Information transfer in P-type electroreceptors.

Abstract

Weakly electric fish continuously emit a quasi-sinusoidal electric organ discharge (EOD) to probe their near environment (electrolocation). P-type tuberous receptors located on their skin respond to the periodic EOD by triggering action potentials in a phase locked manner. It is observed that the intervals between firing times are random multiples of the EOD period. This is known as skipping. Weak carrier amplitude modulations caused by relevant stimuli are encoded by P-type receptors through modulation of their output firing rate. We investigate the effect of P---the baseline firing probability per EOD cycle of a receptor---as well as of other parameters on the quality of information transfer in four biophysically plausible numerical receptor models. In particular, we study how internal noise affects the transduction of random EOD modulations, since noise is perhaps essential for good neural computation. Information is quantified using the stimulus reconstruction technique. We discuss the firing characteristics of the four considered models and discuss their relevance as models of P-afferents. Our information measurements indicate that the presence of noise may enhance information transfer in these receptors. And the coding quality is found to not depend on P alone, but also on the actual combination of biophysical parameters that determine P.