CAREER: Detection and localization of communication signals during motion in the electrosensory system.

West Virginia University Research Corporation, Morgantown WV

Investigators

Abstract

Localizing the source of a signal is difficult, particularly when the signal is faint and moving. The ability of the sensory system to extract spatial information has been explored in various systems but scientists still do not understand well the mechanisms that allow this localization process to remain accurate in challenging conditions, particularly when movements occur. In order to identify generic mechanisms that enhance the localization process across sensory systems, a unique organism will be examined. Weakly electric fish must detect and localize other individuals based on the electric signal they emit. The localization process has similarities with both the visual system, where a map is created at the first level of the sensory system, and the auditory system where location is computed by comparing inputs at the two ears. Since these fish localize each other while moving, they are well suited to address the question: are there generic mechanisms, similar across modalities, that enhance the localization process in difficult and changing conditions. Experiments characterizing spatial interactions of these fish, physiological recordings that identify neural mechanisms and modelling studies recapitulating the proposed neural dynamic will allow a deeper understanding of this localization process. A robotic interface will allow a precise interaction with the experimental fish and will also permit to get high school students involved in the project by having them contribute to the design of the robotic component and then participate in its operation during experiments. The goal of this project is to determine how motion influences the coding of weak electrosensory signals and how network dynamic is adapted to realistic movement patterns. Social interactions among these fish rely on the detection and localization of the electric field each fish generates. Although temporal coding of conspecific signals is thoroughly understood, nothing is known about how the location of a conspecific is extracted and how motion affects the detection and localization process. The experiments will provide new insight into sensory processing by showing how realistic signals -that include movement- are encoded and how network dynamic is adapted to typical movements in order to support the efficient extraction of weak cues. The hypothesis is that the encoding of both the presence and location of a conspecific will be enhanced when sender and receiver move in a realistic manner. It is further hypothesized that feedback inputs will sharpen the spatial representation and enhance the detectability of moving signals. To test the hypotheses, the project is divided in 3 aspects: the signal, the coding accuracy and the influence of feedback. The sensory flow experienced by the animal will be characterized via behavioral recordings and 3D modelling of the sensory environment. Neural recordings in the primary sensory area will allow clarifying how signal coding is affected by motion. Finally, the network mechanisms involved in shaping sensory processing will be identified by pharmacological manipulation of feedback pathways and large-scale modelling of the network. This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.