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How does green light stimulate ipRGC neuro axon secretion?

Discussion in 'Ask Jack' started by John Schumacher, Oct 8, 2020.

  1. We know that green light stimulates melatonin secretion and expression of CLOCK and BMAL1 in the hypothalamus.
    We know melanopsin (OPN4)-photosensitive pigment expressed by intrinsically photosensitive retinal ganglion cells (ipRGC) contributed to a better understanding of the neural bases of the non-image-forming system. https://link.springer.com/article/10.1186/s40101-016-0091-9

    In humans, melanopsin is expressed in a small subset of cells representing only 1–2 % of all retinal ganglion cells. Photoreceptors measure the intensity of light (irradiance detection) with a maximum sensitivity toward short light wavelength (blue ~ 460–480 nm). Melanopsin ipRGC have a low spatial resolution and long latencies as compared to cone and rod responses, and they show the ability to integrate photic energy over long periods of time.

    The classical photopic system in humans includes three types of cones showing mean peak sensitivity (λ max) at 555 nanometers (nm), i.e., the green part of the light visible spectrum. S-cones express the short-wavelength-sensitive opsin cyanolabe (λ max 420 nm), M-cones express chlorolabe opsin (λ max 535 nm), and L-cones express a red-shifted opsin, the erythrolabe (λ max 565 nm).


    The current believe is that there is a monosynaptic pathway, the retinohypothalamic tract, conveys light information from ipRGC axons; and that through the retinohypothalamic tract, the ipRGC from the retina is directly connected to the suprachiasmatic nuclei of the anterior hypothalamus.

    So we know light stimulus characteristics influence the photoreceptor’s contribution to specific non-image-forming (NIF) system responses.

    My question from a light-water-magnetizm point of view: How does green light stimulate ipRGC neuro axon secretion?

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