Call them daydream believers. Brain-imaging experts from Canada and around the world have joined forces to investigate the architecture of an idle mind to learn more about mental illness and Alzheimer's disease.
They pooled brain scans from more than 1,400 healthy volunteers who were asked to sit in a magnetic resonance imager and do nothing in particular.
The results, published this week in the Proceedings of the National Academy of Sciences, offer the most detailed picture yet of the distinctive circuitry associated with daydreaming and a wandering mind.
That circuitry, called the default mode network, is far from frivolous. It is active for at least a third of our waking hours and burns through a lot of energy. It may keep the brain primed for action and help establish our sense of who we are.
Many neuroscientists say it provides an important window into how the brain works and a new way to understand mental illness, intelligence, unconscious problem solving, Alzheimer's and aging.
The network was remarkably similar in all the volunteers in the study, says the University of Western Ontario's Peter Williamson.
But there were differences between men and women, and in young people compared to older ones.
The next step, Dr. Williamson says, is to figure out what differences in the default network mean. Why do women have stronger connections in the network? Why do the connections weaken with age? Is the circuitry different in people who suffer from mental illness?
The default mode network got its name in 2001 after scientists conducting brain-imaging studies noticed a common pattern of high-energy activity when they asked people to take a break from the task they had been assigned, like memorizing a list of words. It is not dedicated exclusively to daydreaming, but it is associated with drifting thoughts.
Many of the parts are located in the cleft between the two hemispheres of the brain. In earlier work, Dr. Williamson and his colleagues found evidence that the network is different in people with schizophrenia, depression and post-traumatic stress disorder(See graphic).
But those studies involved relatively small numbers of patients. Pooling brain scans allows researchers to study a much larger sample of patients than any one centre can do on its own, Dr. Williamson says.
It is interesting to speculate about why women have stronger connections in the default mode network than men.
"I am sure that my wife would tell you that it suggests that females are more thoughtful than males, but it probably is just another illustration that male and female brains are different," he says.
Children also daydream. Brain-imaging studies involving babies (the scans were taken for medical reasons) suggest that newborns don't have a default mode network.
But by two weeks, a primitive and incomplete version is up and running. In the baby and early toddler years, more regions are connected to the network than in adults, but they get cut off as the brain matures.
It appears to change again in adolescence and then in middle and old age.
The latest research supports earlier findings that connections within the default network become weaker as we age.
The network also gets harder to suppress, says Cheryl Grady, a scientist at Baycrest's Rotman Research Institute in Toronto.
"Older adults have trouble turning off the stuff that goes in your head most of the time," she says.
It is a phenomenon that is exaggerated in patients with Alzheimer's disease, yet is a feature of healthy aging that kicks in between 40 and 60, Ms. Grady says.
It can pose problems in some situations, but it may also lead to broader or more creative thinking, and an ability to see connections between things.
"You may have a richer inner life," she says.
*****
WAKING HOURS
It is probably an understatement to say that we spend at least a third of our waking hours daydreaming, says the University of BritishColumbia's
Kalina Christoff. That figure is based on experiments in which volunteers wore beepers. When they went off, they had to answer questions about what they were thinking and doing. People may have been reluctant to confess they weren't paying attention, she says.
Women are more likely than men to have problem-solving daydreams, studies suggest, but are less likely to have reveries of a sexual nature or in which they play a heroic role.
In surveys, "current concerns," like work or family, top the list of daydreaming hot topics. The exception is in males, age 17-29. They daydream more about sex.
They pooled brain scans from more than 1,400 healthy volunteers who were asked to sit in a magnetic resonance imager and do nothing in particular.
The results, published this week in the Proceedings of the National Academy of Sciences, offer the most detailed picture yet of the distinctive circuitry associated with daydreaming and a wandering mind.
That circuitry, called the default mode network, is far from frivolous. It is active for at least a third of our waking hours and burns through a lot of energy. It may keep the brain primed for action and help establish our sense of who we are.
The network was remarkably similar in all the volunteers in the study, says the University of Western Ontario's Peter Williamson.
But there were differences between men and women, and in young people compared to older ones.
The next step, Dr. Williamson says, is to figure out what differences in the default network mean. Why do women have stronger connections in the network? Why do the connections weaken with age? Is the circuitry different in people who suffer from mental illness?
The default mode network got its name in 2001 after scientists conducting brain-imaging studies noticed a common pattern of high-energy activity when they asked people to take a break from the task they had been assigned, like memorizing a list of words. It is not dedicated exclusively to daydreaming, but it is associated with drifting thoughts.
Many of the parts are located in the cleft between the two hemispheres of the brain. In earlier work, Dr. Williamson and his colleagues found evidence that the network is different in people with schizophrenia, depression and post-traumatic stress disorder(See graphic).
But those studies involved relatively small numbers of patients. Pooling brain scans allows researchers to study a much larger sample of patients than any one centre can do on its own, Dr. Williamson says.
It is interesting to speculate about why women have stronger connections in the default mode network than men.
"I am sure that my wife would tell you that it suggests that females are more thoughtful than males, but it probably is just another illustration that male and female brains are different," he says.
Children also daydream. Brain-imaging studies involving babies (the scans were taken for medical reasons) suggest that newborns don't have a default mode network.
But by two weeks, a primitive and incomplete version is up and running. In the baby and early toddler years, more regions are connected to the network than in adults, but they get cut off as the brain matures.
It appears to change again in adolescence and then in middle and old age.
The latest research supports earlier findings that connections within the default network become weaker as we age.
The network also gets harder to suppress, says Cheryl Grady, a scientist at Baycrest's Rotman Research Institute in Toronto.
"Older adults have trouble turning off the stuff that goes in your head most of the time," she says.
It is a phenomenon that is exaggerated in patients with Alzheimer's disease, yet is a feature of healthy aging that kicks in between 40 and 60, Ms. Grady says.
It can pose problems in some situations, but it may also lead to broader or more creative thinking, and an ability to see connections between things.
"You may have a richer inner life," she says.
*****
WAKING HOURS
It is probably an understatement to say that we spend at least a third of our waking hours daydreaming, says the University of British
Women are more likely than men to have problem-solving daydreams, studies suggest, but are less likely to have reveries of a sexual nature or in which they play a heroic role.
In surveys, "current concerns," like work or family, top the list of daydreaming hot topics. The exception is in males, age 17-29. They daydream more about sex.
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