LIVIVO - The Search Portal for Life Sciences

zur deutschen Oberfläche wechseln
Advanced search

Search results

Result 1 - 10 of total 115

Search options

  1. Article ; Online: Melanopsin enhances image persistence.

    Woelders, Tom / Allen, Annette E / Lucas, Robert J

    Current biology : CB

    2023  Volume 33, Issue 23, Page(s) 5048–5056.e4

    Abstract: Contributions of the inner retinal photopigment melanopsin to human visual perception are incompletely understood. Here, we use a four-primary display to produce stimuli differing in melanopsin versus cone contrast in psychophysical paradigms in eight ... ...

    Abstract Contributions of the inner retinal photopigment melanopsin to human visual perception are incompletely understood. Here, we use a four-primary display to produce stimuli differing in melanopsin versus cone contrast in psychophysical paradigms in eight subjects with normal color vision. We address two predictions from electrophysiological recordings of the melanopsin system in non-human mammals: melanopsin influences color and/or supports image persistence under visual fixation. We first construct chromatic contrast sensitivity contours for stimuli differing in melanopsin excitation presented as a central annulus (10°) or peripheral (22.5°) spot. We find that although including melanopsin contrast produces modest changes in the average chromatic coordinates in both eccentricities, this occurs equally at low (0.5 Hz) and higher (3.75 Hz) temporal frequencies, arguing that it reflects divergence in cone spectral sensitivity in our participants from that captured in standardized cone fundamentals rather than a melanopsin contribution to color. We continue to ask whether the established ability of melanopsin to sustain firing of visual neurons under extended light exposure has a visual correlate, using the optical illusion of Troxler fading in which blurred spots in periphery disappear during visual fixation. We find that introducing additional melanopsin contrast (+28% Michelson contrast) to either bright or dark spots increases fading latency by 35% ± 8.8% and 41% ± 13.6%, respectively. Our data argue that the primary contribution of melanopsin to perception under these conditions is not to provide a color percept but rather to enhance persistence of low spatial frequency patterns during visual fixation.
    MeSH term(s) Animals ; Humans ; Photic Stimulation ; Retina/physiology ; Retinal Cone Photoreceptor Cells/physiology ; Vision, Ocular ; Rod Opsins/physiology ; Mammals
    Chemical Substances melanopsin ; Rod Opsins
    Language English
    Publishing date 2023-11-14
    Publishing country England
    Document type Journal Article ; Research Support, Non-U.S. Gov't
    ZDB-ID 1071731-6
    ISSN 1879-0445 ; 0960-9822
    ISSN (online) 1879-0445
    ISSN 0960-9822
    DOI 10.1016/j.cub.2023.10.039
    Database MEDical Literature Analysis and Retrieval System OnLINE

    More links

    Kategorien

  2. Article ; Online: The Impact of Pupil Constriction on the Relationship Between Melanopic EDI and Melatonin Suppression in Young Adult Males.

    Schöllhorn, Isabel / Stefani, Oliver / Lucas, Robert J / Spitschan, Manuel / Epple, Christian / Cajochen, Christian

    Journal of biological rhythms

    2024  , Page(s) 7487304241226466

    Abstract: The pupil modulates the amount of light that reaches the retina. Not only luminance but also the spectral distribution defines the pupil size. Previous research has identified steady-state pupil size and melatonin attenuation to be predominantly driven ... ...

    Abstract The pupil modulates the amount of light that reaches the retina. Not only luminance but also the spectral distribution defines the pupil size. Previous research has identified steady-state pupil size and melatonin attenuation to be predominantly driven by melanopsin, which is expressed by a unique subgroup of intrinsically photosensitive retinal ganglion cells (ipRGCs) that are sensitive to short-wavelength light (~480 nm). Here, we aimed to selectively target the melanopsin system during the evening, while measuring steady-state pupil size and melatonin concentrations under commonly experienced evening light levels (<90 lx). Therefore, we used a five-primary display prototype to generate light conditions that were matched in terms of L-, M-, and S-cone-opic irradiances, but with high and low melanopic irradiances (~3-fold difference). Seventy-two healthy, male participants completed a 2-week study protocol. The volunteers were assigned to one of the four groups that differed in luminance levels (27-285 cd/m
    Language English
    Publishing date 2024-02-13
    Publishing country United States
    Document type Journal Article
    ZDB-ID 896387-3
    ISSN 1552-4531 ; 0748-7304
    ISSN (online) 1552-4531
    ISSN 0748-7304
    DOI 10.1177/07487304241226466
    Database MEDical Literature Analysis and Retrieval System OnLINE

    More links

    Kategorien

  3. Article ; Online: Divergent G-protein selectivity across melanopsins from mice and humans.

    McDowell, Richard J / Rodgers, Jessica / Milosavljevic, Nina / Lucas, Robert J

    Journal of cell science

    2022  Volume 135, Issue 6

    Abstract: Melanopsin is an opsin photopigment and light-activated G-protein-coupled receptor; it is expressed in photoreceptive retinal ganglion cells (mRGCs) and can be employed as an optogenetic tool. Mammalian melanopsins can signal via Gq/11 and Gi/o/t ... ...

    Abstract Melanopsin is an opsin photopigment and light-activated G-protein-coupled receptor; it is expressed in photoreceptive retinal ganglion cells (mRGCs) and can be employed as an optogenetic tool. Mammalian melanopsins can signal via Gq/11 and Gi/o/t heterotrimeric G proteins, but aspects of the mRGC light response appear incompatible with either mode of signalling. We use live-cell reporter assays in HEK293T cells to show that melanopsins from mice and humans can also signal via Gs. We subsequently show that this mode of signalling is substantially divergent between species. The two established structural isoforms of mouse melanopsin (which differ in the length of their C-terminal tail) both signalled strongly through all three G-protein classes (Gq/11, Gi/o and Gs), whereas human melanopsin showed weaker signalling through Gs. Our data identify Gs as a new mode of signalling for mammalian melanopsins and reveal diversity in G-protein selectivity across mammalian melanopsins.
    MeSH term(s) Animals ; GTP-Binding Proteins/genetics ; GTP-Binding Proteins/metabolism ; HEK293 Cells ; Humans ; Mammals/metabolism ; Mice ; Optogenetics ; Rod Opsins/genetics ; Rod Opsins/metabolism
    Chemical Substances Rod Opsins ; melanopsin ; GTP-Binding Proteins (EC 3.6.1.-)
    Language English
    Publishing date 2022-03-21
    Publishing country England
    Document type Journal Article ; Research Support, Non-U.S. Gov't
    ZDB-ID 2993-2
    ISSN 1477-9137 ; 0021-9533
    ISSN (online) 1477-9137
    ISSN 0021-9533
    DOI 10.1242/jcs.258474
    Database MEDical Literature Analysis and Retrieval System OnLINE

    More links

    Kategorien

  4. Article ; Online: A Bright Idea for Improving Spatial Memory.

    Milosavljevic, Nina / Brown, Timothy M / Lucas, Robert J

    Neuron

    2021  Volume 109, Issue 2, Page(s) 197–199

    Abstract: In this issue of Neuron, Huang et al. (2021) reveal a new influence of light on memory. They show that in mice, daily exposure to bright light over several weeks produces lasting increases in spatial memory and assign this effect to a circuit originating ...

    Abstract In this issue of Neuron, Huang et al. (2021) reveal a new influence of light on memory. They show that in mice, daily exposure to bright light over several weeks produces lasting increases in spatial memory and assign this effect to a circuit originating in the retina and encompassing the ventral lateral geniculate and reuniens nuclei.
    MeSH term(s) Animals ; Mice ; Midline Thalamic Nuclei ; Neurons ; Retina ; Spatial Memory
    Language English
    Publishing date 2021-01-20
    Publishing country United States
    Document type Journal Article ; Research Support, Non-U.S. Gov't ; Comment
    ZDB-ID 808167-0
    ISSN 1097-4199 ; 0896-6273
    ISSN (online) 1097-4199
    ISSN 0896-6273
    DOI 10.1016/j.neuron.2020.12.020
    Database MEDical Literature Analysis and Retrieval System OnLINE

    More links

    Kategorien

  5. Article: Colour and melanopsin mediated responses in the murine retina.

    Mouland, Joshua W / Watson, Alex J / Martial, Franck P / Lucas, Robert J / Brown, Timothy M

    Frontiers in cellular neuroscience

    2023  Volume 17, Page(s) 1114634

    Abstract: Introduction: ...

    Abstract Introduction:
    Language English
    Publishing date 2023-03-13
    Publishing country Switzerland
    Document type Journal Article
    ZDB-ID 2452963-1
    ISSN 1662-5102
    ISSN 1662-5102
    DOI 10.3389/fncel.2023.1114634
    Database MEDical Literature Analysis and Retrieval System OnLINE

    More links

    Kategorien

  6. Article ; Online: Melanopic irradiance defines the impact of evening display light on sleep latency, melatonin and alertness.

    Schöllhorn, Isabel / Stefani, Oliver / Lucas, Robert J / Spitschan, Manuel / Slawik, Helen C / Cajochen, Christian

    Communications biology

    2023  Volume 6, Issue 1, Page(s) 228

    Abstract: Evening light-emitting visual displays may disrupt sleep, suppress melatonin and increase alertness. Here, we control melanopic irradiance independent of display luminance and colour, in 72 healthy males 4 h before habitual bedtime and expose each of ... ...

    Abstract Evening light-emitting visual displays may disrupt sleep, suppress melatonin and increase alertness. Here, we control melanopic irradiance independent of display luminance and colour, in 72 healthy males 4 h before habitual bedtime and expose each of them to one of four luminance levels (i.e., dim light, smartphone, tablet or computer screen illuminance) at a low and a high melanopic irradiance setting. Low melanopic light shortens the time to fall asleep, attenuates evening melatonin suppression, reduces morning melatonin, advances evening melatonin onset and decreases alertness compared to high melanopic light. In addition, we observe dose-dependent increases in sleep latency, reductions in melatonin concentration and delays in melatonin onset as a function of melanopic irradiance-not so for subjective alertness. We identify melanopic irradiance as an appropriate parameter to mitigate the unwanted effects of screen use at night. Our results may help the many people who sit in front of screens in the evening or at night to fall asleep faster, feel sleepier, and have a more stable melatonin phase by spectrally tuning the visual display light without compromising the visual appearance.
    MeSH term(s) Male ; Humans ; Sleep Latency ; Melatonin ; Sleep ; Emotions ; Health Status
    Chemical Substances Melatonin (JL5DK93RCL)
    Language English
    Publishing date 2023-03-01
    Publishing country England
    Document type Journal Article ; Research Support, Non-U.S. Gov't
    ISSN 2399-3642
    ISSN (online) 2399-3642
    DOI 10.1038/s42003-023-04598-4
    Database MEDical Literature Analysis and Retrieval System OnLINE

    More links

    Kategorien

  7. Article ; Online: Mammalian inner retinal photoreception.

    Lucas, Robert J

    Current biology : CB

    2013  Volume 23, Issue 3, Page(s) R125–33

    Abstract: It is now a decade since the first published reports that a small proportion of mammalian retinal ganglion cells are directly photoresponsive. These cells have been termed intrinsically photosensitive retinal ganglion cells (ipRGCs) and comprise a small ... ...

    Abstract It is now a decade since the first published reports that a small proportion of mammalian retinal ganglion cells are directly photoresponsive. These cells have been termed intrinsically photosensitive retinal ganglion cells (ipRGCs) and comprise a small proportion of the total population of retinal ganglion cells. The demonstration that these ganglion cells respond to light even when isolated from the rest of the retina established them as potentially autonomous photoreceptors, overturning the dogma that all visual information originates with rods and cones. It also provided a focus for what has developed into a new branch of visual science. Here we place the discovery of ipRGCs into context and review the development of this field over the last decade, with particular emphasis on prospects for practical application.
    MeSH term(s) Animals ; Humans ; Photoreceptor Cells, Vertebrate/physiology ; Retinal Ganglion Cells/physiology ; Rod Opsins/physiology ; Vision, Ocular/physiology
    Chemical Substances Rod Opsins ; melanopsin
    Language English
    Publishing date 2013-02-04
    Publishing country England
    Document type Journal Article ; Research Support, Non-U.S. Gov't ; Review
    ZDB-ID 1071731-6
    ISSN 1879-0445 ; 0960-9822
    ISSN (online) 1879-0445
    ISSN 0960-9822
    DOI 10.1016/j.cub.2012.12.029
    Database MEDical Literature Analysis and Retrieval System OnLINE

    More links

    Kategorien

  8. Article ; Online: Modulations in irradiance directed at melanopsin, but not cone photoreceptors, reliably alter electrophysiological activity in the suprachiasmatic nucleus and circadian behaviour in mice.

    Mouland, Josh W / Martial, Franck P / Lucas, Robert J / Brown, Timothy M

    Journal of pineal research

    2021  Volume 70, Issue 4, Page(s) e12735

    Abstract: Intrinsically photosensitive retinal ganglion cells convey intrinsic, melanopsin-based, photoreceptive signals alongside those produced by rods and cones to the suprachiasmatic nucleus (SCN) circadian clock. To date, experimental data suggest that ... ...

    Abstract Intrinsically photosensitive retinal ganglion cells convey intrinsic, melanopsin-based, photoreceptive signals alongside those produced by rods and cones to the suprachiasmatic nucleus (SCN) circadian clock. To date, experimental data suggest that melanopsin plays a more significant role in measuring ambient light intensity than cone photoreception. Such studies have overwhelmingly used diffuse light stimuli, whereas light intensity in the world around us varies across space and time. Here, we investigated the extent to which melanopsin or cone signals support circadian irradiance measurements in the presence of naturalistic spatiotemporal variations in light intensity. To address this, we first presented high- and low-contrast movies to anaesthetised mice whilst recording extracellular electrophysiological activity from the SCN. Using a mouse line with altered cone sensitivity (Opn1mw
    MeSH term(s) Animals ; Behavior, Animal/radiation effects ; Circadian Rhythm/physiology ; Circadian Rhythm/radiation effects ; Humans ; Light/adverse effects ; Male ; Mice ; Mice, Inbred C57BL ; Mice, Transgenic ; Retinal Cone Photoreceptor Cells/radiation effects ; Rod Opsins/radiation effects ; Suprachiasmatic Nucleus/physiology
    Chemical Substances Rod Opsins ; melanopsin
    Language English
    Publishing date 2021-04-01
    Publishing country England
    Document type Journal Article
    ZDB-ID 632697-3
    ISSN 1600-079X ; 0742-3098
    ISSN (online) 1600-079X
    ISSN 0742-3098
    DOI 10.1111/jpi.12735
    Database MEDical Literature Analysis and Retrieval System OnLINE

    More links

    Kategorien

  9. Article: Quantitative characterisation of ipRGCs in retinal degeneration using a computation platform for extracting and reconstructing single neurons in 3D from a multi-colour labeled population.

    Procyk, Christopher A / Rodgers, Jessica / Zindy, Egor / Lucas, Robert J / Milosavljevic, Nina

    Frontiers in cellular neuroscience

    2022  Volume 16, Page(s) 1009321

    Abstract: Light has a profound impact on mammalian physiology and behavior. Intrinsically photosensitive retinal ganglion cells (ipRGCs) express the photopigment melanopsin, rendering them sensitive to light, and are involved in both image-forming vision and non- ... ...

    Abstract Light has a profound impact on mammalian physiology and behavior. Intrinsically photosensitive retinal ganglion cells (ipRGCs) express the photopigment melanopsin, rendering them sensitive to light, and are involved in both image-forming vision and non-image forming responses to light such as circadian photo-entrainment and the pupillary light reflex. Following outer photoreceptor degeneration, the death of rod and cone photoreceptors results in global re-modeling of the remnant neural retina. Although ipRGCs can continue signaling light information to the brain even in advanced stages of degeneration, it is unknown if all six morphologically distinct subtypes survive, or how their dendritic architecture may be affected. To answer these questions, we generated a computational platform-BRIAN (Brainbow Analysis of individual Neurons) to analyze Brainbow labeled tissues by allowing objective identification of voxels clusters in Principal Component Space, and their subsequent extraction to produce 3D images of single neurons suitable for analysis with existing tracing technology. We show that BRIAN can efficiently recreate single neurons or individual axonal projections from densely labeled tissue with sufficient anatomical resolution for subtype quantitative classification. We apply this tool to generate quantitative morphological information about ipRGCs in the degenerate retina including soma size, dendritic field size, dendritic complexity, and stratification. Using this information, we were able to identify cells whose characteristics match those reported for all six defined subtypes of ipRGC in the wildtype mouse retina (M1-M6), including the rare and complex M3 and M6 subtypes. This indicates that ipRGCs survive outer retinal degeneration with broadly normal morphology. We additionally describe one cell in the degenerate retina which matches the description of the Gigantic M1 cell in Humans which has not been previously identified in rodent.
    Language English
    Publishing date 2022-11-01
    Publishing country Switzerland
    Document type Journal Article
    ZDB-ID 2452963-1
    ISSN 1662-5102
    ISSN 1662-5102
    DOI 10.3389/fncel.2022.1009321
    Database MEDical Literature Analysis and Retrieval System OnLINE

    More links

    Kategorien

  10. Article ; Online: Associations between light exposure and sleep timing and sleepiness while awake in a sample of UK adults in everyday life.

    Didikoglu, Altug / Mohammadian, Navid / Johnson, Sheena / van Tongeren, Martie / Wright, Paul / Casson, Alexander J / Brown, Timothy M / Lucas, Robert J

    Proceedings of the National Academy of Sciences of the United States of America

    2023  Volume 120, Issue 42, Page(s) e2301608120

    Abstract: Experimental and interventional studies show that light can regulate sleep timing and sleepiness while awake by setting the phase of circadian rhythms and supporting alertness. The extent to which differences in light exposure explain variations in sleep ...

    Abstract Experimental and interventional studies show that light can regulate sleep timing and sleepiness while awake by setting the phase of circadian rhythms and supporting alertness. The extent to which differences in light exposure explain variations in sleep and sleepiness within and between individuals in everyday life remains less clear. Here, we establish a method to address this deficit, incorporating an open-source wearable wrist-worn light logger (SpectraWear) and smartphone-based online data collection. We use it to simultaneously record longitudinal light exposure (in melanopic equivalent daylight illuminance), sleep timing, and subjective alertness over seven days in a convenience sample of 59 UK adults without externally imposed circadian challenge (e.g., shift work or jetlag). Participants reliably had strong daily rhythms in light exposure but frequently were exposed to less light during the daytime and more light in pre-bedtime and sleep episodes than recommended [T. M. Brown
    MeSH term(s) Adult ; Humans ; Wakefulness ; Sleepiness ; Sleep/physiology ; Circadian Rhythm/physiology ; United Kingdom ; Melatonin
    Chemical Substances Melatonin (JL5DK93RCL)
    Language English
    Publishing date 2023-10-09
    Publishing country United States
    Document type Journal Article ; Research Support, Non-U.S. Gov't
    ZDB-ID 209104-5
    ISSN 1091-6490 ; 0027-8424
    ISSN (online) 1091-6490
    ISSN 0027-8424
    DOI 10.1073/pnas.2301608120
    Database MEDical Literature Analysis and Retrieval System OnLINE

    More links

    Kategorien

To top