For thousands of years, questions about how humans understand their location in their environment, and how they develop a sense of distance, have intrigued philosophers and scientists. How do we know where we are? How can we find the way from one place to another? How can we store this information in such a way that we can immediately find the way the next time we trace the same path? It was 20th century advances in psychology and neuroscience that allowed researchers to probe such questions experimentally. The 2014 Nobel Prize for Physiology or Medicine has been awarded to John O’Keefe, May-Britt Moser, and Edvard Moser, for discovering the networks of cells that form the brain’s “inner GPS”: the system of cells that helps it work out where it is, how to get from one place to another and store information for future reference.
The abbreviation GPS has become part of our everyday vocabulary: thanks to the high-tech mobiles which are a common place. The Global Positioning System (GPS) is a space-based satellite navigation system that provides location and time information in all weather conditions, anywhere on or near the earth where there is an unobstructed line of sight to four or more of the GPS satellites. A sense of place and navigational ability are both central to our existence. Most of our memories are linked to a physical place, meaning that much information we remember and use in daily life has a spatial context to it and leads to the question how these properties are represented in the brain?
The research dates back to 1971, when Dr. O’Keefe was studying the hippocampus, an area of the brain responsible for memory. He connected electrodes to rat brains and let them move freely in a room. He observed that a certain nerve cells always got activated when the rat was in a particular spot. When the rats were in other parts of the room, other nerve cells became active. To confirm this, he monitored the rat movement in a different part of the room where another set of cells got activated. When the rat circled back to the original position, the original set of cells was reactivated. These cells were not just registering the location but they were also mapping the entire place. He concluded the activity of these cells must form an inner map of the rat’s whereabouts and dubbed them “place cells”.
This was the first component of the positioning system. The idea of place cells was considered too simple and it took several years to catch on! In 1996, the husband-and-wife team of Edvard Moser and May-Britt Moser worked with O’Keefe to learn how to record the activity of cells in the hippocampus. John O’Keefe has been a mentor to the Mosers at some points and trained them in techniques they have been using since. The next vital component of the brain’s inner GPS came to light in 2005, when Mosers identified another type of nerve cell located in the entorhinal cortex that act as a coordinate system that enables precise positioning and path-finding. The Mosers called these cells as “grid cells”. The “grid cells” work with “place cells” as well as other cells to form the brain’s positioning system.
Although the O’Keefe-Mosers discoveries occurred while working with rats in the laboratory, more recent research with brain imaging techniques, as well as studies of patients who have brain surgery, have shown that the human brain also has place cells and grid cells. The human brain’s spatial navigation system appears to be composed of similar nerve cells. The pioneering research by O’Keefe and the Mosers will help understand how diseases like Alzheimer’s affect navigation. The hippocampus and entorhinal cortex are affected early on in Alzheimer’s patients, leading to spatial disorientation. Many stroke patients are unable to recognise their surroundings. The knowledge about the brain’s positioning system can also help understanding of what causes loss of spatial awareness in stroke patients. Alzheimer’s is the most common form of dementia and affects 44 million people worldwide. The findings help explain working of the brain in the positioning context. The next step would be to develop medicines and therapies to handle the cases of brain diseases.
O’Keefe, who holds both American and British citizenships, is a professor of cognitive neuroscience and the director of the Sainsbury Wellcome Centre in Neural Circuits and Behaviour at the University College London. May-Britt Moser is a professor of neuroscience and director of the Centre for Neural Computation at the Norwegian University of Science and Technology in Trondheim. Her husband Edvard Moser is also a professor at the university, and director of the Kavli Institute for Systems Neuroscience.
Five annual Nobel Prizes have been awarded since 1901 for achievements in physics, chemistry, physiology or medicine, literature and peace. In 1969 a sixth was added, for economic sciences. So far, the prizes have been awarded 567 times to 889 people and organisations. The prize money of 8 million Swedish kronor (about $1.2 million) took an interesting split. Half went to O’Keefe and the other half went jointly to the Mosers, who are a couple.
The author of this note strongly conjectures that the brains of certain animals must be having specialised cells called “magnet cells”. This conjecture is supported by the findings that certain birds including pigeons and certain fish can detect magnetic fields. The navigation abilities of many migratory birds, fish and other animals have been well-documented, again pointing to a “magnetic compass system” in their brains. These cells may be absent or inactive in humans.
[SAMEEN AHMED KHAN is on the Engineering Department, Salalah College of Technology (SCOT), Salalah, Oman. rohelakhan@yahoo.com]