Fig. 1.

(color online) a Construction of synfire chain embedding in a population of neurons. A sequence of excitatory pools (green ellipses) is formed by randomly selecting n _E distinct neurons from the excitatory population (large green circle) with replacement to form each pool; two such selections are indicated in brown. A corresponding sequence of inhibitory pools (red) is formed from the inhibitory population (red). Each neuron appears in many pools; e.g. each of the neurons in blue appears in two of the pools shown. Links consist of all-to-all connections from each excitatory pool to the next excitatory pool as well as to the corresponding inhibitory pool (arrows). b Pairwise couplings (green arrows) between chains (green line segments) form a recurrent structure in which each chain has exactly two successors, chosen at random. For clarity the inhibitory pools are not shown. An initial pulse packet stimulus is the ancestor of a branching tree of ongoing pulse packet activity (blue), limited in size by extinctions (red). Loops may also be encountered