Congratulations to John O’Keefe, May-Britt Moser and Edvard Moser for receiving the 2014 Nobel Prize in Medicine. The prize is for discovering “the brain’s navigation system”: place cells, cells in the hippocampus which are active whenever a rat is in a particular place, and grid cells, cells in the entorhinal cortex which are active when the animal is at multiple locations in a grid pattern.
Former Yerkes researcher Beth Buffalo and herÂ graduate studentÂ Nathan KillianÂ were the first to directly detect, via electrode recordings, grid cells in the brains of non-human primates. Buffalo is now at the University of WashingtonÂ and Killian is at Harvard Medical School.
A significant difference about theirÂ experiments was that theyÂ could identify grid cellsÂ when monkeys were moving their eyes, suggesting that primates don’t have to actually visit a place to construct the same kind of mental map. Another aspect of grid cells in non-human primates not previously seen with rodents is that the cells’ responses change when monkeys are seeing an image for the second time.
Following that report, grid cells were also directlyÂ detected inÂ human epilepsy patients. The Mosers themselves notedÂ in a 2014Â review, “It will be interesting to see whether the same cells that respond to visual movement in monkeys also respond to locomotion, or whether there is a separate system of grid cells that is responsive to locomotion.”
When processing what the eyes see, the brains of primates don’t use square grids, but instead use triangles, research from Yerkes neuroscientist Beth Buffalo’s lab suggests.
Elizabeth Buffalo, PhD
She and graduate student Nathan Killian recently published (in Nature) their description of grid cells, neurons in the entorhinal cortex that fire when the eyes focus on particular locations.
Their findings broaden our understanding of how visual information makes its way into memory. It also helps us grasp why deterioration of the entorhinal cortex, a region of the brain often affected early by Alzheimer’s disease, produces disorientation.
The Web site RedOrbit has an extended interview with Buffalo. An excerpt:
The amazing thing about grid cells is that the multiple place fields are in precise geometric relation to each other and form a tessellated array of equilateral triangles, a â€˜gridâ€™ that tiles the entire environment. A spatial autocorrelation of the grid field map produces a hexagonal structure, with 60Âº rotational symmetry. In 2008, grid cells were identified Gafas Ray Ban outlet in mice, in bats in 2011, and now our work has shown that grid cells are also present in the primate brain.
Please read the whole thing!
Grid cells fire at different rates depending on where the eyes are focused. Mapping that activity across the visual field produces triangular patterns.
Elizabeth A. Buffalo, PhD
The National Academy of Sciences (NAS) has recognized 13 individuals with awards acknowledging extraordinary scientific achievements in the areas of biology, chemistry, physics, economics and psychology.
Elizabeth A. Buffalo, PhD, a researcher at the Yerkes National Primate Research Center, is one of two recipients of the Troland Research Awards. Buffalo is being honored for innovative, multidisciplinary study of the hippocampus and the neural basis of memory. Troland Research Awards of $50,000 are given annually to recognize unusual achievement by young investigators and to further empirical research in experimental psychology.
The recipients will be honored in a ceremony on Sunday, May 1, during the NAS 148th annual meeting.