A team of scientists from the United States and China announced last week that, for the first time, they had found a means of selectively and safely erasing memories in mice, using the signaling molecule ?CaMKII. It's a big step forward, and one that will be of considerable interest to the military, which has devoted efforts to memory manipulation as a means of treating post-traumatic stress disorder. But some military research has moved in another direction entirely.

In the 1980s, researchers found that even low-level exposure to a beam of electronscaused rats to forget what had just happened to them (an effect known as retrograde amnesia — the other version, anteretrograde amnesia, is when you can't form new memories). The same effect was also achieved with X-rays. The time factor was not large — it only caused memory loss about the previous four seconds — but the effect was intriguing.

One theory was that the amnesia was a result of the brilliant flash experienced when the electron beam struck the retina. And, indeed, it turned out that it is possible to produce amnesia in rodents using a flash of light:

Retrograde amnesia was demonstrated for the 80-, 85-, and 100-V foot-shock test trials. At 40 V the voltage may not have been great enough to be felt by the subject. For groups examined at shock levels above 100 V, the foot shock was so potent that a photoflash was ineffective in producing RA. Our conclusion was that the photoflash was an effective amnesiac until the intensity of the foot shock became more potent than the photoflash; this is consistent with the recency theory generated in serial learning and memory tasks.

This might help explain some of the disorienting effects of strobe lights used as nonlethal weapons, but there seems to have been little further research on this.

However, there have been plenty of studies on the physical effects of radio and microwave exposure on the brain. Many of those investigations have been conducted by the military.

The Air Force Research Laboratory's Human Effectiveness Directorate has carried out its own experiments in this area, which did not confirm the results of earlier studies suggesting that microwaves could cause memory loss. (The report is now removed from the AFRL website, alas.) Most scientists chalk up such effects to heating. But the Directed Energy Bioeffects division continues to research the human effects of various forms of radiation. What's more, a 2003 paper on microwave effects on the nervous system, from a team that includes Navy and Air Force scientists, states that

"research with isolated brain tissue has provided new results that do not seem to rely on thermal mechanisms." It is hard to assess the real effect on working memory and other brain functions, they add.

*"The many exposure parameters such as frequency, orientation, modulation, power density, and duration of exposure make direct comparison of many experiments difficult…. It is concluded that the diverse methods and experimental designs as well as lack of replication of many seemingly important studies prevents formation of definite conclusions concerning hazardous nervous system health effects from RF [radio frequency] exposure." *

Still, it’s interesting to see that the notes for a classified course run by the Directed Energy Professionals Society (the people who build laser and microwave weapons) include "memory loss" as a potential effect of such devices.

I doubt whether they have a functioning Men In Black-style

"Neuralizer." But as memory research continues to advance, it certainly starts to look like more of a possibility.

[Photo: Columbia Pictures]