  We consider the effect of distributed delays in neural feedback systems. The
avian optic tectum is reciprocally connected with the nucleus isthmi.
Extracellular stimulation combined with intracellular recordings reveal a range
of signal delays from 4 to 9 ms between isthmotectal elements. This observation
together with prior mathematical analysis concerning the influence of a delay
distribution on system dynamics raises the question whether a broad delay
distribution can impact the dynamics of neural feedback loops. For a system of
reciprocally connected model neurons, we found that distributed delays enhance
system stability in the following sense. With increased distribution of delays,
the system converges faster to a fixed point and converges slower toward a
limit cycle. Further, the introduction of distributed delays leads to an
increased range of the average delay value for which the system's equilibrium
point is stable. The enhancement of stability with increasing delay
distribution is caused by the introduction of smaller delays rather than the
distribution per se.
