Computational model of the jamming avoidance response in the electric fish Gymnotus carapo

Abstract

The unperturbed electric organ discharges of Gymnotus carapo fish are highly periodic with interpulse intervals around 40 ms. The ‘jamming avoidance response’ happens when fish interact and is a transitory interval shortening in the fish with the faster discharge that decreases the likelihood that pulses from it and the other fish will coincide. Our model’s basic components match certain experimentally demonstrated facts. First, recurrence equations reproduce the periodic unperturbed discharges. Secondly, when an isolated pulse arrives, the two intervals following that with the pulse are shortened by amounts that decrease up to a minimum and then increase. Simulations demonstrated that this model reproduces satisfactorily the jamming avoidance response. Two additional conditions were demonstrably necessary: (i) one was that every pulse arrive within the hot cophase window (and not elsewhere); (ii) the other condition was that, along successive pulses, the respective cophases decrease by moderate amounts. In short, we conclude that the fish’s jamming avoidance response can involve the simple computational rules implied by the proposed equations.