(A) Inputs from LN5M and AN1M (orange and green shaded areas) to LN3M and output of LN3M (red line) for three input delays from LN5M to LN3M (‘rebound delay’ ). The rebound delay is defined as the delay added to the output of LN5M in the model. The effective delay between the AN1M and LN5M inputs to LN3M depends on the pulse pattern (black, top, pulse duration 20 ms, pause 18 ms). An intermediate delay of 11 ms produces the most overlap between the AN1M and LN5M inputs for that stimulus and hence the strongest responses in LN3M. Vertical black line marks an AN1M response peak, arrows point from the nearest LN5M response peak. (B) Preferred periods for LN3M (red), LN4M in an intact model (purple), and LN4M in a model without inhibition from LN2M to LN4M (blue) as a function of the rebound delay. The preferred period increases with rebound delay for all three cases. (C) Response fields for LN3M (left), LN4M in an intact network (middle), and for LN4M in a model without inhibition in LN4M from LN2M (right) (color coded, see color bar). The rebound delay was set to 21 ms, which increases the preferred period in both LN3M and LN4M to 50 ms (left, compare B). However, increasing the delay also decreases the preferred duty cycle in LN4M (middle). Removing the inhibition from LN2M in LN4M abolishes the change in duty cycle preference (right). Anti-diagonal lines mark the preferred period of 50 ms for each response field, and lines starting at the origin mark the preferred duty cycle. (D) Same as (B) but for the preferred duty cycle. With increasing delay, the preferred duty cycle for LN4M approaches 0.25 but is stable for LN3M and for LN4M without inhibition (Figure 5—figure supplement 2). (E) Inputs to LN4M (middle, green: inhibition from LN2M; red: excitation from LN3M) and output of LN4M (bottom, purple) for the intact network in (C) and for three different stimulus sequences with a pulse period of 54 ms and increasing duty cycles (top, black). Responses are shown for the second pulse in a train. Excitatory input from LN3M is weaker and overlaps more with the inhibition for high duty cycles (compare amplitude and latency of response peaks in LN3M), leading to a reduction in LN4M responses with increasing duty cycle. Y-scales are identical for all three panels and were omitted for clarity. (F) Dependence of peak amplitude (top) and peak latency (time from pulse onset to response peak, middle) of inputs to LN4M (red: excitation from LN3M; green: inhibition from LN2M) on pulse duty cycle for the intact network in (C). Weaker and later excitation suppresses LN4M responses for pulse trains with high duty cycles (bottom, purple). (G) Four sources of suppression in the network: the inhibitory lobe in the filter of AN1M (green), adaptation in AN1M (cyan) and LN3M (red), and inhibition in LN4M from LN2M (purple). Shown are responses to a pulse pattern (top black, 20 ms pulse duration and 20 ms pause) when the source of suppression is present (dashed lines) or absent (solid lines). Removing suppression produces stronger or more sustained responses. ‘A’ and ‘I’ refer to adaptation and inhibition, respectively. (H) Response fields (color coded, see color bar) for the network output (LN4M) after removing different sources of suppression. The presence or absence of different sources of suppression is marked with a ‘+’ and a ‘–’, respectively. Removing suppression in the network increases the preferred duty cycle. Lines mark the preferred pulse duty cycle, and black dots indicate the preferred pulse duration and pause. (I) Preferred duty cycle in LN4M as a function of the number of sources of adaption present in the model. Black dots show the preferred duty cycle of individual model variants, the purple line shows the average over models for a given number of adaptation sources. Adaptation decreases the preferred duty cycle (Pearson’s r = 0.78, p=3 × 10-4). See Figure 2—figure supplement 1 for details. The pulse trains for all simulations in this figure had a duration of 600 ms and were interleaved by chirp pauses of 200 ms to ensure that trains contained enough pulses even for long pulse durations and pauses. Rebound delay set to 21 ms in (C) and (E–I) to make changes in the duty cycle preference more apparent.