Melatonin Regulates Daily Variations in Electric Behavior Arousal in Two Species of Weakly Electric Fish with Different Social Structures

2016 ◽  
Vol 87 (4) ◽  
pp. 232-241 ◽  
Author(s):  
Adriana Migliaro ◽  
Ana Silva
Keyword(s):  
Social Behavior ◽  
Discharge Rate ◽  
Biological Rhythms ◽  
Arginine Vasotocin ◽  
Weakly Electric Fish ◽  
Environment Variables ◽  
Electric Behavior ◽  
Nocturnal Increase ◽  
External Stimuli ◽  
Weakly Electric

Timing is crucial for social interactions. Animal behavior is synchronized with biotic and abiotic environment variables ensuring that the activity phase of conspecifics occurs during the same period of the day. As biological rhythms are embedded in the complex integrative control of the brain, it is fundamental to explore its interaction with environmental and social factors. This approach will unravel the link between external stimuli carrying information on environmental cycles and the neural commands for behavior, including social behavior, associated with precise phases of those cycles. Arousal in the solitary Gymnotus omarorum and in the gregarious Brachyhypopomus gauderio is characterized by a nocturnal increase in the basal discharge rate of electric behavior, which is mild and transient in G. omarorum and large and persistent in B. gauderio. In this study, we show that the major integrator of social behavior, AVT (arginine vasotocin), is not involved in the nocturnal increase of electric behavior basal rate in isolated animals of either species. On the other hand, endogenous melatonin, the major modulator of the circadian system, is responsible for the nocturnal increase in electric behavior in isolated individuals of both species.

Sensitivity to novel feedback at different phases of a gymnotid electric organ discharge

2002 ◽  
Vol 205 (21) ◽  
pp. 3307-3320
Author(s):  
Stefan Schuster ◽  
Natalie Otto
Keyword(s):  
Current Flow ◽  
Electric Organ Discharge ◽  
Discharge Rate ◽  
Electric Organ ◽  
Weakly Electric Fish ◽  
Spatiotemporal Pattern ◽  
Switch Closure ◽  
Tail Region ◽  
Gymnotid Fish ◽  
Weakly Electric

SUMMARY Weakly electric fish communicate and electrolocate objects in the dark by discharging their electric organs (EOs) and monitoring the spatiotemporal pattern of current flow through their skin. In the South-American pulse-type gymnotid fish these organs often are intriguingly complex, comprising several hundreds of electrogenic cells (electrocytes) of various morphologies,innervation patterns and abilities to generate a spike, distributed over nearly the full length of the fish. An attractive idea is that different parts of the organ may serve distinct functions in electrocommunication and electrolocation. Recent studies support this notion and suggest that the currents produced during the final phase of the electric organ discharge (EOD)are used for communication. Here, we explore a method to directly assess the relevance of the various currents for electrolocation. In this new method, the pattern of current flow during a gymnotid EOD is changed selectively at distinct phases of the EOD so that currents generated by known electrocyte groups are affected. We have studied the roles played by the various currents for the detection of novel feedback at the trunk/tail region of the gymnotid fish Gymnotus carapo. An experimental animal rested in a cage and two electrodes were placed at a close distance to its trunk and tail. An electronic switch briefly connected these electrodes during a selected phase within an EOD and the shunting of EOD current that resulted from switch closure was directly monitored. G. carapo responded with an acceleration of its discharge rate to novelties in the EOD feedback that occurred only for a fraction of a single EOD. Controls in which the switch was closed during the silent intervals between successive EODs showed that the fish responded to the changes in EOD feedback and not to unrelated artefacts of the brief switch closure. Fish responded to shunting of current during all phases; the sensitivity was highest during the final headnegative phase but the magnitude of shunted current was largest in the preceeding phase. The current produced during the final part of the EOD is thus not reserved for communication as previously suggested but plays a predominant role in electrolocation at the trunk and tail region of G. carapo.

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).

scholarly journals Arginine Vasotocin Modulates a Sexually Dimorphic Communication Behavior in the Weakly Electric fish APTERONOTUS LEPTORHYNCHUS

2001 ◽  
Vol 204 (11) ◽  
pp. 1909-1923 ◽  
Author(s):  
Joseph Bastian ◽  
Stephanie Schniederjan ◽  
Jerry Nguyenkim
Keyword(s):  
Electric Fish ◽  
Electric Organ Discharge ◽  
Electric Organ ◽  
Arginine Vasotocin ◽  
Weakly Electric Fish ◽  
Type I ◽  
Sexually Dimorphic ◽  
Type Ii ◽  
Apteronotus Leptorhynchus ◽  
Weakly Electric

SUMMARY South American weakly electric fish produce a variety of electric organ discharge (EOD) amplitude and frequency modulations including chirps or rapid increases in EOD frequency that function as agonistic and courtship and mating displays. In Apteronotus leptorhynchus, chirps are readily evoked by the presence of the EOD of a conspecific or a sinusoidal signal designed to mimic another EOD, and we found that the frequency difference between the discharge of a given animal and that of an EOD mimic is important in determining which of two categories of chirp an animal will produce. Type-I chirps (EOD frequency increases averaging 650Hz and lasting approximately 25ms) are preferentially produced by males in response to EOD mimics with a frequency of 50–200Hz higher or lower than that of their own. The EOD frequency of Apteronotus leptorhynchus is sexually dimorphic: female EODs range from 600 to 800Hz and male EODs range from 800 to 1000Hz. Hence, EOD frequency differences effective in evoking type-I chirps are most likely to occur during male/female interactions. This result supports previous observations that type-I chirps are emitted most often during courtship and mating. Type-II chirps, which consist of shorter-duration frequency increases of approximately 100Hz, occur preferentially in response to EOD mimics that differ from the EOD of the animal by 10–15Hz. Hence these are preferentially evoked when animals of the same sex interact and, as previously suggested, probably represent agonistic displays. Females typically produced only type-II chirps. We also investigated the effects of arginine vasotocin on chirping. This peptide is known to modulate communication and other types of behavior in many species, and we found that arginine vasotocin decreased the production of type-II chirps by males and also increased the production of type-I chirps in a subset of males. The chirping of most females was not significantly affected by arginine vasotocin.

scholarly journals Mixed selectivity coding of sensory and motor social signals in the thalamus of a weakly electric fish

2021 ◽  
Author(s):  
Avner Wallach ◽  
Alexandre Melanson ◽  
Andre Longtin ◽  
Len Maler
Keyword(s):  
Social Behavior ◽  
Mate Selection ◽  
Electric Fish ◽  
Neural Representation ◽  
Weakly Electric Fish ◽  
Social Signals ◽  
Communication Signals ◽  
Low Dimensional ◽  
High Level ◽  
Weakly Electric

Recent studies have shown that high-level neural activity often exhibits mixed selectivity to multi-variate signals. How such representations arise and how they modulate natural behavior is poorly understood. The social behavior of weakly electric fish is relatively low-dimensional and easily reproduced in the laboratory. Here we show how electrosensory signals related to courtship and rivalry in Apteronotus leptorhynchus are represented in the preglomerular nucleus, the thalamic region exclusively connecting the midbrain with the pallium. We show that preglomerular cells convert their midbrain inputs into a mixed selectivity code that includes corollary discharge of outgoing communication signals. We discuss how the preglomerular pallial targets might use these inputs to control social behavior and determine dominance in male-male competition and female mate selection during courtship. Our results showcase the potential of the electrocommunication system as an accessible model for studying the neural substrates of social behavior and principles of multi-dimensional neural representation.

scholarly journals Neural activity in a hippocampus-like region of the teleost pallium is associated with active sensing and navigation

eLife ◽  
2019 ◽  
Vol 8 ◽  
Author(s):  
Haleh Fotowat ◽  
Candice Lee ◽  
James Jaeyoon Jun ◽  
Len Maler
Keyword(s):  
Neural Activity ◽  
Electric Organ Discharge ◽  
Discharge Rate ◽  
Electric Organ ◽  
Weakly Electric Fish ◽  
Active Sensing ◽  
Head Region ◽  
Hippocampal Ca3 ◽  
And Control ◽  
Weakly Electric

Most vertebrates use active sensing strategies for perception, cognition and control of motor activity. These strategies include directed body/sensor movements or increases in discrete sensory sampling events. The weakly electric fish, Gymnotus sp., uses its active electric sense during navigation in the dark. Electric organ discharge rate undergoes transient increases during navigation to increase electrosensory sampling. Gymnotus also use stereotyped backward swimming as an important form of active sensing that brings objects toward the electroreceptor dense fovea-like head region. We wirelessly recorded neural activity from the pallium of freely swimming Gymnotus. Spiking activity was sparse and occurred only during swimming. Notably, most units tended to fire during backward swims and their activity was on average coupled to increases in sensory sampling. Our results provide the first characterization of neural activity in a hippocampal (CA3)-like region of a teleost fish brain and connects it to active sensing of spatial environmental features.

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