A four year old Mexican redknee tarantula named Lola is introduced to the crowd at a Leesburg, Va., New Year’s Eve celebration in 2004. (Matt McClain/The Washington Post)

The tarantula sits in an open cage in the center of the room, dark and hairy and as big as a man’s fist. Its eight thick legs, sharp fangs and large glassy eyes are enough to give anyone the creeps, let alone someone who has feared spiders all her life, such as the woman standing at the far side of the room, looking distraught.

The woman, a participant in a study on arachnophobia, has one task: touch the tarantula.

Warily, she makes her way toward the creature. She extends her hand. She drops it into the jar. She touches the animal’s furry back.

She looks at the grad student standing by, aghast. Then an expression of triumph lights up her face.

“Can I do it again?”

Merel Kindt, the Dutch psychologist co-running the study, laughed at the recollection of the woman and 14 others she’d treated for arachnophobia.

“They couldn’t believe it,” she told The Washington Post. “They went on and on. One even asked if they could have it in their hand.”

Kindt and Marieke Soeter, a colleague at the the University of Amsterdam, are authors of a report published Tuesday in the journal Behavioral Psychiatry that describes how a two-minute treatment can be used to rewrite fear memories. After being treated with a drug called propranolol while contemplating being forced to touch a spider — something they would never be able to do under normal circumstances — all 15 patients were far better at overcoming their fear than those in two control groups.

“As a therapist, I almost cannot believe it,” Kindt said. 

Most psychologists spend weeks, even years, helping their patients cope with fear. Kindt had seemingly accomplished it in just two minutes.

[Scientists may have found a way to make you forget that you’re addicted to meth]

It worked because of a complex process called “memory reconsolidation.” Psychologists still debate about how, and whether, it works, but the gist is this: When a memory is recalled — having to be near a spider, for example — the brain retraces the neural circuitry associated with it. That makes the memory unstable.

If patients are administered a drug that interrupts reconsolidation, the memory can be broken. They won’t suddenly forget what spiders are, but the thought of one won’t be associated with a rush of fear. This is what happened with Kindt’s propranolol patients. They erased their spider fear memories and then rewrote them with one of triumph — touching the tarantula a week after their treatment. When they returned to her lab three months and a year later, the effects stuck. Most of the treatment group reported being even less fearful three months after the experiment than they were on the day of their spider-touching success.

Though the study is good news for anyone with a fear of spiders, Kindt has broader ambitions for her propranolol research. She argues that interrupting reconsolidation could play a huge role in the future of psychotherapy, saying that it’s a cheaper, more efficient and potentially more effective treatment than the ones we use now. If it works — and that’s still a big “if” — it could be used to ease the pain of post traumatic stress disorder and lessen the burden of debilitating anxiety. It could restore control to people whose lives have been ruled by fear.

It’s a bold claim, one that Kindt and researchers like her are still trying to sell to the rest of the psychiatry and neuroscience community. First of all, the notion of reconsolidation upends a lot of common thinking on the way memory works. And then there’s the ethical question: Should psychiatrists really be changing people’s memories?

Most people tend to think of memory as a neural record, a catalogue of tiny home videos stored inside a person’s brain that can be lugged out of storage and replayed upon request. But the process of recollection is much more malleable and more fallible than simply sticking a dusty tape in a VCR.

Memories rely on chains of reactions in the brain, signals sent from neuron to neuron across the tiny connecting spaces between them called synapses. Neurons remain relatively stable over the course of our lives, but as we study and experience, regret and forget, our synapses are constantly changing. Learn something, and the synapses needed to know it will be chemically strengthened. Recall it later, and the brain retraces the original memory’s route, further solidifying it. Eventually, proteins will be deployed to formalize the pathway, paving over what had once been a dirt footpath and turning it into long term memory. That is consolidation. And once a memory is consolidated, many scientists long thought, it’s fixed. The VHS might get broken or lost, but there’s no changing its content.

[Why we can’t trust Ben Carson’s memories — or anyone else’s]

But in 1999, neuroscientist Karim Nader began testing that notion in experiments with mice. He conditioned the animals to associate a high-pitched beep with an electric shock. Before long, the rats knew to freeze in fear whenever they heard the beep, prepared for the shock they believed would come. The memory associating the noise with pain had been consolidated.

But then Nader gave the rats a dose of the antibiotic anisomycin, which is required for protein synthesis in the brain, while playing the beeping noise. Suddenly, the rats began to ignore the tone. They were no longer afraid.

Nader’s explanation, published in a 2000 study in the journal Nature, was that memories must be reconsolidated every time they are recalled. Those supposedly permanent neural pathways require upkeep each time they’re used. And for a brief time during reconsolidation, the memory becomes vulnerable — interrupting the reconsolidation process with a drug is like allowing someone to sneak onto a construction site and rearrange the paving stones, maybe even to steal them away.

“Karim came into the field of memory like a ball of fire,” New York University neuroscientist Joseph LeDoux, who coauthored Nader’s report, told Forbes in 2007.

Kindt, the co-author of the arachnophobia study, said it was Nader’s work that inspired her to focus her research on reconsolidation theory. Working as a clinical psychologist she was often frustrated by the shortcomings of classic treatments such as exposure or extinction training — a treatment in which an arachnophobe, for example, would be progressively exposed to the spiders they fear. Sometimes extinction training worked, sometimes it didn’t. Sometimes it lasted, sometimes the patient relapsed. Besides, extinction therapy doesn’t change the old, bad memory of trauma; it just adds a new, calm one alongside it. And it takes several sessions of forcing a patient to endure their biggest fear before results even begin to show.

In 2009, Kindt and Soeter published their first study on using propranolol, a beta-blocker sometimes used to treat anxiety disorders, to undo fear conditioning in healthy human volunteers. Only recently have they started studying its effect on people suffering from phobias.

[A baffling medical puzzle: How a man’s trip to the dentist cost him the ability to form new memories]

There are extra challenges to using a reconsolidation treatment on human patients. For one thing, the drugs used to block protein synthesis in animals can be toxic — propranolol, which Kindt uses, is safer but also seems to have a less dramatic effect. For another, most human fears aren’t easily isolated in a lab. Sure, you can control a person’s exposure to a tarantula in a clinical setting, but what about fear of death? What about the trauma at the root of a veteran’s PTSD?

Psychologists also haven’t reached a consensus on the effectiveness of reconsolidation-based treatments. Though the process has been proven in animal studies, the research on reconsolidation in humans isn’t yet conclusive. A review of research conducted in 2011 found flaws in Kindt’s 2009 study and other research on reconsolidation in humans. The results were difficult to reproduce and often inconsistent across measures of fear, and researchers couldn’t yet prove that their intervention worked because it interfered with reconsolidation. The review called for more research into how exactly reconsolidation works in humans and how doctors can block it.

Then there are the philosophical debates.

“I was at a conference not that long ago where the idea [of reconsolidation interventions] was brought up,” Paul Reber, director of Northwestern University’s Brain, Behavior, and Cognition program, told the Atlantic last year. “It led to a lot of animated discussion: If you could edit your own memories, are there any memories you’d want to get rid of? If you have a memory of a painful event, do you lose some part of yourself if you get rid of it? Would that be worth the trade?”

“Obviously,” he added, “it’s not a simple question.”

But Kindt said that what she’s doing is not erasing a memory — it’s disentangling a memory from an intense emotional response. In fact, many of her patients still thought they were afraid of spiders when they were called into her lab a week after their treatment for the touch-the-tarantula moment of truth. Asked how they felt approaching the hairy, many-legged creature in the center of the room, they were nervous, reluctant, repulsed.

But their blood didn’t race as much. Their hand didn’t shake as much. When the time came, their bodies were able to do the thing they thought they couldn’t.

And then they asked to do it again.