Download or read book Intrinsically Photosensitive Melanopsin Retinal Ganglion Cell Contributions to the Post illumination Pupil Response and Circadian Rhythm written by Emma Louise Markwell and published by . This book was released on 2011 with total page 125 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Melanopsin Vision written by Daniel S. Joyce and published by Cambridge University Press. This book was released on 2023-01-31 with total page 75 pages. Available in PDF, EPUB and Kindle. Book excerpt: Intrinsically photosensitive retinal ganglion cells (ipRGGs) are the most recently discovered photoreceptor class in the human retina. This Element integrates new knowledge and perspectives from visual neuroscience, psychology, sleep science and architecture to discuss how melanopsin-mediated ipRGC functions can be measured and their circuits manipulated. It reveals contemporary and emerging lighting technologies as powerful tools to set mind, brain and behaviour.
Download or read book Webvision written by Helga Kolb and published by . This book was released on 2007 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Influence of Light Exposure on the Melanopsin Driven Pupil Response and Circadian Rhythm written by Kaleb S. Abbott and published by . This book was released on 2018 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: Exposure to increasing amounts of artificial light during the night may contribute to the high prevalence of reported sleep dysfunction. Release of the sleep hormone melatonin is mediated by the intrinsically photosensitive retinal ganglion cells (ipRGCs). ipRGCs signal environmental light, with pathways to the midbrain to control pupil size and circadian rhythm. Evidence suggests that light exposure plays a role in refractive error development. This study sought to investigate whether melatonin level and sleep quality can be modulated by decreasing nighttime input to the ipRGCs. Another goal was to investigate links between light exposure, ipRGCs, refractive error, and sleep. Methods: Experiment 1: Subjects (ages 17-42, n=21) wore short wavelength-blocking glasses prior to bedtime for two weeks. The ipRGC-mediated post illumination pupil response (PIPR) was measured before and after the experimental period. Stimulation was presented with a Ganzfeld stimulator, including 1 second (s) and 5 s long and short wavelength light, and the pupil was imaged with an infrared camera. Pupil diameter was measured before, during and for 60 s following stimulation, and the 6 s and 30 s PIPR and area under the curve (AUC) following light offset were determined. Subjects wore an Actigraph device for objective measurements of activity, light exposure, and sleep. Saliva samples were collected to assess melatonin content. The Pittsburgh Sleep Quality Index (PSQI) was administered to assess subjective sleep quality. Experiment 2: Fifty subjects, aged 17-40, participated (19 emmetropes and 31 myopes). A subset of subjects (n = 24) wore an Actiwatch Spectrum for one week. The Pittsburgh Sleep Quality Index (PSQI) was administered, and saliva samples were collected for melatonin analysis. The post illumination pupil response (PIPR) to 1 second (s) and 5s long and short wavelength stimuli was measured. Pupil metrics included the 6s and 30s PIPR and early and late area under the curve. Results: Experiment 1: Subjects wore the blue-blocking glasses 3:57 ± 1:03 hours each night. After the experimental period, the pupil showed a slower redilation phase, resulting in a significantly increased 30 s PIPR to 1 s short wavelength light, and decreased AUC for 1 s and 5 s short wavelength light, when measured at the same time of day as baseline. Nighttime melatonin increased from 16.1 ± 7.5 pg/mL to 25.5 ± 10.7 pg/mL (p
Download or read book Updates on Intrinsically Photosensitive Retinal Ganglion Cells written by Zhang Yan and published by Scientific Research Publishing, Inc. USA. This book was released on 2021-09-03 with total page 84 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Assessment of the IpRGC Contribution to the Human Pupillary Light Reflex Using a Commercial Pupillometer written by Nicholas Tyler Perichak and published by . This book was released on 2015 with total page 58 pages. Available in PDF, EPUB and Kindle. Book excerpt: Intrinsically photosensitive retinal ganglion cells (ipRGCs) are a rare subgroup of retinal ganglion cells that contain the photopigment melanopsin. These cells are irradiance detectors that send information to the brain to control circadian rhythms and pupil size. ipRGCs mediate the sustained pupil response occurring post-illumination, due to their prolonged firing post-light offset. They are most sensitive to light with a wavelength of 480 nm. Their unique temporal properties have been used previously to assess the ipRGC contribution to human pupillary light reflex (PLR) by demonstrating a difference in the post-illumination pupil response between flickering red and blue light. My goal for this study was to determine if a commercial pupillometer, the RAPDx (Konan Medical), is capable of detecting the ipRGC contribution to the human PLR. A total of 13 healthy subjects (ages: 23-30) were presented with three types of flickering (0.1 Hz) stimuli: red light only, blue light only, and alternating red and blue light. The stimuli were presented using the RAPDx, which recorded pupil size under infrared illumination. Pupil size was captured every 25 milliseconds by the RAPDx pupillometer. Pupil fluctuation (constriction and re-dilation) in responses to the light stimuli were recorded and analyzed.
Download or read book Retinal Development written by Evelyne Sernagor and published by Cambridge University Press. This book was released on 2012-11-29 with total page 369 pages. Available in PDF, EPUB and Kindle. Book excerpt: This advanced text, first published in 2006, takes a developmental approach to the presentation of our understanding of how vertebrates construct a retina. Written by experts in the field, each of the seventeen chapters covers a specific step in the process, focusing on the underlying molecular, cellular, and physiological mechanisms. There is also a special section on emerging technologies, including genomics, zebrafish genetics, and stem cell biology that are starting to yield important insights into retinal development. Primarily aimed at professionals, both biologists and clinicians working with the retina, this book provides a concise view of vertebrate retinal development. Since the retina is 'an approachable part of the brain', this book will also be attractive to all neuroscientists interested in development, as processes required to build this exquisitely organized system are ultimately relevant to all other parts of the central nervous system.
Download or read book Left in the Dark written by Wisse Pier Meijden and published by . This book was released on 2018 with total page 144 pages. Available in PDF, EPUB and Kindle. Book excerpt: The non-image forming effects of environmental light are critically mediated by intrinsically photosensitive retinal ganglion cells (ipRGCs) that are characterized by their expression of melanopsin, which is a photopigment that is maximally responsive to light in the blue part of the spectrum. The ipRGC-mediated effects of light can typically endure far beyond light offset, with widespread functional consequences, including changes in various aspects of human sleep. The present thesis investigated such sleep-related post-illumination effects in the context of physiology and behavior. In chapter 2 and 3, we presented a post-illumination pupil response (PIPR) after blue light assessment method that yields a robust and feasible estimate of the functionality of an individual’s intrinsic melanopsin-based phototransduction circuitry. In chapter 4, we showed that the PIPR after blue light was more pronounced in individuals with a later sleep timing. Following red light, sleep propensity is promoted, as indicated by our physiological and behavioral findings in chapter 5. Chapter 6 added to chapter 2 and 5 indicating that task demands and mental effort should be taken into account in order to correctly interpret changes in physiological and behavioral reflections of the central and autonomic nervous system. It appears timely to consider large-scale follow-up studies to contribute to the multivariate fingerprint of the non-image forming effects of light on human physiology and behavior and to further evaluate the clinical application of light therapy in the treatment of sleep disorders.
Download or read book The Pupil Behavior Anatomy Physiology and Clinical Biomarkers written by Andrew J. Zele and published by Frontiers Media SA. This book was released on 2020-06-22 with total page 306 pages. Available in PDF, EPUB and Kindle. Book excerpt: This eBook is a collection of articles from a Frontiers Research Topic. Frontiers Research Topics are very popular trademarks of the Frontiers Journals Series: they are collections of at least ten articles, all centered on a particular subject. With their unique mix of varied contributions from Original Research to Review Articles, Frontiers Research Topics unify the most influential researchers, the latest key findings and historical advances in a hot research area! Find out more on how to host your own Frontiers Research Topic or contribute to one as an author by contacting the Frontiers Editorial Office: frontiersin.org/about/contact.
Download or read book Circadian and Visual Neuroscience written by and published by Elsevier. This book was released on 2022-08-05 with total page 380 pages. Available in PDF, EPUB and Kindle. Book excerpt: Circadian and Visual Neuroscience, Volume 273 in the Methods in Enzymology series, highlights new advances in the field with this new volume presenting interesting chapters on topics including Optical set-ups, Psychophysics of Luminance and Color Vision, Psychophysics of non-visual photoreception PRC/IRC/DRC/Spectral Sensitivity, Circadian and visual photometry, Modelling (retina), Modelling (circadian), Techniques for examining vision at the cellular level, Advanced techniques for characterizing the world hyperspectrally, Circadian physiology in mice: Melanopsin, Circadian physiology in mice: Color and cones, Translational aspects of animal studies, Retinal clocks, Primate non-visual physiology, Light and mood in animal models, and much more. - Provides the authority and expertise of leading contributors from an international board of authors - Presents the latest release in Progress in Brain Research series - Updated release includes the latest information on Circadian and Visual Neuroscience
Download or read book Seeing Without Rods Or Cones Contributions of Intrinsically photosensitive Retinal Ganglion Cells to the Image forming Visual System written by Stewart Madon and published by . This book was released on 2013 with total page 322 pages. Available in PDF, EPUB and Kindle. Book excerpt: "It was long thought that rods and cones were the only components of the mammalian retina capable of conveying light information to the brain. Recently, a novel class of transduction-capable retinal ganglion cells containing the photopigment melanopsin were discovered in the mammalian retina identified as an “intrinsically photosensitive retinal ganglion cell” or ipRGC. Most of the functionality associated with ipRGCs has been linked to nonperceptual, non-cortical visual operations such as circadian (day-night) phase modulation and pupillary constriction. More recently, however, two subpopulations of ipRGCs have been identified called M1 and M2 cells, with the latter showing “blue-yellow” chromatic opponency that possibly links to brightness or colour pattern vision – properties associated with the retinogeniculostriate, or image-forming visual system. The present study expands on the current understanding of these putative image-forming non-traditional photoreceptor systems. To this end, I developed two stimulus paradigms that target short-wavelength-sensitive cones (S-cones) to tease out the unique contributions of ipRGCs that have neural associations with S-cone visual functioning. In the first paradigm, I measured detection thresholds using short-wavelength selective stimuli that are temporally presented with either an onset or offset “sawtooth” profile to ascertain ipRGC input to the S-OFF, “brightness” pathways. The results revealed differences in the asymmetry between S-ON and S-OFF pathways dependent upon adapting field conditions that were expected to influence ipRGCs over other photoreceptors. In the second experiment, I used a modification of an S-cone contrast sensitivity task employing homochromatic “blue” sine-grating gabors of varying spatial frequencies to directly test ipRGC involvement in spatial pattern vision. The results from the second experiment showed a slight advantage to the perception of low spatial frequency gabors superimposed on chromatic adapting fields that were expected to influence ipRGCs more than the others. Preliminary evidence supporting a spatial tuning property of ipRGCs was also found. Overall, these findings suggest that ipRGCs have measurable influences on conscious, image-forming perceptions, and shed further light on the microcircuitry of the retinogeniculate pathway."-- from abstract.
Download or read book Towards a Chromatic Pupillometry Protocol for Assessing Melanopsin driven Post illumination Pupil Response in Basic Science and Clinical Investigations written by Shaobo Lei and published by . This book was released on 2016 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Pediatric Neuro Ophthalmology written by Michael C. Brodsky and published by Springer Science & Business Media. This book was released on 2012-12-06 with total page 692 pages. Available in PDF, EPUB and Kindle. Book excerpt: Pediatric Neuroophthalmology details the diagnostic criteria, current concepts of pathogenesis, neuroradiological correlates, and clinical management of a large group of neuroophthalmic disorders that present in childhood. Surprisingly distinct from neuroophthalmic disorders afflicting adults, this set of diseases falls between the cracks of most ophthalmology training, and thus, warrants a practical, clinical guide for the practitioner in ophthalmology - the neuroophthalmologist, pediatric ophthalmologist, general ophthalmologist - as well as neurologists and for residents. The authors, leading pediatric ophthalmologists, have taken this difficult subject matter and developed an accessible, user-friendly manual with a detailed approach to the recognition, differential diagnosis, and management of pediatric neuroophthalmologic disorders.
Download or read book The Retina and Circadian Rhythms written by Gianluca Tosini and published by Springer Science & Business Media. This book was released on 2014-01-09 with total page 245 pages. Available in PDF, EPUB and Kindle. Book excerpt: Daily rhythms are a ubiquitous feature of living systems. Generally, these rhythms are not just passive consequences of cyclic fluctuations in the environment, but instead originate within the organism. In mammals, including humans, the master pacemaker controlling 24-hour rhythms is localized in the suprachiasmatic nuclei of the hypothalamus (SCN). This circadian clock is responsible for the temporal organization of a wide variety of functions, ranging from sleep and food intake, to physiological measures such as body temperature, heart rate and hormone release. Moreover, accumulating evidence suggests that dysfunction of the circadian rhythms due to genetic mutations or environmental factors (i.e., jet-lag or shift work) contribute to the development of many pathologies, including sleep disorders, mood and affective disorders such as major depression, bipolar disorder and schizophrenia, as well as the risk of metabolic and cardiovascular disorders.
Download or read book The Retina written by John E. Dowling and published by Harvard University Press. This book was released on 2012-01-15 with total page 610 pages. Available in PDF, EPUB and Kindle. Book excerpt: John Dowling’s The Retina, published in 1987, quickly became the most widely recognized introduction to the structure and function of retinal cells. In this Revised Edition, Dowling draws on twenty-five years of new research to produce an interdisciplinary synthesis focused on how retinal function contributes to our understanding of brain mechanisms. The retina is a part of the brain pushed out into the eye during development. It retains many characteristics of other brain regions and hence has yielded significant insights on brain mechanisms. Visual processing begins there as a result of neuronal interactions in two synaptic layers that initiate an analysis of space, color, and movement. In humans, visual signals from 126 million photoreceptors funnel down to one million ganglion cells that convey at least a dozen representations of a visual scene to higher brain regions. The Revised Edition calls attention to general principles applicable to all vertebrate retinas, while showing how the visual needs of different animals are reflected in their retinal variations. It includes completely new chapters on color vision and retinal degenerations and genetics, as well as sections on retinal development and visual pigment biochemistry, and presents the latest knowledge and theories on how the retina is organized anatomically, physiologically, and pharmacologically. The clarity of writing and illustration that made The Retina a book of choice for a quarter century among graduate students, postdoctoral fellows, vision researchers, and teachers of upper-level courses on vision is retained in Dowling’s new easy-to-read Revised Edition.
Download or read book Ultrastructure of Melanopsin Expressing Retinal Ganglion Cell Circuitry in the Retina and Brain Regions that Mediate Light Driven Behavior written by Yu Hsin Liu and published by . This book was released on 2017 with total page 150 pages. Available in PDF, EPUB and Kindle. Book excerpt: Melanopsin-expressing retinal ganglion cells (mRGC) are intrinsically photosensitive and combine their melanopsin-based photoresponses with rod and cone signals to convey light information to a subset of retinal brain targets. mRGC axons to non-image forming (NIF) visual centers are essential for the proper functioning of processes like circadian photoentrainment and pupillary light reflex. Surprisingly, mRGCs also send axons to image-forming regions of the brain. It is unknown how mRGCs mediate such diverse functions. Classically, a cell's morphology and location in a biological system is a direct reflection of its synaptic connections and, by definition, their function. mRGCs can be divided into five subtypes (M1-M5) based on morphology and dendritic stratification in the inner plexiform layer. In the classical sense, since M1s send axons to only a subset of mRGC-target regions and are the only subtype that monostratify in the OFF-sublamina, M1s likely serve a distinct function from other subtypes. However, M1s, like all mRGCs, exhibit an ON-response. This reveals a hole in what we understand about intraretinal connectivity and attenuates the weight that should be afforded to stratification in determining function. While the other mRGC subtypes have distinct morphology and branching patterns, it is unknown whether they serve specific functions. Thus, in order to explore the structure-function relationship of mRGC subtypes, we must consider connectivity. Unfortunately, the variable expression of melanopsin protein between subtypes and across the architecture of a single mRGC and the lack of unique markers for up- and downstream interactors has precluded rigorous study of mRGC connectivity in the retina and central targets. We use a correlated light and electron microscopy label and serial blockface scanning electron microscopy to explore the architecture and synaptic partners of mRGCs in an attempt to better understand the connectivity of mRGC subtypes. We show significant differences in the ultrastructure of mRGC axonal terminals in mRGC-recipient brain regions, stratification-specific differences in mRGC dendrites, and catalog the intraretinal connections specific to mRGC subtypes.
Download or read book Regulation of Retinal Dopaminergic Amacrine Neuron Activity by Intrinsically Photosensitive Retinal Ganglion Cells in Normal and Diseased Retinas written by and published by . This book was released on 2015 with total page 332 pages. Available in PDF, EPUB and Kindle. Book excerpt: Dopaminergic amacrine (DA) neurons produce and secrete the key neurotransmitter dopamine which plays diverse and important roles in the retina, modulating both visual (i.e. retinal light adaptation) and non-visual (i.e. circadian rhythm) functions. Previous studies demonstrated that the electrical activity of DA neurons that triggers dopamine release is regulated by light via rod and cone photoreceptors. In addition, DA neurons are excited by light through melanopsin-expressing intrinsically photosensitive retinal ganglion cells (ipRGCs). This finding raised a number of questions: (1) Is melanopsin the sole photopigment that mediates retrograde signaling from ipRGCs? (2) What are the routes of retrograde signal transmission? (3) What are the pre- and postsynaptic mechanisms responsible for signal transmission? (4) How is the retrograde signaling pathway altered in the absence of rod and cone photoreceptors? For my dissertation research, I used electrophysiology, pharmacology, and transgenic mouse models to address these critical questions. First, I demonstrated that melanopsin exclusively mediated DA neuron light responses in retinal degeneration l (rdl) retinas, in which rods and cones degenerate soon after birth, by genetically ablating melanopsin in the rdl model. Second, I found that intraretinal axon collaterals of ipRGCs constituted the retrograde pathway to DA neurons, conveying melanopsin-based signals from inner to outer retina. Third, I demonstrated that retrograde signal transmission was mediated by presynaptic N-type voltage-gated calcium channels and worked primarily through postsynaptic calcium-impermeable AMPA-type glutamate receptors. Last, I found that DA neuron activity was altered in rdl, as evidenced by reduced spontaneous bursting and increased light-evoked responses with age. The results have provided new information about the molecular, synaptic, and circuit mechanisms by which DA neuron activity is regulated by ipRGCs and how DA neurons and the retrograde signaling pathway are altered in retinal degenerative disease. This information has enhanced our understanding of the roles of dopamine and melanopsin in modulating retinal function and entraining the retinal circadian clock in healthy and diseased retinas.
