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 potential oscillation with each successive cycle. In place cells, a type of neuron found in the hippocampal region of the brain, phase precession is believed to play a major role in the neural coding of information. John O'Keefe, who later shared the 2014 Nobel Prize in Physiology or Medicine for his discovery that place cells help form a "map" of the body's position in space, co-discovered phase precession with Michael Recce in 1993.
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.
A place cell is a kind of pyramidal neuron in the hippocampus that becomes active when an animal enters a particular place in its environment, which is known as the place field. Place cells are thought to act collectively as a cognitive representation of a specific location in space, known as a cognitive map. Place cells work with other types of neurons in the hippocampus and surrounding regions to perform this kind of spatial processing. They have been found in a variety of animals, including rodents, bats, monkeys and humans.
A rat with an electrode implanted
