Scientific studies show that adolescent brains are in flux, still building themselves well into adulthood, right? That certainly is the story we have heard over and over again. And it is true that existing studies show that the fatty coating of neurons changes during childhood and adolescence (never mind that the relevance of that is unclear when it comes to ascriptions of legal or moral responsibility). But what is scientific fact today may not be the fact of tomorrow.
A new study in the journal Nature strongly suggests that the formation of new neurons does not occur in adulthood and probably ends in childhood:
A new study in the journal Nature strongly suggests that the formation of new neurons does not occur in adulthood and probably ends in childhood:
New neurons continue to be generated in the subgranular zone of the dentate gyrus of the adult mammalian hippocampus. This process has been linked to learning and memory, stress and exercise, and is thought to be altered in neurological disease. In humans, some studies have suggested that hundreds of new neurons are added to the adult dentate gyrus every day, whereas other studies find many fewer putative new neurons. Despite these discrepancies, it is generally believed that the adult human hippocampus continues to generate new neurons. Here we show that a defined population of progenitor cells does not coalesce in the subgranular zone during human fetal or postnatal development. We also find that the number of proliferating progenitors and young neurons in the dentate gyrus declines sharply during the first year of life and only a few isolated young neurons are observed by 7 and 13 years of age...
This post reflects an impressive lack of understanding about brain development. The issue in the first paragraph is about mylenation of existing neurons. It is not that adolescents don't have the neurons, it is that because they are no mylenated they are most less efficient in signal transmission. It is established that mylenation, the covering of neurons with an insulating layer of fat occurs last in the neurons that connect to the frontal cortex, which regulates impulse control. While there has been excessive generalization about the effects of this, it is fairly clear that in emotional situations adolescents have poor impulse control compared to adults. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4182916/
This has absolutely nothing to do with the growth of neurons. The entire post is a giant non sequitur. You might want to learn something before you write about it next time.
Fuzzy,
The issue is what confidence can we have in regards to the supposed hard facts that we have about brain science. For years, BNDF was gospel, so much so, that it was posited as a major mechanism of action of antidepressants. Now, well, BNDF seems like dim light in the rear view mirror.
The truth is we really don't understand much about impulse control at the neuronal level. We certainty don't have hard data showing that teens who are more impulsive than their peers have less myelination - not to mention those teens who commit serious crimes.
What is needed in the area of brain science is some humility, which is sorely lacking.
Fuzzy: I suggest that you curb your rancor when exchanging views on this blog. Dr. Erickson hardly needs a lecture from you.
These two things are totally unrelated. Did you read the article I linked to, which is actually quite humble and points out the ways in which impulsivity in adolescents has been exaggerated and the ways in which it has been established.In what way does the study you post undermine anything related to impassivity in adolescents? Are you positing that one study suggesting that one aspect of developmental neuroscience may be incorrect undermines everything? That's quite a broad claim.
"Are you positing that one study suggesting that one aspect of developmental neuroscience may be incorrect undermines everything?"
No one who fairly reads the original post and the follow up comment would attribute such a broad meaning.