The Experts below are selected from a list of 408 Experts worldwide ranked by ideXlab platform

Jacob Engelmann - One of the best experts on this subject based on the ideXlab platform.

  • The Use of Supervised Learning Models in Studying Agonistic Behavior and Communication in Weakly Electric Fish
    'Frontiers Media SA', 2021
    Co-Authors: Federico Pedraja, Jacob Engelmann, Hendrik Herzog, Sarah Nicola Jung
    Abstract:

    Despite considerable advances, studying electrocommunication of weakly electric fish, particularly in pulse-type species, is challenging as very short signal epochs at variable intervals from a few hertz up to more than 100 Hz need to be assigned to individuals. In this study, we show that supervised learning approaches offer a promising tool to automate or semiautomate the workflow, and thereby allowing the analysis of much longer episodes of behavior in a reasonable amount of time. We provide a detailed workflow mainly based on open resource software. We demonstrate the usefulness by applying the approach to the analysis of dyadic interactions of Gnathonemus Petersii. Coupling of the proposed methods with a boundary element modeling approach, we are thereby able to model the information gained and provided during agonistic encounters. The data indicate that the passive electrosensory input, in particular, provides sufficient information to localize a contender during the pre-contest phase, fish did not use or rely on the theoretically also available sensory information of the contest outcome-determining size difference between contenders before engaging in agonistic behavior

  • spatial learning through active electroreception in Gnathonemus Petersii
    Animal Behaviour, 2019
    Co-Authors: Nicola S Jung, Silke Kunzel, Jacob Engelmann
    Abstract:

    Navigation is a ubiquitous challenge to mobile animals as it is essential for finding mates, food and shelter. It can rely on self-generated (idiothetic) as well as external (allothetic) information. The contribution of either source of information depends on multiple factors, including the sensory modality. Far-range modalities such as vision have frequently been studied in the context of navigation, but the extent to which near-range sensory systems provide information for navigation is much less understood. Here we focused on spatial learning in the weakly electric fish Gnathonemus Petersii. During their nocturnal excursions these fish typically rely on their short-range active electric sense to explore their environment. We addressed how these fish navigate and how electrosensory information is integrated in navigation. All fish learned to localize a target in a Barnes-like maze. In a series of transfer tests, we found that fish followed an idiothetic navigation strategy. When this strategy failed, fish were able to integrate electrosensory information to complete the task. Our results indicate that the active electric sense contributes to navigation in a resource-efficient and context-dependent manner. Together they show that weakly electric fish can incorporate highly localized sensory input in egocentric navigation. Extending these results will be important to reveal the sensory mechanisms of egocentric navigation in fish as well as to research whether and how spatially confined near-range sensory information might be used to form global representations of space.

  • physiological evidence of sensory integration in the electrosensory lateral line lobe of Gnathonemus Petersii
    PLOS ONE, 2018
    Co-Authors: Sylvia Fechner, Kirsty Grant, Gerhard Von Der Emde, Jacob Engelmann
    Abstract:

    : Mormyrid fish rely on reafferent input for active electrolocation. Their electrosensory input consists of phase and amplitude information. These are encoded by differently tuned receptor cells within the Mormyromasts, A- and B-cells, respectively, which are distributed over the animal's body. These convey their information to two topographically ordered medullary zones in the electrosensory lateral line lobe (ELL). The so-called medial zone receives only amplitude information, while the dorsolateral zone receives amplitude and phase information. Using both sources of information, Mormyrid fish can disambiguate electrical impedances. Where and how this disambiguation takes place is presently unclear. We here investigate phase-sensitivity downstream from the electroreceptors. We provide first evidence of phase-sensitivity in the medial zone of ELL. In this zone I-cells consistently decreased their rate to positive phase-shifts (6 of 20 cells) and increased their rate to negative shifts (11/20), while E-cells of the medial zone (3/9) responded oppositely to I-cells. In the dorsolateral zone the responses of E- and I-cells were opposite to those found in the medial zone. Tracer injections revealed interzonal projections that interconnect the dorsolateral and medial zones in a somatotopic manner. In summary, we show that phase information is processed differently in the dorsolateral and the medial zones. This is the first evidence for a mechanism that enhances the contrast between two parallel sensory channels in Mormyrid fish. This could be beneficial for impedance discrimination that ultimately must rely on a subtractive merging of these two sensory streams.

  • somatotopic map of the active electrosensory sense in the midbrain of the mormyrid Gnathonemus Petersii
    The Journal of Comparative Neurology, 2016
    Co-Authors: Vanessa Hollmann, Volker Hofmann, Jacob Engelmann
    Abstract:

    In many vertebrates parallel processing in topographically ordered maps is essential for efficient sensory processing. In the active electrosensory pathway of mormyrids afferent input is processed in two parallel somatotopically ordered hindbrain maps of the electrosensory lateral line lobe (ELL), the dorsolateral zone (DLZ), and the medial zone (MZ). Here phase and amplitude modulations of the self-generated electric field were processed separately. Behavioral data indicates that this information must be merged for the sensory system to categorically distinguish capacitive and resistive properties of objects. While projections between both zones of the ELL have been found, the available physiological data suggests that this merging takes place in the midbrain torus semicircularis (TS). Previous anatomical data indicate that the detailed somatotopic representation present in the ELL is lost in the nucleus lateralis (NL) of the TS, while a rough rostrocaudal mapping is maintained. In our study we investigated the projections from the hindbrain to the midbrain in more detail, using tracer injections. Our data reveals that afferents from both maps of the ELL terminate in a detailed somatotopic manner within the midbrain NL. Furthermore, we provide data indicating that phase and amplitude information may indeed be processed jointly in the NL. J. Comp. Neurol. 524:2479-2491, 2016. © 2016 Wiley Periodicals, Inc.

  • spatial resolution of an eye containing a grouped retina ganglion cell morphology and tectal physiology in the weakly electric fish Gnathonemus Petersii
    The Journal of Comparative Neurology, 2013
    Co-Authors: Roland Pusch, Hansjoachim Wagner, Gerhard Von Der Emde, Jacob Engelmann
    Abstract:

    The retina of the weakly electric fish Gnathonemus Petersii is a so-called grouped retina where photoreceptors are bundled. These bundles are regarded as functional units and this type of retinal specialization is uniquely found in teleosts. To understand how this anatomical organization influences visual information processing we investigated the morphology and distribution of retinal ganglion cells (GCs) and the response properties of retinal afferents terminating in the major retinorecipient area, the optic tectum. GCs were classified based on their dendritic morphology (dendritic field diameters 280 μm: giant GCs). Within these classes subtypes were distinguished based on the ramification patterns of the dendrites in the sublaminae of the inner plexiform layer. Properties of presumed optic nerve terminals were investigated in the optic tectum using extracellular recordings. Physiological classes could be observed based on their response to visual stimuli (on; off; on-off, and fast units). Receptive field sizes and spatiotemporal properties were classified and the topographical representation of the visual space was mapped in the tectum. Gratings of low spatial frequencies were best responded to and followed up to high temporal frequencies (>30 Hz). Most of the recorded units were directionally selective. No evidence of distorted topographies in the tectum was found, i.e., no overrepresentation of the retina was seen in the tectum opticum. The grouped retina of G. Petersii seems to be optimized for the detection of large, fast objects in an environment of low optical quality. J. Comp. Neurol. 521:4075-4093, 2013. © 2013 Wiley Periodicals, Inc.

Kirsty Grant - One of the best experts on this subject based on the ideXlab platform.

  • physiological evidence of sensory integration in the electrosensory lateral line lobe of Gnathonemus Petersii
    PLOS ONE, 2018
    Co-Authors: Sylvia Fechner, Kirsty Grant, Gerhard Von Der Emde, Jacob Engelmann
    Abstract:

    : Mormyrid fish rely on reafferent input for active electrolocation. Their electrosensory input consists of phase and amplitude information. These are encoded by differently tuned receptor cells within the Mormyromasts, A- and B-cells, respectively, which are distributed over the animal's body. These convey their information to two topographically ordered medullary zones in the electrosensory lateral line lobe (ELL). The so-called medial zone receives only amplitude information, while the dorsolateral zone receives amplitude and phase information. Using both sources of information, Mormyrid fish can disambiguate electrical impedances. Where and how this disambiguation takes place is presently unclear. We here investigate phase-sensitivity downstream from the electroreceptors. We provide first evidence of phase-sensitivity in the medial zone of ELL. In this zone I-cells consistently decreased their rate to positive phase-shifts (6 of 20 cells) and increased their rate to negative shifts (11/20), while E-cells of the medial zone (3/9) responded oppositely to I-cells. In the dorsolateral zone the responses of E- and I-cells were opposite to those found in the medial zone. Tracer injections revealed interzonal projections that interconnect the dorsolateral and medial zones in a somatotopic manner. In summary, we show that phase information is processed differently in the dorsolateral and the medial zones. This is the first evidence for a mechanism that enhances the contrast between two parallel sensory channels in Mormyrid fish. This could be beneficial for impedance discrimination that ultimately must rely on a subtractive merging of these two sensory streams.

  • The midbrain precommand nucleus of the mormyrid electromotor network
    2015
    Co-Authors: Gerhard Von Der Emde, Leonel Gómez Sena, Rafaella Niso, Kirsty Grant
    Abstract:

    The functional role of the midbrain precommand nucleus (PCN) of the electromotor system was explored in the weakly electric mormyrid fish Gnathonemus Petersii, using extracellular record-ing of field potentials, single unit activity, and microstimulation in vivo. Electromotor-related field potentials in PCN are linked in a one-to-one manner and with a fixed time relationship to the electric organ discharge (EOD) command cycle, but occur later than EOD command activity in the medulla. It is suggested that PCN electromotor-related field potentials arise from two sources: (1) antidromically, by backpropagation across electrotonic syn-apses between PCN axons and command nucleus neurons, and (2) as corollary discharge-driven feedback arriving from the com-mand nucleus indirectly, via multisynaptic pathways. PCN neurons can be activated by electrosensory input, bu

  • dendritic spike back propagation in the electrosensory lobe of Gnathonemus Petersii
    The Journal of Experimental Biology, 2005
    Co-Authors: Leonel Gomez, Morten Kanneworff, Ruben Budelli, Kirsty Grant
    Abstract:

    SUMMARY Spike timing-dependent plasticity that follows anti-Hebbian rules has been demonstrated at synapses between parallel fibers and inhibitory interneurons known as medium ganglionic layer (MG) neurons in the cerebellum-like electrosensory lobe of mormyrid fish. This plasticity is expressed when presynaptic activation is associated with a characteristically broad, postsynaptic action potential, lasting 7-15 ms, occurring within a window of up to 60-80 ms following synaptic activation. Since the site of plastic change is presumably in the apical dendrites, it is important to know where, when and how this broad spike is generated and the manner in which such events propagate within the intrinsic network of the electrosensory lobe. The electrosensory lobe has a strict layered organization that makes the preparation suitable for one dimension current source density analysis. Using this technique in an `in vitro9 interface slice preparation, we found that following either parallel fiber stimulation or an orthogonal field stimulus, a sink appeared in the ganglionic layer and propagated into the molecular layer. Intracellular records from MG somata showed these stimuli evoked broad action potentials whose timing corresponds to this sink. TTX application in the deep fiber layer blocked the synaptically evoked ganglionic layer field potential and the `N39 wave of the outer molecular layer field potential simultaneously, while the molecular layer `N19 and `N29 waves corresponding to synaptic activation of the apical dendrites remained intact. These results confirm the hypothesis that the broad spikes of MG cells originate in the soma and propagate through the molecular layer in the apical dendritic tree, and suggest the possibility that this backpropagation may contribute to `boosting9 of the synaptic response in distal apical dendrites in certain circumstances.

  • The midbrain precommand nucleus of the mormyrid electromotor network.
    Journal of Neuroscience, 2000
    Co-Authors: Gerhard Von Der Emde, Rafaella Niso, Leonel Gómez-sena, Kirsty Grant
    Abstract:

    The functional role of the midbrain precommand nucleus (PCN) of the electromotor system was explored in the weakly electric mormyrid fish Gnathonemus Petersii, using extracellular recording of field potentials, single unit activity, and microstimulation in vivo. Electromotor-related field potentials in PCN are linked in a one-to-one manner and with a fixed time relationship to the electric organ discharge (EOD) command cycle, but occur later than EOD command activity in the medulla. It is suggested that PCN electromotor-related field potentials arise from two sources: (1) antidromically, by backpropagation across electrotonic synapses between PCN axons and command nucleus neurons, and (2) as corollary discharge-driven feedback arriving from the command nucleus indirectly, via multisynaptic pathways. PCN neurons can be activated by electrosensory input, but this does not necessarily activate the whole motor command chain. Microstimulation of PCN modulates the endogenous pattern of electromotor command in a way that can mimic the structure of certain stereotyped behavioral patterns. PCN activity is regulated, and to a certain extent synchronized, by corollary discharge feedback inhibition. However, PCN does not generally function as a synchronized pacemaker driving the electromotor command chain. We propose that PCN neurons integrate information of various origins and individually relay this to the command nucleus in the medulla. Some may also have intrinsic, although normally nonsynchronized, pacemaker properties. This descending activity, integrated in the electromotor command nucleus, will play an important modulatory role in the central pattern generator decision process.

  • the electric image in weakly electric fish physical images of resistive objects in Gnathonemus Petersii
    The Journal of Experimental Biology, 1998
    Co-Authors: A A Caputi, Kirsty Grant, Ruben Budelli, Curtis C Bell
    Abstract:

    The present study describes a measurement-based model of electric image generation in the weakly electric mormyrid fish Gnathonemus Petersii. Measurements of skin impedance, internal resistivity and fish body dimensions have been used to generate an electrical-equivalent model of the fish and to calculate electrical images and equivalent dipole sources for elementary resistive objects. These calculations allow us to understand how exafferent and reafferent signals are sensed by electroreceptors. An object's electric image consists of the modulation of the transcutaneous voltage profile generated by the fish's own discharge. The results suggest a set of rules for electrolocation: (1) the side of the fish where modulation is larger indicates the side on which the object is situated; (2) the object's position in the electroreceptive field is indicated by the point of maximum modulation of the transcutaneous voltage; (3) the degree of focus of the image indicates the distance to the object. In addition, center-surround opposition originating at pre-receptor level is proposed. Both experimental measurements and modeling indicate that fish skin impedance is relatively low (400-11 000 cm 2 ) and mainly resistive. This low skin impedance appears to enhance the local electric organ discharge modulation, the center-surround effect, the signal-to-noise ratio for electrolocation and the active space for electrocommunication.

Peter Rask Møller - One of the best experts on this subject based on the ideXlab platform.

  • the optomotor response in weak electric mormyrid fish can they see
    Ethology, 2010
    Co-Authors: Claudine Teyssedre, Peter Rask Møller
    Abstract:

    The present study has explored the optomotor response in two species of mormyrid fish, Gnathonemus Petersii and Brienomyrus niger. Both species tended to follow a black and white striped stimulus pattern under illumination levels of 6, 12, and 60 lx. The optomotor response ceased to occur under 540 lx. The behavioral data support earlier histological findings implicating the mormyrid retina in dim light vision.

  • short range navigation of the weakly electric fish Gnathonemus Petersii l mormyridae teleostei in novel and familiar environments
    Ethology, 2010
    Co-Authors: Peter Rask Møller, Peter Cain, William Gerin
    Abstract:

    We investigated the electrolocation performance of the weakly electric fish, Gnathonemus Petersii, in novel and familiar environments. By selectively interfering with the fish's sensory input, we determined the sensory channels necessary for navigation and orientation. The fish's task was to locate a circular aperture (diameter: 64 mm) in a wall dividing a 200–1 aquarium into two equal compartments. To assess the fish's performance, we measured (1) the time it took the fish to locate the aperture, (2) the height at which it contacted the divider, (3) its electric organ discharge rate, and (4) the frequency of divider crossings. In the first experiment (novel environment), 50 naive G. Petersii assigned to five groups of 10 fish each (intact, blind, electrically “silent,” blind and “silent,” and shamoperated animals) were tested with the aperture presented randomly in one of three positions (aperture center: 7.6, 17.7, 27.8 cm from the bottom). In a novel environment, G. Petersii depend on active electrolocation. Despite the changing aperture position, over the 15 trials, fish with a functioning electric organ found the aperture, whereas those without one did not. The electric organ discharge rate was inversely correlated with the amount of time spent searching for the aperture. In a second experiment (familiar environment) 20 intact fish learned the position of a fixed aperture. When we subsequently denervated the electric organ in 10 of these animals, their performance did not differ significantly from that of their conspecifics. Thus, once the fish were familiar with the aperture's position, they no longer depended on active electrolocation. We interpret and discuss this behavior as evidence for a “central expectation” and discuss its possible role in electronavigation.

  • The anal fin complex in a weakly discharging electric fish, Gnathonemus Petersii(Mormyridae)
    Journal of Fish Biology, 2005
    Co-Authors: L. Greisman, Peter Rask Møller
    Abstract:

    An examination of the permanent bony structures of the anal fin complex in the mormyrid fish, Gnathonemus Petersii, revealed two new structural sexual dimorphisms: longer proximal pterygiophores and wider anal fin rays in males than in females. Both structures are thought to facilitate the male’s courtship-associated anal fin reflex. Adult male mormyrid fishes are characterized by a dorsally directed indentation of the posterior body wall (anal fin indentation). The expression of this indentation in males, presumably driven by anal fin musculature, was correlated with the fish’s gonadal state: large indentations were associated with high gonado-somatic indices and small indentations with low indices.

  • effects of social interaction on the electric organ discharge in a mormyrid fish Gnathonemus Petersii mormyridae teleostei
    The Journal of Experimental Biology, 2003
    Co-Authors: Thomas A Terleph, Peter Rask Møller
    Abstract:

    African weakly discharging electric fish (Mormyridae) use their self-generated electric signals and electroreceptive abilities for orientation and communication in the context of courtship and territorial interactions. This paper documents socially mediated changes in the electric organ discharge (EOD) of subadult Gnathonemus Petersii under non-breeding environmental conditions. Increases in EOD duration and changes in the relative phase amplitudes occurred in dominant fish during same-sex (male-male, female-female) and opposite-sex interactions. Similar changes were also observed in fish that were restricted in their physical interactions, suggesting that direct contact is not necessary to induce dominance-typical EOD waveforms. The possible communicative functions of these changes are discussed.

  • a sexually dimorphic basal anal fin ray expansion in the weakly discharging electric fish Gnathonemus Petersii
    Journal of Fish Biology, 1998
    Co-Authors: B. Pezzanite, Peter Rask Møller
    Abstract:

    Male Gnathonemus Petersii (Mormyridae) exhibit two structural, sexually dimorphic characters: anal-fin ray bone expansion and an indentation of the posterior ventral body wall (formerly described as anal-fin indentation). Females lack this bone expansion, but may show a slight indentation. Morphometric data on both characters were obtained from radiographs of 414 fish (males and females) ranging in size from 60 to 276 mm Ls. Both body wall indentation and bone expansion began to develop in males of about 120 mm Ls. At 160–180 mm, the sex ratio of fish with expansion to fish without expansion was 50 : 50. Androgens seem to affect the expression of both these sexual dimorphisms. Bone expansion may provide increased bone surface for muscle attachment and thus facilitate the anal-fin reflex during courtship behaviour.

Curtis C Bell - One of the best experts on this subject based on the ideXlab platform.

  • the electric image in weakly electric fish physical images of resistive objects in Gnathonemus Petersii
    The Journal of Experimental Biology, 1998
    Co-Authors: A A Caputi, Kirsty Grant, Ruben Budelli, Curtis C Bell
    Abstract:

    The present study describes a measurement-based model of electric image generation in the weakly electric mormyrid fish Gnathonemus Petersii. Measurements of skin impedance, internal resistivity and fish body dimensions have been used to generate an electrical-equivalent model of the fish and to calculate electrical images and equivalent dipole sources for elementary resistive objects. These calculations allow us to understand how exafferent and reafferent signals are sensed by electroreceptors. An object's electric image consists of the modulation of the transcutaneous voltage profile generated by the fish's own discharge. The results suggest a set of rules for electrolocation: (1) the side of the fish where modulation is larger indicates the side on which the object is situated; (2) the object's position in the electroreceptive field is indicated by the point of maximum modulation of the transcutaneous voltage; (3) the degree of focus of the image indicates the distance to the object. In addition, center-surround opposition originating at pre-receptor level is proposed. Both experimental measurements and modeling indicate that fish skin impedance is relatively low (400-11 000 cm 2 ) and mainly resistive. This low skin impedance appears to enhance the local electric organ discharge modulation, the center-surround effect, the signal-to-noise ratio for electrolocation and the active space for electrocommunication.

  • electric organ corollary discharge pathways in mormyrid fish
    Journal of Comparative Physiology A-neuroethology Sensory Neural and Behavioral Physiology, 1995
    Co-Authors: Curtis C Bell, K Dunn, C Hall, Angel A Caputi
    Abstract:

    Corollary discharge signals associated with the motor command that elicits the electric organ discharge are prominent in the electrosensory lobe of mormyrid fish (Gnathonemus Petersii). Central pathways and structures that convey these signals from the motor command nucleus to the electrosensory lobe are known anatomically, but these structures and their contributions to the various corollary discharge phenomena have not been examined physiologically. This study examines one such structure, the mesencephalic command associated nucleus (MCA).

  • Responses of cells in the mormyrid electrosensory lobe to EODs with distorted waveforms: implications for capacitance detection
    Journal of Comparative Physiology A-neuroethology Sensory Neural and Behavioral Physiology, 1994
    Co-Authors: G. Von Der Emde, Curtis C Bell
    Abstract:

    Mormyrid fish (Gnathonemus Petersii) can discriminate between ohmic and capacitive electrical objects during active electrolocation. The neural basis of this ability was investigated by recording cells in the dorsolateraland medial zones of the electrosensory lobe. Natural electric organ discharges (EODs) distorted by capacitive objects and EODs with computer generated phase shifts were used as stimuli.

Engelmann Jacob - One of the best experts on this subject based on the ideXlab platform.

  • The Use of Supervised Learning Models in Studying Agonistic Behavior and Communication in Weakly Electric Fish
    'Frontiers Media SA', 2021
    Co-Authors: Pedraja Federico, Engelmann Jacob, Herzog Hendrik, Jung, Sarah Nicola
    Abstract:

    Pedraja F, Herzog H, Engelmann J, Jung SN. The Use of Supervised Learning Models in Studying Agonistic Behavior and Communication in Weakly Electric Fish. Frontiers in Behavioral Neuroscience. 2021;15: 718491.Despite considerable advances, studying electrocommunication of weakly electric fish, particularly in pulse-type species, is challenging as very short signal epochs at variable intervals from a few hertz up to more than 100 Hz need to be assigned to individuals. In this study, we show that supervised learning approaches offer a promising tool to automate or semiautomate the workflow, and thereby allowing the analysis of much longer episodes of behavior in a reasonable amount of time. We provide a detailed workflow mainly based on open resource software. We demonstrate the usefulness by applying the approach to the analysis of dyadic interactions of Gnathonemus Petersii. Coupling of the proposed methods with a boundary element modeling approach, we are thereby able to model the information gained and provided during agonistic encounters. The data indicate that the passive electrosensory input, in particular, provides sufficient information to localize a contender during the pre-contest phase, fish did not use or rely on the theoretically also available sensory information of the contest outcome-determining size difference between contenders before engaging in agonistic behavior. Copyright © 2021 Pedraja, Herzog, Engelmann and Jung

  • Spatial learning through active electroreception in Gnathonemus Petersii
    'Elsevier BV', 2019
    Co-Authors: Jung, Sarah Nicola, Künzel Silke, Engelmann Jacob
    Abstract:

    Jung SN, Künzel S, Engelmann J. Spatial learning through active electroreception in Gnathonemus Petersii. ANIMAL BEHAVIOUR. 2019;156:1-10.Navigation is a ubiquitous challenge to mobile animals as it is essential for finding mates, food and shelter. It can rely on self-generated (idiothetic) as well as external (allothetic) information. The contribution of either source of information depends on multiple factors, including the sensory modality. Far-range modalities such as vision have frequently been studied in the context of navigation, but the extent to which near-range sensory systems provide information for navigation is much less understood. Here we focused on spatial learning in the weakly electric fish Gnathonemus Petersii. During their nocturnal excursions these fish typically rely on their short-range active electric sense to explore their environment. We addressed how these fish navigate and how electrosensory information is integrated in navigation. All fish learned to localize a target in a Barnes-like maze. In a series of transfer tests, we found that fish followed an idiothetic navigation strategy. When this strategy failed, fish were able to integrate electrosensory information to complete the task. Our results indicate that the active electric sense contributes to navigation in a resource-efficient and context-dependent manner. Together they show that weakly electric fish can incorporate highly localized sensory input in egocentric navigation. Extending these results will be important to reveal the sensory mechanisms of egocentric navigation in fish as well as to research whether and how spatially confined near-range sensory information might be used to form global representations of space. (C) 2019 The Association for the Study of Animal Behaviour. Published by Elsevier Ltd. All rights reserved

  • Physiological evidence of sensory integration in the electrosensory lateral line lobe of Gnathonemus Petersii
    'Public Library of Science (PLoS)', 2018
    Co-Authors: Fechner Sylvia, Von Der Emde Gerhard, Grant Kirsty, Engelmann Jacob
    Abstract:

    Fechner S, Grant K, von der Emde G, Engelmann J. Physiological evidence of sensory integration in the electrosensory lateral line lobe of Gnathonemus Petersii. PLOS ONE. 2018;13(4): e0194347.Mormyrid fish rely on reafferent input for active electrolocation. Their electrosensory input consists of phase and amplitude information. These are encoded by differently tuned receptor cells within the Mormyromasts, A- and B-cells, respectively, which are distributed over the animal’s body. These convey their information to two topographically ordered medullary zones in the electrosensory lateral line lobe (ELL). The so-called medial zone receives only amplitude information, while the dorsolateral zone receives amplitude and phase information. Using both sources of information, Mormyrid fish can disambiguate electrical impedances. Where and how this disambiguation takes place is presently unclear. We here investigate phase-sensitivity downstream from the electroreceptors. We provide first evidence of phase-sensitivity in the medial zone of ELL. In this zone I-cells consistently decreased their rate to positive phase-shifts (6 of 20 cells) and increased their rate to negative shifts (11/20), while E-cells of the medial zone (3/9) responded oppositely to I-cells. In the dorsolateral zone the responses of E- and I-cells were opposite to those found in the medial zone. Tracer injections revealed interzonal projections that interconnect the dorsolateral and medial zones in a somatotopic manner. In summary, we show that phase information is processed differently in the dorsolateral and the medial zones. This is the first evidence for a mechanism that enhances the contrast between two parallel sensory channels in Mormyrid fish. This could be beneficial for impedance discrimination that ultimately must rely on a subtractive merging of these two sensory streams

  • Sensory flow as a basis for a novel distance cue in freely behaving electric fish
    'Society for Neuroscience', 2017
    Co-Authors: Hofmann Volker, Sanguinetti-scheck, Juan Ignacio, Gómez-sena Leonel, Engelmann Jacob
    Abstract:

    Hofmann V, Sanguinetti-Scheck JI, Gómez-Sena L, Engelmann J. Sensory flow as a basis for a novel distance cue in freely behaving electric fish. The Journal of neuroscience : the official journal of the Society for Neuroscience. 2017;37(2):302-312.The sensory input that an animal receives is directly linked to its motor activity. Behavior thus enables animals to influence their sensory input, a concept referred to as active sensing. How such behavior can serve as a scaffold for generating sensory information is of general scientific interest. In this article, we investigate how behavior can shape sensory information by using some unique features of the sensorimotor system of the weakly electric fish.Based on quantitative behavioral characterizations and computational reconstruction of sensory input, we show how electrosensory flow is actively created during highly patterned, spontaneous behavior in Gnathonemus Petersii The spatiotemporal structure of the sensory input provides information for the computation of a novel distance cue, which allows for a continuous estimation of distance. This has significant advantages over previously known non-dynamic distance estimators as determined from electric image blur.Our investigation of the sensorimotor interactions in pulsatile electrolocation show, for the first time, that the electrosensory flow contains behaviorally relevant information only accessible through active behavior. As patterned sensory behaviors are a shared feature of (active) sensory systems, our results have general implications for the understanding of (active) sensing, with the proposed sensory flow based-measure being potentially pertinent to a broad range of sensory modalities. SIGNIFICANCE STATEMENT: Acquisition of sensory information depends on motion, as either an animal or its sensors move. Behavior can thus actively influence the sensory flow, and in this way, behavior can be seen as a manifestation of the brain's integrative functions. The properties of the active pulsatile electrolocation system in Gnathonemus Petersii allow for the sensory input to be computationally reconstructed, enabling us to link the informational content of spatiotemporal sensory dynamics to behavior. Our study reveals a novel sensory cue for estimating depth that is actively generated by the fishes' behavior. The physical and behavioral similarities between electrolocation and other active sensory systems suggest that this may be a mechanism shared by (active) sensory systems. Copyright 2016 the authors

  • Somatotopic map of the active electrosensory sense in the midbrain of the mormyrid Gnathonemus Petersii
    'Wiley', 2016
    Co-Authors: Hollmann Vanessa, Hofmann Volker, Engelmann Jacob
    Abstract:

    Hollmann V, Hofmann V, Engelmann J. Somatotopic map of the active electrosensory sense in the midbrain of the mormyrid Gnathonemus Petersii. Journal of Comparative Neurology. 2016;524(12):2479-2491.In many vertebrates parallel processing in topographically ordered maps is essential for efficient sensory processing. In the active electrosensory pathway of mormyrids afferent input is processed in two parallel somatotopically ordered hindbrain maps of the electrosensory lateral line lobe (ELL), the dorsolateral zone (DLZ), and the medial zone (MZ). Here phase and amplitude modulations of the self-generated electric field were processed separately. Behavioral data indicates that this information must be merged for the sensory system to categorically distinguish capacitive and resistive properties of objects. While projections between both zones of the ELL have been found, the available physiological data suggests that this merging takes place in the midbrain torus semicircularis (TS). Previous anatomical data indicate that the detailed somatotopic representation present in the ELL is lost in the nucleus lateralis (NL) of the TS, while a rough rostrocaudal mapping is maintained. In our study we investigated the projections from the hindbrain to the midbrain in more detail, using tracer injections. Our data reveals that afferents from both maps of the ELL terminate in a detailed somatotopic manner within the midbrain NL. Furthermore, we provide data indicating that phase and amplitude information may indeed be processed jointly in the NL. J. Comp. Neurol. 524:2479-2491, 2016. 2016 Wiley Periodicals, Inc. 2016 Wiley Periodicals, Inc