The Nobel Peace Prize in Physiology or Medicine for 2014 was awarded to John O'Keefe, May-Britt Moser and Edvard Moser.
The award calls attention to their study of the brain cells that are damaged in Alzheimer's disease, and it recognizes the discovery of brain cells that form a positioning mechanism in our brain. These cells are located in the hippocampus and entorhinal cortex, the same regions devastated early in the course of Alzheimer's disease.
Alzheimer's disease impacts many cognitive functions, and difficulties with memory are often some of the earliest reported symptoms. However, deficits in spatial processing in the visual system may manifest earlier. But because of the subtleties of these losses, they often go unrecognized. Having trouble understanding visual images and spatial relationships is among the top 10 warning signs of Alzheimer's disease.
The region of the brain processing visual functioning beyond simple acuity — the visual association area — was found to have Alzheimer's disease pathology at an even higher rate than the memory areas in brains with Alzheimer's disease from tissue donors participating in the Framingham Heart Study. Tests of visual objects and spatial perception have been found to differentiate Alzheimer's disease pathology from other neurodegenerative diseases impacting cognition.
O'Keefe discovered in his rodent studies that there were certain nerve cells in the animal's brain that became active when the animal was in a familiar environment. O'Keefe called these "place cells" and determined that the cells were building an inner cognitive map of the environment while registering the visual input. He theorized that a memory of an environment was a specific combination of place cells.
The Mosers also identified what they considered place cells while mapping the connections to the hippocampus in rats moving in a familiar room and observed significant activity in the entorhinal cortex. They found a unique pattern of collective activity and circuitry that correlated to the animal's head direction.
They considered the circuitry to constitute a comprehensive positioning system in the brain. The theoretical memory of such cells allows the animals to exhibit memory-mediated allocentric behavior, the ability to cognitively perceive the environment from a stationary point of view.
Understanding how these cells are formed and the circuitry will be of benefit in understanding human performance and navigation skills. Those with Alzheimer's disease have impaired memory for allocentric and real space configurations.
Having an animal model to work with will facilitate our understanding of the disruptions in this area of memory formation and enable the development of treatments.
