In popular culture, amnesia is often thought of as an absence of memory. Characters and movies, television shows, and soap operas constantly hit their heads and forget who they are and the people around them. Just last week a student from North Dakota went missing for a week before resurfacing in Arizona and claiming that her disappearance was a result of her amnesia. That has since been called into question.
But researchers at the University of Toronto have a different hypothesis – people with amnesia are not missing memories necessarily. While there is certainly a memory deficit, researchers found that people with amnesia suffer from memory clutter - or too many irrelevant memories. This theory could have profound impacts on cognitive rehabilitation and may help improve symptoms for people suffering from the condition.
Damage caused to the perirhinal cortex region of the brain, located by the ears, can cause amnesia, which affects sufferers’ ability to recognize objects as well as people. The study gave tasks for two people suffering from this type of amnesia, in which they needed to assess whether two images were the same or slightly different. The images were blobs with distinctive lines, and were shown at different rotations.
At the beginning of the experiment, people with amnesia were able to discern whether two images were the same at the same level as healthy people. But as the experiment wore on, their ability to do so turned off. Researchers realized that, as the experiment dragged on, irrelevant memories of previous images clouded participants’ ability to complete the task. Small details caused the problems, not the entire image. Once researchers removed common elements of images, like the tilt of a line, the study participants’ performance drastically improved.
While researchers are excited, it is important to note that the sample size is small. In addition, one hopes that the study would be recreated with people suffering from other types of amnesia, rather than the one caused by perirhinal cortex damage, to see if all people with amnesia suffer from memory clutter.
The findings from the study are published in the latest issue of Neuron.