Encoding electric signals by Gymnotus omarorum: Heuristic modeling of tuberous electroreceptor organs

Waveform sensitivity of electroreceptors in the pulse weakly electric fish Gymnotus omarorum

“…This study extends our previous work on waveform encoding in the pulse gymnotiform Gymnotus omarorum Richer-de-Forges, Crampton and Albert 2009, using objects with capacitive impedance Cilleruelo and Caputi, 2012). We compared in non-anesthetized and non-curarized selfdischarging fish the response of burst duration coders to probe objects having resistive or capacitive impedance that changed the sLEOD amplitude and waveform over a wide range.…”

“…Moreover, a previous report in the same genus suggests that burst duration coder subtypes cannot be distinguished on the basis of best frequency or threshold at best frequency because these parameters are widely distributed in both classes (Watson and Bastian, 1979). The additional role of the relative phases amongst the frequency components of the EOD waveform was also postulated theoretically (Cilleruelo and Caputi, 2012). However, in the case of our experiments, capacitance provokes a non-independent change of amplitude and phase of such components and, therefore, further reductionist studies independently altering phase and amplitude of the waveform frequency components would be required to pinpoint their relative roles in receptor responsiveness.…”

“…This variable should express a combination of amplitude and phase of the different sLEOD frequency components. Heuristic modeling of receptor responsiveness (Cilleruelo and Caputi, 2012) accounts for previous data (Bastian, 1976(Bastian, , 1977Bennett, 1971;McKibben et al, 1993;Yager and Hopkins, 1993;Watson and Bastian, 1979). Such a model, consisting of four stages (high-pass filtering, resonance, rectification and pulse encoding; Cilleruelo and Caputi, 2012) predicts the sensitivity of receptors to distortions in the amplitude and phase spectra of the natural stimulus waveform.…”

“…In fact, changes in the waveform of the foveal sLEOD that do not affect the total energy of the stimulus signal (as measured by its root mean squared value, rms) are detected by the fish, as shown by strong novelty responses in Gymnotus omarorum to changes in waveform only (reported as Gymnotus carapo in Aguilera and Caputi, 2003). In addition, electroreceptor modeling showed the possibility that these receptors were able to respond differently to capacitive and resistive objects (Cilleruelo and Caputi, 2012). However, to the extent of our knowledge, the effect of changes in sLEOD waveform on primary afferent responses themselves has not been well examined in pulse gymnotiforms.…”

Waveform Sensors: The Next Challenge in Biomimetic Electroreception

“…The calcium concentration increase due to calcium channel opening links the opening probability of neighbor calcium and potassium channels causing membrane resonance and therefore changes in electroreceptor responsiveness to different waveform. Cilleruelo and Caputi's extended Bennett's model for gymnotiformes ( Figure 1B, 64 ) suggested an electronic implementation using discrete elements. 65 This test of function suggested that the same algorithms and structure can be implemented using integrated nanotechnologies.…”