Free will takes flight: how our brains respond to an approaching menace

Aug 23, 2007

Wellcome Trust scientists have identified for the first time how our brain's response changes the closer a threat gets. Using a "Pac Man"-like computer game where a volunteer is pursued by an artificial predator, the researchers showed that the fear response moves from the strategic areas of the brain towards more reactive responses as the artificial predator approaches.

When faced with a threat, such as a large bear, humans, like other animals, alter their behaviour depending on whether the threat is close or distant. This is because different defence mechanisms are needed depending on whether, for example, the bear is fifty feet away, when being aware of its presence may be enough, or five feet away, when we might need to fight or run away.

To investigate what happens in the brain in such a situation, researchers at the Wellcome Trust Centre for Neuroimaging at UCL, London, created a game where subjects were chased through a maze by an artificial predator – if caught, they would receive a mild electric shock. The researchers then measured their brain activity using functional magnetic resonance imaging (fMRI). The results are published today in the journal Science.

When the artificial predator was in the distance, the researchers observed activity in lower parts of the prefrontal cortex just behind the eyebrows. Activity in this area – known as the ventromedial prefrontal cortex – increases during anxiety and helps control strategies on how to respond to the threat.

However, as the predator moved closer, the brain activity shifted to a region of the brain responsible for more primitive behaviour, namely the periaqueductal grey. The periaqueductal grey is associated with quick-response survival mechanisms, which include fight, flight and freezing. This region is also associated with the body's natural pain killer, opioid analgesia, preparing the body to react to pain.

Dr Dean Mobbs from UCL, lead author on the study, says: "Without fear, animals would not react to threats. This is a poor survival strategy and makes it more likely that the animal will be eaten and not pass on its genes.

"The most efficient survival strategy will depend on the level of threat we perceive. This makes sense as sometimes being merely wary of a threat is enough, but at other times we need to react quickly. The closer a threat gets, the more impulsive your response will be – in effect, the less free will you will have."

Although this natural defence mechanism is beneficial in evolutionary terms, Dr Mobbs believes that malfunctions in the system might help explain why some people suffer from anxiety disorders and panic attacks.

"When our defence mechanisms malfunction, this may result in an over-exaggeration of the threat, leading to increased anxiety and, in extreme cases, panic," says Dr Mobbs. "Although brain-imaging studies like ours cannot directly help to cure such disorders, they do improve our understanding of how the emotional system operates. This is the first step to helping people with anxiety-related disorders."

Source: Wellcome Trust

Explore further: First vital step in fertilization between sperm and egg discovered

add to favorites email to friend print save as pdf

Related Stories

Study says sharks/rays globally overfished

Jan 21, 2014

(Phys.org) —One quarter of the world's cartilaginous fish, namely sharks and rays, face extinction within the next few decades, according to the first study to systematically and globally assess their fate.

Brain has specific radar for snakes

Oct 28, 2013

Ever wonder why snakes inspire such fear? A new study on monkeys out Monday says the brain has specific cells that fire off rapid warnings when confronted with slithery danger.

Experiment explores innate visual behavior in mice

Oct 10, 2013

When you're a tiny mouse in the wild, spotting aerial predators—like hawks and owls—is essential to your survival. But once you see an owl, how is this visual cue processed into a behavior that helps you ...

Recommended for you

Researchers transplant regenerated oesophagus

Apr 15, 2014

Tissue engineering has been used to construct natural oesophagi, which in combination with bone marrow stem cells have been safely and effectively transplanted in rats. The study, published in Nature Communications, shows ...

User comments : 0

More news stories

HIV+ women respond well to HPV vaccine

HIV-positive women respond well to a vaccine against the human papillomavirus (HPV), even when their immune system is struggling, according to newly published results of an international clinical trial. The study's findings ...

Progress in the fight against quantum dissipation

(Phys.org) —Scientists at Yale have confirmed a 50-year-old, previously untested theoretical prediction in physics and improved the energy storage time of a quantum switch by several orders of magnitude. ...

Revealing camouflaged bacteria

A research team at the Biozentrum of the University of Basel has discovered an protein family that plays a central role in the fight against the bacterial pathogen Salmonella within the cells. The so cal ...