A study conducted by researchers at Carnegie Mellon University and the University of Pittsburgh involving an amnesia-inducing drug has shed light on how we form new memories.
For a paper to be published in the July edition of the journal Psychological Science, researchers gave participants material to remember in two experimental sessions -- once after being injected with a saline placebo and once after an injection of midazolam, a drug used to relieve anxiety during surgical procedures that also causes short-term anterograde amnesia, the most common form of amnesia. Anterograde amnesia, which was portrayed in the film "Memento," impairs a person's ability to form new memories while leaving old ones unharmed.
The study revealed that the drug prevented people from linking a studied item to the experimental context. That linkage is necessary for a process known as recollection, in which people retrieve contextual details involved in the experience of studying the information. People sometimes recognize something as having been studied without using recollection (in this case, without remembering details of the study event) if the item seems sufficiently familiar -- a process called familiarity. Although the recollection process was affected by the drug, the familiarity process was not. This is the same pattern that is found with patients suffering from anterograde amnesia. They are unable to form new associations, severely limiting the accuracy of their recognition judgments.
"This helps us understand the general functions of memory. It helps us to relate, for example, the memory declines seen in old age to those seen in patients with hippocampal damage," said Lynne Reder, a professor of psychology at Carnegie Mellon and the study's lead author.