Count and spark? The echo response of the weakly electric fish Gnathonemuspetersii to series of pulses

Authors
Citation
S. Schuster, Count and spark? The echo response of the weakly electric fish Gnathonemuspetersii to series of pulses, J EXP BIOL, 204(8), 2001, pp. 1401-1412
Citations number
24
Language
INGLESE
art.tipo
Article
Categorie Soggetti
Biology,"Experimental Biology
Journal title
JOURNAL OF EXPERIMENTAL BIOLOGY
ISSN journal
0022-0949 → ACNP
Volume
204
Issue
8
Year of publication
2001
Pages
1401 - 1412
Database
ISI
SICI code
0022-0949(200104)204:8<1401:CASTER>2.0.ZU;2-0
Abstract
Weakly electric fish of the pulse type electrolocate objects in the dark by emitting discrete electric organ discharges (EODs) separated by intervals of silence. Two neighbouring pulse-type fish often reduce the risk of disch arging simultaneously by means of an 'echo response': one fish will respond to a neighbour's EOD with a discharge of its own following at a fixed shor t latency so that its EOD will occur long before the next EOD of its neighb our. Although working elegantly for two partners, this simple strategy shou ld fail in larger groups because two fish could discharge in response to th e same EOD of a third fish. Here, I show that the mormyrid fish Gnathonemus petersii could use a simple mechanism to reduce this problem. Individuals were stimulated with two closely spaced pulses, the second following so as to coincide with an echo given in response to the first. W the fish examine d were able to respond more to the second pulse so that most of their echoe s did not collide with the second pulse. An analysis was made of how echoin g more to the second pulse depends on (i) the delay at which the stimulus f ollowed the last spontaneous EOD, (ii) the spontaneous firing rate, (iii) t he intensity of the stimulus, (iv) the number of stimulus pulses, (v) the i nterval between stimulus pulses, and (vi) the level of previous stimulation with double pulses. The results suggest that echoing more in response to t he second pulse is probably because the first pulse causes an after-effect whose inferred properties would be compatible with the properties of the mo rmyromast afferences thought to be involved in the echo response.