We all have things in our past that we'd like to forget -
bad break-ups, traumatic experiences, loss. No matter how hard we try, these
memories can continue to haunt us, occasionally triggering conditions such as
anxiety, phobias, or post-traumatic stress disorder. But scientists are now on
the verge of being able to change that for good, with the discovery that our
memories aren't as permanent as we once thought.
In fact, researchers have now figured out how to delete,
change, and even implant memories - not just in animals, but in human subjects.
And drugs that rewire our brains to forget the bad parts are already on the
horizon, as PBS documentary Memory Hackers highlighted
over the weekend.
If it all sounds a little science fiction, that's because it
is - films such as Eternal Sunshine for the Spotless Mind and Total
Recall have long toyed with the idea of altering our memories. But
thanks to the advances in neurological scanning technology over the past few
decades, we're now closer than you might realise to making these technologies
(or something similar) a reality.
So how do you go about deleting a memory? To understand
that, you need to understand how memories form and are kept alive in our brains
in the first place.
In the past, scientists used to think that memories were
stored in one specific spot, like a neurological file cabinet, but they've
since realised that every single memory we have is locked up in connections
across the brain.
To explain it simply, a memory is formed when proteins
stimulate our brains cells to grow and form new connections - literally
rewiring our minds' circuitry.
Once that happens, a memory is stored in your mind, and for
most of us, it'll stay there as long as we occasionally reflect upon it or
revisit it.
So far, so simple. But what many people don't realise is
that those long-term memories aren't stable. In fact, every time we revisit a
memory, that memory becomes malleable again, and is reset stronger and more
vividly than before.
This process is known as reconsolidation, and it explains
why our memories can sometimes change slightly over time - for example, if you
fell off your bike, each time you remember it and get upset about it, you're
restrengthening the connections between that memory and emotions such as fear
and sadness. Eventually just the thought of a bike could be enough to make you
terrified. Alternatively, most of us have had the experience of a
once-traumatic memory becoming laughable years later.
The reconsolidation process is so important, because it's a
point at which scientists can step in and 'hack' our memories.
"The research suggests memories can be manipulated
because they act as if made from glass, existing in a molten state as they are
being created, before turning solid," Richard Gray explains
for The
Telegraph. "When the memory is recalled, however, it becomes
molten again and so can be altered before it once more resets."
Numerous studies have now shown that by blocking a chemical
called norepinephrine - which is involved in the fight or flight response and
is responsible for triggering symptoms such as sweaty palms and a racing heart
- researchers can 'dampen' traumatic memories, and stop them being associated
with negative emotions.
For example, at the end of last year, researchers from the
Netherlands demonstrated they could take
away arachnophobes' fear of spiders by using a drug called propranolol
to block norepinephrine.
To figure this out, the team took three groups of
arachnophobes. Two of these groups were shown a tarantula in a glass jar to
trigger their fearful memories of spiders, and were then either given propranolol
or a placebo. The third group was simply given propranolol without being shown
a spider, to rule out the possibility that the drug on its own was responsible
for reducing their fear.
Over the next few months, the groups were all presented with
another tarantula and their fear response was measured. The
results were pretty incredible - while the group given the placebo and
those given propranolol without being exposed to a spider showed no change in
their fear levels, arachnophobes who were shown the spider and given the drug
were able to touch the tarantula within days. Within three months, many of them
felt comfortable holding the spider, and their fear hadn't come back even after
a year. It was like their fear had been deleted.
The same drug was also tested back
in 2007 on victims of a past trauma. The participants were given either
propranolol or a placebo each day for 10 days, and were asked to describe their
memories of the traumatic event.
Those that were given the drug didn't forget the experience,
but a week later they were able to recount it with much less stress than they
originally had. In mice, a similar technique has been used to make mice
'forget' that a particular sound was associated with an electric
shock, while leaving other memories intact.
So far, researchers haven't tried to explicitly delete a
memory in its entirety from humans (that we know of, at least), due to the
ethical implications, but the evidence suggests that it's something that would
be possible, given the right combination of drugs and recall exercises.
Perhaps even more worrying is the research into how easy it
is for scientists to implant false memories into people. By manipulating the
same reconsolidation process, psychologist
Julia Shaw has shown that it's possible to make people remember a
crime they never committed - and even provide vivid details about the fictional
event.
Source: Science Alert
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