Melanopsin photoreception differentially modulates rod-mediated and cone-mediated human temporal vision

Samir Uprety; Prakash Adhikari; Beatrix Feigl; Andrew J Zele

doi:10.1016/j.isci.2022.104529

Melanopsin photoreception differentially modulates rod-mediated and cone-mediated human temporal vision

iScience. 2022 Jun 3;25(7):104529. doi: 10.1016/j.isci.2022.104529. eCollection 2022 Jul 15.

Authors

Samir Uprety^{1

2}, Prakash Adhikari^{1

2}, Beatrix Feigl^{1

3

4}, Andrew J Zele^{1

2}

Affiliations

¹ Centre for Vision and Eye Research, Queensland University of Technology (QUT), Brisbane, QLD 4059, Australia.
² School of Optometry and Vision Science, Queensland University of Technology (QUT), Brisbane, QLD 4059, Australia.
³ School of Biomedical Sciences, Queensland University of Technology (QUT), Brisbane, QLD 4059, Australia.
⁴ Queensland Eye Institute, Brisbane, QLD 4101, Australia.

Abstract

To evaluate the nature of interactions between visual pathways transmitting the slower melanopsin and faster rod and cone signals, we implement a temporal phase summation paradigm in human observers using photoreceptor-directed stimuli. We show that melanopsin stimulation interacts with and alters both rod-mediated and cone-mediated vision regardless of whether it is perceptually visible or not. Melanopsin-rod interactions result in either inhibitory or facilitatory summation depending on the temporal frequency and photoreceptor pathway contrast sensitivity. Moreover, by isolating rod vision, we reveal a bipartite intensity response property of the rod pathway in photopic lighting that extends its operational range at lower frequencies to beyond its classic saturation limits but at the expense of attenuating sensitivity at higher frequencies. In comparison, melanopsin-cone interactions always lead to facilitation. These interactions can be described by linear or probability summations and potentially involve multiple intraretinal and visual cortical pathways to set human visual contrast sensitivity.

Keywords: Applied sensory psychophysics; Cellular neuroscience; Sensory neuroscience.