Yesterday 06:37 PM
https://www.eurekalert.org/news-releases/1143797
EXCERPTS: When retinitis pigmentosa takes a person's sight, the standard clinical test goes flat: no response, no signal, nothing. Yet the retina behind that flat line is anything but quiet. Researchers at the Jules-Gonin Eye Hospital, part of the Faculty of Biology and Medicine of the University of Lausanne, have recorded the spontaneous electrical activity of the retina -in darkness, with no light stimulation -and found it producing abnormal rhythms never before measured in a living person.
The findings are published in Nature Communications. Retinitis pigmentosa is a group of genetic diseases that progressively destroy the photoreceptors, the cells that capture light. At an advanced stage, the electroretinogram -the reference test for retinal function - detects nothing. The trace is flat.
But a flat trace is not a dead retina. Behind the lost photoreceptors, several layers of neurons survive and rewire, a process called retinal remodelling that has been documented for some twenty years in donor tissue examined after death. What no one had done was measure the activity of those rewired circuits in a living eye.
[...] A pilot study then enrolled five patients at an advanced stage of the disease and eight sighted volunteers. Recordings lasted forty minutes, eyes closed, in darkness, using thread electrodes already common in routine clinical care. The patients' retinas showed markedly stronger oscillatory activity than the sighted participants', in a frequency range close to the one seen in mice -the first evidence that degenerating human retinas are functionally, not just anatomically, remodelled.
In animals, the team went a step further. A drug that boosts the retina's own inhibitory signalling quieted the abnormal rhythm. And with the noise reduced, transcorneal electrical stimulation reached the visual cortex more effectively, at lower current and the retina became easier to drive.
Therapies that aim to restore sight -retinal implants, optogenetics, regenerative approaches -all depend on the surviving retina being able to listen. If it is busy talking to itself, that is a problem... (MORE - missing details, no ads)
EXCERPTS: When retinitis pigmentosa takes a person's sight, the standard clinical test goes flat: no response, no signal, nothing. Yet the retina behind that flat line is anything but quiet. Researchers at the Jules-Gonin Eye Hospital, part of the Faculty of Biology and Medicine of the University of Lausanne, have recorded the spontaneous electrical activity of the retina -in darkness, with no light stimulation -and found it producing abnormal rhythms never before measured in a living person.
The findings are published in Nature Communications. Retinitis pigmentosa is a group of genetic diseases that progressively destroy the photoreceptors, the cells that capture light. At an advanced stage, the electroretinogram -the reference test for retinal function - detects nothing. The trace is flat.
But a flat trace is not a dead retina. Behind the lost photoreceptors, several layers of neurons survive and rewire, a process called retinal remodelling that has been documented for some twenty years in donor tissue examined after death. What no one had done was measure the activity of those rewired circuits in a living eye.
[...] A pilot study then enrolled five patients at an advanced stage of the disease and eight sighted volunteers. Recordings lasted forty minutes, eyes closed, in darkness, using thread electrodes already common in routine clinical care. The patients' retinas showed markedly stronger oscillatory activity than the sighted participants', in a frequency range close to the one seen in mice -the first evidence that degenerating human retinas are functionally, not just anatomically, remodelled.
In animals, the team went a step further. A drug that boosts the retina's own inhibitory signalling quieted the abnormal rhythm. And with the noise reduced, transcorneal electrical stimulation reached the visual cortex more effectively, at lower current and the retina became easier to drive.
Therapies that aim to restore sight -retinal implants, optogenetics, regenerative approaches -all depend on the surviving retina being able to listen. If it is busy talking to itself, that is a problem... (MORE - missing details, no ads)