In a study testing the eye movement and corresponding brain activity, psychologists at Baycrest’s Rotman Research Institute (RRI) may have uncovered one of the primary causes of memory lapses in older adults.
Growing forgetfulness it not an unusual complaint amongst older adults; aging is often associated with longer learning times, increased difficulty recollecting simple facts or memories, and greater tendency to lose or misplace objects. While this seems to have been accepted by the scientific community, researchers have been unsure what causes this weakened memory. Some have guessed that it has to do with decreased blood flow to the brain or loss of brain cells. Previous research has even suggested that forgetfulness may be due to the creation of abnormal brain tissue called brain lesions.
However, researchers at RRI have recently published a study in the journal Neuropsychologia which seems to provide greater insight into the subject and provide some more definite answers.
In previous studies, RRI researchers have tested the connection between seeing and remembering by studying and recording subjects’ brain activity through functional magnetic resonance imaging (fMRI) readings. When a new object is placed in front of a person, the fMRI readings have shown that there in increased activity in the hippocampus, a portion of the brain and the limbic system that scientists believe is responsible for consolidating short-term memories to long-term memories.
When the person is shown the object again, there is less activity in the hippocampus, suggesting that the object and the memory has already been “learned.” This pattern is weakened, however, in older adults.
Jennifer Ryan, an RRI senior scientist and Reva James Leeds Chair in Neuroscience and Research Leadership, explained why the study was important.
“Eye movements are important for gathering information from the world and the memory centre of the brain — the hippocampus — is important for binding this data together to form a memory of what our eyes see,” Ryan said in a press release.
She went on to explain the results of the study.
“We found that older adults are not building up the memory in the same way as younger adults. Something is falling apart somewhere along the path of taking in visual information through the eyes and storing what is seen into a memory.”
In their recent study, RRI researchers gathered 21 adults between the ages 64 and 79 and 20 young adults between the ages of 19 and 28. As participants were shown new images and faces on a screen, researchers measured their corresponding eye movement and brain activity. While the group of older adults clearly demonstrated greater eye movements while looking at the images, their brain activity was measured to be significantly lower than that of the young adults.
Ryan believes this shows a disconnect between eye movement and storing information.
“These findings demonstrate that the eyes and brain are taking in information from their surroundings, but the linkage aspect of creating a memory appears to be broken,” Ryan said. “When the memory isn’t being created, the object continues to remain unfamiliar to a person, even when they have seen it multiple times.”
The researchers hope to continue studying the relationship between eye movement and activity in the brain with the hope that these correlations could one day be used to predict and diagnose Alzheimer’s disease and other similar forms of dementia. While dementia is not classified as a specific disease, it is a group of symptoms that are associated with the severe declination of memory, so much so that it affects day to day activities. Therefore, the researchers hope that with further similar experiments and studies, a cognitive assessment of eye movement and brain activity could be developed in order to properly diagnose older patients.
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