Automatic Realistic Real Time Stimulation/Recording in Weakly Electric Fish: Long Time Behavior Characterization in Freely Swimming Fish and Stimuli Discrimination

Abstract

Weakly electric fish are unique model systems in neuroethology, that allow experimentalists to non-invasively, access, central nervous system generated spatio-temporal electric patterns of pulses with roles in at least 2 complex and incompletely understood abilities: electrocommunication and electrolocation. Pulse-type electric fish alter their inter pulse intervals (IPIs) according to different behavioral contexts as aggression, hiding and mating. Nevertheless, only a few behavioral studies comparing the influence of different stimuli IPIs in the fish electric response have been conducted. We developed an apparatus that allows real time automatic realistic stimulation and simultaneous recording of electric pulses in freely moving Gymnotus carapo for several days. We detected and recorded pulse timestamps independently of the fish’s position for days. A stimulus fish was mimicked by a dipole electrode that reproduced the voltage time series of real conspecific according to previously recorded timestamp sequences. We characterized fish behavior and the eletrocommunication in 2 conditions: stimulated by IPIs pre-recorded from other fish and random IPI ones. All stimuli pulses had the exact Gymontus carapo waveform. All fish presented a surprisingly long transient exploratory behavior (more than 8 h) when exposed to a new environment in the absence of electrical stimuli. Further, we also show that fish are able to discriminate between real and random stimuli distributions by changing several characteristics of their IPI distribution.

Evidence for mutual allocation of social attention through interactive signaling in a mormyrid weakly electric fish

“…Gymnotiform Gymnotus carapo exhibit a strongly reduced sensitivity for electric signals directly after they generate an EOD (42). In an interactive electrical playback protocol, G. carapo preferentially discharged within the time window during which the receptors of the conspecific represented by the playback would have been more sensitive to the signals of the fish, which may enable these animals to adjust their EODs with respect to those of a conspecific, depending on an intent to communicate (43). Similarly, the corollary discharge, generated in the mormyrid brain each time an EOD is initiated, results in inhibitory postsynaptic potentials of up to 10 ms that are measurable in the nucleus of the electrosensory lateral line lobe (nELL) (37).…”

Modular Acquisition and Stimulation System for Timestamp-Driven Neuroscience Experiments

“…The system described in this paper (source code at [8]) can be applied to neuroscience research both on in vivo or in vitro experiments requiring deterministic timing and synchronous stimuli generation, such as the study of neural coding on the visual system of flies [21]. It can also be applied to experiments in neuroethology, for example on the analysis of electrocommunication signals produced by pulse-type electric fish [22,23,24,25]. The employed digital pulse timestamping technique allows to achieve a measurement precision in the order of 1 µs, much higher than most ADC-based acquisition systems.…”

Individual discrimination of freely swimming pulse-type electric fish from electrode array recordings

“…In order to acquire good quality labeled training and testing data, covering the system dynamics over most of the operating range, it is important to get the fish to swim around all aquarium. In Gymnotus sp., this usually occurs naturally, as the fish has a tendency to explore the surroundings when it is moved to a different environment [8]. The experimenter can also arouse an inactive animal by mechanically disturbing the aquarium.…”

“…Recording from freely swimming fish is challenging and traditional techniques based in arrays of electrodes fixed in the aquarium are still employed [6][7][8]. The idea is similar to using an electrode array to record from neurons in the central nervous system of an animal [9,10], however, here the spiking "neurons" are not stationary in space and the problem resembles, but it is even more complicated than, that of recording from arrays of electrodes which present drift along time [11].…”

“…Most of the existing works try to discriminate individuals by employing non-automatic procedures involving visual inspection of EOD pulse amplitude and duration [14], sometimes aided by video recordings that allow inferring fish position, which is then manually correlated to pulse amplitude and polarity changes [5]. Still, those methods are time-consuming and often applied solely to a few minutes of experimental data, and therefore they do not produce sufficient input to enable statistical and information-theoretic approaches [8] to study spike train coding [19].…”