Amnesiac has trouble with faces, except Paris Hilton

Date: Wednesday Nov. 9, 2011 2:28 PM ET

A 22-year-old woman with a problem in a key part of her brain is offering Toronto researchers new insights into the way humans recall new information. And while she might not realize it, Paris Hilton helped a little too.

The woman, known only as "HC," has had problems with her long-term memory since she was born. She was deprived of oxygen in her first week of life, and as a result, a tiny part of her brain called the hippocampus developed poorly, growing to only about half the size that it should.

Since the hippocampus plays an important role in helping us organize both our short-term and long-term memory, HC often has trouble recalling events from even a few years ago. And yet, she is otherwise normal: she's graduated from a technical college and is an avid film buff and celebrity watcher. She simply has trouble remembering such things as being a flower girl in her cousin's wedding.

HC's particular injury provided researchers at Baycrest's Rotman Research Institute with a unique opportunity to learn about the role the hippocampus plays in both short-term and long-term memory.

What they found was that the hippocampus is indeed crucial for forming short-term memories but only if the material that's being remembered is brand new. If the item is familiar to the person say, the face of Paris Hilton to an avid celebrity watcher "HC" then there's no problem. The brain appears to use other parts of the brain to store the memory.

The case study was led by Baycrest's Rotman Research Institute, along with the University of Toronto.

HC was compared to 20 other undergraduate students who took part in a number of experiments to test their "working memory," which is the memory we use to retain information for several seconds. Our working memory helps us to remember a phone number, for example, but then wipes it clean again, so that it's difficult for most of us to remember that phone number a month or even a week! later.< /p>

In the first experiment, the participants were shown 40 famous faces and 40 non-famous faces in sequence. After a short delay, the participants werethen asked to pick that face from a choice of two faces. HC had more difficulty recalling non-famous, unfamiliar faces than the control group. She scored 70 per cent compared to the control group's 81 per cent.

But when she was shown familiar famous faces, she scored 85 per cent exactly the same as the control group. Her "working memory" performance was best for famous faces with which she was most familiar such as perennial party girl, Paris Hilton.

The researchers found similar results when HC was asked remember familiar words, such as "direction," compared to less familiar words, such as "fledgling." She performed poorly on the unfamiliar words but as well as the control group on familiar words.

The case study should offer important insights into the nuanced workings of short-term memory, says Rotman scientist Dr. Fergus Craik, a collaborator on the study.

"Our findings add to the growing evidence that short-term memory is not intact in amnesia. However, to my knowledge, we are the first to directly test the hypothesis that short-term memory functions better if the information has some past familiarity to the person," he said in a news release.

The study is posted online in the science journal Neuropsychologia, ahead of publication.