By disrupting the memories of cocaine-addicted lab rats, researchers were able to keep the rats from seeking out a fix for up to a month. Researchers say the new study points the way towards possible drug therapies for human addicts, because memory is one of the main reasons why drug addicts who have gone sober suddenly find themselves jumping off the wagon. Environmental cues like visiting a place where you were high can make you remember the drug and weaken your resistance to taking it again [io9].
In the experiment, psychologists taught rats to associate a flashing light with the delivery of cocaine to their cages, making the light a “drug-associated memory.” Then researchers gave half the addicted rats a dose of a drug that interferes with proteins called NMDA-type glutamate receptors in rat brains. Previous work on addiction and post-traumatic stress has shown that these proteins—which are found on the surface of brain cells—are essential to memory formation. The receptors are also crucial to reconsolidating a memory—moving it from its storage area in long-term memory to brain regions that handle short-term memory [Scientific American].
The rats that hadn’t received the drug continued to associate the flashing light with a cocaine delivery, and kept scurrying to the cocaine delivery spot, even when the coke was not forthcoming for weeks. But the mice that had received the memory-scrambling drug quickly stopped responding to the flashing light. In the report, published in the Journal of Neuroscience [subscription required], researchers say that several similar drugs are already on the market for other conditions, and could be tested on human addicts.
Researchers say that the therapy may work by interfering with the drug-associated memory while the rat is in the process of recalling it. Scientists have long known that short-term memories needed to be “consolidated” into long-term storage, but once there, they were assumed to be fairly fixed. In recent years, scientists … have called that into question, arguing that “reactivating” memories opens neurochemical space to change or even erases the recollection [Wired News].