> Adult hippocampal neurogenesis is a process that describes the generation of new functional DGCs from adult neural stem cells through the amplification of intermediate progenitors and neuroblasts, as well as the integration of these new neurons into the existing neural circuits.
Source: https://www.nature.com/articles/s41380-018-0036-2#:~:text=Ad....
To me the premise that the possibility of changing my brain through fasting is unquestionably a silver bullet free of tradeoffs is suspect. Or to put it another way, the fact that fasting had a particular effect does not imply that effect is a positive one.
Furthermore, hunger is a strong motivation toward behaviors that are ethically suspect in its absence. A full belly is a rung up Maslow’s hierarchy.
People who spend their days starving mice at scale have incentives to interpret that starvation in positive ways. It would be hard to rationalize starvation and vivisection otherwise and still consider one’s life choice reasonable and ethical. Hence, I am skeptical of acting in the ways an optimistic interpretation of the report suggests. YMMV.
Presumably neurogenesis is occurring all the time and is restricted to a small set of regions in the brain and the new neurons form in just those very strict set of regions. Those neurons are not moving to the neocortex, just a few millimeters within the dentate gyrus. That is to say even robust neurogenesis is not likely to change your mind, cognitive experience, personality or intelligence in any measurable way.
But the parent comment is unfair insofar as scientists don't randomly chose to food deprive or "vivisect" animals because they think it's intrinsically fun. Running these experiments requires a huge amount of annoying busy work that I can't imagine anyone choosing to do without being paid or having some other motive.
In particular, the reason intermittent fasting is studied is because there's a large and increasing body of research that suggests that it may be of benefit to a wide variety of health measures.
The business of cutting apart animals and looking at the insides claim revealed knowledge isn’t new. The Romans called it “haruspicy” and also built wealthy bureaucratic institutions in service of narratives useful to the powerful.
Contemporary interest in fasting research is helpful to those who find advantage in moralizing upon obesity. Intermittent fasting is a virtue reserved for those with food security. It’s attractive to people whose socio-economic status insures that going hungry is a choice and a display of will power. Not weakness. The conclusion that it makes such people smarter is self serving.
The preponderance of health evidence is that starvation is detrimental to human health and creates long term cognitive problems. But lab mice are an industrial product and labs are industrial institutions and the money keeps flowing so long as the results are acceptable to those providing it. That’s the way it has been for millennia.
Anyone care to ELI5 please?
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).
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.
What about teeth?