Exact, Dynamically Routable Current Propagation in Pulse-Gated Synfire   Chains
  Neural oscillations can enhance feature recognition, modulate interactions between neurons, and improve learning and memory. Simulational studies have shown that coherent oscillations give rise to windows in time during which information transfer can be enhanced in neuronal networks. Unanswered questions are: 1) What is the transfer mechanism? And 2) how well can a transfer be executed? Here, we present a pulse-based mechanism by which graded current amplitudes may be exactly propagated from one neuronal population to another. The mechanism relies on the downstream gating of mean synaptic current amplitude from one population of neurons to another via a pulse. Because transfer is pulse-based, information may be dynamically routed through a neural circuit. We demonstrate the amplitude transfer mechanism in a realistic network of spiking neurons and show that it is robust to noise in the form of pulse timing inaccuracies, random synaptic strengths and finite size effects. In finding an exact, analytical solution to a fundamental problem of information coding in the brain, graded information transfer, we have isolated a basic mechanism that may be used as a building block for fast, complex information processing in neural circuits. 
Andrew T. Sornborger and Louis Tao
q-bio.NC