The energetics of electric organ discharge generation in gymnotiform weakly electric fish

Salazar, Vielka L.; Krahe, Rüdiger; Lewis, John E.

doi:10.1242/jeb.082735

Cited by 58 publications

(55 citation statements)

References 95 publications

(143 reference statements)

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“…The existence of two distinct states in sensory sampling can be explained by the high metabolic cost of maintaining the EODs (Salazar et al, 2013); thus, animals save significant energy by switching to lower sensory sampling rates at rest. Unlike motor activities, sensory processing in the brain is normally hidden from outside observers, but in Gymnotus sp., transitions between two distinct modes of sensory sampling provide a window to the internal sensory dynamics from spontaneously behaving animals for extended periods.…”

Section: Discussionmentioning

confidence: 99%

Enhanced sensory sampling precedes self-initiated locomotion in an electric fish

Jun

Longtin

Maler

2014

Journal of Experimental Biology

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Cortical activity precedes self-initiated movements by several seconds in mammals; this observation has led into inquiries on the nature of volition. Preparatory neural activity is known to be associated with decision making and movement planning. Selfinitiated locomotion has been linked to increased active sensory sampling; however, the precise temporal relationship between sensory acquisition and voluntary movement initiation has not been established. Based on long-term monitoring of sensory sampling activity that is readily observable in freely behaving pulse-type electric fish, we show that heightened sensory acquisition precedes spontaneous initiation of swimming. Gymnotus sp. revealed a bimodal distribution of electric organ discharge rate (EODR) demonstrating down-and up-states of sensory sampling and neural activity; movements only occurred during up-states and up-states were initiated before movement onset. EODR during voluntary swimming initiation exhibited greater trial-to-trial variability than the sound-evoked increases in EODR. The sampling variability declined after voluntary movement onset as previously observed for the neural variability associated with decision making in primates. Spontaneous movements occurred randomly without a characteristic timescale, and no significant temporal correlation was found between successive movement intervals. Using statistical analyses of spontaneous exploratory behaviours and associated preparatory sensory sampling increase, we conclude that electric fish exhibit key attributes of volitional movements, and that voluntary behaviours in vertebrates may generally be preceded by increased sensory sampling. Our results suggest that comparative studies of the neural basis of volition may therefore be possible in pulse-type electric fish, given the substantial homologies between the telencephali of teleost fish and mammals.

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Section: Discussionmentioning

confidence: 99%

Enhanced sensory sampling precedes self-initiated locomotion in an electric fish

Jun

Longtin

Maler

2014

Journal of Experimental Biology

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“…Other papers in this special issue address in depth the mechanisms of phenotypic conversion from muscle to EO (Güth, et al, 2013;Unguez et al, 2013) and the energetics of electrical signaling (Salazar et al, 2013). Accordingly, these topics will not be discussed at length here.…”

Section: Electrocytes: the Cellular Basis Of Electrogenesismentioning

confidence: 99%

Electrocyte physiology: 50 years later

Markham

2013

Journal of Experimental Biology

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SummaryWeakly electric gymnotiform and mormyrid fish generate and detect weak electric fields to image their worlds and communicate. These multi-purpose electric signals are generated by electrocytes, the specialized electric organ (EO) cells that produce the electric organ discharge (EOD). Just over 50years ago the first experimental analyses of electrocyte physiology demonstrated that the EOD is produced and shaped by the timing and waveform of electrocyte action potentials (APs). Electrocytes of some species generate a single AP from a distinct region of excitable membrane, and this AP waveform determines EOD waveform. In other species, electrocytes possess two independent regions of excitable membrane that generate asynchronous APs with different waveforms, thereby increasing EOD complexity. Signal complexity is further enhanced in some gymnotiforms by the spatio-temporal activation of distinct EO regions with different electrocyte properties. For many mormyrids, additional EOD waveform components are produced by APs that propagate along stalks that connect postsynaptic regions to the main body of the electrocyte. I review here the history of research on electrocyte physiology in weakly electric fish, as well as recent discoveries of key phenomena not anticipated during early work in this field. Recent areas of investigation include the regulation of electrocyte activity by steroid and peptide hormones, the molecular evolution of electrocyte ion channels, and the evolutionary selection of ion channels expressed in excitable cells. These emerging research areas have generated renewed interest in electrocyte function and clear future directions for research addressing a broad range of new and important questions.

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“…There is a rich and rapidly growing literature on the behavior, neuroethology, physiology, energetics, and hormonal basis of EOD generation and EOD plasticity in Brachyhypopomus -focused primarily on the model species B. gauderio, which is reviewed in part by Assad et al ( , 1998, Stoddard (2006), Gavassa et al (2013), Markham (2013), Silva et al (2013), and Salazar et al (2013).…”

Section: Functional Biology and Ecology Specializations Associated Wmentioning

confidence: 99%

A taxonomic revision of the Neotropical electric fish genus Brachyhypopomus (Ostariophysi: Gymnotiformes: Hypopomidae), with descriptions of 15 new species

et al. 2016

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The bluntnose knifefish genus Brachyhypopomus Mago-Leccia, 1994, is diagnosed from other Rhamphichthyoidea (Rhamphichthyidae + Hypopomidae) by the presence of a disk-like ossification in the anterior portion of the palatoquadrate, and by the following external characters: short snout, 18.7-32.6% of head length Gymnorhamphichthys, Iracema, and Rhamphichthys), absence of a paired accessory electric organ in the mental or humeral region (vs. presence in Hypopygus and Steatogenys), presence of 3-4 pectoral proximal radials (vs. 5 in Akawaio), presence of the antorbital + infraorbital, and the preopercular cephalic lateral line canal bones (vs. absence in Racenisia). Brachyhypopomus cannot be diagnosed unambiguously from Microsternarchus or from Procerusternarchus on the basis of external characters alone. Brachyhypopomus comprises 28 species. Here we describe 15 new species, and provide redescriptions of all 13 previously described species, based on meristic, morphometric, and other morphological characters. We include notes on ecology and natural history for each species, and provide regional dichotomous keys and distribution maps, based on the examination of 12,279 specimens from 2,787 museum lots. A lectotype is designated for Brachyhypopomus pinnicaudatus (Hopkins, Comfort, Bastian & Bass, 1990 Peixes elétricos do gênero Brachyhypopomus Mago-Leccia, 1994, são diagnosticados dos outros Rhamphichthyoidea (Rhamphichthyidae + Hypopomidae) pela presença de uma ossificação discóide na porção anterior do palatoquadrado, e pelos seguintes caracteres externos: focinho curto, 18,7-32,6% do comprimento da cabeça (vs. 33,3-68,6% em Hypopomus, Gymnorhamphichthys, Iracema e Rhamphichthys), ausência de um órgão elétrico acessório pareado na região mental ou humeral (vs. presença em Hypopygus e Steatogenys), presença de 3-4 proximais peitorais radiais (vs. 5 em Akawaio), presença do antiorbital + infraorbital, e dos canais ossificados da linha lateral da região cefálica do pré-opérculo (vs. ausência em Racenisia). Brachyhypopomus não pode ser diagnosticado de maneira não-ambígua de Microsternarchus ou Procerusternarchus, com base em caracteres de morfologia externa. Brachyhypopomus compreende 28 espécies válidas. Aqui nós descrevemos 15 espécies novas, e fornecemos a redescrição de 13 espécies previamente descritas, baseado em caracteres merísticos, morfométricos e outros caracteres morfológicos. Nós incluímos notas sobre à ecologia e história natural para cada uma das espécies, e fornecemos chaves dicotômicas regionais e mapas de distribuição baseado no exame de 12.279 espécimes de 2.787 lotes de museus. Um lectótipo é designado para Brachyhypopomus pinnicaudatus (Hopkins, Comfort, Bastian & Bass, 1990

show abstract

The energetics of electric organ discharge generation in gymnotiform weakly electric fish

Cited by 58 publications

References 95 publications

Enhanced sensory sampling precedes self-initiated locomotion in an electric fish

Enhanced sensory sampling precedes self-initiated locomotion in an electric fish

Electrocyte physiology: 50 years later

A taxonomic revision of the Neotropical electric fish genus Brachyhypopomus (Ostariophysi: Gymnotiformes: Hypopomidae), with descriptions of 15 new species

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