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:/ Anyone care to ELI5 please?

pkaye 6y ago
Seems like a literal translation would be "creation of neurons in the hippocampus". And the hippocampus is associated with memory and learning.
- globular-toast 6y ago
  Is it good or bad?
epmaybe 6y ago
Fasting -> new brain cells and brain connections in a specific part of the brain. At least that’s the correlation they’re going for
jmcgough 6y ago
I worked in a neurogenesis lab for three years, so my attempt: The cells in our body are continuously replaced throughout our life, with the exception of our brain cells. For many many years we believed that mammals didn't create new brains cells in adulthood. You were born, your brain grew and developed as you became an adult, and then you were done. About 20 years ago we realized that that was mostly true, but small parts of the brain continued to produce neurons through adulthood. This happens in two important parts of the brain: - the hippocampus, which is associated with memory - the olfactory bulb, which is associated with sense of smell (and memories related to it). Humans have a relatively weak sense of smell, and if we create new neurons in the olfactory bulb it's much less than other mammals. The process is convoluted, but small regions of the brain create those new neurons and they migrate through fluid-filled holes in your brain - most die, but a small % survive and incorporate themselves into that brain structure. The key thing to realize is that neurogenesis accounts for a tiny fraction of the neurons in our brain, and yet it's still an important process. So why does adult neurogenesis matter, and what does it do for us? Neurogenesis is tied to our ability to learn and form new memories. So, if it's impaired, our ability to learn is reduced. There are tons of things that impact it - age, sleep levels, exercise, among others. In the lab I worked at, we used to induce a form of brain damage to rats which greatly impaired neurogenesis, then run them through mazes, which they did quite poorly at. We took some of those same brain-damaged rats and had them run in exercise wheels for two weeks, and they were suddenly doing just fine at maze tasks. When we stained and looked at their brain, their neurogenesis rate was back up to (or even above) normal levels. We've known for a long time that exercise is great for your health, and there's a growing body of evidence that the same is true for intermittent fasting. What's interesting is that it's not just good for your overall body health, but both can help keep your brain working optimally by increasing neurogenesis and BDNF (which protects your existing neurons).
- ckemere 6y ago
  It's worth noting that there's some controversy about the extent of adult neurogenesis in humans. If it exists it's likely at the scale of a few neurons per day. Whether or not that means that increasing it by fasting is important is unclear.
  - jmcgough 6y ago
    Yeah, a 2018 UCSF study was unable to find any adult neurogenesis in humans, so it's still a controversial subject when it comes to humans. Even if we had confidence that adult neurogenesis occurs in humans, we can't really expose humans to a stimuli, kill them and then do a BrdU stain, so it's difficult to know how well any rat study translates over to humans.
    - ckemere 6y ago
      The early evidence in humans was based on radioisotopes present in the atmosphere after atomic tests. You could diffentiate neurons in people's brains (after they died) if they had been born before the 1940s.
- loco5niner 6y ago
  >The cells in our body are continuously replaced throughout our life, with the exception of our brain cells. What about teeth?

Seems like a literal translation would be "creation of neurons in the hippocampus". And the hippocampus is associated with memory and learning.

globular-toast 6y ago
Is it good or bad?

epmaybe 6y ago

Fasting -> new brain cells and brain connections in a specific part of the brain. At least that’s the correlation they’re going for

jmcgough 6y ago

I worked in a neurogenesis lab for three years, so my attempt: The cells in our body are continuously replaced throughout our life, with the exception of our brain cells. For many many years we believed that mammals didn't create new brains cells in adulthood. You were born, your brain grew and developed as you became an adult, and then you were done. About 20 years ago we realized that that was mostly true, but small parts of the brain continued to produce neurons through adulthood. This happens in two important parts of the brain: - the hippocampus, which is associated with memory - the olfactory bulb, which is associated with sense of smell (and memories related to it). Humans have a relatively weak sense of smell, and if we create new neurons in the olfactory bulb it's much less than other mammals. The process is convoluted, but small regions of the brain create those new neurons and they migrate through fluid-filled holes in your brain - most die, but a small % survive and incorporate themselves into that brain structure. The key thing to realize is that neurogenesis accounts for a tiny fraction of the neurons in our brain, and yet it's still an important process. So why does adult neurogenesis matter, and what does it do for us? Neurogenesis is tied to our ability to learn and form new memories. So, if it's impaired, our ability to learn is reduced. There are tons of things that impact it - age, sleep levels, exercise, among others. In the lab I worked at, we used to induce a form of brain damage to rats which greatly impaired neurogenesis, then run them through mazes, which they did quite poorly at. We took some of those same brain-damaged rats and had them run in exercise wheels for two weeks, and they were suddenly doing just fine at maze tasks. When we stained and looked at their brain, their neurogenesis rate was back up to (or even above) normal levels. We've known for a long time that exercise is great for your health, and there's a growing body of evidence that the same is true for intermittent fasting. What's interesting is that it's not just good for your overall body health, but both can help keep your brain working optimally by increasing neurogenesis and BDNF (which protects your existing neurons).

ckemere 6y ago
It's worth noting that there's some controversy about the extent of adult neurogenesis in humans. If it exists it's likely at the scale of a few neurons per day. Whether or not that means that increasing it by fasting is important is unclear.
- jmcgough 6y ago
  Yeah, a 2018 UCSF study was unable to find any adult neurogenesis in humans, so it's still a controversial subject when it comes to humans. Even if we had confidence that adult neurogenesis occurs in humans, we can't really expose humans to a stimuli, kill them and then do a BrdU stain, so it's difficult to know how well any rat study translates over to humans.
  - ckemere 6y ago
    The early evidence in humans was based on radioisotopes present in the atmosphere after atomic tests. You could diffentiate neurons in people's brains (after they died) if they had been born before the 1940s.
loco5niner 6y ago
>The cells in our body are continuously replaced throughout our life, with the exception of our brain cells. What about teeth?