https://www.sciencefacts.net/parts-of-a-neuron.html
https://vcresearch.berkeley.edu/news/new-neurons-help-us-remember-fear
What is Adult Hippocampal Neurogenesis?
In the 1990s Elizabeth Gould discovered that adult mammalian brains could engender new neurons, confined primarily to the dentate gyrus of the hippocampus – a brain region known to be a substrate for learning and memory. (New neurons have also been reported in the neocortex (ref, ref, ref) and hypothalamus (ref) although the extent of neurogenesis in these areas remains controversial (ref).) Histological marker studies have demonstrated that the daily production of several thousand (e.g. 5000-10,000) new dentate hippocampal neurons, a process termed neurogenesis, occurs in a variety of adult mammals including mice, rats, tree-shrews, marmoset and macaque monkeys, and (as studies in the late 1990s showed) humans (ref). The total number of dentate hippocampal neurons is estimated to be between 1.5–2.0 million in the adult rat (ref). Turnover rate of mature dentate gyrus cells in humans has been estimated at ∼1.75% a year (ref).什么是成人海马神经发生?
20世纪90年代，伊丽莎白·古尔德发现，成年哺乳动物的大脑可以产生新的神经元，这些神经元主要局限于海马体的齿状回——众所周知，海马体是学习和记忆的基质。(新神经元也在新皮层(ref, ref, ref)和下丘脑(ref)中被报道，尽管这些区域的神经发生程度仍存在争议(ref)。)组织学标记研究表明，每天产生数千(如5000- 10000)新的齿状海马神经元，这个过程被称为神经发生，发生在各种成年哺乳动物中，包括小鼠、大鼠、树鼩、狨猴和猕猴，以及(如20世纪90年代后期的研究所示)人类(参考文献)。成年大鼠海马齿状神经元的总数估计在150 - 200万个之间(参考文献)。据估计，人类成熟齿状回细胞每年的更替率约为1.75%(参考文献)。https://www.hrplab.org/adult-hippocampal-neurogenesis-review/
Omega-3 Fatty Acids Protect the Brain against Ischemic ...
https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3905150
Jan 29, 2014 · The present study tests the hypothesis that omega-3 polyunsaturated fatty acids (n-3 PUFAs) attenuate ischemic neuronal injury by activating nuclear factor E2-related factor 2 (Nrf2) and upregulating heme oxygenase-1 (HO-1) in both in vitro and in vivo models. We observed that pretreatment of rat primary neurons with docosahexaenoic acid (DHA) significantly reduced neuronal death following oxygen-glucose deprivation.
Cited by: 118
Publish Year: 2014
Author: Meijuan Zhang, Meijuan Zhang, Meijuan Zhang, Suping
DHA and Our Brains
By Zach Nasr
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The Importance of Omega-3’s:
DHA is one of the most important omega-3 fatty acids in our diet. First off, what is an omega-3 fatty acid? There are two essential fatty acids (EFA’s) which are alpha linoleic acid (an omega-3 fatty acid), and linoleic acid (an omega-6 fatty acid).
They are called “essential” because our bodies cannot produce them so we must acquire them from food sources. When it comes to omega-3’s, there are three main players:
ALA (alpha linoleic acid)
EPA (eicosapentaenoic acid)
DHA (docosahexaenoic acid)
ALA must be acquired from food sources because we can’t create it. The other two Omega-3’s are often also considered to be essential by many experts, but they are “conditionally essential” because ALA can be converted into EPA and DHA.
The problem is that our bodies’ ability to convert ALA into EPA is typically only about 10% (depending on what study you look at), and our ability to convert EPA into DHA is only about 1% of that initial 10%!
Love Your Liver
Additionally, this conversion occurs in the liver, and only works if your liver is functioning optimally.
Since we live in a world that we humans have filled with pollution, most people’s livers are dealing with a total crisis of contamination, so this conversion is likely even less!
DHA and Your Brain
As you will read, these fatty acids are very important for brain health, but because we technically can convert ALA into DHA and EPA, there is no officially set recommended daily intake.
In this article, we will talk about what these fatty acids do, how much to take, and some easy ways that we can supply these nutrients.
Why is DHA so special?
DHA is the rarest needed fat that we find in foods, and it is the final stage of the conversion process that Omega-3’s undergo in our bodies. If we can get an optimal amount from diet and/or supplementation, then it takes the pressure off our liver to convert other omega-3’s into DHA.
Much of the research on Omega-3’s show DHA specifically to have the most beneficial effects on memory, and brain health. In the Chicago study (1), a strong neuroprotective effect was observed with DHA that was not seen to the same degree with EPA.
Several studies have also shown that people with Alzheimer’s have severely low levels of DHA in key areas of the brain related to memory formation like the hippocampus (2)(3).
In another study at Rotterdam (4), it was discovered that eating even one meal per week that included fatty fish like salmon could reduce the incidence of cognitive decline and dementia by up to 60%!
DHA also helps improve cognitive abilities in aging rats who do not have a neurodegenerative disease (5). Other studies show DHA improving cognitive abilities, and learning in healthy young rats as well (6) which means that you do not have to be sick to get better from using DHA!
Many of these health benefits come from the antioxidant, and anti-inflammatory effects of DHA shown in the image below. However, many of the brain benefits, as you will soon see, come from the fact that it is a crucial structural component of the brain itself.
The next crucial piece of this omega-3 puzzle lies in fetal brain development and the first few years of our lives which are some of the most formative years for our brains and neurons.
I have often stated the importance of healthy fats because our brains are about 60% fat. I also like to remind everyone that our brains consume about 25% of our total energy and nutrition even though our brains make up only a small part of our body mass.
When we are in the womb, this energy consumption goes up to 70%! Almost all of our energy resources go to building our brain and nervous system when we are a fetus, and DHA is a crucial part of this building process.
Our Brain and Our Eyes
DHA makes up about 30% of our brain matter and approximately 50% of the retinal structure in our eyes. Adding DHA to your diet not only increases cognitive function, but it also increased visual acuity in developing humans and animals (7).
As if this were not enough of a reason to make sure you are getting enough DHA in your diet, another study found that babies born with neurological problems had low levels of DHA, and other important fatty acids, and had elevated levels of trans fats in their brains (8).
Avoid Trans Fats and Get DHA
Humans are basically just grown up babies which is why we recommend avoiding trans fats and other inflammatory fats, and adding in anti-inflammatory fats like DHA and EPA into your diet. DHA reduces inflammation by reducing the expression of Nf-kB (Nuclear factor kappa-beta) among many other anti-inflammatory actions shown in the image below.
Nf-kB is an inflammatory marker in our bodies that we can measure that can generally show us how much inflammation or oxidative stress is occurring in out bodies.
How Big of a Problem is This?
What’s pretty scary is that we in the United States have an imbalance of fats in our diets that is reaching epidemiological proportions. It is recommended that we eat a 1:1 ratio or at most a 1:2 ratio of omega-3 fatty acid to Omega-6 fatty acid.
However, the average American eats between 1:16 and 1:36 ratio of Omega-3 to Omega-6. Many of us are eating too many fried foods that are cooked in rancid (oxidized) Omega-6 oils like vegetable oil, canola oil, cottonseed oil, soybean oil, and other common polyunsaturated fatty acids (PUFA’s).
In order for our bodies to properly metabolize these fats, we need a balance of them in pretty even ratios.
Some oils like olive oil are naturally in a healthy balance of Omega-3 to Omega-6, while oils like vegetable oil (which are not actually made from vegetables, but from the seeds of grasses) are almost entirely Omega-6 fatty acids.
Ventresca Tuna Bellies from Vital Choice: 3550 mg total omega-3’s per 1/2 can:
EPA 840 mg • DHA 2430 mg
How Much is Enough?
The American Heart Association says that we should eat two or more servings (3.5 oz.) of fatty fish like salmon, sardines, tuna, etc. in order to support cardiovascular health, but a dietary survey of shows that most Americans eat half that amount or less.
According to one dietary study (9), most Americans get a dose of combined EPA and DHA equalling 100-200mg per day while many experts recommend getting at least 650mg (combined EPA/DHA) per day, and I like my intake to be at least 500mg of DHA a day. More is even more beneficial as “Supplemental intakes of EPA and DHA combined at doses up to 5 g/day… do not raise safety concerns for adults.” CITE
What About Vegan Sources?
ALA can be found in many vegetarian and vegan sources like flax, hemp, and chia seeds while EPA and DHA (the important conditionally essential fatty acids) are primarily found in animal foods like fatty fish and eggs.
If you are a vegan, then I highly recommend supplementing EPA and DHA. Luckily, there is one vegan source of EPA and DHA that is cold-pressed from algae. You can find our favorite vegan omega-3 supplement (including EPA and DHA) by clicking on the image below.
DHA and Our Brains - Learn how to Feed a Brain! https://feedabrain.com/dha/
BIRTH TO AGE 3 SEES THE FASTEST RATE OF BRAIN DEVELOPMENT IN THE ENTIRE HUMAN LIFE SPAN.
Though you may think your darling is growing like a weed as chubby toddlerhood gives way to lanky kid, in the first three years of your child’s life, their brain is growing faster than any other body part. At birth, a baby's brain is about one-third the size of an adult's brain. In 90 days, it more than doubles its volume, to 55 percent of its final size. The cerebellum in particular, a brain structure at the back of the brain involved in controlling movement, grows the fastest of all brain structures; in just three months it will be 110 percent bigger than it was at birth.
出生到3岁是人类一生中大脑发育速度最快的时期。
虽然你可能认为你的宝贝正在像野草一样生长，因为胖乎乎的蹒跚学步已经让位给了瘦长的孩子，但在孩子生命的前三年里，他们的大脑比身体其他任何部位都生长得更快。出生时，婴儿的大脑只有成人大脑的三分之一大小。在90天内，它的体积增加了一倍多，达到最终体积的55%。尤其是小脑，它位于大脑后部，参与控制运动，是所有大脑结构中生长最快的;仅仅三个月后，它就会比出生时大110%。
大脑的发育~包括神经元的形成和突触的增加
4. MOST OF THE ENERGY A BABY EXPENDS IS CONCENTRATED IN THE BRAIN.
As a result of all that rapid brain development, 60 percent of a baby’s metabolic energy (primarily the consumption of glucose) is spent on growing those soon-to-be massive brains. In contrast, the brain of an adult uses only about 25 percent of the body’s metabolic energy.
4. 婴儿消耗的大部分能量集中在大脑。
由于大脑的快速发育，婴儿60%的代谢能量(主要是消耗葡萄糖)都花在了那些即将成为庞然大物的大脑的生长上。相比之下，成年人的大脑只消耗身体25%的代谢能量。10 Amazing Facts About the Infant Brain | Mental Floss
https://www.mentalfloss.com/article/70105/10-amazing-facts-about-infant-brain#:~:text=%2010%20Amazing%20Facts%20About%20the%20Infant%20Brain,IN%20THE%20ENTIRE%20HUMAN%20LIFE%20SPAN.%20More%20
90% of Brain Growth Happens Before Kindergarten At birth, the average baby’s brain is about a quarter of the size of the average adult brain. Incredibly, it doubles in size in the first year. It keeps growing to about 80% of adult size by age 3 and 90% – nearly full grown – by age 5. The brain is the command center of the human body. A newborn baby has all of the brain cells (neurons) they’ll have for the rest of their life, but it’s the connections between these cells that really make the brain work. Brain connections enable us to move, think, communicate and do just about everything. The early childhood years are crucial for making these connections. At least one million new neural connections (synapses) are made every second, more than at any other time in life.
90%的大脑发育发生在幼儿园之前
出生时，婴儿的大脑平均只有成人大脑的四分之一。令人难以置信的是，它的体积在第一年就翻了一番。到3岁时，它会持续增长到成年的80%，到5岁时，它会增长到90%——几乎完全长大。
大脑是人体的指挥中心。一个新生儿拥有他们一生中所拥有的所有脑细胞(神经元)，但真正让大脑工作的是这些细胞之间的连接。大脑连接使我们能够移动、思考、交流和做任何事情。童年早期是建立这些联系的关键时期。每秒钟至少产生100万个新的神经连接(突触)，比生命中的任何时候都多。
Brain Development - First Things First
https://www.firstthingsfirst.org/early-childhood-matters/brain-development/
健康分享：大部分的大脑神经细胞是在胚胎时期形成的
人大脑中的大多数神经元都是在出生之前产生的。
但大脑的一些区域在出生后产生新的神经元，这个过程被称为产后神经发生。
包括小脑和前额叶皮质在内的一些区域在婴儿期继续增加新的神经元。科学家们相信，大脑中至少有一个区域—负责学习和记忆的海马体——会在人的一生中不断产生新的神经元。
大脑发育从怀孕三周后开始，怀孕后期，胚胎从母体获得的能量的60%用于构建大脑。
每天200毫克的DHA是满足胎儿大脑发育的最低摄入量。
你的脑细胞是与生俱来的，还是长出来的?
作者Elizabeth Gould Source BrainFacts/SfN发表于2017年2月23日
你大脑中的大多数神经元都是在你出生之前产生的。但大脑的一些区域在出生后产生新的神经元，这个过程被称为出生后神经发生。
包括小脑和前额叶皮质在内的一些区域在婴儿期继续增加新的神经元。科学家们相信，大脑中至少有一个区域——海马体——会在人的一生中不断产生新的神经元。
有趣的是，这个大脑区域与学习和记忆有关。海马体形成对事件和经历的记忆。一些科学家认为，向海马体中添加新的神经元可能会增强学习和记忆，因为新的神经元比旧的神经元更具可塑性，这意味着它们可以更容易地修改它们的连接，以形成和存储记忆。
尽管海马体提供了成人大脑中神经发生的最佳证据，但大脑的其他部分也可能有同样的能力，而不断改进的新技术可能帮助我们确定这是否是事实。事实上，最近的证据表明，成年人的神经发生也发生在人的纹状体中，这是一个对形成习惯很重要的大脑区域。对成人神经发生的了解将使我们能够利用这种能力来修复和替换因损伤和疾病失去的神经元——但这还需要很长时间。
值得注意的是，神经元并不是构成大脑的唯一细胞。科学家们早就观察到，大脑的其他细胞，即神经胶质细胞，也会再生。神经胶质细胞的职责包括维持血脑屏障、保护神经元不受病原体侵害和控制神经元功能，它约占人类大脑质量的一半，并不断更新和替换。因此，大脑中的神经元和神经胶质细胞的更新比你想象的要多得多。
关于作者
伊丽莎白·古尔德
伊丽莎白·古尔德(Elizabeth Gould)是普林斯顿大学的心理学和神经科学教授。她研究的是成年哺乳动物大脑的结构可塑性。Are you born with all your brain cells, or do you grow new ones?
https://www.brainfacts.org/ask-an-expert/are-you-born-with-all-your-brain-cells-or-do-you-grow-new-ones
Researchers discover the source of new neurons in brain's hippocampus
Findings extend understanding of how a continuous supply of neurons throughout life is connected with learning and memory
Date: March 28, 2019
Source: University of Pennsylvania School of Medicine
Summary:
Researchers have shown, in mice, that one type of stem cell that makes adult neurons is the source of this lifetime stock of new cells in the hippocampus. These findings may help neuroscientists figure out how to maintain youthful conditions for learning and memory, and repair and regenerate parts of the brain after injury and aging.
It was once believed that mammals were born with the entire supply of neurons they would have for a lifetime. However, over the past few decades, neuroscientists have found that at least two brain regions -- the centers of the sense of smell and the hippocampus, the seat of learning and memory -- grow new neurons throughout life.
Researchers from the Perelman School of Medicine at the University of Pennsylvania have shown, in mice, that one type of stem cell that makes adult neurons is the source of this lifetime stock of new cells in the hippocampus. Published this week in Cell, these findings may help neuroscientists figure out how to maintain youthful conditions for learning and memory, and repair and regenerate parts of the brain after injury and aging.
"We've shown for the first time, in mammals, that neurons in the dentate gyrus of the hippocampus grow and develop from a single population of stem cells, over an entire lifespan," said senior author Hongjun Song, PhD a professor of Neuroscience. "The new immature neurons are more flexible in making connections in the hippocampus compared to mature neurons, which is paramount for healthy learning, memory, and adjusting mood."
The researchers showed that the neural stem cells they found had a common molecular signature across the lifespan of the mice. They did this by labeling neural stem cells in embryos when the brain was still developing and following the cells from birth into adulthood. This approach revealed that new neural stem cells with their precursor's label were continuously making neurons throughout an animal's lifetime.
"This process is unique in the brain," said co-senior author Guo-li Ming, MD, PhD, a professor of Neuroscience. "In the hippocampus, these cells never stop replicating and contribute to the flexibility of the brain in mammals."
This capacity is called plasticity, which is the brain's ability to form new connections throughout life to compensate for injury and disease and to adjust in response to new input from the environment. Ming likens the process of new neuron growth in the hippocampus to adding new units into the circuitry of the brain's motherboard.
The teams' next steps will be to look for the same neural stem cells in other mammals, most importantly in humans, starting the search in post-mortem brain tissue, and to investigate how this population of neural stem cells are regulated.研究人员在大脑的海马体中发现了新神经元的来源
这些发现拓展了人们对生命中神经元的持续供应是如何与学习和记忆联系在一起的理解
日期:2019年3月28日
资料来源:宾夕法尼亚大学医学院
简介:
研究人员在老鼠身上发现，一种产生成年神经元的干细胞是海马状突起中终生储存新细胞的来源。这些发现可能有助于神经科学家找出如何保持学习和记忆的年轻状态，并在受伤和衰老后修复和再生大脑的某些部分。
人们曾经相信哺乳动物一出生就拥有它们一生所需的全部神经元。然而，在过去的几十年里，神经科学家已经发现，至少有两个大脑区域——嗅觉中心和海马体(学习和记忆的中枢)——会在一生中产生新的神经元。
宾夕法尼亚大学(University of Pennsylvania)佩雷尔曼医学院(Perelman School of Medicine)的研究人员在小鼠身上发现，一种制造成体神经元的干细胞是海马区终生储存新细胞的来源。本周发表在《细胞》(Cell)杂志上的这些发现，可能会帮助神经科学家找出如何保持学习和记忆的年轻状态，并在受伤和衰老后修复和再生大脑的某些部分。
资深作者、神经科学教授宋洪军博士表示:“我们首次证明，哺乳动物海马齿状回的神经元在整个生命周期中由单一种群的干细胞生长和发育。”“与成熟神经元相比，新的未成熟神经元在海马体中的连接更灵活，这对健康的学习、记忆和调节情绪至关重要。”
研究人员发现，他们发现的神经干细胞在小鼠的整个生命周期中具有共同的分子特征。他们在大脑还处于发育阶段时标记胚胎中的神经干细胞，并跟踪这些细胞从出生到成年。这种方法表明，带有前体标记的新神经干细胞在动物的一生中不断制造神经元。
“这一过程在大脑中是独一无二的，”资深合著者、神经科学教授、医学博士李明国(音译)说。“在海马体中，这些细胞从未停止复制，并为哺乳动物大脑的灵活性做出贡献。”
这种能力被称为可塑性，它是大脑在一生中形成新的连接，以补偿受伤和疾病，并对来自环境的新输入做出调整的能力。Ming将海马体中新神经元的生长过程比作在大脑主板电路中添加新单元。
研究小组的下一步将是在其他哺乳动物身上寻找同样的神经干细胞，最重要的是在人类身上，开始在死后的脑组织中寻找，并研究神经干细胞是如何被调控的。
This work was funded by the National Institutes of Health (P01NS097206, R37NS047344, R35NS097370, R01MH105128), EMBO, and the Swedish Research Council.
https://www.sciencedaily.com/releases/2019/03/190328150854.htm
https://vcresearch.berkeley.edu/news/new-neurons-help-us-remember-fear
The chemical compounds called cannabinoids, found in cannabis and hemp, are also produced naturally in the body from omega-3 fatty acids. A new study in animal tissue reveals the cascade of chemical reactions that convert omega-3 fatty acids into cannabinoids that have anti-inflammatory benefits.
Omega-3 Fatty Acids Reduce Inflammation through Cannabinoids
todayspractitioner.com/cannabis/omega-3-fatty-acids-reduce-inflammation-throug…
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Natural cannabinoids from omega-3 fatty acids combat ...
https://www.medicalnewstoday.com/articles/318528
Jul 20, 2017 · These molecules come from cannabinoids that are made naturally from omega-3 fatty acids, which are essential nutrients found in meat, fish, eggs, and nuts. The results of a …
