If you have ever wondered why sleepwalkers can navigate their surroundings without bumping into obstacles , a new study may hint at the answer . Scientists have discovered that navigational cells in the brain are just as active when we are asleep as when we are awake . The finding builds on last year 's discovery of the brain ’ s ‘ GPS system ’ which comprises clusters of cells that give us a sense of direction . Scientists have revealed that navigational brain cells ( an illustration of neurons is shown ) are just as active when we are asleep as when we are awake . They made their discovery in the brains of mice . Researchers from NYU Langone Medical Centre , in New York , focused on the 'head direction system ' in mice , which acts as a compass . The brain cells in the systems fire more whenever a creature ’ s head points in a certain direction . They found that these head direction neurons are active during sleep . The researchers studied brain activity in mice during deep , or rapid eye movement ( REM ) sleep , that ’ s a stage known for intense dreaming activity in humans , during which brain electrical activity is virtually indistinguishable from that when awake . They found that during deep sleep , the 'needle ' of the brain compass in the mice moved at the same speed when they were asleep , as when they were awake . The researchers studied brain activity in mice during slow-wave and rapid eye movement ( REM ) sleep , that ’ s a stage known for intense dreaming activity in humans , during which brain electrical activity is virtually indistinguishable from that when awake . A stock image is shown . For the first time , conscious memories have been implanted into the minds of mice while they slept . Scientists from the Industrial Physics and Chemistry Higher Educational Institution in Paris , France , used the brain 's replay process - that of replaying the day 's events - to create new memories in the brains of mice , while they slept . The team , led by Karim Benchenane , focused on place cells - which are neurons that fire in response to thinking about , or being in , a specific place – and help animals and humans form internal maps . He monitored the activity of these cells when the mice explored an ‘ arena ’ using electrodes , isolating the cell that fired in a certain arena location . While the mice slept , they monitored the creature ’ s brain activity and when the specific place cell fired , an electrode stimulated the brain areas linked to reward . When the mice woke up , they immediately scurried to the location that was linked to the rewarding feeling , showing that a new pleasant memory of the place had been formed by the scientists . The feat offers hope that the same technique could one day be used to change human memories , which could help people who replay traumatic events over and over in their minds . During slow-wave periods of sleep however , when brain activity significantly decreases , they found a 10-fold acceleration of activity , so that the mice were ‘ looking around ’ even more than when they were awake . ‘ We have long known that the brain is at work during sleep , ’ said senior Gyorgy Buzsaki , Biggs Professor of Neural Sciences at the university . ‘ But now we know how it is working in one of the seemingly simpler senses - head orientation - or our sense of where we look at in any given space . ‘ The direction sense is an essential part of our navigation system , since it can reset our internal compass and maps instantaneously , as , for example , when we emerge from the subway and try to orient ourselves. ’ The finding could lead to new treatments for navigational problems , which are among the first major symptoms of Alzheimer ’ s disease and other neurological disorders . For the two year study , described in the journal Nature Neuroscience , researchers videotaped the head movements of mice and recorded the electrical activity in the head-direction regions of the sleeping animals . They focused on the antero-dorsal thalmic nucleus and postsibiculum regions of the brain . The recordings were then compared with similar readings made in the same mice while they were awake and navigating in various environments . Lead author of the study , Dr Adrien Peyrache , said : ‘ The coordinated activity during the majority of sleep likely represents a consolidation of places , events and times , a sort of navigational backup system in the brain , during which the brain stores a map to memory. ’ The next step will be to monitor other parts of the mouse brain involved in more complex forms of behaviours to see if similar neural activity patterns are at work . Researchers are also planning experiments to test whether head direction and navigation can be electrically controlled and predicted in advance . The finding could lead to new treatments for navigational problems , which are among the first major symptoms of Alzheimer ’ s disease and other neurological disorders .
Brain ’ s ‘ GPS system ’ was only discovered by scientists last year . the Industrial Physics and Chemistry Higher Educational Institution experts studied brain cells that act as a compass in the brains of mice . They found that during deep sleep , the 'needle ' of the brain compass in the mice moved at the same speed when they were asleep . Finding could lead to new treatments for navigational problems in humans .