Monday, May 16, 2022

What Is The Last Part Of The Brain To Develop

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Brain Maturity Extends Well Beyond Teen Years

When Do Emotions Develop?

    Under most laws, young people are recognized as adults at age 18. But emerging science about brain development suggests that most people don’t reach full maturity until the age 25. Guest host Tony Cox discusses the research and its implications with Sandra Aamodt, neuroscientist and co-author of the book Welcome to Your Child’s Brain.


    I’m Tony Cox and this is TELL ME MORE from NPR News. Michel Martin is away. We’d like to spend this part of the program talking about the passage from childhood to adulthood and how that may be tougher for one distinct group of young people.

    Most of the privileges and responsibilities of adulthood are legally granted by the age of 18. That’s when you can vote, enlist in the military, move out on your own, but is that the true age of maturity? A growing body of science says, no. That critical parts of the brain involved in decision-making are not fully developed until years later at age 25 or so.

    In a moment, we’ll hear about how child advocates are hoping to use this research to change the laws about their foster care. But first, to learn more about adolescent brain development and maturity, we are joined now by neuroscientist, Sandra Aamodt. She is the coauthor of the book, “Welcome to Your Child’s Brain: How the Mind Grows from Conception to College.”

    Sandra, welcome to the program. It’s nice to have you.

    DR. SANDRA AAMODT: It’s nice to be here.

    AAMODT: Especially around about the age of 15 or so. Yes.

      What Can Harm Fetal Brain Development

      One of the largest contributors to fetal harm is alcohol. Drinking while pregnant can severely impact the growth and development of the babys brain. Alcohol consumption can cause fetal alcohol syndrome, which causes brain damage and problems with a babys growth. Babies with fetal alcohol syndrome may have a certain cast to their facial features, including drooping eyes. They may also experience speech delays and mild to severe retardation. There is no known safe amount of alcohol to consume while pregnant, and the effects of fetal alcohol syndrome are irreversible. If you are having trouble abstaining from drinking, its important to discuss this with your doctor right away.

      One of the largest contributors to fetal harm is alcohol. Drinking while pregnant can severely impact the growth and development of the babys brain.

      Smoking is also harmful to a babys development overall, including low birth weight and a reduction of the formation of neurons in the brain. Cigarette smoke, and the chemicals it contains, also impact the communication between neurons.

      If you dont have a cat, its best to wait until after you have the baby to get one. Feline feces can contain parasites that cause toxoplasmosis, which can be harmful to your baby and especially their brain. If you do have a cat, get someone else to clean the litter box and be sure to wear gloves if you do it yourself.

      Final Thoughts: Brain Development Continues Throughout 20s

      Neuroscientists largely agree that the human brain hasnt fully developed until the mid-20s. Although the changes that the brain incurs after adolescence are not well-studied, increases in myelination and pruning of neural pathways are believed to occur. Additionally our personality as well as development of the prefrontal cortex is finalized well into our 20s.

      Although you may consider yourself an adult at age 18, keep in mind that your brain still has a ways to develop. Your cognition, ability to assess risk, and think logically will continue to improve as you age. This is considerably different than neuroscience views of the past in which we thought the brain was done developing in the teenage years.

      And despite the fact that brain development may be done by our 30s, it doesnt mean that someone with a fully developed brain cannot change it. There is considerable evidence to suggest that we can still change our own brains with a process called neuroplasticity. Our brains are constantly adapting to our environment, experiences, and other inputs to which it is exposed.

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        How To Support Your Babys Brain Development

        Its important to consume at least 600 mg of folate, or folic acid, during the first trimester and 400 mg later in pregnancy. This vitamin supports brain and spinal development, ensuring that the spinal tube fuses correctly and stimulating the growth of the brain throughout your pregnancy. Prenatal vitamins, created specifically to deliver the nutrients necessary during pregnancy, contain extra folate. If you arent getting enough from your diet, consult with your doctor about the best kind of prenatal vitamins for you. You can also get folate naturally from your food, specifically flax seed, whole grains, and leafy green vegetables.

        Its important to consume at least 600 mg of folate, or folic acid, during the first trimester and 400 mg later in pregnancy. This vitamin supports brain and spinal development, ensuring that the spinal tube fuses correctly and stimulating the growth of the brain throughout your pregnancy.

        Eating a balanced diet of whole foods and drinking plenty of water will help your baby’s brain develop properly.

        When Does A Fetus Develop A Brain

        The frontal lobe is the last part of the brain to develop...

        Fetal brain development starts probably before you even realize youve conceived. When youre just 5 weeks pregnant, the first neural cells begin to divide and differentiate into neurons and glia .

        Also at about week 5 of pregnancy, the neural plate folds onto itself to form the neural tube, which closes by about week 6 of pregnancy to eventually become the brain and spinal cord.

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        Brain Development In Adolescence

        Current studies demonstrate that brain structures and processes change throughout adolescence and, indeed, across the life course . These findings have been facilitated by imaging technologies such as structural and functional magnetic resonance imaging . Much of the popular discussion about adolescent brain development has focused on the comparatively late maturation of the frontal lobes , although recent work has broadened to the increasing âconnectivityâ of the brain.

        Throughout childhood and into adolescence, the cortical areas of the brain continue to thicken as neural connections proliferate. In the frontal cortex, gray matter volumes peak at approximately 11 years of age in girls and 12 years of age in boys, reflecting dendritic overproduction . Subsequently, rarely used connections are selectively pruned making the brain more efficient by allowing it to change structurally in response to the demands of the environment . Pruning also results in increased specialization of brain regions however, the loss of gray matter that accompanies pruning may not be apparent in some parts of the brain until young adulthood . In general, loss of gray matter progresses from the back to the front of the brain with the frontal lobes among the last to show these structural changes .

        Why Does The Brain Take So Long To Develop

        Human beings are the only animals that are born completely helpless, and we have the biggest size of adult brain. If we were born with an adult-sized brain our heads would not fit through our mothers’ hips. Brain development that continues after birth also helps us better adapt to our living environment and increases our chance of survival.

        We used to think that once children had gone through puberty and growth had finished, development was complete. Then MRI scanners were invented and they showed that the brain goes on changing for a long time after puberty has finished, and may not be complete until nearly 30 years of age.

        The following image shows that the brain doesn’t change much in size between 5 and 20 years of age. What changes is the colour. The blue colour shows all the connections happening between all the parts of the brain that are already formed.

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        Brain Development During Pregnancy

        Its probably unsurprising that an impressive amount of brain development happens during pregnancy. After all, an impressive amount of development in general is taking place for that little embryo of yours. This development is the foundation of your babys intelligence for the rest of their lives. In this section, well discuss how your babys brain grows during pregnancy, and what you can do to protect and support that growth.

        The Teenage Brain: Why Some Years Are Crazier Than Others

        2-Minute Neuroscience: Early Neural development

        Neurobiologist Robert Sapolsky explains how your first 25 years will shape the next 50.

        ROBERT SAPOLSKY: Neurobiologically, the single most important fact about, say, a 20-year-old brain is the fact that almost all of it is already matured, fully wired upmyelinated, a jargon-y term for it. The reward dopamine system has been going full blast since somewhere around like early puberty. All of the brain is totally up to speedexcept for the frontal cortex. Probably the most interesting fact about human development is that the frontal cortex is the last part of the brain to fully mature. It is not completely online until you’re about 25 years old, which is mind-boggling to think about.

        What does that explain? That explains why adolescents are adolescent in their behavior. The sensation-seeking and the risk-taking the highs are higher and the lows are lower, because the steadying frontal cortical hand there isn’t fully up to speed yet, and everything else is a gyroscope out of control. And that’s where the impulsivity is from. And that’s where the extremes of behavior, and that’s why most crime is committed by people at a stage whose frontal cortex is not fully developed yet. That is why most people who do astonishing, wondrously self-sacrificial things don’t have the frontal cortex that’s fully in gear yet either, and it’s not in a position to convince them yet, ‘Ah, that’s somebody else’s problem. Look the other way.’

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        The Formation Of The Neural Tube: The First Brain Structure

        Changes in the morphology of the embryo in the embryonic period. The formation of the neural tube occurs between E19 and E29. a. The emergence of the neural ridges is observed on E19. b. The ridges fold over to begin the process of neural tube formation. c. Closure of the neural tube begins on E22 in central regions of the newly forming neural tube. d. Closure continues in rostral and caudal direction. The anterior neuropore closes on E25, and the posterior on E27. e. Following the closure of the neural tube, the embryo begins to expand particularly in anterior regions. The primary vesicles are evident by E28. These include the Prosencephalon, Mesencephalon, and Rhombencephalon. f. By E49 the secondary vesicles emerge. The Prosencephalon differentiates into the Telencephalon and Diencephalon, and the Rhombencephalon into the Metencephalon and Myelencephalon. Illustrations by Matthew Stiles Davis reprinted by permission of the publisher from THE FUNDAMENTALS OF BRAIN DEVELOPMENT: INTEGRATING NATURE AND NURTURE by Joan Stiles, Cambridge, Mass.: Harvard University Press, Copyright © 2008 by the President and Fellows of Harvard College

        The Importance Of Early Childhood Experiences For Brain Development

        Children are born ready to learn, and have many skills to learn over many years. They depend on parents, family members, and other caregivers as their first teachers to develop the right skills to become independent and lead healthy and successful lives. How the brain grows is strongly affected by the childs experiences with other people and the world. Nurturing care for the mind is critical for brain growth. Children grow and learn best in a safe environment where they are protected from neglect and from extreme or chronic stressexternal icon with plenty of opportunities to play and explore.

        Parents and other caregivers can support healthy brain growth by speaking to, playing with, and caring for their child. Children learn best when parents take turns when talking and playing, and build on their childs skills and interests. Nurturing a child by understanding their needs and responding sensitively helps to protect childrens brains from stress. Speaking with children and exposing them to books, stories, and songs helps strengthen childrens language and communication, which puts them on a path towards learning and succeeding in school.

        When children are at risk, tracking childrens development and making sure they reach developmental milestones can help ensure that any problems are detected early and children can receive the intervention they may need.

        Learn more about supporting early childhood experiences:

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        What Parents Can Do

        If youre trying to make sense of it all and doing your best to support your teens growth, here are a few suggestions to consider:

        Discuss pros and cons with your teen. When your teen comes to you with a problem, help your teen identify the consequences or results of their actions. If there is a choice your teen must make, help them see the pros and cons of each choice. Because the prefrontal cortex is still developing, teens tend to be more impulsive. However, by helping them think through a situation, you help them make neural connections that build logical and rational thinking, which they will need as healthy and responsible adults.

        Show interest in your teen. With all the growth teens go through, they may feel an inability to relate to their parents or other members of the family. You can support your teen by showing interest in what they like, such as their music, games, hobbies, and other interests. This also helps build neural connections in their brain that what they are interested in matters to you.

        Encourage your teen to try new things. There is a lot of growth happening in the teen brain. The teen wants to try new things, explore the world, and role-play. A parent with a deeper understanding of a teens brain growth might encourage this for more neural connection and healthy growth.

        A Historical Perspective On Development And Maturity


        Throughout history there have been biological benchmarks of maturity. For example, puberty has often been used as the transition point into adulthood. As societal needs have changed, so too have definitions of maturity. For example, in 13th century England, when feudal concerns were paramount, the age of majority was raised from 15 to 21 years, citing the strength needed to bear the weight of protective armor and the greater skill required for fighting on horseback . More recently, in the United States the legal drinking age has been raised to 21, whereas the voting age has been reduced to 18 years so as to create parity with conscription . Similarly, the minimum age to be elected varies by office in the U.S.: 25 years for the House of Representatives, 30 years for the Senate, and 35 years for President. However, individuals as young as 16 can be elected Mayor in some municipalities. The variation evident in age-based definitions of maturity illustrates that most are developmentally arbitrary . Nonetheless, having achieved the legal age to participate in a given activity often comes to be taken as synonymous with the developmental maturity required for it.

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        Development Of Logical Reasoning

        During early childhood, your child will make decisions using incomplete or incorrect logic and reasoning. This is part of normal early childhood development. Proper instruction and encouragement from authority figures, such as parents and teachers, will help them overcome their initially simplistic view of the world around them. School and various preschool activities will help a lot with this development, but there are also plenty of activities you can do with your child to help them learn!

        Synaptogenesis And Synaptic Pruning

        While most of the brains 100 to 200 billion neurons are present at birth, they are not fully mature. Each neural pathway forms thousands of new connections during infancy and toddlerhood. Synaptogenesis, or the formation of connections between neurons, continues from the prenatal period forming thousands of new connections during infancy and toddlerhood. During the next several years, dendrites, or connections between neurons, will undergo a period of transient exuberance or temporary dramatic growth . There is such a proliferation of these dendrites during these early years that by age 2 a single neuron might have thousands of dendrites.

        After this dramatic increase, the neural pathways that are not used will be eliminated through a process called synaptic pruning, where neural connections are reduced, thereby making those that are used much stronger. It is thought that pruning causes the brain to function more efficiently, allowing for mastery of more complex skills . Experience will shape which of these connections are maintained and which of these are lost. Ultimately, about 40 percent of these connections will be lost . Transient exuberance occurs during the first few years of life, and pruning continues through childhood and into adolescence in various areas of the brain. This activity is occurring primarily in the cortex or the thin outer covering of the brain involved in voluntary activity and thinking.

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        Parts Of Prefrontal Cortex

        The prefrontal cortex is located at the very front of the brain. It is part of the brains wrinkled outer layer called the cortex. In adults, the prefrontal cortex takes up nearly a third of this outer layer.

        There are competing theories about how best to categorize the parts of the prefrontal cortex. The brain is very interconnected, both physically and functionally. It is difficult to point to a specific part of the brain and say that this section alone controls a certain ability.

        In general, though, the prefrontal cortex can be divided into three parts according to which functions they serve.

      • The medial prefrontal cortex contributes to attention and motivation. It can be thought of as a metaphorical start button, allowing people to begin an activity when it is time to do so. Lesions in this area cause people to become apathetic and unfocused. They may have trouble acting spontaneously or initiating speech. They could also have trouble concentrating on a task once it has started.
      • Lastly, the lateral prefrontal cortex allows people to create and execute plans. This region also helps individuals organize actions in a certain sequence, such as when a person needs to follow a recipe. Injuries to this region can interfere with peoples abilities to switch between tasks, recall where an instruction came from, or adapt to changes in rules.
      • References:

      • Hathaway, W. R., & Newton, B. W. . Neuroanatomy, prefrontal cortex. Retrieved from
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