What does it take to navigate space? According to researchers and neuroscientists, moving through an environment involves sensory cues, interacting neurological processes, as well as the formation of mental representations linked to memory. For many people, their navigational abilities effectively decide their level of independence as well as their degree of confidence. At different ages, a person's natural ability to perform these functions may change while individual differences become increasingly prominent in the later stages of life.

A recent study conducted by researchers who recorded the brain activity in epilepsy patients has found evidence that human brains possess grid cells, as hypothesized, along with previously observed place cells and direction cells.

Location Cues

Sending information to place cells and the hippocampus, a grid cell is a type of neuron that fires at regular intervals along with other grid cells in networked, triangular patterns whenever people move about an environment. This brain activity, synchronized and networked among place cells and direction cells, helps form the internal representation of location. What is fascinating to scientists about grid cell functioning is that, no matter the individual and idiosyncratic features of a particular environment, the brain imposes its own triangular coordinate system or grid in order to 'understand' and navigate it.

Grid cells are located in the entorhinal cortex, which is part of the medial temporal lobe, a region of the cerebral cortex. The entorhinal cortex, according to Princeton University educational materials, "functions as a hub in a widespread network for memory and navigation." Previously identified in rats, bats, and monkeys, this is the first time that scientists have located grid cells in human beings.

To discover whether human brains included grid cell activity, researchers at Drexel University tested 14 patient-volunteers who had previously implanted electrodes in their brains. All of these patients have a drug-resistant form of epilepsy, so the electrodes were not implanted as part of this experiment but exist as an aspect of their ongoing treatment. While these 14 volunteers were tasked with playing a video game — finding hidden objects in a virtual environment by navigating with a joystick — the researchers tracked the neuronal activity in their brains.

"Recording neuronal activity from neurosurgical patients performing a virtual-navigation task, we identified cells exhibiting grid-like spiking patterns in the human brain," wrote the researchers. Yet the game involved not only driving around an open space and searching for objects, but also remembering where they were so that they could be relocated once becoming newly invisible.

Speaking with The Scientist, lead-research Joshua Jacobs noted that grid cells may also be involved in human memory, particularly episodic memory. "In short, everything we learn about navigation is not only important for navigation, but also for understanding the neural basis of memory more generally," Jacobs said.

Other researchers have also been interested in links between navigation and other mental characteristics. For instance, one set of researchers working jointly in the United States and Hungary studied navigational strategy preferences and their link to psychological states.

Gender Issues

Scientists have demonstrated that sex differences exist in human navigational ability, with men generally showing superior skills in virtual maze tasks (even when researchers control for greater video game experience) as well as in real environments. Yet, better performance on the part of men is not found in all tasks; when people learn spatial layout from direct experience, men generally perform better, but when they learn from maps or when they are tested on route knowledge, men do not perform better, according to a review published in Trends in Cognitive Science.

Men and women, the authors reported, tend to use different environmental cues and strategies for navigation and orientation. "Women typically report navigating on the basis of local landmarks and familiar routes, whereas men report using cardinal directions, environmental geometry and metric distances, a result which has been supported by neuroimaging findings," wrote authors Thomas Wolbers and Mary Hegarty.

This finding was verified by studies conducted in the U.S. and Hungary, where researchers found that men in both countries reported greater preference for a strategy of orienting to global reference points, whereas women reported greater preference for a strategy based on route information. Psychological state may impact these findings. "A higher level of wayfinding anxiety was reported by Americans, and women in both countries reported greater wayfinding anxiety than did men," reported the authors of the cross-cultural study. The authors suggest that one reason for gender differences may be the fact that, while children, girls are generally more restricted than boys to explore outdoors and are also more frequently chaperoned by adults due to safety concerns. Boys, then, may develop greater confidence, leading to their choice of navigational strategy.

As brain scientists continue to map and understand neuronal activity, they may soon discover other possible reasons to explain the ways in which gender influences navigational sense.

Sources: Lawton CA, Kallai J. Gender Differences in Wayfinding Strategies and Anxiety About Wayfinding: A Cross-Cultural Comparison. Sex Roles. 2002.

Jacobs J, Weidemann CT, Miller JF, et al. Direct recordings of grid-like neuronal activity in human spatial navigation. Nature Neuroscience. 2013.

Wolbers T, Hegarty M. What determines our navigational abilities? Trends in Cognitive Science. 2010.