“The common wisdom was that once an experience was consolidated in long-term memory, it was stable,” says neurobiologist Yadin Dudai of the Weizmann Institute of Science in Israel. “Some of us now think that a memory may return to its embryonic state when it’s activated.” In the lab, experiments point in both directions. Joseph LeDoux, the Henry and Lucy Moses Professor of Science at New York University, was able to block the process of encoding a conditioned fear response in rats by injecting a drug, anisomycin, into their brains. The drug inhibits the synthesis of proteins and thus blocks the formation, or consolidation, of a memory. Twenty-four hours later, the rats’ conditioned fear response seemed to disappear. Yet a study recently published in the Proceedings of the National Academy of Sciences found that the memory was only temporarily blocked. This time, University of Pennsylvania researchers conditioned rodents, treated them with anisomycin, and then examined them 21 days later. They remembered the conditioned behavior.
Just to confuse the issue further, research that has just been published finds that in rats conditioned to fear a shock to the foot, memory formation and subsequent recall, or reconsolidation, are actually separate processes, and thus established memories may be malleable and sensitive to disruption. Although both an original memory and its retrieval/reconsolidation may be blocked temporarily by anisomycin, University of Cambridge psychologist Barry Everitt and his colleagues found that the two processes depend on different chemicals within the hippocampus. The initial formation of long-term memory requires a chemical called brain-derived neurotrophic factor, while subsequent recall depends on a transcription factor called Zif268. The processes are related but fundamentally different—and so the researchers conclude that repeated remembering does not create a duplicate of the original memory. If we can isolate the chemicals involved in how memories are recalled, we may someday have new drugs to help treat phobias, post-traumatic stress disorder, and intrusive memories.
In real life, McNally says, memories do change. Yale University psychiatrist Steven Southwick surveyed Gulf War veterans first one month, then two years after traumatic events. About half the veterans who checked off events on the first survey failed to check off some of the same events after two years had passed. The timbre and quality of memories changes over time too. McNally gave a questionnaire to personnel 6 months after a fatal shooting at a grammar school in suburban Chicago. The same questionnaire was given again 18 months after the shooting. “Each person remembered the event differently at 18 months than at 6 months,” says McNally. At the second interview, those who had more severe symptoms of post-traumatic stress disorder recalled the event as more harrowing, while memories were recalled as less harrowing by those who had recovered.
We create our memories even as they create us—a Möbius strip, an Escher print, a double helix, if you will, from which the blueprint of self emerges. It’s both dazzling and chilling to realize that the narrative arc of our lives relies on a phenomenon that is by turns robust, fallible, malleable, potent, slippery, inventive, and above all, powerfully yoked to emotion.
If we are storytellers, even inaccurate ones, how does that serve us? “What has been missing from all the theories of false memory,” says Clancy, “is the desire for meaning. I think psychologists are tone deaf to this. It’s a very important ideological factor in the development of any belief. Alien abductees talk about the fact that they don’t feel alone in the universe any longer.” When McNally and Clancy asked abductees if they were glad they’d had these experiences, “we only had one person say no. Everyone else said it was initially disorienting and frightening but that they eventually put it all in a spiritual perspective.”
So how and why would an individual develop a story line as unusual as abduction? Are there any common ingredients? Part of the answer may derive from a physiologically dramatic and terrifying phenomenon called sleep paralysis. In classic sleep paralysis, a person wakes early from a dream and is unable to move (as is standard during REM sleep). In many of these cases, people also generate vivid dream images called hypnopompic hallucinations. Many alien abductees experience sleep paralysis, and if they don’t understand the phenomenon and believe their otherworldly hallucinations are real, says McNally, they may seek out therapy, hypnosis, or bodywork, thereby “recovering” additional memories. “These folks are very open to what we might call New Age beliefs, such as reincarnation, energy therapies, astrology, reincarnation, and telepathy.”
Will Beuche sees it this way: “I won’t call abduction a spiritual experience, but by its very nature it casts you into reflection about your existence . . . you feel you’re behind the scenes of a theater, of an incredible play . . . this play we’re all in.”
But he might as well be talking about the phenomenon of memory itself—in which we somehow weave and unweave ourselves by our own hand.
PUTTING FREUD TO THE TEST: CAN MEMORIES BE REPRESSED?
Freud’s theory of repression has intrigued psychologists since the 1930s, but nobody has proved it exists. Cognitive neuroscientist Michael Anderson, who runs a memory lab at the University of Oregon, believes he’s got the goods. “You don’t have to subscribe to highly specialized mechanisms like the ones Freud might have proposed,” says Anderson. “You can explain it with very well-respected ideas in neuroscience and psychology.” For instance, he says, we all exercise what is known as executive control. We can focus our attention on one thing and ignore distractions. Scientists have shown a sequence of letters to individuals and told them that each time they see a letter, they should press a key—except when the letter X appears. “These are called go/no-go procedures,” says Anderson. “They’re set up so the individual gets into a rhythm of seeing letters and pressing the key, and when X appears, they have to stop themselves.” Monkey studies have shown that the no-go response is associated with specific regions of the frontal cortex.
To test a similar paradigm in memory, Anderson created a think/no-think procedure for recalling word pairs. In a study they found that the subjects, when prompted, could push the second word in a learned word pair out of awareness, which made it harder to recall later. Recently, Anderson and his colleagues used the same think/no-think procedure along with fMRI. In a study published in Science in January 2004, they found that suppressing recollection reduced the activity of the hippocampus, the small organ that shuttles short-term memories into long-term storage. They also found greater activity in many areas of the prefrontal cortex, the same areas that are active in go/no-go procedures.
Daniel Schacter, a Harvard University psychologist, warns that Anderson’s results do not address the issue of whether traumatic memories can be repressed. He says that Anderson’s work fits Freud’s first definition of repression—an intentional attempt to banish distressing experiences from conscious awareness. Freud later used the term to refer to a defense mechanism that operated beyond a person’s awareness. That model of repression has never been proved to exist.
Psychologist Henry L. Roediger III of Washington University in St. Louis says he has failed to replicate Anderson’s work. Anderson responds that Roediger was using a slightly different and earlier design and that the results have been replicated elsewhere. Roediger says: “If repression hinges on this teeny-weeny change, then it is not very robust. I’m not saying the effect can’t be obtained—I’m just saying it’s hard to obtain.”
“I don’t subscribe to the view that repression needs to be unconscious, complete, or permanent,” says Anderson. “It can be a process that requires effort over time and may lead people to forget all or part of an unwanted experience. Even if somebody doesn’t forget the Holocaust, for instance, they may forget details over time. This may actually help. We need to find out how people cope with distressing memories. That’s why this is a pretty damned important topic to research.” —J. N.
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