May 17 2004
Amnesia sufferers can lose their short-term memories within one minute of the initial thought. While such things as head injuries and strokes are known to cause amnesia, very little is known about why such severe memory loss occurs. However, a University of Missouri-Columbia researcher has discovered that some amnesiacs can maintain their memories for a longer period of time if they spend time sitting in a dark, quiet room.
“This discovery might provide us with a better understanding of what causes amnesia,” said Nelson Cowan, an MU psychology professor who conducted the study along with Nicoletta Beschin of the Department of Rehabilitation Unit in Somma Lombardo, Italy, and Sergio Della Sala of the University of Aberdeen, United Kingdom. “It also will help us better determine different types of amnesia as well as better therapeutic applications.”
Cowan conducted two experiments with people who have amnesia caused by either a head injury or stroke. In the first experiment, participants reviewed six lists of 15 unrelated words. After the participants read the words they were tested in six different conditions, one of which was to lie quietly in a darkened room with no outside interference, trying not to fall asleep, for 10 minutes.
After 10 minutes, the participants were asked to recall any of the words. Cowan found that although severe memory loss occurred following activity-filled conditions, 60 percent of the patients experienced much less memory loss after sitting in the darkened room.
In the second experiment, Cowan and his team extended the retention time to one hour. Each participant listened to stories and was then tested using four of the six conditions used in the first experiment. At the end of the hour they were asked to tell the researchers as much about the story as they could. Cowan found that when the participants were left alone in the darkened room, they were able to remember more than seven times the amount of information as those in the activity-filled conditions. This was true even when the participants appeared to sleep during the hour.
“One intriguing aspect of the study was that there was similar preservation of the participant’s memory in a quiet, dark room both when they were awake and when they were asleep,” Cowan said.
Cowan’s study recently was published in the neurological journal Brain.