Structural and functional aspects of the fast electrosensory pathway in the electrosensory lateral line lobe of the pulse fish Gymnotus carapo

Castelló, María E.; Caputi, Ángel A.; Trujillo‐Cenóz, O.

doi:10.1002/(sici)1096-9861(19981130)401:4<549::aid-cne7>3.3.co;2-8

Cited by 11 publications

(33 citation statements)

References 34 publications

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“…As studied by Hofmann et al 26 , it would be interesting to investigate the object's electric image flow during free-swimming depending on the object distance, shape, size, and material. Ultimately, our methods combined with neural recordings from freely swimming fish [44][45][46] may reveal novel insights by observations of changes in neural activity and EOD rate while the fish engages in object exploration or social interactions.…”

Section: Discussionsupporting

confidence: 86%

Long-term Behavioral Tracking of Freely Swimming Weakly Electric Fish

Jun

Longtin

Maler

2014

JoVE

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Long-term behavioral tracking can capture and quantify natural animal behaviors, including those occurring infrequently. Behaviors such as exploration and social interactions can be best studied by observing unrestrained, freely behaving animals. Weakly electric fish (WEF) display readily observable exploratory and social behaviors by emitting electric organ discharge (EOD). Here, we describe three effective techniques to synchronously measure the EOD, body position, and posture of a free-swimming WEF for an extended period of time. First, we describe the construction of an experimental tank inside of an isolation chamber designed to block external sources of sensory stimuli such as light, sound, and vibration. The aquarium was partitioned to accommodate four test specimens, and automated gates remotely control the animals' access to the central arena. Second, we describe a precise and reliable real-time EOD timing measurement method from freely swimming WEF. Signal distortions caused by the animal's body movements are corrected by spatial averaging and temporal processing stages. Third, we describe an underwater near-infrared imaging setup to observe unperturbed nocturnal animal behaviors. Infrared light pulses were used to synchronize the timing between the video and the physiological signal over a long recording duration. Our automated tracking software measures the animal's body position and posture reliably in an aquatic scene. In combination, these techniques enable long term observation of spontaneous behavior of freely swimming weakly electric fish in a reliable and precise manner. We believe our method can be similarly applied to the study of other aquatic animals by relating their physiological signals with exploratory or social behaviors. Video LinkThe video component of this article can be found at

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Section: Discussionsupporting

confidence: 86%

Long-term Behavioral Tracking of Freely Swimming Weakly Electric Fish

Jun

Longtin

Maler

2014

JoVE

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“…The precise synchronism between spherical cells is revealed by the sharpness and phase locking of the lemniscal compound action potential, and by the strong correlation between the amplitude of primary afferent and lemniscal compound action potentials (Szabo et al, 1975;Castelló et al, 1998). The lowresponsiveness window prevents the subsequent activation of the path by externally generated, potentially interfering signals (Schlegel, 1973;Castelló et al, 1998).…”

Section: Introductionmentioning

confidence: 91%

“…These afferents encode the amplitude of the local stimulus using the latency of a single spike. Pulse marker afferents terminate centrally on the cell bodies of spherical cells in the deeper layers of the ELL by way of morphologically mixed synapses (Castelló et al, 1998;Réthelyi and Szabo, 1973).…”

Section: Introductionmentioning

confidence: 99%

“…Spherical cells have few short dendrites that make gap junctions with the soma of neighboring spherical cells, and also receive chemical axosomatic or axodendritic contacts from thin fibers from still unknown origin (Castelló et al, 1998). Spherical cell axons project to the mesencephalic magnocellular nucleus by way of the lateral lemniscus.…”

Section: Introductionmentioning

confidence: 99%

“…We have previously implemented a methodology to record the activity of electrosensory structures in vivo in the freely moving fish (Castelló et al, 1998;Pereira et al, 2005). We found that the characteristic sign of the activation of the fast electrosensory pathway is a brief compound action potential occurring shortly after the self-generated or conspecificgenerated EODs.…”

Section: Introductionmentioning

confidence: 99%

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The role of single spiking spherical neurons in a fast sensory pathway

Nogueira

Castelló

Caputi

2006

Journal of Experimental Biology

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SUMMARY One difficulty in understanding the brain is that of linking the structure of the neurons with their computational roles in neural circuits. In this paper we address this subject in a relative simple system, the fast electrosensory pathway of an electric fish, where sensory images are coded by the relative latency of a volley of single spikes. The main input to this path is a stream of discrete electric images resulting from the modulation of a self-generated carrier by the environment. At the second order cell level, a window of low responsiveness, reducing potential interference from other stimuli, follows activation of the path. In the present study, we further characterize the input–output relationship at the second order neurons by recording field potentials, and ascertain its cellular basis using in vitro whole cell patch recordings. The field potentials from freely behaving, socially interacting fish were obtained from chronically implanted fish restrained in a mesh pen. In addition, at the end of some experiments the fish was curarized and the fast electrosensory path responses to artificial stimuli were further explored. These in vivo approaches showed that larger stimuli cause larger and longer windows of low responsiveness. The simple spherical geometry of the second order cells allowed us to unveil the membrane mechanisms underlying this phenomenon in vitro. These spherical cells respond with a single spike at the onset of current steps of any amplitude and duration, showing inward and outward rectification, and a long refractory period. We postulate that a low-threshold K+ conductance generates the outward rectification. The most parsimonious interpretation of our data indicates that slow deactivation of this conductance causes the long refractory period. These non-linear properties of the membrane explain the single spiking profile of spherical cells and the low-responsiveness window observed in vivo. Since the electric organ discharges are emitted at intervals slightly longer than the duration of the low-responsiveness window,we propose that the described cellular mechanisms allow fish streaming self-generated images.

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Functional foveae in an electrosensory system

Bacelo

Engelmann

Hollmann

et al. 2008

J of Comparative Neurology

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Several species of Mormyrid weakly electric fish have a mobile chin protuberance that serves as a mobile antenna during prey detection, tracking behaviors, and foraging for food. It has been proposed that it constitutes a fovea of the electrosensory system. The distribution of the three types of receptor organs involved in active imaging of the local surroundings, prey detection, and passive electroreception, and their central projection to the electrosensory lobe (ELL), have been studied in Gnathonemus petersii. Density distributions were compared for different body regions. Primary afferent projections were labeled with biocytin or biotinylated dextrans. This showed that there is considerable central "over-representation" of the mandibular and nasal regions of the sensory surface involved in electrolocation, at the expense of the other body regions investigated. This over-representation is not a mere effect of the very high density of receptor organs in these areas, but is found to be due to central magnification. This magnification differs between the subclasses of electroreceptors, suggesting a functional segregation in the brain. We conclude that the chin protuberance and the nasal region are the regions of greatest sensitivity for the resistive, capacitive, and low-frequency characteristics of the environment, and are probably most important in prey detection, whereas other regions of the skin with a lesser resolution and sensitivity to phase distortion of the EOD, in particular the trunk, are probably designed for imaging larger, inanimate features of the environment. Our data support the hypothesis that the chin appendage and nasal region are functionally distinct electrosensory foveae.

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Structural and functional aspects of the fast electrosensory pathway in the electrosensory lateral line lobe of the pulse fish Gymnotus carapo

Cited by 11 publications

References 34 publications

Long-term Behavioral Tracking of Freely Swimming Weakly Electric Fish

Long-term Behavioral Tracking of Freely Swimming Weakly Electric Fish

The role of single spiking spherical neurons in a fast sensory pathway

Functional foveae in an electrosensory system

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