During embryogenesis, when the child grows in the womb, the brain‘s predispositions also form and differentiate. This is referred to as brain development. This continues even after birth. If disturbances occur during brain development, this can lead to serious problems.
What is brain development?
Brain development continues after birth. Newborns already have the majority of neurons needed, with 100 billion neurons in the brain. Brain development can be roughly divided into embryonic and postnatal brain development. In the embryonic period, the tissue structures of the nervous system develop through processes of cell differentiation and specialization. Newborns thus possess formed tissues that make up the brain and nervous system. Brain development continues after birth. Newborns already possess the majority of neurons needed, with 100 billion neurons in the brain. Nevertheless, an infant’s brain weighs only about a quarter of that of an adult. Postnatally, thickening processes of certain nerve fibers take place in the brain. In addition, connections are made. Until puberty, the brain undergoes such structural developments. Even after that, however, the brain is not a static organ, but continues to develop within the framework of neuronal plasticity. Synapses change depending on how they are used by the individual. Links are loosened again. New connections are established. Such processes are important phenomena within all learning processes. Play and varied experiences therefore promote multiple connections within the brain. The brain is the most complex organ in humans and has phylogenetically evolved from simple precursors. Ontogenetically, the brain is permanently exposed to changes over the course of a human lifetime, beginning with its formation in the womb and continuing until death.
Function and task
The development of the brain and nervous system begins in the third week of pregnancy. Within the next five weeks of development, the brain and spinal cord are fully laid out as neural structures during neurulation. In the following period, vast numbers of nerve cells are formed through cell division, some of which are broken down again before birth. While still in the womb, the first information reaches the embryonic brain, for example through the language of the parents or through music. At birth, there are around 100 billion neurons in the brain. However, the brain increases greatly in weight and size during infancy, as the first connections are made between the individual neurons and many nerve fibers thicken. The growth in thickness corresponds to a sheathing of the nerve fibers, which results in higher signal conductivity. Once thickness growth is complete, the infant can perceive stimuli from the environment more quickly and respond to them all the faster. In the infant, reflexes originating in the spinal cord are particularly relevant in this context. Only after about six months does the brain reach a stage of development that enables the baby to control the upper body and limbs. Somewhat later, the control centers for the legs are also fully developed in the brain. In the toddler phase, brain development advances rapidly. At about two years of age, many nerve fibers in the spinal cord, afterbrain and cerebellum reach their final strength and the complex coordination of movements slowly becomes possible. The toddler can now walk, run and pick up objects. From the age of three, the number of synapses increases in the brain. It is only from this age that a highly complex network of neurons is formed, connecting each neuron with other neurons (nerve cells). From the third to the tenth year of life, the number of synapses exceeds that of an adult by a factor of two. By adolescence, the number of synapses decreases again, as connections that are hardly used regress. From puberty onward, the total number of synapses hardly changes at all. The fact that young children have a far greater number of synapses speaks to their ability to adapt and learn. Which synapses persist depends on the skills learned. What the child has experienced or learned so far has an influence on the brain structures. The development of memory is also a part of brain development.Long-term memory, for example, does not develop until the age of six. At this age, logical thinking, arithmetic ability and socially appropriate behavioral skills develop in the anterior cerebral cortex. From the age of ten, brain development corresponds to optimization in terms of the abilities and memory capacities developed up to that point. Until death, the brain can restructure itself in moderation and learn new things. The brain is a flexible and adaptable organ until old age.
Diseases and disorders
Embryonic brain development is the basis of brain development. However, it is during this period that the neuronal structures of the organ are vulnerable to outside influences. For this reason, the embryonic brain is extremely sensitive to toxic influences such as alcohol consumption, nicotine, radiation or nutrient deficiencies throughout pregnancy. Certain diseases of the mother can also cause damage to the fetal brain. Accordingly, there are many embryopathies. Alcohol embryopathy, for example, is the medical term for malformations that have formed due to alcohol consumption during pregnancy. In many cases, the brain is also affected, as it is sometimes the most sensitive to toxins. Genetic factors can also negatively affect embryonic brain development. In many genetic mutations, the brain is also affected, which can result in mental retardation, for example. However, since developmental processes continue to take place in the brain even after birth, incorrect handling of the infant can also have far-reaching consequences. For example, if toddlers don’t have enough opportunities to act out their curiosity, fewer synapses have been shown to form in their brains. At a certain point, brain development in terms of cell development is finally complete. The nerve cells of the brain show the highest specialization of all body cells. For this reason, the brain is considered to have only limited regenerative capacity. When nerve cells of the brain are damaged in the course of trauma, inflammation, infection or neurological diseases and degeneration, there is usually a permanent defect in these cells. However, because the brain is a flexible organ, intact regions can often take over the tasks of damaged regions. This relationship can be traced, for example, in stroke patients who are learning to walk and talk again.
