WE NOW HAVE THE POWER TO ERASE BAD MEMORIES

     We all have memories we wish we could purge from our brains. Bad breakups, traumatic injuries, embarrassing social missteps... sigh. If only we had access to that same funky memory-erasing procedure that Jim Carrey had done in Eternal Sunshine of the Spotless Mind.

     Excellent news: It turns out that technology isn't all that far-fetched. A team of researchers is hard at work developing new methods that enable us to selectively "forget" unpleasant memories. Here's the lowdown.

Memories are surprisingly easy to manipulate

     Here's a wild fact: Every time you recall a specific memory, you change it ever so slightly. Psychologists frequently compare our memories to an ongoing game of telephone inside our brains; they are altered each time they're retrieved, constantly shifting into something different. Was it cloudy or sunny when you were at the beach that day you saw a shark? Were you 12 or 10 years old? Those might be details you just want to remember, or that someone else suggested to be true.

     If you have a particularly painful memory, scientists can take advantage of its flimsy nature and neutralize the feelings of sadness, fear, or embarrassment that you associate with it. One method is to block norepinephrine -- the chemical associated with our fight-or-flight response -- while triggering the memory. This changes the way the memory is "put back" after it's been retrieved, a process known as "reconsolidation."

     In one successful case, featured in a NOVA special about memory hacking, researchers in the Netherlands exposed arachnophobes to live tarantulas in a cage, triggering intense pangs of fear. Then they administered beta-blockers -- which are typically used to treat high blood pressure, but are also known to restrict norepinephrine levels. It proved pretty damn effective: Those same arachnophobes were able to gradually eradicate their fear from their brains, and even touch the tarantulas during follow-up sessions mere days after the first exposure. Obviously this is just an early trial, but the future potential for this kind of science has big implications.

We could eliminate the sadness associated with a loved one's death and other serious traumas

     Difficult memories associated with a bad breakup  are one thing, but some hyper-specific memories are so gruesome (deadly accidents, war-zone trauma, etc.) they often set off prolonged periods of PTSD, and quite literally ruin lives. In these more extreme cases, scientists are experimenting with a therapy that involves xenon gas, which is primarily used as an anesthetic in Europe. The gas targets certain brain receptors that are closely related to learning and memory, and thus, when administered using something like an asthma inhaler while triggering a specific bad memory, it can strip any and all negative feelings associated with it, rendering it innocuous. 

Scientists could one day "incept" our brains to alter memories while we sleep

     The procedure offered by Lacuna Inc. in Eternal Sunshine involves an electric brain scanner that targets and zaps Jim Carrey's painful memories while he sleeps. Turns out, scientists can accomplish something similar with mice by "incepting" their brains while they're asleep.

     Essentially it involves mapping a mouse's brain -- identifying the cells that are activated by certain activities or locations -- then manipulating those particular cells while they're sleeping using an electrode to link them to a reward signal whenever they fire. The scientists were able to engineer positive associations with particular places so successfully, that when the mice awoke, they headed straight toward the locations that were linked to the reward signal.

     Of course, a lot more work needs to be done before anyone lets doctors manipulate individual memory associations like this in humans. Memory is so inextricably linked to our understanding of ourselves and the world, even the slightest screw-up could have devastating consequences. But then again, once it's made available, who wouldn't be tempted to risk a little bit in exchange for peace of mind and oblivious nirvana?