The
discovery of neurogenesis, the birth of new neurons in adult brains, was a huge
scientific discovery. Neurogenesis was found in rats, birds, mice, monkeys, and
in the human hippocampus throughout the years. However, new findings claim that
neurogenesis in fact does not occur, according to Helen Shen from the
Scientific American. Neuroscientist Arturo Alvarez-Buylla examined numerous
samples of human hippocampi, both after death and during brain surgery. His
team found evidence of many new neurons until one year of life. After that
time, there are few new neurons in young children and none in adults.
Another
neuroscientist, Pasko Rakic, says that this finding "shows very convincing
evidence of a lack of neurogenesis in the adult human hippocampus but also
shows that some of the evidence presented by other studies was not
conclusive." He has a very strong view that neurogenesis is not supported
by scientific findings. On the other hand, neuroscientist Fred Gage claims that
neurogenesis needs to be studied differently and have more lax criteria since
it is an ongoing process. Both of these statements have data backing them up,
furthering the debate about neurogenesis. These findings only further the need
for more research on this phenomenon.
This
evidence and the topic of neurogenesis relate to what we learned about the
hippocampus and memory. The hippocampus is associated with memory, and damage to
the hippocampus leads to numerous deficits. For example, patient HM had his
whole hippocampus removed to help control his epileptic seizures. His seizures
came under control, but he was no longer able to form new memories. Similarly,
patient EP could no longer form new short-term memories after suffering from
viral encephalitis that destroyed part of his medial temporal lobe, including
his hippocampus. These two patients provide evidence that the hippocampus is a
crucial part of memory formation in the human brain.
This
evidence and current research on neurogenesis lead to questions about treatment
for neurodegenerative disease. Diseases like Alzheimer's show a progressive
decline in a patient's memory due to plaques of beta-amyloid and tangles of
neurons, ultimately leading to cell death. If neurogenesis were in fact
possible, there is hope that one day researchers would be able to find a cure
for neurodegenerative diseases. Researchers might find a way for Alzheimer’s
patients to create or obtain new neurons to replace the ones that have tangled
and died. This could also extend to areas in the brain, other than the hippocampus.
If evidence of neurogenesis is found in other places, patients who suffer brain
damage now have the possibility that their brain might one day return to normal
function (or at least be closer to it than without neurogenesis).
Your article defiantly caught my attention! The reason why is that I originally thought neurogenesis was a widely agreed upon concept in the scientific community. It’s crazy to learn that not only are there a group of neuroscientists who do not believe in neurogenesis, but there are studies that back that up as well. One part of your blog mentioned a study done by Arturo Alvarez-Buylla, who found evidence that neuronal growth stopped after one year of life in the human brain. With that in mind, I believe neurogenesis is an exciting topic, but as humans sometimes we get too excited and it causes us to disregard opposing evidence. I also liked how you tied this information to what we learned in class about the role of the Hippocampus when it comes to memory, and the devastating effects it could have on us if there is damage to that area.
ReplyDeleteThis is an interesting article - thanks for sharing. The topic of neurogenesis is huge and exciting, but sort of a dead end when it comes to adults. After reading your blog I did some research myself and, like you said, although new neurons are being produced throughout the first year of life, neurogenesis stops after that. I wonder if, since "neurogenesis" only lasts through the first year of birth, has to be a genetic factor - in which the people that do not produce enough neurons in that first year are the ones that are more susceptible for neurodegenerative diseases. It is interesting to think how if neurogenesis continued throughout our whole life, would that decrease our risks for neurodegenerative diseases and the severity of TBIs or lesions? Also during my search I found a researcher that tells us to not worry about neurogenesis when our brains are still capable of neuroplasticity!
ReplyDeleteThis was an interesting article. The first thing that came to mind when I read this was brain plasticity. Although it is not the same concept as neurogenesis, it was once a concept that many scientists were strongly convinced that it is false. I don't know much about neurogenesis however, if this was actually true then wouldn't we see a lot less age-related brain disease? I can see why this is such a controversial topic but it would be amazing for the future if neurogenesis can guide the prevention of certain brain diseases. Of course there are factors in aging that one cannot prevent but memory is different.
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