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Scientists have made sense of why some of us have no sense of direction.

They've pinpointed signals in the human brain that determine how good we are at navigating.

This inbuilt compass tells us which way were are facing and works out which way to turn to go where we want. And in those with a poor sense of direction, the signals are fuzzier.

The results, by a team at the University College London, suggest that we have networks of brain cells dedicated to specific compass points, such as north and south. The cells that sense north - for example, light up when we face north – and also spring to life when we think about turning to the north

The researchers, from University College London, scanned the brains of 16 men and women as they played a computer game that tested their ability to navigate.

The results suggest that we have networks of brain cells dedicated to specific compass points, such as north and south.

The cells that sense north light up when we face north – and also spring to life when we think about turning to the north.

If we are facing north but planning to walk east, two sets of cells are involved.

All of the cells are found in a part of the brain called the entorhinal region.

Researcher Dr Hugo Spiers said: 'In this simple test, we were looking to see which areas of the brain were active when participants were considering different directions.

'We were surprised to see that the strength and consistency of brain signals from the entorhinal region noticeably influenced people's performance in such a basic task.

LONDON CABBIES WHO PASS THE KNOWLEDGE HAVE LARGER BRAINS

Studies suggest that a cab driver's brain may change to accommodate an internal 'map' of their city

Cabbies who have memorised London's 25,000 streets and landmarks have a larger volume of 'grey matter'.

But this change only occurs in those who successfully pass the exams.

Studies suggest that the brain may change to accommodate an internal 'map' of London.

Only around half of trainees finally make the grade as London taxi drivers by passing the Knowledge test.

Scientists followed a group of 79 trainee drivers and a 'control group' of 31 non-taxi drivers.

MRI scans were used to take brain structure 'snapshots' of the volunteers, who were also given certain memory tasks.

At the start of the study, there were no obvious differences between participants' brains.

Three to four years later, significant differences were seen.

The 39 trainees who qualified had greater volumes of grey matter in their posterior hippocampus than the 40 who failed, or the non-taxi drivers.

'This type of "homing signal" has been thought to exist for many years, but until now it has remained purely speculation.'

Dr Martin Chadwick, lead author of the study, said: 'Our results provide evidence to support the idea that your internal "compass" readjusts as you move through the environment.

'If you get lost after taking too many turns, this may be because your brain could not keep up and failed to adjust your facing and goal directions.'

With just 16 people taking part in the study, the researchers weren't able to tell if there is a difference between the sexes' ability to navigate.

If we are facing north but planning to walk east, two sets of cells are involved. All of the cells are found in a part of the brain called the entorhinal region (red)

Dr Spiers said: 'My guess is that there probably isn't.

'Some studies have shown that women have a better visual memory – you can show them a scene and they will remember it better than men.

'Men, in contrast, can work with the geometry and rotate things in their mind better.

'But when you bring it all together, the difference disappears.'

The research, published in the journal Current Biology, could lead to ways of training the brain to improve sense of direction.

It could also help shed light in dementia.

The entorhinal region is one of the first parts of the brain affected by Alzheimer's disease, so the findings may also help to explain why people start to get lost in the early stages of the disease.

It is hoped that a version of the navigation test used in study could be used detect Alzheimer's early and monitor its progress.

This year's Nobel Prize for Medicine was awarded to another UCL researcher for work on our inner 'sat nav'.

Dr John Isaac, of Wellcome Trust which funded the latest research, said: 'Neuroscientists have made huge advances in our understanding of how we navigate space, widely recognised after this year's Nobel prizes, and this research is yet another step forward.

'Why some people are better navigators than others is intrinsically interesting, but it also helps us explain the processes that go wrong in people with degenerative brain disorders such as dementia.

'An estimated 850,000 people are living with dementia in the UK, many of whom suffer deterioration in their navigational skills, leaving them lost and confused.'