Most of us are happy to blame our forgetfulness on our age, but this might not be the inevitability we all believe. Recent research has started to suggest that our memory may be more stable across individuals than we once thought.
One type of memory which is disproportionally affected by age is the ability to link together different elements of an event. Therefore, as part of the Stanford Aging and Memory study, 100 participants aged between 60 and 82 took part in an fMRI experiment.[1]Trelle, A.N., Carr V.A., Guerin, S.A., Thieu, M.W., Jayakumar, M., Guo, W., Nadiadwala, A., Corso, N.K., Hunt, M.P., Litovsky, C.P., Tanner, N.J., Deutsch, G.K., Bernstein, J.D., Harrison, M.B., Khazenzon, A.M., Jiang, J., Sha, S.J., Fredericks, C.A., Rutt, B.K., Mormino, E.C., Kerchner, G.A. and Wagner, A.D. (2020) Hippocampal and cortical mechanisms at retrieval explain variability in episodic remembering in older adults. eLife 9
fMRI (functional magnetic resonance imaging) studies are useful to identify activity within the brain. When a region of the brain is activated, blood flow to that part of the brain is increased. If you are given certain tasks to do like reading aloud or doing simple mathematics, different parts of your brain are active to help you complete the task. fMRI can detect these changes in blood flow and can help researchers to identify which parts of the brain are activated. This can help us to understand which brain regions are important for certain tasks
Participants in the Stanford study were shown words which were paired with pictures of famous people and places. in the scanner they were given the words and had to recall the associated picture. Researchers found very similar patterns of brain activation in these older adults that are found in younger adults; in particular increases in activation in the hippocampus.
The hippocampus is a region of the brain (named for its resemblance to the shape of a seahorse) which is associated with remembering events. When we remember events, there is an increase in activation in the hippocampus, along with patterns of activity across the brain which reflect the brain activity when the event was initially experienced – as if we are replaying the event as we remember it. This is sometimes known as ‘mental time travel’.
Previously these patterns of activation have only been found in younger adults so it was striking to see these similar patterns in older generations. However, despite these striking similarities, this study did find that the ability to accurately recall the events declined with age. Importantly though, regardless of age, the strength of the activation of the hippocampus and the ‘mental time travel’ was associated with a better memory.
This suggests that regardless of age, those of us who are better at ‘mental time travel’ may be better at remembering previous events. This might be something which is fairly stable across individuals and may explain why some of us are better at recalling events, irrespective of our age. This ability to mentally travel back in time may also be indicative of other aspects of brain health but more research is needed to fully understand these links.
So, the next time you’re struggling to remember a face or an event, try calling one of your older relatives to see if their mental time travel is actually better than yours!
References
