Nobel Prize honors researchers' discovery of brain's 'GPS' system

The 2014 Nobel Prize in Physiology or Medicine honors three researchers who have pioneered the discovery of the brain cells, circuits and encoding patterns that allow us to remember where we’ve been, to plot the route ahead and to position ourselves within our environment.

The work of John O’Keefe, May-Britt Moser and Edvard I. Moser helps us understand why the brains of London taxi drivers, who have mastered the most minute spatial details of their city, have a brawnier hippocampal region than those of ordinary folk. It has helped deepen understanding of how Alzheimer’s disease robs people of their ability to navigate once-familiar places. And it has laid the foundation for understanding how time, place and experience are melded together in forming the memories by which we define ourselves.

More fundamentally, the work of the trio of researchers awarded the Nobel Prize this year has helped neuroscientists to conceptualize the brain as a system of specialized cells and interlocking circuits that work together to generate complex behavior.

Working in Canada and London in the 1970s, physiological psychologist O’Keefe — one of three researchers to share the 2014 prize — recorded the electrical activity in the brains of free-roaming rodents to demonstrate that cells in a seahorse-shaped brain structure called the hippocampus form cognitive maps of environments the animals explored. They became known as “place cells.”

Almost 30 years later, May-Britt Moser and Edvard I. Moser, a husband-and-wife team of neuroscientists working in Norway, would discover that even before the place cells in a rodent’s hippocampus began firing, similar kinds of cells in the neighboring entorhinal cortex, which extends into the hippocampus, fire in a unique grid-like pattern.

Firing in regular hexagonal patterns, these “grid cells” appeared to encode different routes, different spatial scales and different points in the environment by firing at distinct rates and frequencies. In the confined space of the medial entorhinal cortex, the Mosers found, a map of any scale or level of complexity could be represented and encoded by distinct patterns of cellular firing.

The collective discoveries of the three scientists “present a paradigm shift in our understanding of how ensembles of specialized cells work together to execute higher cognitive functions,” wrote Drs. Ole Kiehn and Hans Forssberg of Sweden’s Karolinska Institute, members of the Nobel Committee who summarized the contributions of O’Keefe and the Mosers in a “scientific background” document.

O’Keefe and the Mosers discovered these spatial cells, circuits and coding patterns in rodents. But they have since been found to exist in mammals up the evolutionary chain. That, says University of Pennsylvania psychology professor Jeffrey Kahana, was key in establishing that the study of mice and rats can be highly useful in unraveling the mysteries of the human brain, including the ways in which it can go wrong when under attack by injury or illness.

Kahana added that the Nobel laureates’ discoveries have also laid the foundation for understanding the kinds of memories by which we define ourselves: the collection of personal experiences psychologists call episodic memory.

“Place and memory are intimately related: Space forms a powerful context in which our memories are encoded,” said Kahana, whose research has extended O’Keefe’s and the Mosers’ work to the study of human memory. “That’s why this model of how the brain maps the world is so important to who we are as human beings.”