Anomalous pupillary responses to M-cone onsets are linked to L:M ratio

Neil R.A. Parry, Elena Rodrigo-Diaz, Ian J. Murray

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M-cone stimulation induces a pupil constriction to stimulus offset, whereas, with L cones, the pupil responds conventionally with a constriction to onset. To test the possibility that this paradox is linked to the LVMratio, we measured the strength of the effect by injecting a variable amount of positive or negative luminance contamination on either side of M-cone isolation and identifying a balance point at which the pupil responded equally to onset and offset.Nineteen individualswere recruited. In observers with lowLVMratio, the paradoxical effect wasweak. There was a significant relationship (r2 =0.561) between the balance point and LVMratio. The effect is likely to be linked to strong inhibitory signals associated with cone-opponent pathways.

Original languageEnglish
Pages (from-to)163-169
JournalOptical Society of America. Journal A: Optics, Image Science, and Vision
Issue number4
Publication statusPublished - 1 Apr 2020


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