A study published recently in the Journal of Neuroscience provides a remarkable finding that may help physicians diagnose epilepsy before the first seizure: People with temporal lobe epilepsy (TLE) have difficulty distinguishing the present from the past.
Study participants underwent two phases. First, the researcher showed the participants a series of images of everyday objects. Second, the researcher showed them another series of images. Some of the images were identical to an image shown in Phase 1; some were completely different images; and some were different, but very similar to an image shown in Phase 1.
The researchers expected that an individual with TLE would be more likely to mistakenly label a different but similar image as identical. In other words, the DG of an individual with TLE wouldn’t be able to identify new details in the different but similar image and would assume the image to be the same as the one experienced during Phase 1.
Their hypothesis was correct. Participants diagnosed with TLE were roughly 50% more likely to label a different but similar image as repeated. To put it another way, they were 50% less likely to identify any new details when the information was similar to previously stored information. Because the brain only stores new details, these participants weren’t storing new memories.
This finding not only could improve the diagnosis of epilepsy before the first seizure, but it also furthers our understanding of the mechanisms behind memory. Linking the function of the dentate gyrus to the ability to identify new information could lead to better care for patients with memory impairments from Alzheimer’s and traumatic brain injury.