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Speed cells in the medial entorhinal cortex

2015; Nature Portfolio; Volume: 523; Issue: 7561 Linguagem: Inglês

10.1038/nature14622

1476-4687

Emilio Kropff, James E. Carmichael, May‐Britt Moser, Edvard I Moser,

Neuroscience and Neuropharmacology Research

Grid cells in the medial entorhinal cortex have spatial firing fields that repeat periodically in a hexagonal pattern. When animals move, activity is translated between grid cells in accordance with the animal’s displacement in the environment. For this translation to occur, grid cells must have continuous access to information about instantaneous running speed. However, a powerful entorhinal speed signal has not been identified. Here we show that running speed is represented in the firing rate of a ubiquitous but functionally dedicated population of entorhinal neurons distinct from other cell populations of the local circuit, such as grid, head-direction and border cells. These ‘speed cells’ are characterized by a context-invariant positive, linear response to running speed, and share with grid cells a prospective bias of ∼50–80 ms. Our observations point to speed cells as a key component of the dynamic representation of self-location in the medial entorhinal cortex. On the basis of neural firing rates a specific class of neuron is identified in the medial entorhinal cortex that linearly encodes information on running speed in a context-independent manner and that is distinct from other functionally specific entorhinal neurons. It has long been postulated that in the entorhinal cortex, grid cells require information on the running speed of the animal in order to properly encode periodic spatial firing fields as an animal moves through its environment. However, the source of such a signal transmitting speed information has not been previously identified. Here, Edvard Moser and colleagues isolate a specific class of neurons in the medial entorhinal cortex (MEC) that encode information linearly on running speed based on neural firing rates. These 'speed cells' are distinct from other functionally specific MEC neurons and encode speed in a context-independent manner.