scholarly journals Flight-Associated Discharge Pattern in a Weakly Electric Fish, Gnathonemus Petersii (Mormyridae, Teleostei)

Behaviour ◽  
1976 ◽  
Vol 59 (1-2) ◽  
pp. 88-94 ◽  
Author(s):  
Bernd Kramer
Keyword(s):  
Motor Activity ◽  
Electric Fish ◽  
Rate Increase ◽  
Discharge Rate ◽  
Weakly Electric Fish ◽  
Discharge Pattern ◽  
Escape Reaction ◽  
Socially Relevant ◽  
Weakly Electric ◽  
Gnathonemus Petersii

AbstractA GnathonEmus petersii which is put into the tank of a Mormyrus rume, or of an electrically silenced G. petersii, displays a discharge rate which is only one fourth (8 Hz) the rate exhibited by an attacking, territory-defending animal. In both instances, the variability of intervals is great. In contrast to the bimodal histogram of an attacking animal, the histogram of an inferior, fleeing fish displays only one mode. This mode is identical to the burst activity-mode of the resting histogram, and different from the swimming histogram mode. So the histogram displayed by an attacked and persecuted animal is significantly different from the histograms exhibited by i) isolated resting, ii) isolated swimming, and iii) attacking fish. During an attack-elicited escape reaction, G. petersii increases its discharge rate up to 55 Hz in a step-like fashion, while regularising the length of successive intervals ("fleeing signal"). The step-like discharge rate increase is also shown by the receiver of an Approach who does not move. This suggests that the step-like discharge rate increase, associated with the escape reaction, is not an incidental response to changed motor activity. The "fleeing signal" presumably is i) an incidental response to a vegetative reaction, or ii) it may have the significance of a signal communicating a socially relevant message (e.g. threat).

A grouped retina provides high temporal resolution in the weakly electric fish Gnathonemus petersii

2013 ◽  
Vol 107 (1-2) ◽  
pp. 84-94 ◽  
Author(s):  
Roland Pusch ◽  
Vanessa Kassing ◽  
Ursula Riemer ◽  
Hans-Joachim Wagner ◽  
Gerhard von der Emde ◽  
...  
Keyword(s):  
Temporal Resolution ◽  
Electric Fish ◽  
Weakly Electric Fish ◽  
High Temporal Resolution ◽  
Weakly Electric ◽  
Gnathonemus Petersii

scholarly journals Modeling the variability of the electromotor command system of pulse mormyrids

2020 ◽  
Author(s):  
Ángel Lareo ◽  
Pablo Varona ◽  
Francisco B. Rodríguez
Keyword(s):  
Genetic Algorithm ◽  
Computational Model ◽  
Electric Fish ◽  
Temporal Structure ◽  
Activity Patterns ◽  
Pulse Generation ◽  
Weakly Electric Fish ◽  
Freely Behaving ◽  
Weakly Electric ◽  
Gnathonemus Petersii

AbstractThe electromotor neural system in weakly electric fish is a network responsible for active electroreception and electrolocation. This system controls the timing of pulse generation in the electrical signals used by these fish for extracting information from the environment and communicating with other specimens. Ethological studies related to fish mating, exploratory, submissive or aggressive behaviors have described distinct sequences of pulse intervals (SPIs). Accelerations, scallops, rasps, and cessations are four patterns of SPIs reported in pulse mormyrids, each showing characteristic temporal structures and large variability both in timing and duration. This paper presents a biologically plausible computational model of the electromotor command circuit that reproduces these four SPI patterns as a function of the input to the model while keeping the same internal parameter configuration. The topology of the model is based on a simplified representation of the network as described by morphological and electrophysiological studies. An initial ad hoc tuned configuration (S-T) was build to reproduce all four SPI patterns. Then, starting from S-T, a genetic algorithm (GA) was developed to automatically find the parameters of the model connectivity. Two different configurations obtained from the GA are presented here: one optimized to a set of synthetic examples of SPI patterns based on experimental observations in mormyrids (S-GA), and another configuration adjusted to patterns recorded from freely-behaving Gnathonemus Petersii specimens (R-GA). A robustness analysis to input variability of these model configurations was performed to discard overfitting and assess validity. Results showed that the four SPI patterns are consistently reproduced, both with synthetic (S-GA) data and with signals recorded from behaving animals (R-GA). This new model can be used as a tool to analyze the electromotor command chain during electrogeneration and assess the role of temporal structure in electroreception.Author summaryWeakly electric fish are a convenient system to study information processing in the nervous system. These fish have a remarkable sense of active electroreception, which allows them to generate and detect electrical fields for locating objects and communicating with other specimens in their surroundings. The electrical signal generated by these fish can be easily monitored noninvasively in freely-behaving animals. Activity patterns in this signal have been associated to different fish behaviors, like aggression or mating, for some species of the mormyridae family. In this work we use discharge patterns recorded from specimens of the Gnathonemus Petersii species along with synthetic data to develop a model of the electromotor command network. The model network is based on morphological and physiological studies in this type of weakly electric fish. The parameters of this model were tuned using a genetic algorithm to fit both synthetic and recorded activity patterns. This computational model allows to simulate the electromotor network behavior under controlled conditions and to test new hypotheses on the generation and function of temporal structure in the signals produced by weakly electric fish.

scholarly journals Sensory influence on navigation in the weakly electric fish Gnathonemus petersii

2017 ◽  
Vol 132 ◽  
pp. 1-12 ◽  
Author(s):  
Sarah Schumacher ◽  
Gerhard von der Emde ◽  
Theresa Burt de Perera
Keyword(s):  
Electric Fish ◽  
Weakly Electric Fish ◽  
Weakly Electric ◽  
Gnathonemus Petersii

scholarly journals Count and spark? The echo response of the weakly electric fish Gnathonemus petersii to series of pulses

2001 ◽  
Vol 204 (8) ◽  
pp. 1401-1412
Author(s):  
S. Schuster
Keyword(s):  
Electric Fish ◽  
Electric Organ ◽  
Weakly Electric Fish ◽  
Simple Strategy ◽  
Mormyrid Fish ◽  
Pulse Type ◽  
After Effect ◽  
Electric Organ Discharges ◽  
Weakly Electric ◽  
Gnathonemus Petersii

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 discharging 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 short latency so that its EOD will occur long before the next EOD of its neighbour. Although working elegantly for two partners, this simple strategy should fail in larger groups because two fish could discharge in response to the 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. All the fish examined were able to respond more to the second pulse so that most of their echoes did not collide with the second pulse. An analysis was made of how echoing more to the second pulse depends on (i) the delay at which the stimulus followed the last spontaneous EOD, (ii) the spontaneous firing rate, (iii) the intensity of the stimulus, (iv) the number of stimulus pulses, (v) the interval between stimulus pulses, and (vi) the level of previous stimulation with double pulses. The results suggest that echoing more in response to the second pulse is probably because the first pulse causes an after-effect whose inferred properties would be compatible with the properties of the mormyromast afferences thought to be involved in the echo response.

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