LINEAR ELECTRICAL FLICKER RESPONSES FROM THE EYE OF THE WOLF SPIDER.

Abstract

The linearity of the retinal action potentials from light adapted eyes of intact wolf spiders has been tested using incremental rectangular shaped stimuli and sine wave stimuli. It has been shown that the flicker responses elicited by 8 % incremental flash trains may be predicted by linear superposition of the responses to the component 8 % incremental flashes. In turn, these flash responses can be predicted from linear superposition of the response to an 8 % incremental step by inverting this step response and adding it to itself at the duration of the flash. By tuned amplification, responses at the frequencies of the first two Fourier components of incremental rectangular wave stimuli have been shown to vary directly in amplitude with the amplitudes of these components as functions of duty cycle. Likewise, responses elicited by sine wave incremental stimuli have amplitudes which vary linearly with stimulus amplitudes and which contain inappreciable harmonics of the stimulus frequencies. Linear transfer functions have been fitted to the amplitudes and phases of sine wave responses as functions of frequency, and the responses to 8 % incremental steps have been satisfactorily predicted therefrom. Finally, from high frequency sine wave responses it is proposed to account for the latent period of the retinal action potential by a large number of exponential delay elements (poles), in the example given on the order of 10 to 12.