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Printable Handouts
Navigable Slide Index
- Introduction
- Talk outline
- The vertebrates: non-mammals
- Non-mammalian vertebrate photosensory cells (1)
- Light through tissues
- Non-mammalian vertebrate photosensory cells (2)
- The vertebrates: mammals
- Mammalian photosensory cells
- Why are mammals and non-mammals so different?
- Vertebrate photoreceptor diversity
- Different uses for light as information source
- Biology of and photoreceptors
- Circadian intro and retinal degenerate mice
- Circadian biology
- Systolic pressure and stroke frequency
- Alertness
- Internal time and external time alignment
- Studies on mice: background
- Normal eye
- SCN lesion
- Covered eye
- Differences in processing
- Another look inside the eye
- 3 types of mutant mice
- Wheel running behaviour
- The circadian system
- Mice can be visually blind but not circadian blind
- Reactions of vision neuroscientists
- Objections to new receptor
- VA-opsin in teleost fish
- Proof of principle
- Normal photosensitivity with fewer rods/cones
- rd/rd cl mice and melanopsin (OPN4)
- Transgenic rd/rd cl mice
- Circadian system in rd/rd cl mice
- Regulation of pineal melatonin
- Acute suppression of pineal melatonin
- Third ocular photoreceptor must exist
- Photosensitive retinal ganglion cells (pRGCs)
- pRGCs in different animal models
- pRGCs complex activity
- pRGCs regulate more than the circadian system
- pRGCs mediate multiple responses to light (1)
- Pupil constriction
- pRGCs mediate multiple responses to light (2)
- What is the light sensitive photopigment of pRGCs?
- Known mouse photopigments
- Pupil constriction in the rd/rd cl mouse
- Phase shifting circadian rhythm in rd/rd cl mouse
- Melanopsin (Opn4)
- Why is it called melanopsin?
- Imaging melanopsin using antibodies
- Photosensitive ganglion cell net
- Melanopsin (Opn4) functional ablation
- Ablating rods, cones and melanopsin
- Ablating rods, cones and melanopsin: results
- Ablating melanopsin only
- Ablating melanopsin only: results
- Complex interaction between rods, cones & pRGCs
- Mouse rod and cone photoreceptors
- Non-image forming light detection in mice (refs.)
- Human studies
- Are humans like mice?
- Case report
- Two patient example
- Activity/rest (sleep) profile
- Control (acquired anophthalmia)
- Normal photoentrainment & melatonin profiles
- Patient pupil constriction in response to bright light
- Patient is unware of bright light
- Two alternative forced choice procedure
- Action spectrum at threshold light level
- Blindness does not mean loss of light detection
- Eye diseases and sleep/wake timing
- Cataract
- Cataract surgery & effect on sleep
- Cataract surgery & sleep: different filtering lenses
- Other eye diseases and sleep/wake timing
- Patients with visual cell loss but intact pRGCs
- Patients with inner retinal cell loss
- Clinical ophthalmology must appreciate all eye roles
- How much light do we need?
- Environmental light levels (Lux)
- Environmental light levels: receptor context
- Inadvertent sleep disruption problems
- Weak light/dark signal
- Environmental light as a time giver
- Talk summary
Topics Covered
- Diversity of vertebrate photoreceptors
- The eye and circadian biology
- Retinal degenerate mice
- Mouse models & photosensitive retinal ganglion cells (pRGCs)
- The photopigment melanopsin (OPN4) and its ablation
- Light and pRGCs human studies (regulation of circadian rhythms)
Links
Series:
Categories:
Therapeutic Areas:
Talk Citation
Foster, R. (2016, September 29). Defining the 3rd photoreceptor system within the eye [Video file]. In The Biomedical & Life Sciences Collection, Henry Stewart Talks. Retrieved December 5, 2024, from https://doi.org/10.69645/SHKN9020.Export Citation (RIS)
Publication History
Financial Disclosures
- Prof. Russell Foster has not informed HSTalks of any commercial/financial relationship that it is appropriate to disclose.
Other Talks in the Series: Biology of the Eye
Transcript
Please wait while the transcript is being prepared...
0:00
My name is Russell Foster.
I'm Professor of Circadian
Neuroscience,
Head of the Nuffield Laboratory
of Ophthalmology,
and Director
of the Sleep and Circadian
Neuroscience Institute
here in Oxford.
What I'd like to consider
in this presentation
is this new photoreceptor system
that's been recently identified
within the eye and so the title is,
"Defining the Third Photoreceptor
System within the Eye."
0:23
Well, I thought I'd cover
in this presentation
are the following topics.
I'd like to consider the diversity
of vertebrate photoreceptors
in place,
the discovery of this new
photoreceptor system within the eye
and within the broader context of
irradiance or brightness detection
of the vertebrate
photoreceptor systems,
then give
a little bit of introduction
into the circadian system
and the early work
with retinal degenerate mice,
and how that led really
to the development
of rodless, coneless mouse,
the rd cl mouse,
and the discovery of these
melanopsin-based
photosensitive
retinal ganglion cells,
and then consider
how this work in rodents
really relates
to clinical ophthalmology
and the human studies
that are currently being undertaken
and then try and follow
with a few summary comments
right at the end.
So let's kick off
with the diversity
of vertebrate photoreceptors.
1:18
If we look at the vertebrates
as a group,
they're about 50 families or more,
and what's very striking is that
the vertebrates can be divided
into two groups
based upon the sort of
photoreceptor systems they use.
So if we consider the birds,
the reptiles, amphibians, fish
and indeed the agnathans,
the lampreys and hagfish,
they have a huge diversity
of photoreceptors.
So let's briefly look at
the diversity of photoreceptors
in these non-mammalian vertebrates.