Men and women may respond differently to danger, a brain scan study suggests.
A team from Krakow, in Poland, used functional magnetic resonance imaging (fMRI) to assess brain activity when 40 volunteers were shown various images.
Men showed activity in areas which dealt with what action they should take to avoid or confront danger.
But the study, presented to the Radiological Society of North America, found more activity in the emotional centres of women’s brains.
The researchers, from Jagiellonian University Hospital in Krakow, carried out scans on 21 men and 19 women.
Brain activity was monitored while the volunteers were shown images of objects and images from ordinary life designed to evoke different emotional states.
The images were displayed in two runs. For the first run, only negative pictures were shown. For the second run, only positive pictures were shown.
While viewing the negative images, women showed stronger and more extensive activity in the left thalamus.
This is an area which relays sensory information to the pain and pleasure centres of the brain.
Men showed more activity in an area of the brain called the left insula, which plays a key role in controlling involuntary functions, including respiration, heart rate and digestion.
In essence, activity in this area primes the body to either run from danger, or confront it head on – the so-called “fight or flight response”.
Researcher Dr Andrzej Urbanik said: “This might signal that when confronted with dangerous situations, men are more likely than women to take action.”
While viewing positive images, women showed stronger activity in an area of the brain associated with memory.
With men, the stronger activity was recorded in an area associated with visual processing.

Middle-aged men and women may be risking arthritis if they overdo their exercise regime, research suggests.
A US study of more than 200 people aged 45 to 55 and of “normal” weight found those doing the most exercise were the most likely to suffer knee damage.
Running and jumping may also do more damage to cartilage and ligaments than swimming and cycling, researchers said.
One arthritis charity said it was important to keep fit and most people would not have any problems.
Osteoarthritis – the most common form of arthritis – is a degenerative joint disease that causes pain, swelling and stiffness and affects 8m people in the UK.
It is more common in women, and the risk increases with age and weight.
Presenting the findings at the annual meeting of the Radiological Society of North America, the researchers said their study included people who had not reported any previous knee pain.
Based on a questionnaire designed to work out how much exercise they do, participants were split into low-, middle- and high-activity groups.
A typical high-activity individual would do several hours of walking, sports or other types of exercise per week, as well as gardening and other household chores.
They then underwent MRI scans of the knee, looking for tears, lesions and other abnormalities in the cartilage and ligaments.
The damage seen was associated solely with activity levels and was not age or gender specific, the researchers said.
And it also seemed to be linked to the type of exercise a person did, although the researchers said this needed to be looked at in other studies.

Tiger Woods has hit out at “unfounded rumours” circulating since his car accident in the early hours of Friday.
The golfer was found semi-conscious with facial injuries after his car reportedly hit a fire hydrant and tree.
In a statement on his website the golfer said the only person responsible for the crash in Florida “was me”.
He added: “The many false, unfounded and malicious rumours that are currently circulating about my family and me are irresponsible.”
The incident occurred in the suburb of Isleworth, an exclusive area near Orlando, at 0225 local time (0725 GMT) on Friday.
Florida police officers were told Woods’ wife Elin had used a golf club to break the car’s rear window and help him out.
Police were expected to question Woods about the incident on Sunday but the Associated Press reported that the meeting was cancelled for the third straight day.
Sgt Kim Montes of the Florida Highway Patrol said Woods’ lawyer did not reschedule the meeting.
In a statement posted online about an hour before he was due to be interviewed, Woods said: “My wife, Elin, acted courageously when she saw I was hurt and in trouble. She was the first person to help me. Any other assertion is absolutely false.
“This incident has been stressful and very difficult for Elin, our family and me. I appreciate all the concern and well wishes that we have received.
“But, I would also ask for some understanding that my family and I deserve some privacy no matter how intrusive some people can be.”
On Sunday authorities released a recording of a 911 emergency call made by the golfer’s neighbour after the incident.
In a shaken voice, he says: “I need an ambulance immediately. I have someone down in front of my house. They hit a pole.”
Woods, who has been married for five years and has two young children, has recently been the subject of tabloid allegations about his private life.
Asked about reports the couple had been arguing in the hours leading up to the crash, the police said they were treating the incident as a traffic accident, not a domestic issue.
According to the highway patrol, alcohol was not a factor in the incident.

BNP leader Nick Griffin, who has said global warming is “essentially a hoax”, will be at the Copenhagen climate change conference.
The MEP will be there representing the European Parliament, as he sits on its environment committee.
The BNP said he would be “the only politician there prepared to say that the science is somewhat dodgy”.
Green Party leader Caroline Lucas told the BBC any suggestion he would have any real influence was “a myth”.
Delegations from 192 countries will hold two weeks of talks in Copenhagen in December aimed at establishing a new global treaty on climate change.
In a speech to the European Parliament last week Mr Griffin claimed those who warned of climate change were “anti-western intellectual cranks” and described climate change as “a secular religious hysteria”.
A BNP spokesman said his appearance in Copenhagen would be a “big opportunity” for the party because “people assume we are only a one-trick pony only interested in race and immigration”.
But Ms Lucas, who is also an MEP, told BBC One’s Andrew Marr Show: “He is one of a number of members of the European Parliament who will go on a delegation.

Four police officers have been shot dead near the McChord Air Force Base in Washington State, US media report.
A sheriff’s department spokesman told KOMO-TV that the officers were shot at the east side of the air force base.
The officers were ambushed as they were at a coffee shop, according to a report from CNN.
A sheriff spokesman described the shooting as an ambush. The air force base is in Pierce County, 40 miles south of Seattle.
More to follow.

Former Secretary of State for Wales Paul Murphy has urged the Welsh Labour leadership winner to include the other two contenders in their new cabinet.
The ballot to replace Rhodri Morgan closes at 1700 GMT, with the result announced on the evening of December 1.
The winner is due to become first minister and head of the Welsh Assembly Government around a week later.
Mr Murphy praised the conduct of Carwyn Jones, Edwina Hart and Huw Lewis throughout the two month campaign.
Ms Hart and Mr Jones are Health Minister and Counsel General respectively, Mr Lewis is AM for Merthyr Tydfil and Rhymney.
Welsh Labour members, local parties, affiliated groups, MPs, AMs and its MEP are eligible to vote, which can be done online until the deadline.

Three top businessmen have set up their own not-for-profit business support service because they say the assembly government’s service is too bureaucratic.
Investment fund manager Paul Ragan, MSS group chief executive Bill Mayne and Cardiff Devils ice hockey owner Matt Burge told the Politics Show Wales public sector provided business support was being held back by too much red tape.
The three have launched a new service called Collateral Thinking.
The assembly government said that was not the experience of the vast majority of companies using their Flexible Support for Business service.
Paul Ragan, who sold his south Wales-based insurance company last year in a multi-million pound deal, said the present business support environment was “stifling”.
“Over a number of years we’ve been frustrated at the lack of support, the bureaucracy and red tape,” he said.
“If you’re the man on the street, if you’re the lady running a business in Abercynon, where do you go, how do you get the help?
“Nobody really knows. It’s complicated, it’s too bureaucratic and if you do manage to find out where you go and how you access this help, be prepared to wait for two, three, four, five, nine months depending on the support you need. There is no guarantee you’ll get there either.”
Fitness instructor and inventor Robert Clarke from Gorseinon, who is hoping to bring a new muscle-stretching machine to market, said delays in getting an assembly government grant had held back his business.
“It stalled the project for two months,” he said.
“If I’m going to bring jobs to Wales it’s very reasonable for me to ask for faster processes.”
Mr Clarke’s company Sportfit is now one of the first companies to receive support from Collateral Thinking.
“Collateral Thinking is born out of our frustration actually of being entrepreneurs in an environment that we don’t think is naturally that suitable for business,” said Mr Mayne, Chief Executive of facilities management company MSS Group.

Wikipedia has disputed claims that it has lost a huge number of editors that help maintain the online encyclopaedia.
On 26 November it was reported that ten times more editors had left Wikipedia in early 2009 than during the same period in 2008.
The group overseeing the reference work said the claims on losses were not accurate, blaming a difference in what counts as an “editor”.
By contrast, it said, the numbers of people editing Wikipedia were stable.
In a blog post the Wikimedia Foundation responded to the publication of a report by researcher Dr Felipe Ortega which said that 49,000 editors had departed Wikipedia in the first three months of 2009.
Dr Ortega’s comparisons suggest that only about 4,900 left the site in the first few months of 2008.
Wikipedia relies on editors to keep the online reference work up to date, expand entries and make corrections.
Writing on the blog, Erik Moeller, deputy director of the Wikimedia Foundation, and Erik Zachte, one of its data analysts, said that while Dr Ortega’s article comprehensively described the challenges and opportunities facing Wikipedia it mischaracterised the changes in its editing population.
The pair said that the numbers of people contributing to Wikipedia hit a high in early 2007, declined slightly and have since stabilised.
“Every month, some people stop writing, and every month, they are replaced by new people,” they wrote.
The confusion arose over the differing definitions of what constitutes an editor. Dr Ortega counted everyone who made one change as an editor giving a total population of three million people.
By contrast, the Wikimedia Foundation counts only people who make five edits or more as an editor. This gives an editing population of about one million people across all languages. Of that total, the English edition of Wikipedia has about 40,000 editors.
The pair also disputed Dr Ortega’s attempt to measure when Wikipedia editors start and stop.

Around 15,000 suspected pirates may soon get legal letters accusing them of illegally sharing movies and games.
ACS:Law plans to send notes to the accused in the new year offering a chance to settle out of court for “several hundreds of pounds”.
A lawyer who has defended people who have received similar letters described it as a “scattergun approach” that would catch “innocent people”.
ACS:Law said it was “unaware” of anyone who had been wrongly sent a letter.
Andrew Crossley of the firm told BBC News it was acting to “eradicate” sharing of its client’s products.
“We give them opportunity to enter into compromise right at the start to avoid having to deal with it [in court],” said Mr Crossley.
If it went to court and the lawyers were successful, he said, damages “would run into several thousands of pounds”.
But consumer group Which? said that it had heard from around 150 consumers who had been “wrongly accused” in similar cases.
“A lot are accused of downloading pornography,” Jaclyn Clarabut of Which? told BBC News. “People find it distressing or embarrassing and pay up.”
Others, she said, “don’t want the threat of court action” hanging over them or cannot afford to pay for a lawyer and settle the claim for the lower figure.
She said that based on previous experience, “a lot of people will be surprised” by the latest wave of letters.
Michael Coyle, lawyer at Southampton based firm Lawdit, described the scheme as “having very little to do with protecting the rights of the copyright holder”.
Instead, he said, it was “more to do with making money from alleging copyright infringements on a massive scale”.
He has represented several hundred clients who have received letters from ACS: Law and other firms. None of his clients has ever been forced by a court to pay a fine, he said, although some clients had decided to settle out of court.

When millions would have done anything to get out, one remarkable British soldier smuggled himself into Auschwitz to witness the horror so he could tell others the truth.
Denis Avey is a remarkable man by any measure. A courageous and determined soldier in World War II, he was captured by the Germans and imprisoned in a camp connected to the Germans’ largest concentration camp, Auschwitz.
But his actions while in the camp – which he has never spoken about until now – are truly extraordinary. When millions would have done anything to get out, Mr Avey repeatedly smuggled himself into the camp.
Now 91 and living in Derbyshire, he says he wanted to witness what was going on inside and find out the truth about the gas chambers, so he could tell others. He knows he took “a hell of a chance”.
“When you think about it in today’s environment it is ludicrous, absolutely ludicrous,” he says.
“You wouldn’t think anyone would think or do that, but that is how I was. I had red hair and a temperament to match. Nothing would stop me.”
He arranged to swap for one night at a time with a Jewish inmate he had come to trust. He exchanged his uniform for the filthy, stripy garments the man had to wear. For the Auschwitz inmate it meant valuable food and rest in the British camp, while for Denis it was a chance to gather facts on the inside.
He describes Auschwitz as “hell on earth” and says he would lie awake at night listening to the ramblings and screams of prisoners.
“It was pretty ghastly at night, you got this terrible stench,” he says.
He talked to Jewish prisoners but says they rarely spoke of their previous life, instead they were focused on the hell they were living and the work they were forced to do in factories outside the camp.
Listen to Denis Avey’s story on BBC News 24 throughout Sunday and on Broadcasting House, BBC Radio 4 at 0900 GMT.
Or listen to it here later
“There were nearly three million human beings worked to death in different factories,” says Mr Avey. “They knew at that rate they’d last about five months.
“They very seldom talk about their civil life. They only talked about the situation, the punishments they were getting, the work they were made to do.”
He says he would ask where people he’d met previously had gone and he would be told they’d “gone up the chimney”.