title: The Physical Mechanism for Retinal Discrete Dark Noise: Thermal Activation or Cellular Ultraweak Photon Emission?
abstract: For several decades the physical mechanism underlying discrete dark noise of photoreceptors in the eye has remained highly controversial and poorly understood. It is known that the Arrhenius equation, which is based on the Boltzmann distribution for thermal activation, can model only a part (e.g. half of the activation energy) of the retinal dark noise experimentally observed for vertebrate rod and cone pigments. Using the Hinshelwood distribution instead of the Boltzmann distribution in the Arrhenius equation has been proposed as a solution to the problem. Here, we show that the using the Hinshelwood distribution does not solve the problem completely. As the discrete components of noise are indistinguishable in shape and duration from those produced by real photon induced photo-isomerization, the retinal discrete dark noise is most likely due to 'internal photons' inside cells and not due to thermal activation of visual pigments. Indeed, all living cells exhibit spontaneous ultraweak photon emission (UPE), mainly in the optical wavelength range, i.e., 350-700 nm. We show here that the retinal discrete dark noise has a similar rate as UPE and therefore dark noise is most likely due to spontaneous cellular UPE and not due to thermal activation.
authors.affiliation: Department of Physics, Isfahan University of Technology, Isfahan 84156-83111, Iran.|School of Physics, Institute for Research in Fundamental Sciences (IPM), Tehran 19395-5531, Iran.
authors.forename: Vahid
authors.initials: V
authors.lastname: Salari
authors.affiliation: Biomedical Optics Research Laboratory, Department of Neonatology, University Hospital Zurich, University of Zurich, 8091 Zurich, Switzerland.|Research Office for Complex Physical and Biological Systems (ROCoS), 8038 Zurich, Switzerland.
authors.forename: Felix
authors.initials: F
authors.lastname: Scholkmann
authors.affiliation: Vision Research Institute, 25 Rita Street, Lowell, MA 01854, United States of America.|Psychoszomatic OutPatient Department of the National Center for Spinal Disorders, Budapest H-1126, Hungary.
authors.forename: Istvan
authors.initials: I
authors.lastname: Bokkon
authors.affiliation: Department of Physics, Isfahan University of Technology, Isfahan 84156-83111, Iran.|School of Physics, Institute for Research in Fundamental Sciences (IPM), Tehran 19395-5531, Iran.
authors.forename: Farhad
authors.initials: F
authors.lastname: Shahbazi
authors.affiliation: Department of Physics, University of Alberta, T6G 2J1, Edmonton, AB, Canada.
authors.forename: Jack
authors.initials: J
authors.lastname: Tuszynski
mesh_terms: D000818:Animals; D003624:Darkness; D006801:Humans; D008954:Models, Biological; D017785:Photons; D020419:Photoreceptor Cells, Vertebrate / Q000166:cytology* / Q000528:radiation effects*; D013696:Temperature