How the brain keeps track of location: From single cells to neural populations
As Professor Jeeves celebrates his 100th birthday this year, we are delighted that Professor Edvard Moser, Professor at the Kavli Institute for Systems Neuroscience and recipient of the 2014 Nobel Prize in Physiology or Medicine has kindly agreed to deliver the lecture.
Details of the event can be found on our .
Abstract
How does the brain know where we are? A central component of the brain’s internal positioning system is a network of grid cells in the medial entorhinal cortex. These cells fire when an animal (or human) occupies specific locations, forming a striking honeycomb-like pattern that provides an internal coordinate system for space. However, while individual grid cells are elements of the brain´s spatial mapping system, navigation takes place in circuits of many thousands of diverse neurons. New recording technologies now allow us to monitor large populations of cells simultaneously in freely moving animals, enabling us to decipher the principles that organise the brain's internal map.
In this lecture, I will first show that the collective activity of grid cells lies on a simple, stable structure – mathematically equivalent to a torus – that persists across behaviour and even during sleep. I will show that this internal map appears abruptly in young rat pups before sensory experience and independent locomotion, suggesting that the brain's spatial map is largely preconfigured by intrinsic circuitry.
Second, I will show that the grid map is highly dynamic. Within fractions of a second, the position encoded by grid cells “sweeps” away from the animal along stereotyped trajectories into the surrounding environment, alternating between left and right, regardless of whether those paths are ever taken. Grid cells thus continuously projects potential routes ahead. These sweeps are coordinated by upstream circuits encoding direction. Beyond their default rhythm, sweeps and direction signals are flexibly modulated toward behaviourally relevant regions. Left and right hemispheres contribute differentially to the alternating sweep pattern. Opposing cell populations in the two hemispheres are active during opposite sweep phases, suggesting a circuit mechanism analogous to central pattern generators in the spinal cord that alternate left and right movements during walking. Together, the findings indicate that the brain’s spatial map is not a passive record of location, but an internally organised, dynamic system that continuously simulates possible movements—providing a foundation for navigation, planning, and flexible behaviour.