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When Is The Brain Developed In A Fetus

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The Organization Of The Mature Brain

Brain Development in the Fetus

The human brain is arguably the most complex of all biological systems. The mature brain is composed of more than 100 billion neurons . Neurons are the information processing cells in the brain . There are many different kinds of neurons that vary in their size and shape as well as in their function. Neurons make connections with other neurons to form the information processing networks that are responsible for all of our thoughts, sensations, feelings and actions. Since each neuron can make connections with more than 1,000 other neurons, the adult brain is estimated to have more than 60 trillion neuronal connections. The point of connection between two neurons is called a synapse.

Schematic drawing of a neuron. Each neuron a single large axon. At the distal tip of the axon is a growth cone that serves to guide the axon to targeted brain regions. Once the axon reaches the target site, synapses, or points of connection, form between the axon and the target neuron. The synapse allows electrochemical signals to be transmitted to the target neuron. Each neuron also has a complex arbor of dendrites that receive information from other neurons. Image in the public domain uploaded from: . Original image from Nicolas Rougier

At What Point Does This Fetus Show Brain Activity

The brain and nervous system is one of the very first things to start forming in your babys body. The processes get started before you even know youre pregnant. But when do we see the first signs of brain activity in a growing fetus?

In week five of pregnancy, the brain cells start to form.

By week eight, the electrical activity begins.

By week ten, the organ inside your babys head is a more recognizable brain.

Fetal brain development then continues for the rest of your pregnancy. And its a good job too, because its how your growing peanut starts to wriggle, stretch, yawn, and even suck their thumb in the womb.

An Overview Of Brain Anatomy

The easiest way to get to know the brain is to learn the main structures of the adult brain and how they relate to its function . It should be kept in mind that the relationship between brain structure and function is never simple. Although we often hear claims about the language area or emotion center of the brain, statements like these are simplifications; in reality, even the simplest mental activities involve multiple brain regions.

The brain can be divided into three major parts. The brain stem, shaped like a widening stalk, connects the spinal cord to the upper brain. It controls reflexes and involuntary processes like breathing and heart rate. Behind the brain stem and below the upper brain is the cerebellum, which is involved in balance and coordination.

The cerebrum, the largest part of the brain, sits above the brain stem and cerebellum. While each of the brains structures plays an essential role, the cerebrum is the area most involved in higher processes like memory and learning. The cerebrums outer surface is called the cerebral cortex. Although less than one-fourth of an inch thick , it is where the brains most advanced activities such as planning and decision-making take place.

Source: Adapted by Bill Day from, 2006.

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What Develops In The First Trimester

The first trimester is a time of rapid development and separation of the various parts of the brain, according to Kecia Gaither, MD, MPH, double board certified in obstetrics and gynecology and maternal-fetal medicine, and director of perinatal services at NYC Health + Hospitals/Lincoln.

Within 4 weeks, the rudimentary structure known as the neural plate develops, which Gaither says is considered the precursor to the nervous system. This plate elongates and folds on itself forming the neural tube the cephalad portion of the tube becomes the brain, while the caudal portion elongates to eventually become the spinal cord, she explains.

The neural tube continues to grow, but around week 6 or 7, Gaither says it closes, and the cephalad portion separates into three distinct parts: front brain, midbrain, and hindbrain.

Its also during this time that neurons and synapses begin to develop in the spinal cord. These early connections allow the fetus to make its first movements.

What You Can Do To Support This Growth

Prenatal exposure to SSRI tied to foetal brain development ...

If you just discovered that you’re pregnant, you will likely spend the next months ahead wondering how your baby is growing and developing. Questions like: “What color will my baby’s eyes be?” or “When can my baby hear me?” may run through your mind. You may even wonder about your baby’s brain development.

Fortunately, fetal brain development typically follows a pretty predictable schedule. In fact, the fetal nervous system, or your baby’s brain and spinal cord, is one of the first systems to develop. So, as you continue along with your prenatal care and get your ultrasounds, your baby also will be moving along and developing at a predictable rate.

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Brain Development In The Postnatal Period

Though the production and migration of neurons are largely prenatal events, proliferation and migration of glial progenitors continues for an extended period after birth, and the differentiation and maturation of these cells continue throughout childhood. The full scope of neuron-glia interactions is still not fully defined, but it is clear that these interactions play an important role in functional organization of neural circuits during postnatal life. Importantly, estimates of the developmental time course in humans of the postnatal processes outlined below are derived by extrapolation from data acquired in other species, often rodents, and from very limited human postmortem material. Unfortunately, the result is much remaining uncertainty about the temporal extent of proliferation, migration, differentiation, and regression during the postnatal period in humans, and about the timing of these processes relative to each other. In vivo brain imaging of children is providing important clues about the time course of age-related biological alterations in the brain, and provides an opportunity to link these changes to evolving behavior.

When Does The Baby Begin Brain Activity

Your fetus will begin the process of developing a brain around week 5 , but it isnt until week 6 or 7 when the neural tube closes and the brain separates into three parts, that the real fun begins. Parts of your babys brain Around week 5, your babys brain, spinal cord, and heart begin to develop.

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Brain Development In The Fetal Period

The fetal period of human development extends from the ninth gestational week through the end of gestation. The gross morphology of the developing brain undergoes striking change during this time. The human brain begins as a smooth, lissencephalic structure and gradually develops the characteristic mature pattern of gyral and sulcal folding. The formation of gyri and sulci follows an orderly sequence. Primary sulci are first seen as grooves positioned in specifically targeted brain regions, secondary branches then begin to form off the primary sulci, followed later by the tertiary branches. The first fissure to form is the longitudinal fissure that separates two cerebral hemispheres. Its development begins in rostral regions as early as GW8 and proceeds caudally until it is complete at GW22. Other primary sulci form between GW14-26. These include: Sylvian, Cingulate, Parieto-Occipital and Calcarine ; Central and Superior Temporal ; and Superior Frontal, Precentral, Inferior Frontal, Postcentral, and Intraparietal . Secondary sulci emerge between GW30-35; formation of tertiary sulci begins during GW36 and extends well into the postnatal period.

The Formation Of The Neural Tube: The First Brain Structure

Science 360: The Developing Brain

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

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Developing The Tools To Study The Brain In Utero

Most of what scientists know about fetal brain development comes from looking at animal brains or analyzing human postmortem samples. This research has provided insights on the development of brain structure but offers few clues about how functional systems become organized.

The earliest investigations of human fetal brain function date back to the 1950s. When researchers placed electrodes on a pregnant womans abdomen and on the walls of her cervix during labor, they could detect electrical impulses that signaled fetal brain activity. Researchers began to notice that certain patterns of electrical activity were associated with neurological abnormalities.

In the 1990s, scientists began experimenting with fMRI to map the connections in different regions in the brain. fMRI detects changes in brain activity associated with changes in blood flow. During fMRI, the patient typically performs a tasklooking at pictures of faces or finger tapping, for instancewhile the machine scans his or her brain. Researchers look for areas of the brain that light up during the task.

Resting-state fMRI offered a more nuanced look at the highways and interstates connecting different brain regions. These connections form the basis of how different regions of the brain communicate with each other. Whereas investigators previously were limited to studying function within a particular brain region, they could now begin to ask big-picture, network-level questions about brain function.

Fetal Brain Development Week 4

The blastocyst can now be called an embryo as it has now reached the uterus and buried itself in the wall. The uterus wall has become thick enough to support the baby. The embryo will now receive all the nourishment from the mother. In this phase, the embryo further develops the three brain sections; forebrain, middle brain and hind brain, along with the optical stalk.

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New Technology Images Fetal Brain Activity In 4d

Method captures moving subjects; provides way to study very early brain development, disorders

Researchers at the University of Washington have pioneered a way to image activity in a babys brain before birth, opening a window on how fetal brains develop. The technique overcomes the biggest problem in functional MRI if the subject moves during scanning, the picture is distorted.

This video shows motion correction of 3D images of a human fetuss brain using the UWs reconstruction techniques.;

Because theres no way to make a squirmy fetus in a mothers uterus hold still, the researchers developed a method that creates a four-dimensional reconstruction of brain activity.

Led by Colin Studholme, UW joint professor of pediatrics and bioengineering, the team published its work in two papers last fall in Human Brain Mapping and Magnetic Resonance in Medicine .

When using MRI to measure brain function, estimating the intensity of the imaging signal is critical. As part of the brain activates, blood vessels in the area react and supply those brain cells with more oxygen, which causes slight changes in intensity in the MRI image. But if the subject moves, this intensity change can be corrupted and its location in the brain is lost.

The method allows the mapping of the brains default mode network and other regions that are active when the brain is at rest, daydreaming or not concentrating on a specific task.

Dr. Colin Studholme, joint professor of pediatrics and bioengineering

Neural Patterning In The Embryonic Period

The Brain before Birth: Using fMRI to Explore the Secrets ...

The transformations in the overall shape of the embryo reflect more specific change in neural patterning within all regions of the embryonic nervous system. These changes mark the beginning of a protracted process of neural patterning within the central nervous system that begins in the embryonic period and extends for many years. The changes are gradual and follow an ongoing course of continuous specification and refinement . The patterning that emerges in the embryonic period provides only a primitive map of eventual nervous system organization, but it sets the stage for later developments. Embryonic patterning affects all brain regions from the forebrain through the spinal column, such that by the end of the embryonic period in GW8 primitive patterning of sensorimotor regions within the neocortex is established , major compartments within diencephalic and midbrain regions have differentiated , and the segmental organization of the hindbrain and spinal column have been specified . Space does not permit an extended discussion of embryonic neural patterning. Rather, one example, focused on very early patterning within the developing neocortex, will serve both to define the construct of neural patterning, and to illustrate the idea of continuous specification and refinement of brain areas.

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How Common Is Anencephaly

Anencephaly is one of the most common types of neural tube defect, affecting about 1 in 1,000 pregnancies. However, most of these pregnancies end in miscarriage, so the prevalence of this condition in newborns is much lower. An estimated 1 in 10,000 infants in the United States is born with anencephaly.

Conflict Of Interest Statement

The authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest.


Blencowe, H., Cousens, S., Oestergaard, M. Z., Chou, D., Moller, A. B., Narwal, R., et al. 2012. National, regional, and worldwide estimates of preterm birth rates in the year 2010 with time trends since 1990 for selected countries: a systematic analysis and implications. Lancet 379:216272. doi: 10.1016/S0140-673660820-4

Bouyssi-Kobar, M., du Plessis, A. J., McCarter, R., Brossard-Racine, M., Murnick, J., Tinkleman, L., et al. 2016. Third Trimester Brain Growth in preterm infants compared with in utero healthy fetuses. Pediatrics 138:e20161640. doi: 10.1542/peds.2016-1640

Volpe, J. J. 2003. Cerebral white matter injury of the premature infant-more common than you think. Pediatrics 112:17680. doi: 10.1542/peds.112.1.176

Men, W., Falk, D., Sun, T., Chen, W., Li, J., Yin, D., et al. 2014. The corpus callosum of Albert Einsteins brain: another clue to his high intelligence? Brain 137:18. doi: 10.1093/brain/awt252

Fischi-Gómez, E., Vasung, L., Meskaldji, D. E., Lazeyras, F., Borradori-Tolsa, C., and Hagmann, P. 2014. Structural brain connectivity in school-age preterm infants provides evidence for impaired networks relevant for higher order cognitive skills and social cognition. Cereb. Cortex 25:2793805. doi: 10.1093/cercor/bhu073

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Brain Development Of Fetus

Expectant mothers are always excited and curious to know about the growth of their little one inside their womb. Besides the physical growth, metal growth is imperative. A specific timeline for the brain development of the fetus is necessary for the mother to act accordingly to ensure the healthy growth of the fetus.

Expectant mothers are always excited and curious to know about the growth of their little one inside their womb. Besides the physical growth, metal growth is imperative. A specific timeline for the brain development of the fetus is necessary for the mother to act accordingly to ensure the healthy growth of the fetus.

How a brain works, and what makes it tick has always intrigued and mesmerized researchers. All progress and regression in our life can be easily attributed to the way our brain works, thinks, deduces, reasons, concludes, etc. Life starts at with the fertilization of the egg, until the eighth week it is called as an embryo. From the eighth week until the moment of birth, it is known as fetus. Brain development involves the formation of the brain, nervous system and spinal cord,; it all begins at the embryonic stage itself.

From Conception To Age Three: An Outline Of Early Brain Development

The Baby Brain
First Trimester

The development of the brain begins in the first few weeks after conception. Most of the structural features of the brain appear during the embryonic period ; these structures then continue to grow and develop during the fetal period .19,20

The first key event of brain development is the formation of the neural tube. About two weeks after conception, the neural plate, a layer of specialized cells in the embryo, begins to slowly fold over onto itself, eventually forming a tube-shaped structure. The tube gradually closes as the edges of the plate fuse together; this process is usually complete by four weeks after conception. The neural tube continues to change, eventually becoming the brain and spinal cord.20,21

About seven weeks after conception the first neurons and synapses begin to develop in the spinal cord. These early neural connections allow the fetus to make its first movements, which can be detected by ultrasound and MRI even though in most cases the mother cannot feel them. These movements, in turn, provide the brain with sensory input that spurs on its development. More coordinated movements develop over the next several weeks.22

Second Trimester

Early in the second trimester, gyri and sulci begin to appear on the brains surface; by the end of this trimester, this process is almost complete. The cerebral cortex is growing in thickness and complexity and synapse formation in this area is beginning.20,21,23

Third Trimester
Year One
Year Two

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