Mauthner cell-initiated abrupt increase of the electric organ discharge in the weakly electric fish Gymnotus carapo

1995 ◽  
Vol 176 (5) ◽  
Author(s):  
A. Falconi ◽  
M. Borde ◽  
A. Hern�ndez-Cruz ◽  
F.R. Morales
Keyword(s):  
Electric Fish ◽  
Electric Organ Discharge ◽  
Electric Organ ◽  
Weakly Electric Fish ◽  
Abrupt Increase ◽  
Mauthner Cell ◽  
Weakly Electric

scholarly journals Electrical signalling of dominance in a wild population of electric fish

2010 ◽  
Vol 7 (2) ◽  
pp. 197-200 ◽  
Author(s):  
Vincent Fugère ◽  
Hernán Ortega ◽  
Rüdiger Krahe
Keyword(s):  
High Frequency ◽  
Electric Fish ◽  
Electric Organ Discharge ◽  
Low Frequency ◽  
Electric Organ ◽  
Weakly Electric Fish ◽  
Dominance Status ◽  
Strong Positive Relationship ◽  
Electrical Signalling ◽  
Weakly Electric

Animals often use signals to communicate their dominance status and avoid the costs of combat. We investigated whether the frequency of the electric organ discharge (EOD) of the weakly electric fish, Sternarchorhynchus sp., signals the dominance status of individuals. We correlated EOD frequency with body size and found a strong positive relationship. We then performed a competition experiment in which we found that higher frequency individuals were dominant over lower frequency ones. Finally, we conducted an electrical playback experiment and found that subjects more readily approached and attacked the stimulus electrodes when they played low-frequency signals than high-frequency ones. We propose that EOD frequency communicates dominance status in this gymnotiform species.

scholarly journals Male-mediated species recognition among African weakly electric fishes

2018 ◽  
Vol 5 (2) ◽  
pp. 170443 ◽  
Author(s):  
Rebecca Nagel ◽  
Frank Kirschbaum ◽  
Jacob Engelmann ◽  
Volker Hofmann ◽  
Felix Pawelzik ◽  
...  
Keyword(s):  
Fish Species ◽  
Electric Fish ◽  
Electric Organ Discharge ◽  
Species Recognition ◽  
Electric Organ ◽  
Sympatric Species ◽  
Weakly Electric Fish ◽  
Offspring Production ◽  
Association Preference ◽  
Weakly Electric

Effective communication among sympatric species is often instrumental for behavioural isolation, where the failure to successfully discriminate between potential mates could lead to less fit hybrid offspring. Discrimination between con- and heterospecifics tends to occur more often in the sex that invests more in offspring production, i.e. females, but males may also mediate reproductive isolation. In this study, we show that among two Campylomormyrus African weakly electric fish species, males preferentially associate with conspecific females during choice tests using live fish as stimuli, i.e. when all sensory modalities potentially used for communication were present. We then conducted playback experiments to determine whether the species-specific electric organ discharge (EOD) used for electrocommunication serves as the cue for this conspecific association preference. Interestingly, only C. compressirostris males associated significantly more with the conspecific EOD waveform when playback stimuli were provided, while no such association preference was observed in C. tamandua males. Given our results, the EOD appears to serve, in part, as a male-mediated pre-zygotic isolation mechanism among sympatric species. However, the failure of C. tamandua males to discriminate between con- and heterospecific playback discharges suggests that multiple modalities may be necessary for species recognition in some African weakly electric fish species.

Precision of the Pacemaker Nucleus in a Weakly Electric Fish: Network Versus Cellular Influences

2000 ◽  
Vol 83 (2) ◽  
pp. 971-983 ◽  
Author(s):  
Katherine T. Moortgat ◽  
Theodore H. Bullock ◽  
Terrence J. Sejnowski
Keyword(s):  
Electric Fish ◽  
Electric Organ Discharge ◽  
Electric Organ ◽  
Spike Timing ◽  
Weakly Electric Fish ◽  
Pacemaker Cells ◽  
Relay Cell ◽  
Spike Timing Precision ◽  
Pacemaker Nucleus ◽  
Weakly Electric

We investigated the relative influence of cellular and network properties on the extreme spike timing precision observed in the medullary pacemaker nucleus (Pn) of the weakly electric fish Apteronotus leptorhynchus. Of all known biological rhythms, the electric organ discharge of this and related species is the most temporally precise, with a coefficient of variation (CV = standard deviation/mean period) of 2 × 10−4 and standard deviation (SD) of 0.12–1.0 μs. The timing of the electric organ discharge is commanded by neurons of the Pn, individual cells of which we show in an in vitro preparation to have only a slightly lesser degree of precision. Among the 100–150 Pn neurons, dye injection into a pacemaker cell resulted in dye coupling in one to five other pacemaker cells and one to three relay cells, consistent with previous results. Relay cell fills, however, showed profuse dendrites and contacts never seen before: relay cell dendrites dye-coupled to one to seven pacemaker and one to seven relay cells. Moderate (0.1–10 nA) intracellular current injection had no effect on a neuron's spiking period, and only slightly modulated its spike amplitude, but could reset the spike phase. In contrast, massive hyperpolarizing current injections (15–25 nA) could force the cell to skip spikes. The relative timing of subthreshold and full spikes suggested that at least some pacemaker cells are likely to be intrinsic oscillators. The relative amplitudes of the subthreshold and full spikes gave a lower bound to the gap junctional coupling coefficient of 0.01–0.08. Three drugs, called gap junction blockers for their mode of action in other preparations, caused immediate and substantial reduction in frequency, altered the phase lag between pairs of neurons, and later caused the spike amplitude to drop, without altering the spike timing precision. Thus we conclude that the high precision of the normal Pn rhythm does not require maximal gap junction conductances between neurons that have ordinary cellular precision. Rather, the spiking precision can be explained as an intrinsic cellular property while the gap junctions act to frequency- and phase-lock the network oscillations.

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