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Study of Electrocommunication in Gymnotus carapo using transfer entropy

Grant number: 14/23119-6
Support type:Scholarships in Brazil - Scientific Initiation
Effective date (Start): December 01, 2014
Effective date (End): November 30, 2015
Field of knowledge:Biological Sciences - Biophysics
Principal Investigator:Reynaldo Daniel Pinto
Grantee:Amanda Sofie Rios
Home Institution: Instituto de Física de São Carlos (IFSC). Universidade de São Paulo (USP). São Carlos , SP, Brazil

Abstract

Electric fish that generate weak bioelectric fields such as the tuvira (Gymnotus carapo), have an electric sensorial system that enables them to make use of self-generated pulses to communicate and construct an "electric image of their surroundings. Recently, it was shown that the neurons dedicated to the identification of the instant of occurrence of self-generated pulses present a refractory period atypically long. Thus, after the fish emits a pulse, part of his nervous system remains insensitive to the pulses emitted by closely located conspecifics. Therefore, this mechanism certainly affects this animal's communication strategy. In this project, we will execute non-invasive experiments in which a real fish will be stimulated by electric pulses that were either pre-recorded from other animals, random or periodic. Also, we have devised experiments in which two fish will be interacting freely in the same aquarium. We will implement information theory techniques such as the Transfer Entropy (TE) to study the effects of the refractory period in the transmission of information: We will use the refractory period (RP) as a parameter to reconstruct the pulse serie of the stimulus based on the response serie (Considering that the stimulus pulses that occur right after an electric discharge from the animal, that is, in an interval that is smaller than the refractory period, will not be detected. These pulses will therefore be removed from the reconstructed pulse serie of the stimulus). The reconstructed stimulus pulse serie and the response pulse serie will then be used to calculate the TE for each value of refractory period being considered. Thus, we will be able to repeat this procedure so as to study how the TE behaves as a function of the RP value. We believe that in the case that the refractory period represents a time scale of segregation between pulses used for electrocommunication and electrolocalization, we will observe maximized TE peaks around a RP value that is similar to the biological RP value. As a result, we would be confirming indirectly the existence of the refractory period in the studied species, establishing a new form of information theory application that can be used in the study of electrocommunication in these animals.