Anticipation and Negative Group Delay in a Retina

TL;DR

This study investigates how retinas can anticipate stimuli using negative group delay, supported by experiments with frog retinas and a theoretical NGD model, revealing the role of OFF responses in anticipation.

Contribution

It demonstrates that the NGD model accurately predicts retinal anticipatory responses and identifies OFF responses as key to the NGD effect in retinas.

Findings

NGD model reproduces experimental anticipatory responses

Prediction horizon depends on stimulus correlation time

Dark Gaussian pulses support NGD mechanism via OFF responses

Abstract

The mechanism of negative group delay (NGD) is used to understand the anticipatory capability of a retina. Experiments with retinas from bull frogs are performed to compare with the predictions of the NGD model. In particulars, whole field stochastic stimulation with various time correlations are used to probe anticipatory responses from the retina. We find that the NGD model can reproduce essential features of experimental observations characterized by the cross correlations between the stimulation and the retinal responses. The prediction horizon of a retina is found to depend on the correlation time of the stimulation as predicted by the NGD model. Experiments with dark and bright Gaussian light pulses further support the NGD mechanism; but only for the dark pulses indicating that the NGD effect of a retina might originate from its OFF response. Our finding suggests that sensory systems capable of using negative feedback for adaptation can give rise to anticipation as a consequence of the delay in the system.