Melanopsin-Positive Intrinsically Photosensitive Retinal Ganglion Cells: From Form to Function

Department of Neuroscience, University of Minnesota, Minneapolis, Minnesota 55455, USA.
The Journal of Neuroscience : The Official Journal of the Society for Neuroscience (Impact Factor: 6.34). 11/2011; 31(45):16094-101. DOI: 10.1523/JNEUROSCI.4132-11.2011
Source: PubMed


Melanopsin imparts an intrinsic photosensitivity to a subclass of retinal ganglion cells (ipRGCs). Generally thought of as irradiance detectors, ipRGCs target numerous brain regions involved in non-image-forming vision. ipRGCs integrate their intrinsic, melanopsin-mediated light information with rod/cone signals relayed via synaptic connections to influence light-dependent behaviors. Early observations indicated diversity among these cells and recently several specific subtypes have been identified. These subtypes differ in morphological and physiological form, controlling separate functions that range from biological rhythm via circadian photoentrainment, to protective behavioral responses including pupil constriction and light avoidance, and even image-forming vision. In this Mini-Symposium review, we will discuss some recent findings that highlight the diversity in both form and function of these recently discovered atypical photoreceptors.

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Available from: Samer Hattar, Jan 17, 2014
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    • "the pineal gland through a polysynaptic pathway beginning with a diverse popula - tion of melanopsin expressing intrinsically photosensitive retinal ganglion cells ( ipRGCs ) located in the retina ( Berson , 2003 ; Schmidt et al . , 2011a ) . These cells play a primary role in circadian entrainment and only a marginal role in low - acuity vision ( Schmidt et al . , 2011b ) . Their axons travel along the non - visual ret - inohypothalamic tract and provide glutamatergic input to cells in the suprachiasmatic nuclei ( SCN ) of the hypothalamus ( Baver et al . , 2008 ) . Collateral axons also innervate the intergeniculate leaflet ( IGL ) and olivary pretectal nucleus ( OPN ) to encode ambient light levels ,"
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    • "However, after the discovery of ipRGCs, pupillometric studies have shown the importance of including color stimulation (Hattar et al., 2002). It seems that at 100 cd/m2, these cells have peak sensitivity to 470 nm wavelength (Ishikawa et al., 2012) and they participate in the pupil light reflex response (Provencio et al., 2000; Berson, 2003; Hatori and Panda, 2010; Schmidt et al., 2011). Blue light is often used to measure ipRGC function (Herbst et al., 2012), whereas red light is used to asses outer retina functioning (rods and predominantly cones) (Leon et al., 2012). "
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