occurred in the two subject groups. If the object of the image changed, the young subjects showed an increase of activity in the right lateral occipital cortex, an area that has been shown to respond to objects. This activation wasn’t seen in older subjects, suggesting they weren’t distinguishing between old and novel.
Dr. Gutchess discussed other experiments, such as one that examined whether relating a list of adjectives either to the self or another person improves memory for the items on the list. Her work has shown that there are different areas being activated in memory tasks between young and old; loss of specificity was seen in more than one study, possibly indicating that older brains are recruiting more areas to help with tasks.
