Phase precession
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Phase precession is a neurophysiological process in which the time of firing of action potentials by individual neurons occurs progressively earlier in relation to the phase of the local field potenti
Action potentials (one in the box) recorded from a single place cell during a burst of activity
Schematic of phase precession in three place cells. A rat runs left-to-right and the firing of the cells (shown as colored tick marks) is spatially localized, with the three place fields (represented by the three colors) overlapping. The local field potential theta rhythm is shown at the bottom in black. The action potentials of each cell occur earlier and earlier with respect to the theta peak on each successive cycle – this is phase precession. One consequence of this is that within a single theta cycle (blue-shaded rectangle, for example) the cells fire in the same sequence in time as their triggering is organized in space: thus converting a spatial code into a temporal one.
Grid cell
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A grid cell is a type of neuron within the entorhinal cortex that fires at regular intervals as an animal navigates an open area, allowing it to understand its position in space by storing and integra
Phase precession
…circuits, or whether phase precession was a peculiar property of hippocampal tissue. The finding that theta wave phase precession is also a property of grid cells in the entorhinal cortex demonstrated that the phenomenon exists in other parts of the brain that also mediate information about movement. Theta wave…
Trajectory of a rat through a square environment is shown in black. Red dots indicate locations at which a particular entorhinal grid cell fired.
Spatial autocorrelogram of the neuronal activity of the grid cell from the first figure.