Researchers discover surprising complexities in the way the brain makes mental maps
Spatial location is closely connected to the formation of new memories. Until now, grid cells were thought to be...
"Spatial location is closely connected to the formation of new memories. Until now, grid cells were thought to be part of a single unified map system. New findings from the Norwegian University of Science and Technology demonstrate that the grid system is in fact composed of a number of independent grid maps, each with unique properties. Each map displays a particular resolution (mesh size), and responds independently to changes in the environment. A system of several distinct grid maps can support a large number of unique combinatorial codes used to associate new memories formed with specific spatial information. (...)
Your brain has at least four different senses of location – and perhaps as many as 10. And each is different. (...) This independence can be used by the brain to create new combinations - many combinations - which is a very useful tool for memory formation. (...)
What makes the discovery of the grid modules so special is that it completely changes our understanding of how the brain physically organizes abstract functions. Previously, researchers have shown that brain cells in sensory systems that are directly adjacent to each other tend to have the same response pattern. This is how they have been able to create detailed maps of which parts of the sensory brain do what.
The new research shows that a modular organization is also found in the highest parts of the cortex, far away from areas devoted to senses or motor outputs. But these maps are different in the sense that they overlap or infiltrate other. It is thus not possible to locate the different modules with a microscope, because the cells that work together are intermingled with other modules in the same area.
“The various components of the grid map are not organized side by side,” “The various components overlap. This is the first time a brain function has been shown to be organized in this way at separate scales. We have uncovered a new way for neural network function to be distributed.” (...) The researchers were surprised, however, when they started calculating the difference between the scales. They may have discovered an ingenious mathematical coding system, along with a number, a constant. (Anyone who has read or seen “The Hitchhiker’s Guide to the Galaxy” may enjoy this.) The scale for each sense of location is actually 42% larger than the previous one. “
We may not be able to say with certainty that we have found a mathematical constant for the way the brain calculates the scales for each sense of location, but it’s very funny that we have to multiply each measurement by 1.42 to get the next one. That is approximately equal to the square root of the number two.”