Talk:Aging brain

Biological immortality and permanent memories
Since adult human brain and nerve cells do not regularly regenerate (as I understand it, its only recently been discovered that new brain and nerve cells can appear after 4 or 5 years of age, and then only rarely), allowing humans to store long-term memories indefinitely, excepting for brain damage, would not a biologically immortal human, whose somatic cells, including brain and nerve cells, only divide in order to replace damaged, destroyed, or aberrant cells, eventually reach his brain's limit for information storage unless he caused himself regular brain damage in order to purge himself of old memories? Has research into biological immortality sparked any neurological research on this topic? It seems that even if a euthereon were biologically immortal, the brain would still have a functional lifespan:  once it's become over-fraught with information, the creation of any new long-term memories after that point would be impossible, unless by some hitherto unknown mechanism the creation of new memories would be possible either by "rewriting" existing brain cells with new memories or "deleting" older brain cells altogether and replacing them. Is enough known about the mammalian brain to guess which, if either, of these two mechanisms is possible without further genetic adaptations to deal with this side-effect of biological immortality (we'll assume for the sake of argument that overcoming the side-effect of increased cancer risk is an integral part of biological immortality, as is an inherent immunity to all but the most rapidly spreading viruses and bacteria, and that this has had no functional impact on the process of creating and storing memories) in a species like Homo sapiens which has almost entirely overcome predation, and which scenerio (rewriting or replacing) is more probable?

This may seem frivolous speculation, but with biological immortality being highly marketable and the number of cosmetic companies that seek a means of attaining it (despite the damage this will do to our planet and our species as a whole), a thorough study of the brain with regard to maturation and senescence would ideally seek to understand the difference between a brain that experiences senescence and one that is biologically immortal, for the same reason drug testers use control groups: to truly understand the effects of senescence on the brain of a given species, we must know what happens to a brain of the same animal species when it doesn't undergo senescence. This is what prompted me to make this post, as it seems there must at least be one or two competing hypotheses, if not an actual theory, concerning the age-independent lifespan of the brain. If the body could live forever, what would happen to the brain? --Þórrstejn [ˡθoɝ.staɪʲn ]: Hammer of Thor  talk  08:34, 22 January 2008 (UTC)

--This is a response to the above post by Þórrstejn [ˡθoɝ.staɪʲn ]: Hammer of Thor :  While your commentary is interesting, it is not well-grounded in recent science on the subject. I don't have much time to go into detail so I'll briefly correct you on the most important erroneous assumption you make here, which is that memory is encoded, somehow, into neurons, the cell bodies themselves. This is, as anyone with even a very simple understanding of neurology would know, completely impossible and false. Based on our current knowledge of neuron cell microbiology, complex information such as memories are not stored inside the cell bodies themselves. No, it is the numerous connections between neurons that lead to the whole effect of memory formation. Dendritic connections between neurons are constantly worn away and reformed, and dendritic growth is something the human brain is capable of doing throughout its life. Dendrites, if you don't know, are the "receiving" ends of neurons, which are branching and tree-like in appearance (hence the name). Therefore, assuming immortality were possible, there is no reason to assume that a constant cycle of memory formation and loss wouldn't also be possible, though unless means of preventing age-related slowing of processing speed due to plaque formation, neuron loss, etc. are discovered, the efficiency of memory formation with very long life would be impaired. --Anonymous —Preceding unsigned comment added by 128.218.154.102 (talk) 23:46, 30 January 2009 (UTC)

The glutamate section should be removed
It is misleading to list glutamate as merely one of several neurotransmitters (or “metabolites,” welp) that show decreases with age. Unlike dopamine and serotonin — which are synthesized and broadly distributed from a few neurons in a few specialized nuclei — glutamate is the primary neurotransmitter of the brain and is expressed in all regions. MRI studies measuring decreases in glutamate with age are likely measuring a decreased number of neurons in those regions. One of the three cited sources for this section even describes correlated decreased gray matter volume in the abstract.

Because of the cardinality of glutamate in subserving all thought, sensory input, and motor output, it should not be listed in the same category as neuromodulators. Changes in glutamate signaling are the bottom line of neuromodulators like dopamine and serotonin. When the modulators start to decline, the brain is working with faulty control systems, but when glutamate starts to decline, the brain is simply not working.

I don’t think the section adds much to our understanding of cognitive decline with aging, and should be removed. I fear it could lead to people trying to “boost glutamate levels” through diet or supplementation, and if they’re successful they’ll have a seizure. At a minimum it should be made more clear that “glutamate levels” essentially are “brain activity levels,” and this type of decline is not amenable to pharmacological intervention in the same way as the neuromodulators. LetThereBeNick (talk) 12:47, 23 April 2020 (UTC)

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