Connectivity properties of the SOM-VIP motif support the amplification in the interneuron network.

(A) Network of inhibitory PV, SOM and VIP neurons with short-term facilitation (STF) of SOM→VIP and VIP→SOM connections (left). STF increases the amplification index. Smaller mutual inhibition strengths are sufficient to achieve an amplification index above the amplification threshold A = 0 (right). Inset: The dynamics of the mutual inhibition strength (’weight’) after a step increase of the presynaptic firing rate from 0/s to 5/s for three different values of the initial release probabilities. STF parameters are equal for SOM and VIP neurons: Us = 0.1 (strong STF), Us = 0.5 (weak STF), Us = 1 (no STF) and τf = 100 ms. (B) Network of inhibitory PV, SOM and VIP neurons with artificially introduced recurrent connections among both SOM and VIP neurons (left). Recurrence leads to a decrease of the amplification index (right). Recurrence strengths are equal for SOM and VIP neurons. Mutual inhibition strength .