Neurobiology Fine Structure of Neural Spiking and Synchronization in the Presence of Conduction Delays

Hippocampal networks of excitatory (E) and inhibitory (I) neurons that produce frequency rhythms display behavior in which the I-cells produce spike doublets when there is strong stimulation at separated sites. It has been suggested that the doublets play a key role in the ability to synchronize over a distance. Here we analyze the mechanisms by which timing in the spike doublet can a ect the synchronization process. The analysis describes two independent e ects: one comes from the timing of excitation from separated local circuits to an inhibitory cell, and the other comes from the timing of inhibition from separated local circuits to an excitatory cell. We show that a network with both of these e ects has di erent synchronization properties than a network with either excitatory or inhibitory type of coupling alone, and we give a rationale for the shorter space scales associated with inhibitory interactions.