Synopsis: Explaining Grid-Cell Firing

A model explains why grid cells—neurons that are part of the brain’s positioning system—fire electrical pulses in hexagonal patterns.
Synopsis figure
M. M. Monsalve-Mercado and C. Leibold, Phy. Rev. Lett. (2017)

The brains of mammals have an internal “GPS” that allows the animals to navigate in the environment. In the hippocampal brain region, neurons called place cells fire electrical pulses when the animal enters specific locations. In the adjacent entorhinal cortex, separate neurons called grid cells fire in regular hexagonal patterns that are thought to form a cognitive map of space. It is unclear, however, how the brain can create these patterns. A new model suggests that they can form through mechanisms similar to those behind many regular patterns seen in nature.

Mauro Monsalve-Mercado and Christian Leibold, both at the Ludwig Maximilian University of Munich, developed their model based on a hypothesis recently proposed by neuroscientists: the firing activity of grid cells may result from that of the place cells. In the model, the movement of an animal in a box generates electrical pulses in place cells, which are fed as inputs to grid cells. The connections between grid cells—and thus their firing patterns—are then altered by neural “plasticity”: each neuron’s connections are weakened or strengthened depending on the timing between the neuron’s input and output.

Running the model’s equations, the authors find that the grid cells’ firing patterns, which are initially random, evolve towards hexagonal configurations as they receive the inputs from the place cells. This process resembles that of pattern-forming phenomena known as Turing instabilities, which are thought to underpin the formation of, for example, zebra stripes and hexagonally shaped bee honeycombs.

This research is published in Physical Review Letters.

–Matteo Rini

Matteo Rini is the Deputy Editor of Physics.


Features

More Features »

Announcements

More Announcements »

Subject Areas

Biological Physics

Previous Synopsis

Particles and Fields

Proton Loses Weight

Read More »

Next Synopsis

Fluid Dynamics

Saturn-Shaped Drops

Read More »

Related Articles

Finding a “Functional” Cure for HIV
Biological Physics

Finding a “Functional” Cure for HIV

A mathematical model could allow researchers to predict if and when the HIV virus will rebound after antiretroviral therapies stop. Read More »

Focus: Explaining the Ruffles of Lotus Leaves
Biological Physics

Focus: Explaining the Ruffles of Lotus Leaves

A new theory accurately predicts a wide range of leaf shapes and explains the differences between dry lotus leaves and those that grow on water. Read More »

Synopsis: Age Determines How a Human Aorta Stretches
Biological Physics

Synopsis: Age Determines How a Human Aorta Stretches

Younger aortas can expand 5 times more than older ones as fluid pumps through them, a finding that could help to design more successful aortic prostheses. Read More »

More Articles