Figure 1.

Robust replay of place cell activity. (A) An animal walks along a path, containing a loop in a 2-dimensional environment. (B) Locations in this path are associated to specific populations of CA3 place cells which fire at high rates if the animal is at said location. In this particular scenario, each position is associated with an ensemble of 100 place cells. Concomitantly, the sequence cells fire following a predefined sequential activity pattern that is explained in detail in section 2.2. Hebbian-like synaptic plasticity connects the sequence cells to the corresponding place cell ensembles. (C) The sequence cell dynamics allow for place cell activity replay on a much shorter timescale and independent of the animal's stopping times and locations. (D) 15 s simulation of place cell activity as the animal walks through the track in (A); a rate plot of the place cell ensembles corresponding to each position the animal walks through is shown; the x axis shows time in seconds, the left y axis shows the track positions corresponding to the place cell populations and the right y axis shows the firing rate of each place cell ensemble corresponding to a particular track position. Note that in addition to the loop in the path, the animal occasionally stays arbitrarily longer at particular locations. (E) Fast replay of the path taken by the animal in less than 100ms; a raster plot of place cell activity is shown; the x axis shows time in milliseconds, the left y axis shows the track positions corresponding to the place cell populations. (F) Reverse replay of the path taken by the animal; a raster plot of place cell is shown; the axis are the same as in (E). Note that each weight in the spiking network is multiplied by a gaussian multiplicative noise.