scholarly journals Patterns of the electric organ discharge during courtship and spawning in the mormyrid fish, Pollimyrus isidori

1989 ◽  
Vol 24 (6) ◽  
pp. 349-368 ◽  
Author(s):  
B. O. Bratton ◽  
B. Kramer
Keyword(s):  
Electric Organ Discharge ◽  
Electric Organ ◽  
Mormyrid Fish

Categorisation of Interpulse Intervals and Stochastic Analysis of Discharge Patterns in Resting Weak-Electric Mormyrid Fish (Gnathonemus Petersii)

Behaviour ◽  
1987 ◽  
Vol 102 (3-4) ◽  
pp. 264-282 ◽  
Author(s):  
Claudine TEYSSÈDRE ◽  
Michel Boudinot ◽  
Catherine Minisclou
Keyword(s):  
Individual Differences ◽  
Stochastic Analysis ◽  
Electric Organ Discharge ◽  
Electric Organ ◽  
Electric Pulses ◽  
Oscillating Systems ◽  
Mormyrid Fish ◽  
Discharge Patterns ◽  
Gnathonemus Petersii ◽  
Criterion Method

AbstractInter-individual similarities in the electric organ discharge activity of immobile, isolated and undisturbed mormyrid fish were investigated. Two types of analysis were performed on the discharge patterns of 10 Gnathonemus petersii: (1) The Bout Interval Criterion method was used to categorise the intervals between consecutive electric pulses; (2) an analysis of sequences of acts was performed to study the serial ordering of the interpulse intervals. Interpulse intervals were demonstrated to belong to distinct classes, having similar limits for most animals. Most fish show five classes of interpulse intervals (23 to 68 ms; 69 to 108 ms; 109 to 170 ms; 171 to 212 ms; >212 ms), to which a sixth class (<23 ms) is added in some cases. Each class contains a similar number of intervals in all individuals. Particular associations were found between the occurrences of interpulse intervals belonging to different classes. Some of these associations (for example BB and EC) are displayed by most fish, whereas others express individual differences in the patterns of discharge. The discharge of immobile, undisturbed, isolated mormyrid fish is thus shown to present many similarities among individuals. Inter-individual differences exist only in the serial ordering of the intervals, where they arc best regarded as variations around a same theme. The absence of overlapping between the two main categories of interpulse intervals (category I: 69 to 108 ms; category II: 171 to 212 ms), as well as the constancy of their baselines, suggest that two oscillating systems participate to the electromotor command. The stochastic analysis of the serial ordering of the interpulse intervals suggest in addition that these two oscillators do not function independently. Momentaneous modifications of the activity of these two oscillators would provide an economical explanation for the various changes in the types of interpulse intervals associated with behavioural state or social interactions.

scholarly journals Electric organ discharge patterns during group hunting by a mormyrid fish

2005 ◽  
Vol 272 (1570) ◽  
pp. 1305-1314 ◽  
Author(s):  
Matthew E Arnegard ◽  
Bruce A Carlson
Keyword(s):  
Low Voltage ◽  
Electric Organ Discharge ◽  
Electric Organ ◽  
Lake Malawi ◽  
Weakly Electric Fish ◽  
Species Flock ◽  
Unexpected Finding ◽  
Size Estimation ◽  
Vertebrate Lineage ◽  
Mormyrid Fish

Weakly electric fish emit and receive low-voltage electric organ discharges (EODs) for electrolocation and communication. Since the discovery of the electric sense, their behaviours in the wild have remained elusive owing to their nocturnal habits and the inaccessible environments in which they live. The transparency of Lake Malawi provided the first opportunity to simultaneously observe freely behaving mormyrid fish and record their EODs. We observed a piscivorous mormyrid, Mormyrops anguilloides , hunting in small groups in Lake Malawi while feeding on rock-frequenting cichlids of the largest known vertebrate species flock. Video recordings yielded the novel and unexpected finding that these groups resembled hunting packs by being largely composed of the same individuals across days. We show that EOD accelerations accompany prey probing and size estimation by M. anguilloides . In addition, group members occasionally synchronize bursts of EODs with an extraordinary degree of precision afforded by the mormyrid echo response. The characteristics and context of burst synchronization suggest that it may function as a pack cohesion signal. Our observations highlight the potential richness of social behaviours in a basal vertebrate lineage, and provide a framework for future investigations of the neural mechanisms, behavioural rules and ecological significance of social predation in M. anguilloides .

Neuronal responses to electrosensory input in mormyrid valvula cerebelli

1978 ◽  
Vol 41 (6) ◽  
pp. 1495-1510 ◽  
Author(s):  
C. J. Russell ◽  
C. C. Bell
Keyword(s):  
Single Unit ◽  
Evoked Potential ◽  
Electric Organ Discharge ◽  
Electric Organ ◽  
Neuronal Responses ◽  
Sensory Stimuli ◽  
Separate Area ◽  
Mormyrid Fish ◽  
Electrosensory Processing ◽  
Gnathonemus Petersii

1. We have examined a large portion of the valvula cerebelli of the mormyrid fish Gnathonemus petersii for responses related to the three known classes of electroreceptors. Evoked potential and extracellular single-unit records from curarized and non-curarized preparations show that a separate area of the valvula is related to each of the different electrosensory modalities. 2. The area related to ampullary receptors is also strongly affected by mechanical stimulation to the skin. In the mormyromast and Knollenorgan regions, responses to sensory stimuli depend on when they are given in relation to the command to fire the electric organ. In the Knollenorgan region the interaction is quite simple. Responses are completely blocked if the stimulus is given during a brief period when the electric organ discharge occurs. A greater variety of interactions is seen in the mormyromast region. 3. Large areas of the valvula do not appear to be clearly and strongly retated to any of the three electrosensory modalities, suggesting the possibility that much of the structure is not devoted to electrosensory processing.

Recurrent Feedback in the Mormyrid Electrosensory System: Cells of the Preeminential and Lateral Toral Nuclei

2005 ◽  
Vol 93 (4) ◽  
pp. 2090-2103 ◽  
Author(s):  
Nathaniel B. Sawtell ◽  
Claudia Mohr ◽  
Curtis C. Bell
Keyword(s):  
Electric Organ Discharge ◽  
Electric Organ ◽  
Motor Command ◽  
Cell Types ◽  
Electrosensory System ◽  
Mormyrid Fish ◽  
Descending Input ◽  
Initial Description ◽  
Electrosensory Processing ◽  
Direct Feedback

Many sensory regions integrate information ascending from peripheral receptors with descending inputs from other central structures. However, the significance of these descending inputs remains poorly understood. Descending inputs are prominent in the electrosensory system of mormyrid fish and include both recurrent connections from higher to lower stages of electrosensory processing and electric organ corollary discharge (EOCD) signals associated with the motor command that drives the electric organ discharge. The preeminential nucleus (PE) occupies a key position in a feedback loop that returns information from higher stages of electrosensory processing to the initial stage of processing in the electrosensory lobe (ELL). This feedback reflects the integration of ascending electrosensory input from ELL, descending input from the lateral toral nucleus (torus), and EOCD inputs to PE. We used intracellular recording and axonal tracing of stained cells to characterize EOCD and electrosensory responses of several cell types in PE and the torus. PE and toral cells exhibit prominent EOCD responses that are not due to EOCD inputs from ELL. PE cells giving rise to a direct feedback projection to ELL respond to electrosensory stimuli with rapid, precisely timed spikes that will affect ELL neurons early during the same EOD cycle. EOCD and electrosensory responses in toral cells are similar to those observed in PE and may be important in shaping feedback to ELL. These results provide an initial description of electrosensory feedback to ELL as well as information about how ascending, descending, and EOCD inputs are combined at higher stages of electrosensory processing.

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