As people get older, forgetfulness and memory lapses can become common. However, it’s not clear what causes these changes. A new study indicates that the answer may lie in the link between what older adults see and the hippocampus. Your eye movements gather information of the world around you, and the hippocampus — which is the memory centre of your brain — binds that information together to form a memory of what your eyes see. But it seems that older adults are not forming memories this way, as younger adults would, and that something along the way is breaking the connection to memory formation.
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To understand this, researchers from the Baycrest’s Rotman Research Institute (RRI) conducted a study that involved 21 older adults (aged between 64 and 79) and 20 younger adults (aged between 19 and 28). The participants were briefly shown faces on a screen where some images were displayed multiple times. As the participants looked at the faces, the scientists analysed eye movements and brain scans of the participants.
In previous studies, the same researchers found that when our eyes view and process more details of the object in front of us, there is more brain activity in the hippocampus. But when the object is seen multiple times, the activity in the memory centre drops, indicating that what is seen is no longer considered new information. But this does not happen in older adults. According to the new study, older adults showed an increase in visual exploration exhibited by greater eye movement, compared to younger adults. But the relationship between visual exploration and corresponding neural responses in the hippocampus was weaker than that of younger adults, demonstrating that memory formation is weak or is not being created. In the case of older adults, when a memory is not forming and even when an object is seen multiple times, it continues to remain unfamiliar to the person.
The findings have further implications for investigating eye movements and related brain activity which could help predict earlier cognitive decline of Alzheimer’s disease or dementia.
Source: Neuropsychologia
