Connecting Our Global Electric Fish Community.
To promote electric fish research
To keep the electric fish community together until we can meet face-to-face again
To give early-career scientists the opportunity of communicating novel data while face-to-face seminars and conferences are not allowed
UPCOMING 2021 DATES:
more 2021 dates to come...
10-11 AM EDT
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May 27 Seminar Presentations
10-11 AM EDT
Speakers to be determined. Stay tuned!
April 29 Seminar Presentations
10-11 AM EDT
Dr. Adriana Migliaro
BIO: Adriana Migliaro is a neurobiologist working at Laboratorio de Neurociencias, Universidad de la República in Montevideo, Uruguay. She is interested in understanding the social brain of electric fish and how the environmental cycles modulate the generation of social behavior.
BIO: Alexandra Rudnaya is a Ph.D. student in the Neuroethology laboratory of Jan Benda and Jan Grewe at the University of Tübingen, Germany. She obtained her Master in Neural and Behavioural Sciences at the Graduate Training Center of Neuroscience (GTC) in Tübingen. In her current work she studies the electrophysiological basis of weakly electric fish communication on high beat frequencies in an electrosensory cocktail-party context.
Title: Social modulation of rhythmic behaviors.
Daily rhythms of behavior often result from the expression of a circadian rhythm modulated and synchronized by abiotic and biotic environmental cues. The nocturnal increase in EOD basal rate of both gymnotiform pulse species, Gymnotus omarorum and Brachyhypopomus gauderio is a circadian rhythm that commands a rhythmic behavior with perceptual and communicative purposes. In nature, the behavioral repertoire has a wider range and social interactions are a fundamental source of behavioral diversity. Recordings of the electric behavior in the natural habitat shed light on the modulatory role of the unique environmental influences as well as on the synchronizing effect of conspecifics in a realistic social context.
Title: Encoding beats beyond Nyquist frequency requires a power-law threshold non-linearity in Apteronotus leptorhynchus.
The social context of encounters in the wave-type gymnotiform fish, Apteronotus leptorhynchus, is characterized by the difference frequency (Df) between the electric organ discharges (EOD) of the two present fish. The superposition of the two EODs results in a beating amplitude modulation. Field studies have demonstrated that Dfs beyond half the EOD frequency of the receiving fish play a role in intraspecific and potentially also in interspecific interactions. These frequencies exceed the ranges so far investigated in electrophysiological studies. Accordingly, it is so far unknown whether and how such high Dfs are encoded in the electrosensory system. In this talk I demonstrate that high beat frequencies of up to several multiples of the EOD frequency are indeed encoded in P-unit primary afferents. The P-unit tuning shows reoccurring regions of slow amplitude modulations at multiples of the EOD frequency of the receiving fish. Extracting such slow amplitude modulations of a carrier requires a threshold non-linearity discarding negative half-waves and raising positive half waves to a power larger than two. For the P-units this might mimics synaptic transmission at the receptor cells. Detailed Leaky Integrate and Fire models (LIF) incorporating this mechanism faithfully reproduce high beat-frequency coding of P-units. Our results clearly refute the idea of electrosensation in wave-type fish being a private, species specific communication channel.
March 25, 2021 Seminar Presentations
BIO: Erika is a PhD candidate in the Carlson Lab at Washington University in St. Louis. She is interested in the principles governing brain evolution. Her graduate research focuses on how behavioral novelty and sensory system co-evolution are related to evolutionary change in brain size and structure and the molecular energetic basis of evolutionary changes in brain size and structure.
Dr. Alexandre Melanson
BIO: Alexandre is an Assistant Professor of Physics at the University of Moncton, Canada, since 2019. His current research interests include sensory biophysics, quantitative behavioural modelling, and the impact of neuronal noise on information processing. He holds a PhD from the University of Ottawa, where he developed effective stochastic models of EOD rate variability under the supervision of Dr. André Longtin.
Title: Convergent mosaic enlargement of brain regions related to the evolution of novel electrosensory systems.
Brain region sizes generally scale allometrically with total brain size, but mosaic increases in brain region volume independent of brain size have been found in several lineages and may be related to the evolution of behavioral novelty. Mormyroids evolved a mosaically enlarged cerebellum and hindbrain, but the relationship to their behaviorally novel electrosensory system remains unclear. We addressed this question using gymnotiforms and Synodontis catfishes, which evolved electrosensory systems to varying degrees, independent of mormyroids. Using mCT scans, we quantified brain region scaling for multiple electrogenic, electroreceptive, and non-electrosensing species. We found mosaic increases in hindbrain, cerebellum, and torus semicircularis associated with the evolution of electrogenesis and electroreceptor type. These results show that evolving electrosensory systems is repeatedly and independently associated with changes in individual brain region sizes independent of total brain size, which suggests that selection can impact structural brain composition to favor specific regions involved in novel behaviors.
Title: Rhythmic electromotor behaviour in pulse-type electric fish is explained by synchronization phenomena.
Rather than wait passively for signals to be detected by their sensors, animals actively move in order to gather information from their environment. When active sensing is performed by means of rhythmic movements, reafferent sensory streams are also rhythmic, which is believed to be advantageous for sensory processing. In this presentation, I will report on a behavioural state of pulse-type weakly electric fish during which the EOD rate becomes oscillatory and is tightly correlated to low-frequency rhythmic movements. The oscillatory nature of this electrosensory sampling strategy is in stark contrast to that exhibited during other behaviours.
To characterize the oscillatory dynamics of these rhythmic behavioural states, they are first identified and extracted from long-term observations of freely-moving fish. A successful classification of behavioural states is then achieved by applying t-Distributed Stochastic Neighbour Embedding (tSNE) to the wavelet spectra of the inter-pulse interval time series. Two dominant frequency bands are identified during these bouts of rhythmic behaviour (~0.5 and ~1 Hz). By analyzing the pair associated bandpass filtered signals, I will show that they exhibit several hallmark features of synchronization, including frequency locking, phase slips and limit cycles of the phase dynamics on the torus.
February 25, 2021 Seminar Presentations
Lisa has been working with respirometry and researching animal physiology since she first started working in a lab as student helper during her Biology Bachelors at Humboldt-Universität zu Berlin. Her Bachelor’s project was focused on the breathing patterns of resting cockroaches, whereas her Master’s project in the Lund Vision Group examined walking dung beetles. With the start of her PhD studies in the Krahe Group, she has not only made the switch from arthropods to vertebrates, but moreover from air-breathing to water-breathing organisms. Add a new sensory modality to the mix and you get a much more complex system than a cockroach in a glass.
Dr. Federico Pedraja
Pedraja is currently a postdoctoral research scientist in Dr. Sawtell lab at Columbia University. His interest is centered in three questions: How are external sensory stimuli perceived, integrated and represented within the central nervous system? How does the nervous system generate appropriate behavioral responses based on this input? and how does this behavior affect perception? He recently finished his PhD in the lab of Dr. Engelmann in Bielefeld, Germany. His PhD focused on the role that motor and electromotor behavior have in sensorimotor integration. Before this he did his MSc and BSc studies in Biology both in Uruguay, his home country, under the supervision of Dr. Ruben Budelli.
Title: Electric Fish in Low Oxygen – Hold on Tight to Your Signal.
EODs are often said to be energetically costly, yet weakly electric fish have metabolic rates far below those of most other teleosts. By putting fish in metabolically challenging situations (e.g. low oxygen partial pressure) while simultaneously recording their oxygen consumption rate and EOD signals, we aim to determine the relationship between energy consumption and sensory acquisition. Our results show an average oxygen uptake rate of Eigenmannia virescens that is distinctly higher than the average rate of Apteronotus albifrons. It is therefore not surprising that the EOD amplitude of E. virescens is affected already at higher oxygen levels than that of A. albifrons. At low oxygen levels, E. virescens appears to save energy by adjusting its signals, whereas A. albifrons seems to reduce its behavioural activity, while maintaining EOD amplitude.
We are currently exploring whether EOD amplitude changes in low-oxygen conditions are a passive consequence of challenging the fish’s metabolism or constitute active regulation of energetic investment in sensory acquisition.
Title: Dynamics of sensorimotor behavior in electrolocation.
Electrolocation can be defined as the ability to detect, locate, and characterize objects in the surrounding world. The first part of the seminar will focus on the question of how learning affects electromotor behavior, by evaluating the ability of the electric fish to detect and infer the direction of the object in a reinforced conditioning paradigm. The second part will extend upon these findings by exploring how versatile fish are in altering their previously learned electromotor behavior.
December 3, 2020 Seminar Presentations
Heba is a Ph.D. Candidate in Dr. Stoddard’s Lab, in the Biological Sciences Department at Florida International University, USA. She has a Master's degree in Biology from Virginia Commonwealth University, USA. She received her B.Sc. Honors and her Master's diploma in Immunology from Assiut University, Egypt, where she first discovered her passion for Animal Physiology. She is interested in understanding the bioenergetic trade-offs in animals and how the regulatory mechanisms mediate the physiological performance traits. Her current research investigates how weakly electric fish regulate trade-offs in competing metabolic demands. She is passionate about empowering women to pursue careers in science and technology.
Dr. Matasaburo Fukutomi
Matasaburo holds a Ph.D. from Hokkaido University in Japan, where he studied multisensory integration of cricket's escape behavior. He is currently a Postdoctoral Research Associate in the Carlson lab at Washington University in St. Louis. His interests include sensorimotor rules and mechanisms underlying natural communication behavior, and their evolutions.
Title: Electric fish regulate trade-offs between competing metabolic demands.
Organisms respond to functional demand conflicts by trading off one physiological function against another. We determined that the high energetic demand of electric signals in male Brachyhypopomus gauderio invokes a metabolic trade-off with other cellular functions. We used increase in the metabolism with thyroxine, and measured energy consumption through oxygen respirometry as we partitioned the energy budget pharmacologically. In males, signal metabolism rose and the standard metabolic rate fell in a one-to-one trade-off. Females did the opposite, where the standard metabolism rose and the signal metabolism dropped; in females, egg production falls under the standard metabolism. These metabolic trade-offs in both sexes favor reproduction at the expense of self-maintenance.
Title: Signal diversification is associated with corollary discharge evolution in mormyrid fish.
Corollary discharges are motor-related timing signals that influence central sensory processing. For example, during communication, sensory responses to self-generated signals are inhibited by a corollary discharge. This sensorimotor function is found in many taxa across animals, but little is known about corollary discharge evolution related to signal diversification. We addressed this question by comparing 7 mormyrid species that have varied EOD durations. We found that fish with long-duration EODs have a delayed corollary discharge, and that this time-shifted corollary discharge optimally blocks sensory responses to self-generated EODs. To our knowledge, these findings provide the first evidence of evolutionary change in corollary discharges.
LINK TO PAPERS
Fukutomi, M. & Carlson, B. A. (2020). Signal diversification is associated with corollary discharge evolution in weakly electric fish. J. Neurosci. 40:6345–6356.
Fukutomi, M. & Carlson, B. A. (2020). A history of corollary discharge: Contributions of mormyrid weakly electric fish. Front. Integr. Neurosci. 14:42.
October 29, 2020 Seminar Presentations
Mariana is a Ph.D. student in the Physiology Department at McGill University in Montreal, Canada. She holds a BSc in Physics from the National Autonomous University of Mexico (UNAM) in Mexico City, where she used to work with rodents. Under the supervision of Dr. Maurice Chacron, she currently studies how serotonin modulates neural and behavioral responses to stimuli in South American weakly electric fish. Some of the results of her research can be found in her group’s website (https://www.mcgill.ca/comp-sys-neuro-lab/).
Dr. Avner Wallach
Avner holds a Ph.D. in Electrical Engineering from the Technion (Israel Institute of Technology). He is currently a postdoctoral research scientist in the Sawtell lab at Columbia University, where he studies sensorimotor processing in freely swimming mormyrids. Prior to that, Avner conducted postdoctoral studies on the rodents’ vibrissal system at the Weizmann Institute of Science and on thalamic processing in the preglomerular complex of gymnotiform fish with Len Maler and André Longtin at the University of Ottawa.
Title: Serotonin enhances neuronal and behavioral responses to electrosensory stimuli in weakly electric fish.
Organisms must constantly alter the flow of sensory information based on context in order to successfully interact with the environment (e.g., looking for food is more important when hungry than satiated). Such alteration is achieved through the action of neuromodulators that shape neural responses such as to optimize encoding of certain stimuli. In my talk, I will present how serotonin affects neural and behavioural responses to stimuli arising during social interactions. By favouring bursting activity, serotonin is shown to alter neural and behavioral responses such as to favor processing of stimuli associated with a particular behavioral context.
Title: An internal model of electrostatics underlies active electrolocation in freely swimming mormyrid fish.
The nervous system must distinguish between self- and externally generated components of sensory input to accurately perceive the world. Some of the clearest insights into the mechanisms underlying this process have come from studies of the initial stages of electrosensory processing in fish, where motor-related signals are used to cancel out self-generated sensory input. However, these studies have been performed exclusively in immobilized preparations, raising the question of whether and how these circuits function under natural conditions. To address this, we developed methods for long-term behavioral and neuronal recording in freely swimming fish. We found that the sensory consequences of the fish’s movements are strongly modulated by features of the external environment. Though such effects are easily explained by basic physics, they imply that the task of reafference cancellation is far more complex than previously appreciated. Nevertheless, we found a subset of ELL neurons that responds exclusively to external sensory input. Modeling and analysis suggest that cancellation mechanisms described previously may require electrosensory feedback in order to operate under natural conditions.
September 24, 2020 Seminar Presentations
Dr. Sophie Picq
BIO: Dr. Sophie Picq is currently a postdoctoral research associate in the Gallant Lab at Michigan State University, where she studies the adaptive significance of variation among the electric signals of African weakly electric fish in Gabon. Prior to that, she studied the evolutionary forces driving diversity in the electric signals of South American weakly electric fish for her MSc research with Dr. Krahe and Dr. Bermingham (McGill & STRI) in Panama. For her PhD, she took a short break from electric fish and studied the genomic, ecological, and behavioral bases of speciation in the Caribbean coral reef hamlet fish in the Puebla lab (GEOMAR, IMPRS). She is fascinated by diversity and the processes that initiate and maintain species division, especially in fish, and is passionate about conducting her research in the field.
BIO: Stefan Mucha is a Ph. D. candidate in the behavioral physiology workgroup at the Humboldt-University of Berlin, Germany. His research focuses on how environmental factors such as oxygen availability shape the behavior and physiology of mormyrid weakly electric fish. To pursue this question, he conducts respirometry experiments and behavioral studies in the laboratory and in the field. You can find out more about Stefan Mucha and his research on Twitter (https://twitter.com/SBiosci), on his blog (https://thefuzzylogic.org/), and on his group's website (https://www.biologie.hu-berlin.de/en/gruppenseiten-en/vhphysiol/research/mormyrids).
Title: Assessing the contributions of sexual and natural selection in the evolution of EOD diversity in the African weakly electric fish, Paramormyrops kingsleyae.
Mormyrids are known for the diversity of their EODs: phase number is one axis of this variation. Species with biphasic EODs have repeatedly evolved from triphasic ancestors, but the evolutionary forces that act on phase number are unknown. One species, P. kingsleyae, presents an opportunity to understand these forces: it is ancestrally triphasic, but evolved biphasic EODs in three independent populations. Recently, we demonstrated EOD variation in P. kingsleyae is not the result of genetic drift and posed the alternative hypotheses of either sexual or natural selection. During a recent expedition to Gabon, we tested whether populations of P. kingsleyae exhibit local EOD preferences using a novel interactive behavioral playback assay. Next, we tested whether populations with different EOD types specialize on different prey items by conducting surveys of local invertebrate communities and stomach contents and performed DNA metabarcoding. In this presentation, I will share recent findings from these ongoing analyses, which will serve as first steps towards identifying the relative contributions of sexual and natural selection in mormyrid EOD evolution.
Title: Bugging the swamp: using microcontrollers to record weakly electric fish in the wild.
Weakly electric fish offer unique opportunities for the monitoring of natural communication and foraging behavior by detecting their electric organ discharges (EODs). However, the equipment needed to record EODs can be a limiting factor for many field studies as it is usually expensive and not built to withstand outdoor conditions. We developed a new approach to record and log EODs using autonomous recording devices based on microcontroller units. We present the first glimpse at field data, recorded at Lake Nabugabo, Uganda, and discuss the possible applications of this emerging technology in ecological field research with weakly electric fish.
2020 Efish Virtual Meeting
THURSDAY, JULY 30
10 AM - NOON
Dr. Jan Benda
Universität Tübingen, Tübingen, Germany
Title: Uncovering the secret lives of electric fish
Electric fish are an exotic but well known model organism for neurophysiological studies at the cellular level because of their unique electric behaviors in the immobilized fish. Despite this we know surprisingly little about their natural behaviors - mating, breeding, territoriality, social interactions, communication, etc. Recent technological progress, however, makes it possible to observe electric fish in their natural habitats. With arrays of electrodes we can observe how these fish move and communicate. But also simple and short recordings with fishfinders - analyzed appropriately - reveal many details of the secret lives of electric fish. I my talk I briefly introduce the methods we are developing for analysing EOD recordings of wave and pulse fish, present a few findings from our recent field recordings, and sketch my vision on citizen science field research on electric fish behavior and ecology.
Dr. Laura Quintana
Instituto de Investigaciones Biológicas Clemente Estable, Montevideo, Uruguay
Title: Regulation of territorial aggression in a weakly electric fish: the role of brain sex steroids.
Understanding the steroid modulation of aggression has gained novel insight by focusing on aggressive behavior uncoupled from the breeding season. Gymnotus omarorum, a weakly electric fish, is a seasonal breeder with year-long territorial aggression. Natural spatial distribution shows that territory size is sexually dimorphic and depends on gonadal hormones in the breeding season, and is independent of sex but determined by body size in the non-breeding season. In line with this, in laboratory settings non-breeding territorial aggression is sexually monomorphic, and outcome depends only on body size. This behavior is independent of gonadal hormones but shows a strong dependence on fast-acting estrogens. Quantification of plasmatic and brain steroids, as well as brain gene expression studies, show that neurosythesized estrogens are the forefront modulators of aggression. This teleost model reveals a role of brain estrogen in the control of non-breeding aggression, a common strategy among distant vertebrate species.
Dr. Harold Zakon
The University of Texas at Austin, Texas, USA
Title: The Case of the Missing Sodium Channel: a molecular mystery partially solved.
As the two groups of weakly electric fish independently evolved electric organs from muscle, a muscle-expressing voltage-gated sodium channel gene lost its expression from muscle and gained it in the EO independently in both lineages; this was the first step by which this gene became specialized for generating electric communication signals. We identified the molecular basis for selective sodium channel gene expression in vertebrate muscle and discovered the processes responsible for its loss of expression from muscle in gymnotiforms. Intriguingly, these same processes did not occur in mormyrids showing that different evolutionary paths may lead to the same end result. Further detective work will be necessary to solve the “mystery of mormyrid muscle.”