14 DAY TRIAL // Most superior life forms on the planet, such as birds and mammals, are able to figure out their location automatically, based on landmarks that are used as reference points for mental maps. But this ability, as common as it is, has remained mysterious until now, and investigators have had no idea that genes are involved in it, though some groups have made this claim. Now, researchers at the Johns Hopkins University have managed to prove it. The findings are published in this week's online Early Edition of the respected journal Proceedings of the National Academy of Sciences (PNAS).
This ability is most obvious when exiting the subway, for example, and realizing that you are walking in the wrong direction. A brief moment of confusion follows and then you immediately realize where you are by analyzing what's around you. This is largely done automatically, and is a trait that is shared by adults, toddlers, rats, chicks and even fish. The geometry of the surroundings is the first thing analyzed, and then a map springs into the mind, showing your location. What the JHU team determined was the fact that genes played a role in this. The work team was based at the Department of Cognitive Science, and was led by Dick and Lydia Todd Professor Barbara Landau.
“We found that people with a rare genetic disorder cannot use one of the very basic systems of navigation that is present in humans as early as 18 months and shared across a wide range of species. To our knowledge, this is the first evidence from human studies of a link between the missing genes and the system that we use to reorient ourselves in space,” she says. Researchers from the Montclair State University in New Jersey, and the University of Chicago, were also involved in the study. In a series of experiments, the group looked at people with Williams syndrome, a rare genetic disorder whose sufferers cannot navigate the physical world around them successfully.
An object was hidden in the corner of a room with black walls, and then the subjects were spun around while blindfolded. When the eye cover was removed, they were asked to find the hidden object, and the participants were all confused as to the object's exact location. “They searched the room for the hidden object randomly, as if they had never before seen the overall geometry of the room or the lengths of the walls and their geometric – left and right – relation to each other,” Landau adds.
“If they could imagine the overall shape of the room's layout – that there are four walls, two of them long and two of them short and that the toy was hidden in a corner that has a short wall on the right and the long wall on the left – then they should have guessed that one of the two 'geometrically equivalent corners' was the right place. This is what typically developing humans do, as early as 18 months of age,” she goes on to say. “Although we are quite far from understanding the links between the specific genes that are missing in Williams syndrome and the behavior they show, such as failure to reorient, it is clear that the missing genes ultimately have some effect on the brain,” she adds.
“Our evidence is the first to directly show a substantial deficit in this reorientation system that is caused by missing genes in humans,” the expert concludes. The investigation was sponsored under a grant from the US National Institutes of Health (NIH).