From static electric images to electric flow: towards dynamic perceptual cues in active electroreception.
Active electroreception is an ancestral trait found in many aquatic vertebrates and has evolved independently in two teleost lineages, the Gymnotiformes and the Mormyriformes. Unique to these so-called weakly electric fish is their ability to actively generate electrical currents in the water and sense the electrical properties of the environment. How natural behavior contributes to this sensory system has been of interest to neuroethologists since the pioneering works of Lissmann. Here we report on a mutual modeling and experimental study of the stimuli available during active electrolocation of Gnathonemus petersii (Mormyridae). We show the validity of the model (I) by demonstrating that localized spatial patterns of object induced modulations in the electric field (electric images) are comparable to experimentally mapped 2-dimensional electric images and (II) by replicating earlier key findings showing that a normalized metric of electric image width provides an unambiguous cue for distance estimation. We then show that electric images and the distance metric vary systematically when an object is moved along the trunk. These potential ambiguities with regard to localization lead us to a spatiotemporal analysis of electric images. We introduce a new temporal metric for distance estimation that is based on the normalized spatial properties of electrical images. Finally, based on a survey of exploratory behavior, we show how objects situated at the tail, a region previously neglected, cast global electric images that extend over the whole sensory epithelium of the animals.
Bielefeld University, Faculty of Biology, AG Active Sensing, Universitätsstraße 25, 33615 Bielefeld, Germany. Electronic address: volker.hofmann@uni-bielefeld.de.
Volker
V
Hofmann
Universidad de la Republica, Facultad de Ciencias, Laboratorio de Neurociencias, Igua 4225, Montevideo, Uruguay.
Juan I
JI
Sanguinetti-Scheck
Universidad de la Republica, Facultad de Ciencias, Laboratorio de Neurociencias, Igua 4225, Montevideo, Uruguay.
Leonel
L
Gómez-Sena
Bielefeld University, Faculty of Biology, AG Active Sensing, Universitätsstraße 25, 33615 Bielefeld, Germany.
Jacob
J
Engelmann
D000818:Animals; D003463:Cues; D004215:Distance Perception / Q000502:physiology*; D004555:Electric Fish / Q000502:physiology*; D004557:Electric Organ / Q000502:physiology*; D004560:Electricity; D004594:Electrophysiology; D007091:Image Processing, Computer-Assisted; D008124:Locomotion; D008954:Models, Biological; D009039:Motion Perception; D017711:Nonlinear Dynamics; D013037:Spatial Behavior / Q000502:physiology*