scholarly journals Decision letter: Peripheral sensory coding through oscillatory synchrony in weakly electric fish

2015 ◽  
Keyword(s):  
Electric Fish ◽  
Weakly Electric Fish ◽  
Sensory Coding ◽  
Weakly Electric ◽  
Peripheral Sensory

scholarly journals Detection of transient synchrony across oscillating receptors by the central electrosensory system of mormyrid fish

eLife ◽  
2016 ◽  
Vol 5 ◽  
Author(s):  
Alejandro Vélez ◽  
Bruce A Carlson
Keyword(s):  
Electric Fish ◽  
Frequency Tuning ◽  
Weakly Electric Fish ◽  
Sensory Coding ◽  
Electrosensory System ◽  
Mormyrid Fish ◽  
Intrinsic Oscillation ◽  
Oscillation Frequencies ◽  
Weakly Electric ◽  
Peripheral Sensory

Recently, we reported evidence for a novel mechanism of peripheral sensory coding based on oscillatory synchrony. Spontaneously oscillating electroreceptors in weakly electric fish (Mormyridae) respond to electrosensory stimuli with a phase reset that results in transient synchrony across the receptor population (<xref ref-type="bibr" rid="bib5">Baker et al., 2015</xref>). Here, we asked whether the central electrosensory system actually detects the occurrence of synchronous oscillations among receptors. We found that electrosensory stimulation elicited evoked potentials in the midbrain exterolateral nucleus at a short latency following receptor synchronization. Frequency tuning in the midbrain resembled peripheral frequency tuning, which matches the intrinsic oscillation frequencies of the receptors. These frequencies are lower than those in individual conspecific signals, and instead match those found in collective signals produced by groups of conspecifics. Our results provide further support for a novel mechanism for sensory coding based on the detection of oscillatory synchrony among peripheral receptors.

Neuronal mechanisms for object discrimination in the weakly electric fish Eigenmannia virescens

1977 ◽  
Vol 66 (1) ◽  
pp. 141-158
Author(s):  
A. S. Feng ◽  
T. H. Bullock
Keyword(s):  
Electric Fish ◽  
Electrical Stimulus ◽  
Weakly Electric Fish ◽  
Object Discrimination ◽  
Lateral Line Nerve ◽  
Response Differentiation ◽  
Neuronal Mechanisms ◽  
Eigenmannia Virescens ◽  
Weakly Electric ◽  
Peripheral Sensory

The peripheral sensory basis for object discrimination was investigated in the weakly electric fish Eigenmannia virescens. Single unit recordings were made from the primary afferent fibres in the posterior branch of the anterior lateral line nerve while the local electric field (self-generated and stimulated) was modified by external resistance and capacitance shunts. Both fibre types (probability and phase coders) responded differentially to capacitance and resistance shunts of equivalent impedence. The degree of response differentiation between the two shunting conditions varied with the intensity of the electrical stimulus at the receptor. These data suggest that the primary electroreceptors can discriminatively encode the two electrical characteristics of ‘objects’. However, since the response of primary electroreceptors also varied with the spatial orientation of the shunting electrodes, central structures must play an important role in object discrimination.

scholarly journals Peripheral sensory coding through oscillatory synchrony in weakly electric fish

eLife ◽  
2015 ◽  
Vol 4 ◽  
Author(s):  
Christa A Baker ◽  
Kevin R Huck ◽  
Bruce A Carlson
Keyword(s):  
Sensory System ◽  
Spike Timing ◽  
Weakly Electric Fish ◽  
Evolutionary Divergence ◽  
Sensory Coding ◽  
Social Environments ◽  
Communication Signals ◽  
Electric Pulses ◽  
Weakly Electric ◽  
Peripheral Sensory

Adaptations to an organism's environment often involve sensory system modifications. In this study, we address how evolutionary divergence in sensory perception relates to the physiological coding of stimuli. Mormyrid fishes that can detect subtle variations in electric communication signals encode signal waveform into spike-timing differences between sensory receptors. In contrast, the receptors of species insensitive to waveform variation produce spontaneously oscillating potentials. We found that oscillating receptors respond to electric pulses by resetting their phase, resulting in transient synchrony among receptors that encodes signal timing and location, but not waveform. These receptors were most sensitive to frequencies found only in the collective signals of groups of conspecifics, and this was correlated with increased behavioral responses to these frequencies. Thus, different perceptual capabilities correspond to different receptor physiologies. We hypothesize that these divergent mechanisms represent adaptations for different social environments. Our findings provide the first evidence for sensory coding through oscillatory synchrony.

scholarly journals Sparse and dense coding of natural stimuli by distinct midbrain neuron subpopulations in weakly electric fish

2011 ◽  
Vol 106 (6) ◽  
pp. 3102-3118 ◽  
Author(s):  
Katrin Vonderschen ◽  
Maurice J. Chacron
Keyword(s):  
Sparse Coding ◽  
Electric Fish ◽  
Neural Representation ◽  
Weakly Electric Fish ◽  
Torus Semicircularis ◽  
Dense Coding ◽  
Natural Stimuli ◽  
Central Neurons ◽  
Weakly Electric ◽  
Peripheral Sensory

While peripheral sensory neurons respond to natural stimuli with a broad range of spatiotemporal frequencies, central neurons instead respond sparsely to specific features in general. The nonlinear transformations leading to this emergent selectivity are not well understood. Here we characterized how the neural representation of stimuli changes across successive brain areas, using the electrosensory system of weakly electric fish as a model system. We found that midbrain torus semicircularis (TS) neurons were on average more selective in their responses than hindbrain electrosensory lateral line lobe (ELL) neurons. Further analysis revealed two categories of TS neurons: dense coding TS neurons that were ELL-like and sparse coding TS neurons that displayed selective responses. These neurons in general responded to preferred stimuli with few spikes and were mostly silent for other stimuli. We further investigated whether information about stimulus attributes was contained in the activities of ELL and TS neurons. To do so, we used a spike train metric to quantify how well stimuli could be discriminated based on spiking responses. We found that sparse coding TS neurons performed poorly even when their activities were combined compared with ELL and dense coding TS neurons. In contrast, combining the activities of as few as 12 dense coding TS neurons could lead to optimal discrimination. On the other hand, sparse coding TS neurons were better detectors of whether their preferred stimulus occurred compared with either dense coding TS or ELL neurons. Our results therefore suggest that the TS implements parallel detection and estimation of sensory input.

scholarly journals The weakly electric fish, Apteronotus albifrons, actively avoids experimentally induced hypoxia

2021 ◽  
Author(s):  
Stefan Mucha ◽  
Lauren J. Chapman ◽  
Rüdiger Krahe
Keyword(s):  
Active Avoidance ◽  
Electric Fish ◽  
Electric Organ ◽  
The Other ◽  
Weakly Electric Fish ◽  
Dissolved Oxygen Concentration ◽  
Shuttle Box ◽  
Freshwater Habitats ◽  
Electric Organ Discharges ◽  
Weakly Electric

AbstractAnthropogenic environmental degradation has led to an increase in the frequency and prevalence of aquatic hypoxia (low dissolved oxygen concentration, DO), which may affect habitat quality for water-breathing fishes. The weakly electric black ghost knifefish, Apteronotus albifrons, is typically found in well-oxygenated freshwater habitats in South America. Using a shuttle-box design, we exposed juvenile A. albifrons to a stepwise decline in DO from normoxia (> 95% air saturation) to extreme hypoxia (10% air saturation) in one compartment and chronic normoxia in the other. On average, A. albifrons actively avoided the hypoxic compartment below 22% air saturation. Hypoxia avoidance was correlated with upregulated swimming activity. Following avoidance, fish regularly ventured back briefly into deep hypoxia. Hypoxia did not affect the frequency of their electric organ discharges. Our results show that A. albifrons is able to sense hypoxia at non-lethal levels and uses active avoidance to mitigate its adverse effects.

scholarly journals Electric signal synchronization as a behavioural strategy to generate social attention in small groups of mormyrid weakly electric fish and a mobile fish robot

2021 ◽  
Author(s):  
Martin Worm ◽  
Tim Landgraf ◽  
Gerhard von der Emde
Keyword(s):  
Small Groups ◽  
Electric Fish ◽  
Social Attention ◽  
Weakly Electric Fish ◽  
Electric Signal ◽  
Fish Robot ◽  
Wide Range ◽  
Signal Synchronization ◽  
Weakly Electric ◽  
Attention Hypothesis

AbstractAfrican weakly electric fish communicate at night by constantly emitting and perceiving brief electrical signals (electric organ discharges, EOD) at variable inter-discharge intervals (IDI). While the waveform of single EODs contains information about the sender’s identity, the variable IDI patterns convey information about its current motivational and behavioural state. Pairs of fish can synchronize their EODs to each other via echo responses, and we have previously formulated a ‘social attention hypothesis’ stating that fish use echo responses to address specific individuals and establish brief dyadic communication frameworks within a group. Here, we employed a mobile fish robot to investigate the behaviour of small groups of up to four Mormyrus rume and characterized the social situations during which synchronizations occurred. An EOD-emitting robot reliably evoked social following behaviour, which was strongest in smaller groups and declined with increasing group size. We did not find significant differences in motor behaviour of M. rume with either an interactive playback (echo response) or a random control playback by the robot. Still, the robot reliably elicited mutual synchronizations with other fish. Synchronizations mostly occurred during relatively close social interactions, usually when the fish that initiated synchronization approached either the robot or another fish from a distance. The results support our social attention hypothesis and suggest that electric signal synchronization might facilitate the exchange of social information during a wide range of social behaviours from aggressive territorial displays to shoaling and even cooperative hunting in some mormyrids.

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