Comparing Memory Lanes

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UHN researchers help to clarify how temporal lobe epilepsy accelerates forgettfulness.
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Every year on March 26, people in countries around the world wear purple and host events to promote epilepsy awareness.

Imagine walking past a bakery with baguettes displayed in the window. Now imagine walking past the same bakery a week later and stopping to look at a display of croissants.

Healthy adults are typically able to recognize that the bakery’s window display has changed. Individuals with temporal lobe epilepsy are much less likely to discern the change in the display.

To better understand why, Dr. Mary Pat McAndrews, Senior Scientist at the Krembil Research Institute, has been studying how memories are formed and recalled in those with temporal lobe epilepsy.

Temporal lobe epilepsy is the most common form of location-related epilepsy and often develops during adolescence. Those with the condition are able to learn and remember without difficulty for many hours, but forget those memories at an unusually fast rate in the following days. When medications do not work, surgery may be an alternative treatment.

“We asked some temporal lobe epilepsy patients who are considering surgery to look at photos of objects paired with photos of scenes—for example, a couch and an apartment building,” describes Samantha Audrain who co-led the study with Dr. McAndrews. “We then recorded how well they remembered these pairings at several timepoints in the following three days and compared the results to those from healthy volunteers.”

“We found that individuals with temporal lobe epilepsy forgot about the object-scene pairings much more quickly than healthy individuals, starting after about six hours,” adds Dr. McAndrews. “These findings agree with the theory that for those with the condition, the part of the brain that helps to process object information makes weaker connections with the part that helps store memories.”

Further exploring why these connections are altered may reveal new strategies for identifying and treating patients who are more likely to experience long-term memory loss due to temporal lobe epilepsy.

This work was supported by the Natural Sciences and Engineering Research Council of Canada and the Toronto General & Western Hospital Foundation.

Audrain S, McAndrews MP. Cognitive and functional correlates of accelerated long-term forgetting in temporal lobe epilepsy. Cortex. 2019 Jan. doi: 10.1016/j.cortex.2018.03.022.

Dr. Mary Pat McAndrews, Senior Scientist, Krembil Research Institute