Prof. Dr. Rüdiger Krahe
Profil
Forschungsthemen3
CL NeuroCure II: Professur Verhaltenspsychologie der Tiere
Quelle ↗Förderer: DFG Exzellenzinitiative Cluster Zeitraum: 03/2016 - 10/2017 Projektleitung: Prof. Dr. Rüdiger Krahe
„Sublethale Effekte von Umweltveränderungen auf tropische Süßwasserfische: Reaktionen eines elektrischen Fisches auf Änderungen von Sauerstoffverfügbarkeit und Temperatur“
Quelle ↗Förderer: DFG Sachbeihilfe Zeitraum: 08/2024 - 07/2027 Projektleitung: Prof. Dr. Rüdiger Krahe
Sublethale Effekte von Umweltveränderungen auf tropische Süßwasserfische: Reaktionen eines elektrischen Fisches auf Änderungen von Sauerstoffverfügbarkeit und Temperatur - Zusatzmittel für Publikationen und Dienstreisen
Quelle ↗Förderer: DFG Sachbeihilfe Zeitraum: 10/2024 - 09/2027 Projektleitung: M. Sc. Stefan Mucha, Prof. Dr. Rüdiger Krahe
Mögliche Industrie-Partner10
Stand: 26.4.2026, 19:48:44 (Top-K=20, Min-Cosine=0.4)
- 55 Treffer62.1%
- Tiere zum Sprechen bringen. Logistik, Wissenschaft, PräsentationP62.1%
- Tiere zum Sprechen bringen. Logistik, Wissenschaft, Präsentation
- Einstein Center for Population DiversityP61.6%
- Einstein Center for Population Diversity
- EU: Context Sensitive Multisensory Object Recognition (HBP)P57.9%
- The Novel Materials Discovery Laboratory (NoMaD)P43.4%
- EU: Context Sensitive Multisensory Object Recognition (HBP)
- 12 Treffer57.9%
- EU: Context Sensitive Multisensory Object Recognition (HBP)P57.9%
- EU: Context Sensitive Multisensory Object Recognition (HBP)
- EU: Context Sensitive Multisensory Object Recognition (HBP)P57.9%
- EU: Context Sensitive Multisensory Object Recognition (HBP)
- 13 Treffer57.9%
- EU: Context Sensitive Multisensory Object Recognition (HBP)P57.9%
- EU: Context Sensitive Multisensory Object Recognition (HBP)
- 12 Treffer57.9%
- EU: Context Sensitive Multisensory Object Recognition (HBP)P57.9%
- EU: Context Sensitive Multisensory Object Recognition (HBP)
- 13 Treffer57.9%
- EU: Context Sensitive Multisensory Object Recognition (HBP)P57.9%
- EU: Context Sensitive Multisensory Object Recognition (HBP)
- 12 Treffer57.9%
- EU: Context Sensitive Multisensory Object Recognition (HBP)P57.9%
- EU: Context Sensitive Multisensory Object Recognition (HBP)
- 37 Treffer57.2%
- EU: Simulation in Multiscale Physical and Biological Systems (STIMULATE)P57.2%
- EU: Simulation in Multiscale Physical and Biological Systems (STIMULATE)
Publikationen25
Top 25 nach Zitationen — Quelle: OpenAlex (BAAI/bge-m3 embedded für Matching).
Nature reviews. Neuroscience · 482 Zitationen · DOI
Communication in troubled waters: responses of fish communication systems to changing environments
2010Evolutionary Ecology · 149 Zitationen · DOI
Journal of Neuroscience · 146 Zitationen · DOI
Despite their simple auditory systems, some insect species recognize certain temporal aspects of acoustic stimuli with an acuity equal to that of vertebrates; however, the underlying neural mechanisms and coding schemes are only partially understood. In this study, we analyze the response characteristics of the peripheral auditory system of grasshoppers with special emphasis on the representation of species-specific communication signals. We use both natural calling songs and artificial random stimuli designed to focus on two low-order statistical properties of the songs: their typical time scales and the distribution of their modulation amplitudes. Based on stimulus reconstruction techniques and quantified within an information-theoretic framework, our data show that artificial stimuli with typical time scales of >40 msec can be read from single spike trains with high accuracy. Faster stimulus variations can be reconstructed only for behaviorally relevant amplitude distributions. The highest rates of information transmission (180 bits/sec) and the highest coding efficiencies (40%) are obtained for stimuli that capture both the time scales and amplitude distributions of natural songs. Use of multiple spike trains significantly improves the reconstruction of stimuli that vary on time scales <40 msec or feature amplitude distributions as occur when several grasshopper songs overlap. Signal-to-noise ratios obtained from the reconstructions of natural songs do not exceed those obtained from artificial stimuli with the same low-order statistical properties. We conclude that auditory receptor neurons are optimized to extract both the time scales and the amplitude distribution of natural songs. They are not optimized, however, to extract higher-order statistical properties of the song-specific rhythmic patterns.
Current Opinion in Neurobiology · 136 Zitationen · DOI
Journal of Neurophysiology · 114 Zitationen · DOI
Multiple topographic representations of sensory space are common in the nervous system and presumably allow organisms to separately process particular features of incoming sensory stimuli that vary widely in their attributes. We compared the response properties of sensory neurons within three maps of the body surface that are arranged strictly in parallel to two classes of stimuli that mimic prey and conspecifics, respectively. We used information-theoretic approaches and measures of phase locking to quantify neuronal responses. Our results show that frequency tuning in one of the three maps does not depend on stimulus class. This map acts as a low-pass filter under both conditions. A previously described stimulus-class-dependent switch in frequency tuning is shown to occur in the other two maps. Only a fraction of the information encoded by all neurons could be recovered through a linear decoder. Particularly striking were low-pass neurons the information of which in the high-frequency range could not be decoded linearly. We then explored whether intrinsic cellular mechanisms could partially account for the differences in frequency tuning across maps. Injection of a Ca2+ chelator had no effect in the map with low-pass characteristics. However, injection of the same Ca2+ chelator in the other two maps switched the tuning of neurons from band-pass/high-pass to low-pass. These results show that Ca2+-dependent processes play an important part in determining the functional roles of different sensory maps and thus shed light on the evolution of this important feature of the vertebrate brain.
Journal of Neuroscience · 90 Zitationen · DOI
The neural computations underlying sensory-guided behaviors can best be understood in view of the sensory stimuli to be processed under natural conditions. This input is often actively shaped by the movements of the animal and its sensory receptors. Little is known about natural sensory scene statistics taking into account the concomitant movement of sensory receptors in freely moving animals. South American weakly electric fish use a self-generated quasi-sinusoidal electric field for electrolocation and electrocommunication. Thousands of cutaneous electroreceptors detect changes in the transdermal potential (TDP) as the fish interact with conspecifics and the environment. Despite substantial knowledge about the circuitry and physiology of the electrosensory system, the statistical properties of the electrosensory input evoked by natural swimming movements have never been measured directly. Using underwater wireless telemetry, we recorded the TDP of Apteronotus leptorhynchus as they swam freely by themselves and during interaction with a conspecific. Swimming movements caused low-frequency TDP amplitude modulations (AMs). Interacting with a conspecific caused additional AMs around the difference frequency of their electric fields, with the amplitude of the AMs (envelope) varying at low frequencies due to mutual movements. Both AMs and envelopes showed a power-law relationship with frequency, indicating spectral scale invariance. Combining a computational model of the electric field with video tracking of movements, we show that specific swimming patterns cause characteristic spatiotemporal sensory input correlations that contain information that may be used by the brain to guide behavior.
Journal of Neuroscience · 75 Zitationen · DOI
Sensory systems evolve in the ecological niches that each species is occupying. Accordingly, encoding of natural stimuli by sensory neurons is expected to be adapted to the statistics of these stimuli. For a direct quantification of sensory scenes, we tracked natural communication behavior of male and female weakly electric fish, <i>Apteronotus rostratus</i>, in their Neotropical rainforest habitat with high spatiotemporal resolution over several days. In the context of courtship, we observed large quantities of electrocommunication signals. Echo responses, acknowledgment signals, and their synchronizing role in spawning demonstrated the behavioral relevance of these signals. In both courtship and aggressive contexts, we observed robust behavioral responses in stimulus regimes that have so far been neglected in electrophysiological studies of this well characterized sensory system and that are well beyond the range of known best frequency and amplitude tuning of the electroreceptor afferents' firing rate modulation. Our results emphasize the importance of quantifying sensory scenes derived from freely behaving animals in their natural habitats for understanding the function and evolution of neural systems.<b>SIGNIFICANCE STATEMENT</b> The processing mechanisms of sensory systems have evolved in the context of the natural lives of organisms. To understand the functioning of sensory systems therefore requires probing them in the stimulus regimes in which they evolved. We took advantage of the continuously generated electric fields of weakly electric fish to explore electrosensory stimulus statistics in their natural Neotropical habitat. Unexpectedly, many of the electrocommunication signals recorded during courtship, spawning, and aggression had much smaller amplitudes or higher frequencies than stimuli used so far in neurophysiological characterizations of the electrosensory system. Our results demonstrate that quantifying sensory scenes derived from freely behaving animals in their natural habitats is essential to avoid biases in the choice of stimuli used to probe brain function.
Journal of Neurophysiology · 71 Zitationen · DOI
We investigated the variability of P-receptor afferent spike trains in the weakly electric fish, Eigenmannia, to repeated presentations of random electric field AMs (RAMs) and quantified its impact on the encoding of time-varying stimuli. A new measure of spike timing jitter was developed using the notion of spike train distances recently introduced by Victor and Purpura. This measure of variability is widely applicable to neuronal responses, irrespective of the type of stimuli used (deterministic vs. random) or the reliability of the recorded spike trains. In our data, the mean spike count and its variance measured in short time windows were poorly correlated with the reliability of P-receptor afferent spike trains, implying that such measures provide unreliable indices of trial-to-trial variability. P-receptor afferent spike trains were considerably less variable than those of Poisson model neurons. The average timing jitter of spikes lay within 1-2 cycles of the electric organ discharge (EOD). At low, but not at high firing rates, the timing jitter was dependent on the cutoff frequency of the stimulus and, to a lesser extent, on its contrast. When spikes were artificially manipulated to increase jitter, information conveyed by P-receptor afferents was degraded only for average jitters considerably larger than those observed experimentally. This suggests that the intrinsic variability of single spike trains lies outside of the range where it might degrade the information conveyed, yet still allows for improvement in coding by averaging across multiple afferent fibers. Our results were summarized in a phenomenological model of P-receptor afferents, incorporating both their linear transfer properties and the variability of their spike trains. This model complements an earlier one proposed by Nelson et al. for P-receptor afferents of Apteronotus. Because of their relatively high precision with respect to the EOD cycle frequency, P-receptor afferent spike trains possess the temporal resolution necessary to support coincidence detection operations at the next stage in the amplitude-coding pathway.
Journal of Experimental Biology · 70 Zitationen · DOI
Gymnotiform weakly electric fish produce an electric signal to sense their environment and communicate with conspecifics. Although the generation of such relatively large electric signals over an entire lifetime is expected to be energetically costly, supporting evidence to date is equivocal. In this article, we first provide a theoretical analysis of the energy budget underlying signal production. Our analysis suggests that wave-type and pulse-type species invest a similar fraction of metabolic resources into electric signal generation, supporting previous evidence of a trade-off between signal amplitude and frequency. We then consider a comparative and evolutionary framework in which to interpret and guide future studies. We suggest that species differences in signal generation and plasticity, when considered in an energetics context, will not only help to evaluate the role of energetic constraints in the evolution of signal diversity but also lead to important general insights into the energetics of bioelectric signal generation.
Neuroscience · 68 Zitationen · DOI
Behavioural Brain Research · 65 Zitationen · DOI
Molecular Ecology · 58 Zitationen · DOI
Emerging fungal diseases have become challenges for wildlife health and conservation. North American hibernating bat species are threatened by the psychrophilic fungus Pseudogymnoascus destructans (Pd) causing the disease called white-nose syndrome (WNS) with unprecedented mortality rates. The fungus is widespread in North America and Europe, however, disease is not manifested in European bats. Differences in epidemiology and pathology indicate an evolution of resistance or tolerance mechanisms towards Pd in European bats. We compared the proteomic profile of blood plasma in healthy and Pd-colonized European Myotis myotis and North American Myotis lucifugus in order to identify pathophysiological changes associated with Pd colonization, which might also explain the differences in bat survival. Expression analyses of plasma proteins revealed differences in healthy and Pd-colonized M. lucifugus, but not in M. myotis. We identified differentially expressed proteins for acute phase response, constitutive and adaptive immunity, oxidative stress defence, metabolism and structural proteins of exosomes and desmosomes, suggesting a systemic response against Pd in North American M. lucifugus but not European M. myotis. The differences in plasma proteomic profiles between European and North American bat species colonized by Pd suggest European bats have evolved tolerance mechanisms towards Pd infection.
Journal of Neuroscience · 58 Zitationen · DOI
Neighboring cells in topographical sensory maps may transmit similar information to the next higher level of processing. How information transmission by groups of nearby neurons compares with the performance of single cells is a very important question for understanding the functioning of the nervous system. To tackle this problem, we quantified stimulus-encoding and feature extraction performance by pairs of simultaneously recorded electrosensory pyramidal cells in the hindbrain of weakly electric fish. These cells constitute the output neurons of the first central nervous stage of electrosensory processing. Using random amplitude modulations (RAMs) of a mimic of the fish's own electric field within behaviorally relevant frequency bands, we found that pyramidal cells with overlapping receptive fields exhibit strong stimulus-induced correlations. To quantify the encoding of the RAM time course, we estimated the stimuli from simultaneously recorded spike trains and found significant improvements over single spike trains. The quality of stimulus reconstruction, however, was still inferior to the one measured for single primary sensory afferents. In an analysis of feature extraction, we found that spikes of pyramidal cell pairs coinciding within a time window of a few milliseconds performed significantly better at detecting upstrokes and downstrokes of the stimulus compared with isolated spikes and even spike bursts of single cells. Coincident spikes can thus be considered "distributed bursts." Our results suggest that stimulus encoding by primary sensory afferents is transformed into feature extraction at the next processing stage. There, stimulus-induced coincident activity can improve the extraction of behaviorally relevant features from the stimulus.
Journal of Experimental Biology · 54 Zitationen
Journal of Experimental Biology · 53 Zitationen · DOI
Gymnotiformes are South American weakly electric fish that produce weak electric organ discharges (EOD) for orientation, foraging and communication purposes. It has been shown that EOD properties vary widely across species and could thus be used as species recognition signals. We measured and quantified the electric signals of various species using a landmark-based approach. Using discriminant function analysis to verify whether these signals are species specific based on different signal parameters, we found that the EOD waveform is a more specific cue than EOD frequency, which shows large overlap across species. Using Apteronotus leptorhynchus as a focal species, we then performed a series of playback experiments using stimuli of different species (varying in frequency, waveform, or both). In an experiment with restrained fish, we found, in contrast to what we predicted, that the choice of stimulus waveform did not affect the production of communication signals. In an experiment with free-swimming fish, the animals spent more time near the playback electrodes and produced more communication signals when the stimuli were within their conspecific frequency range. Waveform again had no measurable effect. The production of communication signals correlated with the frequency difference between the stimulus and the fish's own EOD, but approach behavior did not.
Biology Letters · 50 Zitationen · DOI
Animals often use signals to communicate their dominance status and avoid the costs of combat. We investigated whether the frequency of the electric organ discharge (EOD) of the weakly electric fish, Sternarchorhynchus sp., signals the dominance status of individuals. We correlated EOD frequency with body size and found a strong positive relationship. We then performed a competition experiment in which we found that higher frequency individuals were dominant over lower frequency ones. Finally, we conducted an electrical playback experiment and found that subjects more readily approached and attacked the stimulus electrodes when they played low-frequency signals than high-frequency ones. We propose that EOD frequency communicates dominance status in this gymnotiform species.
Journal of Neurophysiology · 48 Zitationen · DOI
The functional role of cholinergic input in the modulation of sensory responses was studied using a combination of in vivo and in vitro electrophysiology supplemented by mathematical modeling. The electrosensory system of weakly electric fish recognizes different environmental stimuli by their unique alteration of a self-generated electric field. Variations in the patterns of stimuli are primarily distinguished based on their frequency. Pyramidal neurons in the electrosensory lateral line lobe (ELL) are often tuned to respond to specific input frequencies. Alterations in the tuning of the pyramidal neurons may allow weakly electric fish to preferentially select for certain stimuli. Here we show that muscarinic receptor activation in vivo enhances the excitability, burst firing, and subsequently the response of pyramidal cells to naturalistic sensory input. Through a combination of in vitro electrophysiology and mathematical modeling, we reveal that this enhanced excitability and bursting likely results from the down-regulation of an A-type potassium current. Further, we provide an explanation of the mechanism by which these currents can mediate frequency tuning.
Neuroscience · 45 Zitationen · DOI
Journal of Experimental Biology · 45 Zitationen · DOI
Males of the moth Symmoracma minoralis (Snellen) (Lepidoptera: Pyralidae, Nymphulinae) were observed producing a high-intensity calling song (95 dB SPL at a distance of 10 cm) with a complex amplitude and frequency modulation (peaks of carrier frequency at 60 and 120 kHz). This sound is produced by a hitherto unknown type of sound organ located in the last abdominal (genital) segment, which may act as a tymbal. The observed directionality of sound output is probably achieved by means of a hollow cone surrounding the sound organ. Electrophysiological recordings revealed that the tympanal organs of S. minoralis are most sensitive in the frequency range from 50 to at least 100 kHz, which is distinctly higher than the minimum threshold levels in most other moths yet examined. The origin of genital sound production is discussed with respect to abdominal pheromone glands and pheromone-releasing movements.
Journal of Comparative Physiology A · 44 Zitationen · DOI
Journal of Biogeography · 39 Zitationen · DOI
Abstract Aim We present a molecular phylogenetic and biogeographical analysis of B rachyhypopomus occidentalis , one of the few gymnotiform electric fish in Central America, to further understand the colonization and diversification processes of primary freshwater fishes over the Central American Isthmus. Location Lower Central America. Methods We used Bayesian and maximum‐likelihood phylogenetic reconstructions using mitochondrial [cytochrome c oxidase subunit I ( COI ) and ATP synthase 6 and 8 ( ATPase 8 / 6 )] and nuclear ( RAG1 and rhodopsin) genes and extensive geographical sampling, together with molecular clock analyses and tests of biogeographical scenarios to assess the timing and mode of dispersal and diversification. Results We identified high levels of phylogeographical structure, with a highly divergent lineage composed of individuals from western Atlantic Panama (Bocas), sister to all trans‐Andean South American and Central American lineages. The Pacific slope of Panama showed surprisingly little genetic structure compared with the Atlantic slope. Molecular‐clock and biogeographical analyses support two waves of colonization originating from South America: a first dispersal event in the late Miocene with the Bocas lineage as the only relict, and a second major colonization in the late Pliocene leading to the establishment of B. occidentalis in all central and eastern Panama drainages. Main conclusions The genetic structure of B. occidentalis over the Isthmian landscape reflects the progressive, complex and dynamic geological evolution of the region. Our results support multiple colonization events, with an ancient Miocene dispersal event followed by a recent rapid expansion in the late Pliocene, probably facilitated by the final closure of the Isthmus, which provided an important corridor.
Journal of Experimental Biology · 38 Zitationen · DOI
Gymnotiform weakly electric fishes generate electric organ discharges (EODs) and sense perturbations of the resulting electric field for purposes of orientation, prey detection and communication. Some species produce oscillatory ('wave-type') EODs at very high frequencies (up to 2 kHz) that have been proposed to be energetically expensive. If high-frequency EODs are expensive, then fish may modulate their EOD frequency and/or amplitude in response to low-oxygen (hypoxic) stress and/or compensate for costs of signalling through other adaptations that maximize oxygen uptake efficiency. To test for evidence of an energetic cost of signalling, we recorded EOD in conjunction with metabolic rates, critical oxygen tension and aquatic surface respiration (ASR(90)) thresholds in Apteronotus leptorhynchus, a species found in high-oxygen habitats, and Eigenmannia virescens, a species more typically found in low-oxygen waters. Eigenmannia virescens had a lower mean ASR(90) threshold and critical oxygen tension compared with A. leptorhynchus, consistent with field distributions. Within each species, there was no evidence for a relationship between metabolic rate and either EOD frequency or amplitude under normoxia, suggesting that there is no significant direct metabolic cost associated with producing a higher frequency EOD. However, when exposed to progressive hypoxia, fish generally responded by reducing EOD amplitude, which may reduce energetic costs. The threshold at which fish reduced EOD amplitude tended to be lower in E. virescens, a pattern consistent with higher tolerance to hypoxic stress. The results of this study suggest that wave-type fish reduce their EOD amplitude to reduce direct energetic costs without reducing metabolic rate under hypoxia.
Journal of Physiology-Paris · 36 Zitationen · DOI
Journal of Experimental Biology · 34 Zitationen · DOI
Field studies on freely behaving animals commonly require tagging and often are focused on single species. Weakly electric fish generate a species- and individual-specific electric organ discharge (EOD) and therefore provide a unique opportunity for individual tracking without tagging. Here, we present and test tracking algorithms based on recordings with submerged electrode arrays. Harmonic structures extracted from power spectra provide fish identity. Localization of fish based on weighted averages of their EOD amplitudes is found to be more robust than fitting a dipole model. We apply these techniques to monitor a community of three species, <i>Apteronotus rostratus</i>, <i>Eigenmannia humboldtii</i> and <i>Sternopygus dariensis</i>, in their natural habitat in Darién, Panama. We found consistent upstream movements after sunset followed by downstream movements in the second half of the night. Extrapolations of these movements and estimates of fish density obtained from additional transect data suggest that some fish cover at least several hundreds of meters of the stream per night. Most fish, including <i>E</i><i>. humboldtii</i>, were traversing the electrode array solitarily. From <i>in situ</i> measurements of the decay of the EOD amplitude with distance of individual animals, we estimated that fish can detect conspecifics at distances of up to 2 m. Our recordings also emphasize the complexity of natural electrosensory scenes resulting from the interactions of the EODs of different species. Electrode arrays thus provide an unprecedented window into the so-far hidden nocturnal activities of multispecies communities of weakly electric fish at an unmatched level of detail.
Journal of Experimental Biology · 33 Zitationen · DOI
Sensory neurons continually adapt their processing properties in response to changes in the sensory environment or the brain's internal state. Neuromodulators are thought to mediate such adaptation through a variety of receptors and their action has been implicated in processes such as attention, learning and memory, aggression, reproductive behaviour and state-dependent mechanisms. Here, we review recent work on neuromodulation of electrosensory processing by acetylcholine and serotonin in the weakly electric fish Apteronotus leptorhynchus. Specifically, our review focuses on how experimental application of these neuromodulators alters excitability and responses to sensory input of pyramidal cells within the hindbrain electrosensory lateral line lobe. We then discuss current hypotheses on the functional roles of these two neuromodulatory pathways in regulating electrosensory processing at the organismal level and the need for identifying the natural behavioural conditions that activate these pathways.
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- Prof. Dr. Rüdiger Krahe
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- Prof. Dr.
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- Lebenswissenschaftliche Fakultät
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- Institut für Biologie
- Arbeitsgruppe
- Behavioral Physiology
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