Polychronization: Computation with Spikes

TLDR

The authors speculate that polychrony may underlie neuronal group selection, cognitive computations, binding and gamma rhythm, attention mechanisms, and consciousness as “attention to memories.” The study presents a minimal spiking network capable of polychronization, producing reproducible time‑locked but non‑synchronous firing patterns with millisecond precision, similar to synfire braids. The network comprises cortical spiking neurons with axonal conduction delays and spike‑timing‑dependent plasticity, and the interaction of these delays and STDP causes the neurons to self‑organize into groups that generate stereotypical polychronous activity, with MATLAB code provided. The network displays sleep‑like oscillations, 40 Hz gamma rhythms, conversion of firing rates to spike timings, and other regimes, and remarkably the number of coexisting polychronous groups far exceeds the number of neurons, yielding an unprecedented memory capacity.

Abstract

We present a minimal spiking network that can polychronize, that is, exhibit reproducible time-locked but not synchronous firing patterns with millisecond precision, as in synfire braids. The network consists of cortical spiking neurons with axonal conduction delays and spike-timing-dependent plasticity (STDP); a ready-to-use MATLAB code is included. It exhibits sleeplike oscillations, gamma (40 Hz) rhythms, conversion of firing rates to spike timings, and other interesting regimes. Due to the interplay between the delays and STDP, the spiking neurons spontaneously self-organize into groups and generate patterns of stereotypical polychronous activity. To our surprise, the number of coexisting polychronous groups far exceeds the number of neurons in the network, resulting in an unprecedented memory capacity of the system. We speculate on the significance of polychrony to the theory of neuronal group selection (TNGS, neural Darwinism), cognitive neural computations, binding and gamma rhythm, mechanisms of attention, and consciousness as “attention to memories.”