Author response image 7. The spontaneous dynamics in a model with asymmetric versus symmetric recurrent connectivity.

(a) The amplitude of spontaneous activity as a function of the external drive (uniform, non-specific drive to all place cells) in an asymmetric network. This is a reproduction of Figure 2—figure supplement 8; the parameters are all the same. (b) A space-time plot of the activity. Replay is always in one direction. (c) Blow-up of the replay activity. (d)-(f) The same for a network with symmetric recurrent activity. In this case we take the synaptic connection from a cell j to a cell i to be ˜w_ij= (w_ij+ w_ji)/2, where w_ijand w_jiare the weights after the exploration of 10 tracks for one hour each. These are exactly the (asymmetric) weights used in (a)-(c). The external input is I_ext= −0.8.