Times On Line – How to forget fear

January 7, 2010 – Times On Line

How to forget fear

New research suggests we may be able to erase traumatic memories. Meet the scientists who can manipulate our minds.

Imagine if you could rewrite your mind as quickly as a document on your computer. No more painful memories, no phobias or ingrained fears, just a blank slate where the scars that mark each human life used to be. This may sound like the stuff of Hollywood fantasy but last month it came a step closer to reality at New York University. By manipulating memory a research team managed to remove a conditioned fear response among volunteers. As scientists learn more about the mechanics of the mind, such targeting and erasing of traumatic recollections will become easier and easier.

Fear tortures all of us in one form or another. The Ancient Greeks blamed sudden knee-knocking terror on a lecherous, goatish divinity, Pan. While his ability to inspire panic was enough to rout the Titans, the force behind it was too mysterious for mere mortals to comprehend. But they knew it when they felt it.

We all recognise the physiological symptoms when danger threatens: our stomachs lurch and adrenalin fires up our muscles. Charles Darwin chronicled this in The Expression of the Emotions in Man and Animal: “…the eyes and mouth are widely opened, and the eyebrows raised. The frightened man at first stands like a statue motionless and breathless, or crouches down as if instinctively to escape observation.”

These reactions are triggered by both memory and instinct. Evolution has endowed us with innate impulses that warn against age-old dangers. Thus spiders or snakes may set our pulses racing, but most of our anxieties are learnt through experience. We recall that something hurt or scared us and these memories help to trigger our nervous system. Neuroscience suggests that both reactions can be traced back to a small almond-shaped part of the human brain, the amygdala. It plays a key role in responding to stimuli, recognising danger from previous situations and sounding the alert.

How to embrace fear

How we recall fear has fascinated scientists for centuries. In 1920, the unfortunate “Little Albert” was one of the early targets for experimentation. Over several months the baby boy became a guinea pig for scientists at Johns Hopkins University in Baltimore. Their aim? To try to condition fear. First, the researchers placed a white rat in front of the baby. This didn’t scare him. Then they linked the appearance of the rodent with a loud bang. After exposure to this combination, Albert began to weep on cue when he saw the rat alone. Their report suggests that his reaction to white fur became so extreme that even a Father Christmas mask induced fear.

Albert’s mother never gave consent, rendering these experiments highly unethical by today’s standards. That said, current approaches are not dissimilar, simply more sophisticated and informed. Last year Merel Kindt and her team at the University of Amsterdam experimented with chemical intervention to dull the emotional sting of a scary memory. Kindt made her considerably more adult Little Alberts anxious by showing them images of spiders and giving them mild electric shocks at the same time. She found that if they took a beta-blocker, propanolol, before reminiscing about their experience, they were no longer scared of the spider images.

This experiment capitalised on the knowledge that traumatic memories are not written just once but every time we remember them. When we first record memories the presence of certain proteins strengthens connections between the synapses — the gaps between nerve cells — in the brain. However, every time we recall these memories subsequently the proteins break down and must be remade from scratch. During this period of reconsolidation our memory is vulnerable to reshaping. Like that open Word document on your laptop, it can be rewritten.

When Kindt gave propanolol to her volunteers she managed to interfere with the process of reconsolidation. If her team didn’t reactivate volunteer memories by showing them the spider pictures, the drug did nothing. But if the spider triggered a fearful response, thus opening the reconsolidation window, the drug managed to interfere with it. Propanolol did not erase these memories; it simply blunted their emotional edge. While the volunteers still expected a shock, they were not scared by the prospect.

The ability to update our memories with new information highlights the flexibility of our brain. Every act of remembering gives us an opportunity to shape memories, or even erase them. The discovery of the reconsolidation window has kick-started a lot of new memory research, advances in which could have important implications for people who suffer from unwanted fearful memories. Potential treatments for anxiety, phobias or post-traumatic stress disorder (PTSD) may be close at hand. Propanolol, or other chemicals that do the same job more effectively, could help sufferers to get on with their lives more easily. These discoveries could have much wider applications than removing fear: for instance, in people who struggle to control their impulses, they may help to erase addictions.

But the possibility of removing past fears ramps up new concerns about ethics, with strident editorials decrying attempts to meddle with the human mind. The most extreme writers describe the research as “threats to human identity” and “the stuff of science-fiction nightmares”. There are inevitable comparisons with the film Eternal Sunshine of the Spotless Mind, in which mind-wiping technology robbed characters of the experiences that enrich our lives and make us human.

These concerns are overblown where propanolol is concerned. The drug merely changes the emotional content of memories, rather than erasing them. Scientists are well aware that fear is a vital teacher: moments of fright are how we learn about dangers. That memory of what went wrong last time we left the stove on could stop us from making costly, even lethal, mistakes.

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