It used to be thought certain memories were forgotten forever

But a study has identified a region of the brain these can be 'tucked away'

Researchers brought them back by prompting subjects and using magnets

This technique could help those with disorders of thought, like depression 

Someone reads a phone number out to you, and you dial the number to ring it, but ten minutes later, would you still remember that number? 

Understanding what kind of information the brain stores, and what it keeps handy for easy access is not fully understood,  but a new study shines light on the concept.

The study says certain memories thought forgotten could be brought back to attention, using magnets.

HELPING PEOPLE WITH DEPRESSION AND SCHIZOPHRENIA 

This work could help treat people with schizophrenia or depression, by finding new ways to control people's thoughts. 

'Many psychiatric diseases are associated with disorders of thought, Professor Postle told MailOnline. 

'For example depression with rumination on negative thoughts; schizophrenia with hallucinations, which amount to attending to and thinking about 'noisy' signals in the brain that psychiatrically healthy people can ignore. 

'One can imagine that our current study might contribute to a better understanding of how people control their thoughts, and potentially interventions that might help people with thought disorders to better control their thoughts.'

Previously it had been thought our 'working memory', which remembers important information for a short amount of time, like dialling a phone number, required sustained activity to keep a hold of the information.

But a new study, from researchers at the University of Wisconsin-Madison, showed brains tuck less-important information away somewhere beyond the reach of the tools that typically monitor brain activity.

The researchers were able to snap the information back into active attention with magnets.

This work could help treat people with schizophrenia or depression, by finding new ways to control people's thoughts.

'A lot of mental illness is associated with the inability to choose what to think about,' said lead author Brad Postle, a psychology professor at the University of Wisconsin-Madison. '

'What we're taking are first steps toward looking at the mechanisms that give us control over what we think about.' 

'Many psychiatric diseases are associated with disorders of thought, Professor Postle told MailOnline.

'For example depression with rumination on negative thoughts; schizophrenia with hallucinations, which amount to attending to and thinking about 'noisy' signals in the brain that psychiatrically healthy people can ignore. 

'One can imagine that our current study might contribute to a better understanding of how people control their thoughts, and potentially interventions that might help people with thought disorders to better control their thoughts.'

Professor Postle says most people feel they are able to concentrate on a lot more than their working memory can actually hold.

'The notion that you're aware of everything all the time is a sort of illusion your consciousness creates,' says Professor Postle. 

'That is true for thinking, too. You have the impression that you're thinking of a lot of things at once, holding them all in your mind. 

'But lots of research shows us you're probably only actually attending to - are conscious of in any given moment - just a very small number of things.'

HOW THE STUDY WORKED 

The researchers conducted a series of experiments in which people were asked to remember two items representing different types of information, using words, faces and directions of motion.

When the researchers gave their subjects a cue as to the type of question that was on its way, the electrical activity and blood flow in the brain associated with the word memory disappeared.

But if a second cue came letting the subject know they would now be asked about that word, the brain activity would jump back up to a level indicating it was the focus of attention.

The researchers were also able to bring the seemingly abandoned items back to mind without cueing their subjects. 

Using a technique called transcranial magnetic stimulation (TMS) the researchers applied a focused electromagnetic field to a precise part of the brain involved in storing the word.

Then they could trigger the sort of brain activity representative of focused attention.

The researchers conducted a series of experiments in which people were asked to remember two items representing different types of information, using words, faces and directions of motion.

When the researchers gave their subjects a cue as to the type of question that was on its way, the electrical activity and blood flow in the brain associated with the word memory disappeared.

But if a second cue came letting the subject know they would now be asked about that word, the brain activity would jump back up to a level indicating it was the focus of attention.

The researchers were also able to bring the seemingly abandoned items back to mind without cueing their subjects. 

Using a technique called transcranial magnetic stimulation (TMS) the researchers applied a focused electromagnetic field to a precise part of the brain involved in storing the word.

Then they could trigger the sort of brain activity representative of focused attention.

'People have always thought neurons would have to keep firing to hold something in memory. Most models of the brain assume that,' said Professor Postle.

'But we're watching people remember things almost perfectly without showing any of the activity that would come with a neuron firing. 

'The fact that you're able to bring it back at all in this example proves it's not gone. It's just that we can't see evidence for its active retention in the brain.'

But not all memories are stored in this area, and the researchers still need to work out what the brain keeps and what is forgotten.

'What's still unknown here is how the brain determines what falls away, and what enables you to retrieve things in the short-term if you need them,' Professor Postle said. 

'We are making some interesting progress with very basic research,' he said.

'But you can picture a point at which this work could help people control their attention, choose what they think about, and manage or overcome some very serious problems associated with a lack of control.'  

Mailonline