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Scientists Find a Brain Circuit That Could Explain Seasonal Depression (npr.org)
An anonymous reader quotes a report from NPR: Just in time for the winter solstice, scientists may have figured out how short days can lead to dark moods. Two recent studies suggest the culprit is a brain circuit that connects special light-sensing cells in the retina with brain areas that affect whether you are happy or sad. When these cells detect shorter days, they appear to use this pathway to send signals to the brain that can make a person feel glum or even depressed. The research effort began in the early 2000s, when [Samer Hattar, an author of the mouse study and chief of the section on light and circadian rhythms at the National Institute of Mental Health] and David Berson, a professor of neuroscience at Brown University, were studying cells in the retina. At the time, most scientists thought that when light struck the retina, only two kinds of cells responded: rods and cones. But Hattar and Berson thought there were other light-sensitive cells that hadn't been identified. The skeptics stopped laughing when the team discovered a third kind of photoreceptor that contained a light-sensitive substance called melanopsin not found in rods and cones. These receptors responded to light but weren't part of the visual system.
[Jerome Sanes, a professor at neuroscience at Brown University, and his team] team put young adults in an MRI machine and measured their brain activity as they were exposed to different levels of light. This allowed the team to identify brain areas that seemed to be receiving signals from the photoreceptors Hattar and Berson had discovered. Two of these areas were in the front of the brain. "It's interesting because these areas seem to be the areas that have been shown in many studies to be involved in depression and other affective disorders," Sanes says. The areas also appeared to be part of the same circuit found in mice. The finding needs to be confirmed. But Hattar is pretty confident that this circuit explains the link between light exposure and mood.
[Jerome Sanes, a professor at neuroscience at Brown University, and his team] team put young adults in an MRI machine and measured their brain activity as they were exposed to different levels of light. This allowed the team to identify brain areas that seemed to be receiving signals from the photoreceptors Hattar and Berson had discovered. Two of these areas were in the front of the brain. "It's interesting because these areas seem to be the areas that have been shown in many studies to be involved in depression and other affective disorders," Sanes says. The areas also appeared to be part of the same circuit found in mice. The finding needs to be confirmed. But Hattar is pretty confident that this circuit explains the link between light exposure and mood.
maybe a holdover from mammalian hibernation instincts?
The emerging roles of melanopsin in behavioral adaptation to light:
https://www.ncbi.nlm.nih.gov/p...
https://en.wikipedia.org/wiki/...
A guy goes into a building every day at lunchtime and eats a sandwich, then leaves. One day there is a murder in the building. Obviously the guy is responsible...
Seven puppies were harmed during the making of this post.
As an animal you're not going to do yourself much good if you burn up a ton of energy or procreate while going into the winter. So it would make evolutionary sense to have a mild seasonal depression: you should just want to hole up somewhere and not do much until conditions improve.
That's why we have traditions of bringing a tree inside and lighting it brightly.
I can post this question because my teacher told me "There are no dumb questions."
So, uh, how does depression enhance our survival probability?
Sometimes it's difficult to know how inherited traits were selected for over the millennia of human development. Generally, a persistent trait can be shown to benefit those who exhibit it. I have to question the conjecture that we have evolved sensors that serve only to make us depressed.
So, while these scientists are looking through their microscopes for answers, they might do well to step back a bit for a broader perspective. Does their theory make sense? Could there be alternate reasons for the existence of these sensors?
In any case, it has long been known that there are photoreceptors in nature other than rods & cones.
...omphaloskepsis often...
So maybe all our excessive screen time isn't so bad after all? As long as we're not showing social media on them...
Why do they keep calling neural pathways circuits? Where's the backchannel? It seems to be one way.
pretty sure I read some news that said they did an analysis of yada yada and decided there was no such thing as seasonal affective disorder. googled it... https://www.scientificamerican...
... they did an analysis of yada yada and decided there was no such thing as seasonal affective disorder. googled it... https://www.scientificamerican...
With headline: "Study Finds "Seasonal Affective Disorder" Doesn't Exist"
Science is about getting closer to the truth by replacing less-accurate, inaccurate, and just plain wrong ideas with ones that are more accurate.
ANY study is subject to being found to be wrong or not-so-hot and its conclusions replaced by better ones.
Even if all the studies were performed perfectly and their data showed very strong support of the conclusions, some fraction would be wrong just because of data "noise".
There is NO "settled science". Just conclusions and models that have held up REALLY well - so far.
Bantam Dominique roosters crow a four-note song. Once you've heard it as "Happy BIRTHday" you can't NOT hear it that way
To feel better :)
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