Wednesday, January 03, 2007

REZA M SYARIEF-HILMIYAH
Mendidik Anak Sejak dalam Kandungan



Bagi Reza, doa dan pendidikan anak berlangsung terus-menerus sejak si buah hati dalam kandungan. Pertanggungjawaban orang tua terhadap kehadiran anak, bagi Reza M Syarif, cuma satu. Yakni, mengarahkan dan mendidik si anak sejak ia masih kecil. Bahkan, sejak anak masih dalam kandungan atau bahkan belum ada tanda-tanda kelahiran sekalipun.

Itulah yang prinsip yang dipegang pasangan Reza M Syarief dengan Hilmiyah dalam mendidik keempat putra-putrinya, yang masing-masing adalah Farhata Atkia (10 tahun), Hanna Sahidah (8), Fajar Ibrahim (6), dan Lutiana Fadlika (4).

Diawali doa
Reza M Syarief yang dikenal sebagai motivator ini mengungkapkan, dalam mendidik anak ia selalu mendasarkan pada tiga tahap dalam perkembangan anak. Tahap sebelum anak lahir, ketika lahir, dan pascakelahiran. Sebelum anak lahir, harus dipersiapkan sejak dini berkaitan dengan nama anak. Bila perlu nama anak mencerminkan situasi ketika lahir dan keinginan yang diharapkan. Termasuk juga dalam melakukan hubungan suami-istri.

''Membaca doa sebelum berhubungan itu sangat penting agar nantinya bila lahir sang anak bisa dijauhi dari pengaruh setan yang seringkali membisiki perbuatan jahat manusia,'' ujar presenter talk show keagamaan di sebuah stasiun televisi swasta ini. Makanya keempat anaknya, merupakan buah hati yang lahir dari doa-doanya dan selalu memberi nama sesuai dengan kondisi dan cita-citanya. Anaknya pertama diberi nama yang menunjukkan rasa syukur pada Allah atas karunianya pemberian anak.

Kemudian secara berurutan, anaknya kedua lahir sewaktu perang Bosnia meletus, sehingga umat Islam justru merindukan mati sahid. Anak ketika lahir saat subuh dengan penuh pengorbanan, dan pada anaknya yang paling bontot lahir saat hidup di desa, sehingga artinya karunia kehidupan. Pemilik perusahaan supertrainer, Rezaleadershipcenter itu menambahkan, menambahkan begitu pula saat sang anak lahir. Tidak lupa keempat anaknya begitu keluar dari rahim istrinya, selalu dibacakan kalimat syahadat dan didengungkan suara azan.

''Kami ingin kalimat-kalimat Allah dibaca sejak dini. Agar nantinya bila sudah besar tahu tahu agama,'' tambahnya.

Beratnya masa perkembangan
Reza melihat masa yang paling berat dalam mendidik anak adalah ketika anak sedang berkembang. Di usia balita, anak selalu diajari mengembangkan kreativitas dengan diberi berbagai permaianan-permaian yang mendidik.

Selain itu setiap kali menjelang, ia biasa membacakan cerita-cerita yang mudah dicerna untuk sang anak. Misalnya dengan diberi cerita-cerita kepahlawanan Islam, dongeng-dongeng atau cerita yang berkaitan dengan kejadian alam. Untuk bisa memperhatikan anak, antara suami dan istri harus bekerja sama saling membantu. Apabila istri yang sibuk, Reza yang mencoba bercerita pada anak-anaknya. Begitu pun sebaliknya hingga sang anak merasa kedua orang tuanya menyayangi.

Konsultan pernikahan di berbagai tempat itu menambahkan, dan yang paling pokok dalam mendidik anak adalah cara memperhatikan pendidikannya selepas balita. Paling tidak, tidak sembarangan memasukkan anak ke sekolah umum. ''Anak harus diberi pendidikan dasar di sekolah yang mendasarkan ada agama terlebih dulu. Bagi saya ini penting untuk dasar mereka besar nanti menjadi manusia beragama,'' tambahnya.

Namun, dia tidak sembarang memasukkan anak ke sekolah berbasis agama. Ia terlebih dulu mensurvei mutu dan fasilitas yang disediakan sekolah. Dan, yang penting, ia berpendapat, si anak jangan dipaksa pada satu tempat saja. ''Anak diberi alternatif supaya bisa memilih,'' katanya.

Sekarang ketiga anaknya bersekolah di SD Islam Terpadu Nurul Fikri. Mereka meraih peringkat akademik di sekolah. Sementara si bungsu yang masih di play group pun tidak tertinggal dalam pergaulan anak sebayanya.


Tuesday, January 02, 2007

Memo From A Child To Parents

1. Don't spoil me. I know quite well that I ought not to have all I ask for. I'm only testing you.

2. Don't be afraid to be firm with me. I prefer it, it makes me feel secure.

3. Don't let me form bad habits. I have to rely on you to detect them in the early stages.

4. Don't make me feel smaller than I am. It only makes me behave stupidly "big".

5. Don't correct me in front of people if you can help it. I'll take much more notice if you talk quietly with me in private.

6. Don't make me feel that my mistakes are sins. It upsets my sense of values.

7. Don't protect me from consequences. I need to learn the painful way sometimes.

8. Don't be too upset when I say "I hate you". Sometimes it isn't you I hate but your power to thwart me.

9. Don't take too much notice of my small ailments. Sometimes they get me the attention I need.

10. Don't nag. If you do, I shall have to protect myself by appearing deaf.

11. Don't forget that I cannot explain myself as well as I should like. That is why I am not always accurate.

12. Don't put me off when I ask questions. If you do, you will find that I stop asking and seek my information elsewhere.

13. Don't be inconsistent. That completely confuses me and makes me lose faith in you.

14. Don't tell me my fears are silly. They are terribly real and you can do much to reassure me if you try to understand.

15. Don't ever suggest that you are perfect or infallible. It gives me too great a shock when I discover that you are neither.

16. Don't ever think that it is beneath your dignity to apologize to me. An honest apology makes me feel surprisingly warm towards you.

17. Don't forget I love experimenting. I couldn't get along without it, so please put up with it.

18. Don't forget how quickly I am growing up. It must be very difficult for you to keep pace with me, but please do try.

19. Don't forget that I don't thrive without lots of love and understanding, but I don't need to tell you, do I?

20. Please keep yourself fit and healthy. I need you.

Building a Child's Self Esteem


"O ye people! Worship your guardian Lord, Who created you and those before you that ye may become righteous." Quran 2:21

Family Life Question: "Children frequently express feelings of not being liked by other children and not being able to do things before making an attempt. What are some ways to encourage self-confidence in children?"

Dear Parents:
Children who are morally and spiritually conscience develop a sense of their own self-worth. Helping our children develop healthy self-esteem is one of the most important things that parents can do for them; it is the foundation of their faith and commitment to Allah. Children need to be assured that they are a special gift from Allah and they are to dedicate their talents and resources to Thy service--this gives them value, purpose and direction for life. Through every phase of a child's development, they need provisions for moral and spiritual enrichment that encourages them to truly reverence Allah and to thus value the beauty in themselves.

"We have indeed created man in the best of molds." (Quran 95:4) There is no fault in Allah's creation; to man, Allah gave the purest and best nature. Our duty is to preserve, and nurture the distinctive character that Allah has created.

Healthy feelings about oneself or high self-esteem is best started in the home, and this needs to be cultivated in our children from birth. Thankfulness for who Allah has made us to be is based primarily on how our parents or guardians view us. Children mirror others' perception of them; they measure themselves by the standards set by those shaping their lives. A child needs our unconditional love. While we may show disapproval of wrong actions, the child still needs to feel cherished. We are guided: "...truly no one despairs of Allah's soothing Mercy, except those who have no faith." (Quran 12:87) Our unconditional compassion for our children will promote and encourage their faith in Allah and instill the thinking that "I am lovable, I am confident."

Persons with healthy self-esteem are more capable of making decisions; they exhibit thankfulness for their accomplishments, are willing to take responsibility, and are better able to cope with stressful situations. They meet and feel enthusiastic about challenges. Often a student with a high IQ and low self-esteem will do poorly in school, while a child with average ability and high self-esteem will excel. The thinking that is cultivated in a person in the early years affects his entire life.

The National PTA along with the March of Dimes has developed a program called "Parenting: The Underdeveloped Skill" to help parents learn to better communicate with their children and to nurture their youngster's self-esteem. Some steps they outline include: "

1. Showing kids how to communicate their feelings, openly and honestly, is a good place for parents to start. Children need to know that even anger and fear are to be appropriately expressed rather than bottled up. Because children learn by example, parents must let their feelings be known.

2. Listening--truly listening to children is a second key to developing good self-esteem. Having parents listen not only enhances children's good feeling about themselves, it also teaches them...(to be caring).

3. Teaching how to get along with others through negotiation and compromise is important.

4. Establishing fair, consistent discipline is one of the other building blocks of good self-esteem.

5. Giving children responsibilities--tasks that are meaningful and 'do-able' and that they can be accountable for also builds self-esteem.

6. Permitting children to make decisions (even an occasional wrong one) helps them learn good judgment.

7. Keeping a sense of humor is important. It can work wonders and helps children keep perspective on what is important.

8. Treating children lovingly, with both respect and courtesy, helps children learn that they are beautiful and worthwhile people. Parents, treat them the way you yourself want to be treated." The Parenting: The Underdeveloped Skill kit is available through the Chicago office of the National PTA.

When we build a warm and friendly relationship with our children, we establish the best opportunity for imparting strong moral and spiritual values to them--the key to high self-esteem.

Embryological Development of the Human Brain

by Arnold B. Scheibel, MD

In the following article, Dr. Scheibel tells the fascinating story of how the brain develops in human beings from conception to birth. He makes clear that this complex, rapidly developing process is affected continually by the environment in which it is taking place. What mothers eat, drink, and feel-- the environments which they themselves experience-- affect daily the neural development of their unborn child.
Nowhere are the beauty and power of life processes better expressed than in the development of the human nervous system. The adult human brain is believed to consist of at least one hundred billion neurons (nerve cells) and probably five to ten times as many neuroglial (functional support) cells. Together these elements make up a three pound mass of protoplasm which is unique on our world and in our solar system and, so far as we now know, in our galaxy.

During the intrauterine period of life, a great excess of neurons is produced-- perhaps twice as many as necessary, but these are winnowed out in the final month or so of pregnancy and in the months just after birth. So great is the profusion of primitive neurons that at least fifty thousand cells are produced during each second of most of intrauterine life to provide the necessary number. So complex are the challenges involved in developing a brain that at least one half of our entire genome (the full catalogue of human genes on all the chromosomes) is devoted to producing this organ that will constitute only two percent of our body weight. It should be realized at this point that for the nine months of intrauterine life and for a short but indeterminate postnatal period, brain growth and development will be largely genetically determined. However, environmental (epigenetic) factors will also be involved almost from the beginning of embryonic life, and will assume an increasingly important role. It is, in fact, the complex intertwining of genetic and epigenetic factors which guarantee the uniqueness of each individual.

The human embryo develops from the union of a single sperm with an egg. In the nine months of pregnancy that follow, the developing organism undergoes a rapid sequence of transformations in which it recapitulates on an extremely compressed time scale the developmental progression of the entire vertebrate lineage. For example, the very early human fetus has gill arches like a fish. These are converted into other structures such as the muscles of the face, larynx and pharynx. Similarly, at a slightly later stage in development, the human embryo has a tail which is rapidly reabsorbed (at about the fortieth day after conception) with further development. The drama of fertilization and development is so intricate and yet so repeatable (only a few percent of embryos fail to develop normally) that it is worth our while to follow the major steps in the process.

THE EGG

The number of potential germinal cells in the human female is limited to about four hundred thousand in both ovaries. Of these, only about three hundred to three hundred fifty will go on to maturity. One will be released, usually one every 28-29 days, approximately half way between menstrual periods. Thus the egg is, biologically speaking, a very rare and valuable entity, and the monthly ceremony of ovulation a celebration of biological immortality.

The female germ cell (oocyte) is released from a small, fluid-filled mound, the ovarian follicle, on the surface of the ovary. Finger-like appendages of the ovarian (Fallopian) tube continuously sweep over the ovarian surface during this period and are usually successful in guiding the oocyte into the open end of the tube. Once in the tube, the oocyte is slowly carried along in the direction of the uterus by two different mechanisms working together. The wall of the tube is made up of continuous coils of smooth (involuntary) muscle which undergo waves of contraction, very much like the peristaltic contraction of the muscles in the intestinal wall. Additionally, the Fallopian tube itself is lined by millions of fine hairs called cilia. These beat in waves which pass along the inner surface of the tube, tending also to move the egg toward the uterus.

THE SPERM

The male germinal cell, the sperm, in contradistinction to the egg, is produced in enormous numbers. Two hundred to three hundred million sperm are usually released in a single ejaculation. Each sperm is little more than a package with one complete set of paternal genes and a powerful tail that must propel the sperm cell through several centimeters of cervix, uterus and Fallopian tube. Once the sperm reaches the uterine end of the Fallopian tube, two familiar mechanisms take over to facilitate its journey. Contractile waves of musculature in the tubal walls and synchronized beating of the lining cilia help the sperm to move outward along the tube in the general direction of the oocyte. Notice here that the tubal musculature and cilia are working in a direction opposite to those in the more peripheral part of the tube which are working on the oocyte. We can almost think of the Fallopian tube as a kind of biological marriage broker, doing its best to bring male and female components together.

FERTILIZATION

When a sperm makes contact with an oocyte (a target approximately one millimeter in diameter) a series of biochemical mechanisms are triggered that result in entry of the sperm head into the egg. With the junction of sperm and egg, a process known as fertilization, a new entity comes into being. This fertilized egg (or ovum) now has a complete (diploid) set of genes, one half from the father and one half from the mother. The maternal donation includes not only the genetic material in the nucleus of the oocyte, but a small extra amount that comes with highly specialized structures from the cytoplasm of the cell. These microscopic structures called mitochondria are necessary for the energy requirements of the cell but also carry genes coding for a group of traits which characteristically pass down to each new generation from the maternal side alone.

EARLY DEVELOPMENT OF THE EMBRYO

Following fertilization there is a period of about 24 hours during which profound and still poorly understood changes occur. The cell then divides into two adherent daughter cells and after another 18-24 hour period, becomes a four celled embryo. It seems probable that until this time, each of the daughter cells maintains the potential to continue development in its own right and become a separate and complete individual. This is the source of identical twins, triplets or quadruplets, when they occur. With successive divisions, this pluripotential quality is lost and the components of the growing cell cluster become progressively more specialized.

As the cells continue to divide and adhere to each other through the 8,16, 32 cell stages etc., the cluster begins to resemble a mulberry and, as a result, this is often referred to as the 'morula' (mulberry) stage. During the following sequence of divisions, the solid mass of daughter cells develop an inner cavity, thereby entering the 'blastocyst' (blast, developing; cyst, sac, stage. At one end of the now hollow, ball-like structure, a cluster of cells grows more rapidly than those around it, becoming the 'inner cell mass'. This is the beginning of the embryo. The remainder of the blastocyst will form the various parts of the embryo/fetus support system, i.e., placenta, amniotic sac, etc.

THE PRIMITIVE CELL LAYERS

Each individual is made up of three different types of tissue. Ectoderm includes all of the packaging elements of the organism, i.e., skin, hair, nails and, interestingly enough, the nervous system. Mesoderm makes up the the major structural components of the body including the great muscle masses, both the voluntary muscles which underlie all of our work, actions and behavior, and the involuntary muscles which make up the walls of all of our organs such as heart and blood vessels, respiratory and gastrointestinal systems, and our bones. Finally the endoderm includes all of the cell systems which line our organs and vessels.

APPEARANCE OF THE NOTOCHORD

The inner cell mass originally differentiates into a layer of primitive (presumptive) ectoderm and an underlying and roughly parallel-lying layer of endoderm. In the area between these two cell layers, a few new cells appear, apparently from the underlying endoderm. These most recent arrivals become the primitive mesoderm. Their first task is to come together to form a long cylindrical structure. In doing this, they are recapitulating the earliest event in the transition from invertebrates to vertebrate forms, a transition which occurred at least six hundred million years ago. This rod-like structure is the notochord, the progenitor of the backbone or vertebral column. We all still carry traces of the old notochord in our own bodies. Our vertebral column is made up of 32 separate vertebrae, piled on each other to form our flexible backbone. Between each vertebra is a small shock absorber or intervertebral disc. In the center of each of these fibrous disks is a small soft area like a cherry inside a hard chocolate. This is the nucleus pulposus, the divided up remnant of our notochord. When we suffer a herniated disc, it is the nucleus pulposus which has been squeezed out of the intervertebral disc and is now playing havoc by pressing on one or more spinal roots. We have literally been 'tripped up' by a vestigial organ more than half a billion years old!

In the case of the developing embryo, the notochord seems to have a highly specific "organizing influence" on the primitive ectoderm layer just above it. Through the release of special chemicals, the overlying ectoderm is induced to divide more rapidly, forming a thickened mass called the neural plate. A crease or fold soon appears in this plate. The crease rapidly deepens and becomes known as the neural groove. The entire embryo is lengthening as this happens. The neural groove continues to deepen until its sides, the neural folds, arch over and fuse with each other forming a short segment of completely enclosed tube. This newly formed "neural tube" will become the nervous system. The actual fusion of the walls to form the tube occurs first in the center of the embryo about midway between front and rear poles of the still rapidly lengthening little organism. However, you can probably visualize how the newly formed section of neural tube rapidly begins to roof over in both a frontward (anterior or rostral) and a backward (posterior or caudal) direction. It is as if there were two zippers in the newly formed roof of the developing neural tube. As these zippers are pulled simultaneously away from each other toward the two ends of the embryo, the neural folds come together and the neural tube lengthens progressively in both directions. Finally the neural tube is almost completely enclosed in both directions, leaving only a small unroofed portion or opening at each end. These residual openings are called neuropores and under normal developmental conditions will soon be closed, thereby forming a complete neural tube. During this process a front-back polarity has been established in the still-lengthening embryo. Accordingly, the small unroofed area of the neural tube at the front end is called the anterior neuropore; the one at the rear end, the posterior neuropore.

INCOMPLETE CLOSURE OF THE TUBE

We have already mentioned the remarkable capacity of the developing nervous system to follow an incredibly complex series of developmental rules laid down progressively by the genes. Nonetheless, errors occur, and the roofing over of the neural groove to form the neural tube represents one point where disturbed development can severely affect the growing embryo. Incomplete closure of the anterior or posterior neuropore represents two such developmental errors during the first trimester which radically alter the future life of the embryo/fetus and infant.

If the anterior neuropore fails to close, the resulting deficit leads to varying degrees of incomplete development of the cerebral hemispheres and brain stem. One of the most frequent and dramatic resulting anomalies is the fetus which is born without cerebral hemispheres and usually without any skull above the level of the eyes. This is the so-called anencephalic child (a- or an- without: cephalon- brain) Strangely enough, this type of extreme anomaly may come to term and under some conditions, live for a week or two following birth. Such a severely deformed infant has only a brain stem (the upward continuation of the spinal cord within the skull) on which to depend for its behavior. This takes care of its basic breathing, cardiovascular, suckling and elimination reflexes. However, little else is possible for the infant and it usually dies within a few days or weeks of birth.

If incomplete closure persists at the posterior neuropore, the fetus will be born with some variant of spina bifida (bifida- split). In the most severe of these, the posterior portion of the spinal cord is totally or partially undeveloped and the entire lower back may be open. Some defects of this sort may be amenable to restorative surgery while others are not compatible with life. There is a more subtle form of this anomaly known as spina bifida occulta (occulta- hidden) where the only residual pathology is a tract or canal, usually of microscopic size, running between the subdural space surrounding the lower tip of the spinal cord and the skin of the lower back. Often, the only sign of such an anomaly is a little patch of hair in the middle of the lower back just above the beginning of the cleft between the buttocks. Although usually asymptomatic, this tiny canal can become infected, usually through trauma, and can form a painful pus-filled sac known as a pilonidal cyst. Early in World War II, one of the more frequent surgical procedures was removal of pilonidal cysts caused by the rough and bouncy ride experienced by soldiers riding in earlier versions of the famous Army jeep.

CLOSURE OF THE NEURAL TUBE

With successful closure of the neural tube, the anterior or rostral (rostral- front) end develops three vesicles which demarcate the territory for cerebral hemispheres and brain stem. Of these, the first and third divide once more forming a series of five vesicles which will become the major portions of the central nervous system within the skull. These consist of the cerebral hemispheres, diencephalon, midbrain, pons and cerebellum and medulla oblongata.

CELL DIFFERENTIATION AND DIVISION

The most dramatic phase of development now shifts to the walls of the neural tube. Here, what is initially a single cell layer of primitive ectoderm begins to divide very rapidly and will in time form virtually all of the central nervous system (brain and spinal cord). Packets of cells 'left over' on each side of the midline, where fusion of the neural folds initially occurred, are known as neural crest cells. These will migrate to a number of sites throughout the body of the developing embryo and form the peripheral nerves, roots, and ganglion cells of the peripheral nervous system.

We have already mentioned how rapidly cell division occurs in the walls of the neural tube. The actual process of mitosis (division) occurs close to the inner edge of the wall. Following this, each daughter cell moves away from this inner boundary to 'put on weight' by synthesizing protein, developing DNA and RNA and the various organelles (tiny intracellular structures necessary for cell life and energy metabolism) involved in its continued existence. The cell then moves back toward the inner boundary or multiplication zone where it undergoes division, thereby producing two more daughter cells and continuing the process. During this period of rapid growth, the entire cycle from cell division to cell division may take as little as an hour and a half. The rapid, geometric increase in the number of these still-primitive cells results in progressive thickening of the walls of the neural tube and the enlargements or vesicles at the anterior end. As these primitive cells continue to divide, subtle decisions begin to be made as to their fate. Some will become neurons while others are fated to become glial cells. The way these decisions are made and the mechanisms involved remain areas of active research interest. The decisions are of more than academic concern, not only for the long-term functioning of the nervous system but for the immediate next step in brain development.

CELL MIGRATION

After a period of active replication, some of these primitive daughter cells initiate the next step in brain development. This involves leaving the old 'home neighborhood' and moving permanently away from the inner multiplication zone to the outer edges of the growing wall of the neural tube. By this process of migration, the walls of the neural tube thicken selectively, coming to resemble increasingly the spinal cord, brain stem, cerebellum and cerebral hemispheres of the mature nervous system. As this thickening occurs, the trip from inner boundary of the neural tube to the outer portions becomes longer and increasingly fraught with potential difficulty. For this reason, some of these daughter cells unselfishly develop into a specialized type of "rope ladder" configuration, the radial glial guide cells, along which the primitive nerve cells (neuroblasts) can migrate. A number of these migrating cells may use the same glial guide cells, literally gliding up the glial 'rope' one after the other. The migration process is a complex one, driven and controlled by a number of different chemical substances. As remarkable as this cooperative process appears, even more remarkable must be the chemical messages which inform the migrating neuroblasts where to stop climbing and get off the ladder.

The most dramatic thickening of the original neural tube occurs in the area of the developing cerebral hemispheres. Here the migratory voyage is the longest and most complex. There are several principles of cortical development which have become apparent in the past several decades and they are worthy of our consideration.

INSIDE OUT DEVELOPMENT

As the primitive neurons or neuroblasts migrate away from the ventricular border where they have undergone multiplication, they move outward toward the external border of the thickening neural tube vesicle (the telencephalon) which is becoming the cortex where most of the higher level mental activity occurs (perception, cognition, etc.) The cerebral cortex of most higher forms is made up of six cell layers. Each layer has its distinct pattern of organization and connections. During the developmental phase which we are following, the cells initially move in to form the deepest or sixth layer. Each successive migration ascends farther, progressively forming more superficial (fifth, fourth, third second and first) layers beyond the layer that was initially laid down. Thus each group of migrating cells must pass through the layers already laid down by the earlier arrivals, thereby following an inside-out sequence of development.

The later arriving cells appear to migrate out along the same radial glial guide cells originally used by the earlier immigrants. It is accordingly very important, that the earlier groups succeed in "getting off" the glial guide cell before the next wave of immigrant cells tries to come up and through. We still do not completely understand how these cells successfully ascend the glial "rope ladder " nor how they know when to get off the ladder, move a little to the side and start to form the appropriate cortical layer. But it should be clear that unless they do release their hold, the next wave of cells coming up the ladder may not be able to get by on their way to a more distant destination. When this happens, the ensuing traffic pile up produces developmental anomalies which can lead to abnormal neuronal connections and disturbed behavior. Two species of mutant mice called, "reeler" and "staggerer" because of their bizarre motor behavior, are believed to result from this type of developmental abnormality. Similar problems in the growing human fetus may contribute to the development of certain types of schizophrenia, temporal lobe epilepsy and, perhaps some forms of dyslexia.

At this point, it can only be speculation, but it is conceivable that some types of severe character disorders may also reflect developmental anomalies. A limited group of data suggest that some individuals with intractable sociopathic deficits show brain changes which could be interpreted as developing during this period of brain formation. This is clearly an area which awaits further exploration.

DEVELOPMENT OF TEMPORARY CONNECTIONS

Another curious mechanism which seems to be involved in cortical development, is the stratagem of developing temporary connections or holding patterns for incoming, cortex-bound fibers until the proper target cells are available for them. A large number of significant fiber connections from structures below the cerebral cortex, particularly in the thalamus, begin to grow into the primitive cortex (or the area where it will develop), before the nerve cells have been able to migrate into their proper layers to receive them. Without target cells, such fibers would turn away or wither. To avoid this, groups of special 'decoy' cells are quickly sent into position before the main migrations begin. One group of decoy neurons locates itself at what will be the margin between the the cortical or gray matter, and the underlying white (fiber-rich) matter. A second group of decoys lines up at the outermost edge of the neural tube wall, at what will be the most superficial layer of the cortex. These serve as temporary targets for the incoming fibers which enthusiastically establish synaptic connections with them. Several weeks later when the great neuroblast migrations have been successfully accomplished, these decoy cells unselfishly disappear, a process which is fascinating in its own right and is now under investigation. The fibers which have been synaptically attached to them are released and are now attracted to a more appropriate, and permanent, set of target cells. This remarkable sequence of processes culminating in a 'change of partners' and the establishment of more definitive cortical connections is also subject to error and the results may include a number of major and minor cognitive and emotional disorders which will show up at various stages in the life of the individual. We are only at the beginning of our understanding of these complex phenomena but certain types of dyslexia may be one of the results of problems during this change of cortical connections.

MATURATION OF NERVE CELLS
Once the primitive migrating nerve cells have reached their final position, they begin to develop extensions from their cell bodies. These will progressively become longer and form the two major types of processes or branches which characterize almost all neurons. Dendritic branches will emerge from many points along the cell body. In the case of most cortical cells, these will become apical and basilar dendrite branches, depending on whether they emerge at the apical end of the somewhat triangular (pyramidal) shaped cell or at the bases. The former will lengthen and grow toward the surface while the latter will branch more profusely and grow to the sides (laterally) and/or somewhat deeper into the cortex. As dendritic branches multiply, they provide an increasing surface area for fiber terminals (synaptic terminals) from other neurons. In general, the larger the number of neuronal connections, the richer the possibilities for neural, and therefore cognitive activity.

The second major type of cell extension, the axon, will set out on a journey of variable length to establish connections with many other neurons, some adjacent to the cell body of origin, others quite distant. Imagine how far an axon must migrate from the cortex if its target area is the lower spinal cord of a basketball player! The distance may be as much as five feet!

One of the more interesting pathways which must be developed during the late prenatal and early postnatal period is the one which crosses from one hemisphere to the other and connects similar (mirror image) point on the two hemispheres. This massive bundle, called the corpus callosum, exerts powerful though subtle effects on the cortex and special modes of examination are necessary to reveal them. The two hemispheres have differing, though complementary, roles and it has been speculated that the corpus callosum facilitates the interaction of these effects. For example, for most of us, specific portions of the left hemisphere (Broca's and Wernicke's areas) are primarily responsible for the semantic and computational aspects of language. Corresponding areas of the right hemisphere are involved in the emotional and prosodic activities and the interweaving of these two facets of language behavior make for interesting and comprehensible narration. If activity of the right hemisphere and its interaction with the left is compromised, either by cortical damage (e.g. a stroke) or by surgical interruption of the corpus callosal fibers, this relationship breaks down. Speech then sounds mechanical and flat, without personal warmth and emotion.

DEVELOPMENT OF MYELIN SHEATHS

A significant aspect of brain development is the continued growth of myelin sheaths around the axons of the cerebral cortex. Myelin is a fatty substance which is deposited around many (though not all) axons as an insulating sheath. Its presence allows conduction of nerve impulses to occur from ten to one hundred times as rapidly as would occur along a non-myelinated axon. Since this obviously increases the efficiency of the axon system (just as increased computing speed enhances the efficiency of a computer), the development of axonal sheaths are taken as a measure of increasing maturity of the neural system involved. Myelin sheath development, or myelinization as it is called, has a rather well recognized time table in the cerebral hemispheres. Fibers serving the primary sensory (touch, vision, audition etc.) and motor areas are myelinated shortly after birth while those which are involved with more complex associative and cognitive functions myelinate later. It is generally believed that fiber systems of the prefrontal lobes (executive functions, intentions, future planning, etc.) are among the latest to myelinate, a process that may go on into young adulthood.

DEVELOPMENT OF SYNAPTIC CONNECTIONS AMONG NEURONS

The elaborate ensembles of neurons, their dendritic branches, and their projective axons communicate via a myriad of connections known as synapses. Each synapse is a point of contiguity (but not continuity) between two neural elements The most usual elements which form synaptic connections are axon terminals with either dendrites or cell bodies although other combinations are possible. In the vast majority of these synapses, small amounts of chemicals (neurotransmitters) are released, crossing the infinitesimal gap between the two elements, thereby carrying the neural message to the next element. Tens of thousands of synapses may cover the dendrites and cell body surface of a single neuron. From this you can easily see that there are enormous numbers of synapses in the entire nervous system, probably trillions! There may be as many as one hundred neurotransmitters and neuromodulators associated with these synapses providing a vast range of possible interaction patterns at these junctions.

The process of synapse formation probably starts in the mid or late second trimester and continues during the life of the individual. Careful ultramicroscopic studies show that synapse formation proceeds at its highest rate during the first 6-8 years of postnatal life, then plateaus and begins to decrease with the onset of puberty. This process of numerical decrease can be thought of as a pruning process in which excess or unwanted connections are discarded. During the first 6-10 years of life, the young individual undoubtedly achieves the highest density of synapses per unit volume of neural tissue (and the highest level of cortical glucose metabolism as revealed by PET scans) that he/she will ever have. This is also a period of enormous information input and acquisition, social, environmental, linguistic, etc. The growing brain may well be in its most sponge-like phase of learning as the child becomes acquainted with the endless range of symbols, rules, facts and behaviors that make it a member of its culture.

DETERMINANTS OF GROWTH AND DEVELOPMENT

We have already suggested that during much of the embryonic and fetal stages of life, genetic influences are of primary significance in development. It must also be realized, however, that the complexity of organization and connections of the nervous system far exceeds the capacity of the genome to specify each cell location, axon trajectory and connection. Instead, a very wide range of diffusible substances and markers are generated at appropriate times by primitive neural components as well as adnexal tissue. These directly affect certain classes of cells or processes, and facilitate the organization and development of the growing system. For instance, the young notochord seems to release factors which stimulate the overlying ectoderm to thicken and invaginate, thereby beginning formation of the neural tube. A little later, cells in the ventral portion of the developing neural tube release factors which specifically direct the trajectory of axons of primitive spinal neurons, thereby initiating the development of the long ascending sensory tracts as well as the peripherally projecting ventral roots. Many such axons, upon reaching their general target zones, carry retrograde substances from these areas back to the cell body of origin, thereby further refining the patterning and terminal distribution of these projecting elements. Thus the local chemical milieu works in complementary fashion with genetic plans to specify central nervous system organization.

A broad range of exogenous factors are also involved, including the health and nutrition of the mother and possible contact with potentially toxic substances (e.g. tobacco, alcohol and other drugs of abuse, certain viruses, etc.) The local dynamic mechanisms of intrauterine life may also be significant, a fact especially noticeable in the case of multiple births where intrauterine position may markedly affect the size and vigor of the newborn. Even the maternal state of mind may be significant, a factor long recognized in the widespread 'old wives' tale' that the infant will bear the visible imprint of an object that frightens its mother during her pregnancy. In a more positive vein, Japanese mothers think happy thoughts (taikyo) during pregnancy to ensure the health and well-being of their infant. Recent data suggest that newborn infants are more likely to respond to sound combinations (words) characteristic of the mother's language than to those of a foreign tongue. By implication, the unborn fetus, especially in the third trimester, may already be sensitive to stimuli in the maternal external environment.

The effects of genetic and epigenetic factors are thus inextricably mingled, from the earliest stages of embryonic development. The remarkable combination of gene-controlled factors, some of them conserved for over a billion years, together with an enormous range of idiosyncratic factors, both internal and external, help account for the uniqueness of each individual.

Fertilization and Embryogenesis


When semen is deposited in the vagina, the spermatozoa travel through the cervix and body of the uterus and into the Fallopian tubes. Fertilization of the ovum (egg cell) usually takes place in the Fallopian tube. Many sperm must cooperate to penetrate the thick protective shell-like barrier that surrounds the ovum. The first sperm that penetrates fully into the egg donates its genetic material (DNA). The resulting combination is called a zygote. The term "conception" refers variably to either fertilization or to formation of the conceptus, which occurs after uterine implantation.

Like every cell in the body, the zygote contains all of the genetic information unique to an individual. Half of the genetic information came from the mother's egg, and the other half from a single sperm. The zygote spends the next few days traveling down the Fallopian tube. Meanwhile it divides several times to form a ball of cells called a morula. Further cellular division is accompanied by the formation of a small cavity between the cells. This stage is called a blastocyst. Up to this point there is no growth in the overall size of the embryo, so each division produces successively smaller cells.

The blastocyst reaches the uterus at roughly the fifth day after fertilization. It is here that lysis of the zona pellucida, a glycoprotein shell, occurs. This is required so that the trophectoderm cells of the blastocyst can come into contact with the luminal epithelial cells of the endometrium. (Contrast this with zona "hatching", an event that occurs in vitro by a different mechanism, but with a similar result). It then adheres to the uterine lining and becomes embedded in the endometrial cell layer. This process is also called "implantation". In most successful human pregnancies, the conceptus implants 8 to 10 days after ovulation (Wilcox et al 1999). The inner cell mass forms the embryo, while the outer cell layers form the membranes and placenta. Together, the embryo and its membranes are referred to as a conceptus, or the "products of conception".

Rapid growth occurs and the embryo's main external features begin to take form. This process is called differentiation, which produces the varied cell types (such as blood cells, kidney cells, and nerve cells). A spontaneous abortion, or miscarriage, in the first trimester of pregnancy is usually due to major genetic mistakes or abnormalities in the developing embryo. During this critical period (most of the first trimester), the developing fetus is also susceptible to toxic exposures, such as:


Fetal Development

From the 8th week until birth (around 38 weeks), the developing human is called a fetus. The fetus is not as sensitive to damage from environmental exposures as the embryo. The majority of structures are already formed in the fetus, but they continue to grow and become functional.

Changes by weeks of age (and weeks of pregnancy)

The following list describes specific changes in human development by week. "Weeks of pregnancy" are dated by obstetricians from the start of the last menstrual period which means that ovulation occurs at the end of the 2nd week

Pre-implantation

Toxic exposures may cause prenatal death but do not cause developmental defects

  • Week 1 (3rd week of pregnancy)
  • Week 2 (4th week of pregnancy)
    • Trophoblast cells surrounding the embryonic cells proliferate and invade deeper into the uterine lining. They will eventually form the placenta and embryonic membranes.
    • Formation of the yolk sac.
    • The embryonic cells flatten into a disk, two-cells thick.
    • If the zygote is going to separate into identical twins, 2/3 of the time it will happen between days 5 and 9. If it happens after day 9, there is a significant risk of the twins being conjoined.

    Embryonic Period

    Toxic exposures often cause major congenital malformations

  • Week 3 (5th week of pregnancy - first missed menstrual period)
    • A notochord forms in the center of the embryonic disk.
    • A neural groove (future spinal cord) forms over the notochord with a brain bulge at one end.
    • Heart tubes begin to fuse.
  • Week 4 (6th week of pregnancy)
    • The embryo measures 4 mm (1/8 inch) in length and begins to curve into a C shape.
    • Somites, the divisions of the future vertebra, form.
    • The heart bulges, further develops, and begins to beat in a regular rhythm.
    • Branchial arches, grooves which will form structures of the face and neck, form.
    • The neural tube closes.
    • The ears begin to form as otic pits.
    • Arm buds and a tail are visible.

  • Week 5 (7th week of pregnancy)
  • Week 6 (8th week of pregnancy)
    • The embryo measures 13 mm (1/2 inch) in length.
    • Lungs begin to form.
    • The brain continues to develop.
    • Arms and legs have lengthened with foot and hand areas distinguishable.
    • The hands and feet have digits, but may still be webbed.
  • Week 7 (9th week of pregnancy)
    • The embryo measures 18 mm (3/4 inch) in length.
    • Nipples and hair follicles begin to form.
    • Location of the elbows and toes are visible.
    • Spontaneous limb movements may be detected by ultrasound.
    • All essential organs have at least begun formation.
  • Week 8 (10th week of pregnancy)
    • Embryo measures 30 mm (1.2 inches) in length.
    • Intestines rotate.
    • Facial features continue to develop.
    • the eyelids are more developed.
    • the external features of the ear begin to take their final shape.

    Fetal Period

    During the fetal period, toxic exposures often cause physiological abnormalities or minor congenital malformation

  • Weeks 9 to 12 (11th to 14th week of pregnancy)
    • The fetus reaches a length of 8 cm (3.2 inches).
    • The head comprises nearly half of the fetus' size.
    • The face is well formed and develops a human appearance.
    • The eyelids close and will not reopen until about the 28th week.
    • Tooth buds, which will form the baby teeth, appear.
    • The limbs are long and thin.
    • The fetus can make a fist with its fingers.
    • Genitals appear well differentiated.
    • Red blood cells are produced in the liver.
  • Weeks 13 to 16 (15th to 18th week of pregnancy)
    • The fetus reaches a length of about 15 cm (6 inches).
    • A fine hair called lanugo develops on the head.
    • Fetal skin is almost transparent.
    • More muscle tissue and bones have developed, and the bones become harder.
    • The fetus makes active movements.
    • Sucking motions are made with the mouth.
    • Meconium is made in the intestinal tract.
    • The liver and pancreas produce fluid secretions.
  • Week 18 (20th week of pregnancy)
    • The fetus reaches a length of 20 cm (8 inches).
    • Lanugo covers the entire body.
    • Eyebrows and eyelashes appear.
    • Nails appear on fingers and toes.
    • The fetus is more active with increased muscle development.
    • "Quickening" usually occurs (the mother can feel the fetus moving).
    • The fetal heartbeat can be heard with a stethoscope.
  • Week 22 (24th week of pregnancy)
    • The fetus reaches a length of 28 cm (11.2 inches).
    • The fetus weighs about 725 g (1 lb 10 oz).
    • Eyebrows and eyelashes are well formed.
    • All of the eye components are developed.
    • The fetus has a hand and startle reflex.
    • Footprints and fingerprints continue forming.
    • Alveoli (air sacs) are forming in lungs.
  • Weeks 23 to 26 (25th to 28th week of pregnancy)
    • The fetus reaches a length of 38 cm (15 inches).
    • The fetus weighs about 1.2 kg (2 lb 11 oz).
    • The brain develops rapidly.
    • The nervous system develops enough to control some body functions.
    • The eyelids open and close.
    • The cochleae are now developed, though the myelin sheaths in neural portion of the auditory system will continue to develop until 18 months after birth.
    • The respiratory system, while immature, has developed to the point where gas exchange is possible.
    • A baby born prematurely at this time may survive, but the possibilities for complications and death remain high.
  • Weeks 27 to 31 (29th to 33rd week of pregnancy)
    • The fetus reaches a length of about 38-43 cm (15-17 inches).
    • The fetus weighs about 2 kg (4 lb 6 oz).
    • The amount of body fat rapidly increases.
    • Rhythmic breathing movements occur, but lungs are not fully mature.
    • Thalamic brain connections, which mediate sensory input, form.
    • Bones are fully developed, but are still soft and pliable.
    • The fetus begins storing iron, calcium, and phosphorus.
  • Week 34 (36th week of pregnancy)
    • The fetus reaches a length of about 40-48 cm (16-19 inches).
    • The fetus weighs about 2.5 to 3 kg (5 lb 12 oz to 6 lb 12 oz).
    • Lanugo begins to disappear.
    • Body fat increases.
    • Fingernails reach the end of the fingertips.
    • a baby born at 36 weeks has a high chance of survival, but may require medical interventions.
  • Weeks 35 to 38 (37th to 40th week of preganancy)
    • The fetus is considered full-term at the 37th week of pregnancy.
    • It may be 48 to 53 cm (19 to 21 inches) in length.
    • The lanugo is gone except on the upper arms and shoulders.
    • Fingernails extend beyond fingertips.
    • Small breast buds are present on both sexes.
    • Head hair is now coarse and thicker