Figure 2.

Schematics of NA detection: Spikes are recorded from a pool of cortical cells (A), forming a set of spike trains (B). The trains are binned and fed into an assembly detection algorithm (C). A relation matrix is built based on the covariance of spike trains, followed by a PCA+ICA community detection algorithm. The assembly detection algorithm identifies neurons with joint activations (pink and orange) and independent neurons (blue) (D). In this work, functional NAs are defined by time-specific coherent modulations in the firing rate. Notice that one neuron may participate in more than one NA.