Non-linear population firing rates and voltage sensitive dye signals in visual areas 17 and 18 to short duration stimuli.

David Eriksson,Tamas Tompa,Per E Roland

doi:10.1371/journal.pone.0002673

Abstract

Visual stimuli of short duration seem to persist longer after the stimulus offset than stimuli of longer duration. This visual persistence must have a physiological explanation. In ferrets exposed to stimuli of different durations we measured the relative changes in the membrane potentials with a voltage sensitive dye and the action potentials of populations of neurons in the upper layers of areas 17 and 18. For durations less than 100 ms, the timing and amplitude of the firing and membrane potentials showed several non-linear effects. The ON response became truncated, the OFF response progressively reduced, and the timing of the OFF responses progressively delayed the shorter the stimulus duration. The offset of the stimulus elicited a sudden and strong negativity in the time derivative of the dye signal. All these non-linearities could be explained by the stimulus offset inducing a sudden inhibition in layers II–III as indicated by the strongly negative time derivative of the dye signal. Despite the non-linear behavior of the layer II–III neurons the sum of the action potentials, integrated from the peak of the ON response to the peak of the OFF response, was almost linearly related to the stimulus duration.

Highlights

In the mammalian eye there are ON center and OFF center ganglion cells providing two major pathways to the lateral geniculate nucleus [1]
We examined the relative changes in the membrane potentials of the neurons in layers I–III of the visual areas 17, 18 from the signals from the voltage sensitive dye
Compared to the condition of showing the gray screen, the square stimulus induced a relative increase of the population membrane potential DV(t)

Summary

Introduction

In the mammalian eye there are ON center and OFF center ganglion cells providing two major pathways to the lateral geniculate nucleus [1]. Short stimuli lasting less than 100 ms are perceived as lasting longer than they do This phenomenon is called visual persistence and has puzzled scientists for more than 200 years [7]. A closer look of the responses of the retinal ganglion cells (cat), shows that when the duration of a stimulus is less than 70 ms, the ON retinal ganglion cells fire for 60–70 ms no matter how short the stimulus is [8]. This effect is not due to changes in the intensity of the stimuli [8,9]

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Results

Conclusion