Brain Development

The homo mindset is considered as the most most-valuable and labyrinthine part of the physical structure consisting of about 180 one thousand million cells (Kolb and Whishaw 84). Of those 180 billion cells, 60 billion neurons be actively involved in theory processing, and each of these may synapses with as many another(prenominal) as 15,000 neighboring neurons. Because of this convolutedity, for many geezerhood researchers in neuroscience have been hesitant to take on the nasty task of explaining the intricacies of the human brain. Prenatal Development The brain is among the first body parts to specialize and function in the embryo.It originates as a flatbed sheet of cells on the upper surface, c totallyed the neural plate. The brain begins to beget amongst the import and third week after fertilization and continue to develop promptly throughout gestation (Spear 406-407). At 3 weeks of embryonic development, a tube appears along the back of the embryo. This is the ne ural tube, from which the entire restless musical arrangement develops. At the top of the tube, three bulges develop to form the three primary(prenominal) divisions of the brain- the forebrain, the midbrain, and the hindbrain, and, behind them, the spinal cord.By the time the embryo is 13 mm (y in) in length the three swellings have become five, as the forebrain itself separates into the expanse to become the intellectual hemispheres and below this the diencephalons. The swellings argon so large that to check them the tube moldiness begin to kink. At 7 weeks, the parts of the evolution neural tube initially form a straight line, merely the tube soon bends so that the forebrain and hindbrain ar at right angles to each other.The hindbrain develops rapidly at this exemplify and begins to sprout a series of nerves (cranial nerves). The forebrain also begins to enlarge, forming deuce bulges. These will become the large, folded cerebrum and underlying structures, such(prenomi nal) as the thalamus. At 11 weeks, most features of the grownup brain appear in rudimentary form. The hindbrain differentiates into the cerebellum (largely concerned with balance and coordination) and the pons and medulla (which control vital functions such as breathing and heartbeat).Meanwhile, the forebrain continues to grow, and the bulk of it the cerebrum begins to overlap the underlying structures. By the fifth month, the wrinkles on the cortical surface of the cerebrum have appeared, and simple tho recognizable EEG patterns have essential. Once the tube has been closed off, the cells within it divide, going through a number of precursor stages before their daughters finally differentiate to give rise to the populations of neurons and glia that will form the adult brain.The rate of cell pro behaviorration is extraordinary an average of more than 250,000 neurons per minute must be formed during the nine months of pregnancya rate dramatically surpassed by that of synapse fo rmation More than 30,000 synapses must be formed per second under every square centimeters of cerebral mantle to generate the complement portray in the early post-natal period. During pregnancy the fetal brain grows dramatically in size and complexity, and the neurons and glia which constitute it must find their appropriate positions and catch up with their ordered touch onions, for instance within the six layers of the cerebral cortex.Because the cells are generated from a single initial sheet, it is necessary for them to migrate considerable distances to their final location. The cerebral hemispheres develop from the front portion of the neural tube, and, as their progenitor cells are formed, by the fifth week of pregnancy, the wall of the tube bulges to form the cerebral vesicles. Over the next hundred days, cells close to the ventricle are indentured to give rise to the neurons which will form the cortex, while the glia are born in a second layer slightly advertise from th e ventricles.The newborn neurons migrate from the ventricular zone towards the surface of the cerebral vesicles, where they neat axons growing in from the region of the developing brainstem, through which the later-born neurons must migrate. ahead birth, massive enlargement of the cerebrum continues. Its most impressive development occurs in the cerebral cortex (the outer layers of the cerebrum) the site of all higher conscious activity. At birth, the cerebrum makes up the bulk of the brain (The American Medical Association 12-13).Hence, by the time of birth, virtually all of the approximately 100 billion neurons in the human brain already are present (Cowan 113-115). Infancy barely even this phenomenal rate of development may be an understatement (Clarke 345). encourage Myers stated that in humans, though the brain tissue from the cerebral cortex has increased in complexity of the neural networks, the number of nerve cells hold outt increase, nevertheless their interconnecti ons do (63) Research in animals indicates that early in development, about twice as many neurons are produced than will be present in the adult brain.In addition, many neurons initially grow axons that connect to the wrong targets. During the normal course of development, the excess neurons die and the inappropriate connections degenerate, leaving the appropriate connections in place (Cowan, Fawcett, OLeary, and Stanfield 1258-1260). Scientists believe that this overproduction and, later, death of neurons and their connections is an important mechanism for forming and fine-tuning the developing nervous system. The brain is not completely developed even in full-term newborn infants.A great deal of brain development takes place in the first few months of postnatal life and, in fact, brain crop continues at least until adolescence (Benjamin, Hopkins, and Nation 313). They just added at birth, the human brain is immature The neural networks that enable infants to walk, talk, and reg ain are still forming. This helps explain why infants memories do not throw overboard during their third or fourth birthdays. In early childhood, the brain also grows rapidly specifically during the first two years after birth (Spear 170).Unlike all other cells in the body, however, the neurons are not usually replaced when they die, and from early infancy onwards there is indeed a small but regular(a) loss of neurons. The growth is accounted for by increases in the number of glial cells, but above all in the massive development of dendritic processes and synaptic connections, as the brain wires itself up in a spectacular interplay of epigenetic specificity and experience-dependent malleabilitythat is, the way that neural pathways are modified as a resolving power of experience and most notably, learning and memory.Although all of a persons neurons are present at birth, the number and complexity of the connections among neurons increase considerably after birth (Parmelee and Si gman 295-98), and this increase is partly responsible for the growth in brain size. Thus, both the increased neural connections and the development of medulla oblongata after birth make possible more and more complex behavior and thought as the child grows. In some areas of the brain, these developmental changes continue until adolescence (Yakovieve & Lecours 5-7).The human brain, and its functions, thus develop at first rapidly and then more steadily over the first few years of infancy, across puberty, and even into late adolescence. Works Cited Benjamin, Ludy, Hopkins, Roy, and Jack Nation. Psychology. 2nd ed. refreshful York Macmillan Publishing Company, 1997. Clarke, P. G. H. Neuronal Death in the development of the vertebrate nervous system. Trends in Neuroscience. Cambridge Harvard University Press, 1995. Cowan,W. M. The development of the brain. Scientific America,241(1989)113-120. Cown,W. M. ,Fawcett,. j. w. , OLeary,. D.D. M. ,& Stanfield,B. B. Regressive Events in Neuroge nesis. Science,225(1991)1258-1260. Clayman,C. B. ,M. D. The Brain and Nervous System. The American Medical Association. 2nd ed. 1997. Kolb,B. , AND Whishaw,I. O. Fundamentals of human neuropsychology. New York Freeman,1995. Parmelee,A. H. , and Sigman,M. D. Prenatal brain development and behavior. In P. H. Mussen (Ed). Handbook of kidskin Psychology,Vol II. Infancy and development psychology. New York John Wiley &Sons, 1984. Spear, Peter D. Psychology prospect on behavior, New York John Wiley &Sons, 1998.