Responses of class R3 retinal ganglion cells of the frog to moving configurational bars: effect of the stimulus velocity.
Discrimination of 'prey' (bars elongated in the direction of movement; W- or H-orientation) and 'non-prey' (bars perpendicular to the direction of movement; A- or V-orientation) stimuli in freely moving amphibians is velocity-invariant. Whether or not this phenomenon is present in cells belonging to a general decision making neuronal process remains questionable. Present investigations report the effect of the angular velocity of the stimulus on the discrimination function of class R3 (transient ON-OFF) retinal ganglion cells. The main conclusions of this work are the following: (1) irrespective of the angular velocity, class R3 neurons always prefer vertically (A-) to horizontally (W-) oriented stripes as long as the stimulus length remains inferior to the receptive field size; (2) this preference for small A-stimuli is best expressed when stimuli are moved at V = 7.6 degrees/s; (3) a preference reversal is induced by stripes longer than the receptive field via a dual process involving both spatial and temporal mechanisms; (4) this preference reversal is velocity-dependent: the longer the bar, the faster the velocity should be.
Département Neurosciences, CNRS, UMR 6558 Faculté des Sciences, Poitiers, France.
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Beauquin
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Gaillard
D000818:Animals; D009039:Motion Perception / Q000502:physiology*; D010775:Photic Stimulation / Q000379:methods; D011893:Rana esculenta / Q000502:physiology*; D012165:Retinal Ganglion Cells / Q000145:classification / Q000502:physiology*; D013997:Time Factors