Fig. 2.

Schematic illustration of the neural architectures considered for short-pass interval counting. A: counting on dis-inhibition circuit motif. From the main afferent, a first layer performs interval selectivity: a relay inhibitory neuron (RI) provides disynaptic inhibition (GABA_A) to a long interval selective neuron (LIN) with subthreshold adaptation strength a. In the second layer, the interval-counting neuron (ICN) combines afferent excitation (AMPA and NMDA) with the interval-selective inhibition from LIN (GABA_A). ICN receives inhibition at every pulse for long IPIs but is dis-inhibited for short IPIs. B: network diagram for a model based on short-term plasticity (STP). Both excitation (AMPA) and inhibition (GABA_A) are triggered at every pulse. Either the excitatory or the inhibitory synapse is dynamic and undergoes substantial short-term plasticity.