The Biological Perspective: Structure of the Brain

In previous articles we have reviewed Perspectives and modes of treatment in general, this time we will discuss more specifically based on a biological perspective
In its most general form the biological perspective holds that biology plays a central role in the development of behavioral disorders in children and adolescents. The conjecture that psychopathology is due to a defective or malfunctioning. Biological system can be traced in the Western world to Greek culture. Hippocrates (460-370 B.C.) who is considered the father of medicine, was an advocate of somatogenesis (soma refers to body, genesis means origin). He postulated that proper mental functioning relied on a healthy brain and that deviant thinking or behavior was thus the result of brain pathology.
The paradigm initially assumed that biology directly causes abnormal behavior. The original psychiatric classification system developed by Kraeplin in the late 1800s, and the forerunner of current systems, was dearly based on this assumption. Early discoveries of biological causes for particular behavioral problems (for example, the revelation that a spirochete bacterium caused syphilis and the mental deterioration of syphilis's late stages) led to the hope that similar causes would be found for all abnormal behavior. With limited exception, this has not proven to be the case.
Today a widely employed conceptualization of the role of biology is die notion of diathesis-stress--that a biological predisposition toward a disorder (a diathesis) interacts with environmental. or life events (stress) to produce a particular behavioral problem. This is a variant of the more broadly conceived notion that biological factors transact with psychological and sociocultural influences.
As we saw in previous article, influence of biological factors on a child's behavior can occur through a variety of mechanisms. Here we will examine three: the structure of the brain, the nervous system and its biochemical functioning, and genetic influences.

The Structure of the Brain
The structural integrity of the nervous system, particularly the brain, is one of the biological influences that has been examined. A cross-section of the human brain is illustrated in figure below. The brain is typically described as being divided into three major subsections: the hindbrain, midbrain, and forebrain.

The hindbrain, which regulates basic body functions such as sleeping, breathing, heart rate, and body movements, includes the cerebellum, pons, and medulla. The midbrain contains much of the reticular activating system, although this extends into the pons and medulla as well. The reticular activating system regulates sleep and waking. The midbrain also coordinates communication between the hindbrain and the forebrain. The forebrain consists of the two cerebral hemispheres connected by the corpus callosum. Each hemisphere has four regions or lobes. The frontal lobes are located near the front of the brain. The temporal lobes are located near the temples on the side of the brain. The parietal lobes are located near the top-rear of the brain and the occipital lobes are located at the rear of the head.
The cerebral hemispheres are involved in a wide variety of activities such a sensory processing, motor control, and higher mental functioning including information processing, learning, and memory. The thalamus and hypothalamus are structures that lie below the cerebral hemispheres, between the forebrain and midbrain. The thalamus is involved in processing and relaying information between the cerebral cortex and other parts of the central nervous system. The hypothalamus regulates basic urges such as hunger, thirst, and sexual activity. The limbic system, which is composed of parts of the cerebral hemispheres, the thalamus, and the hypothalamus, through its regulation of the endocrine glands and the autonomic nervous system (discussed below), plays a central role in the regulation of emotions and biological urges.
Actual damage to the structural or physiological integrity of the biological system may produce a variety of intellectual and behavioral difficulties. Such known or presumed influence on behavior may occur during pregnancy (prenatally). at about the time of birth (perinataly), or during later development (postnatally).

Prenatal influences. "Damage to the developing fetus by toxic substances is receiving a great deal of public and professional attention. At one time it was believed that the placenta protected the fetus from harmful substances that might enter the mother's blood stream. We now know that a variety of teratogens appear to be related to fetal death, disease, malformation, or functional/behavioral effects (Jacobson, Jacobson, and Fein, 1986). The effects of drugs such as thalidomide, alcohol, tobacco, cocaine, heroin, and methadone on prenatal development have received a great deal of study. The potential negative effects of radiation and environmental contaminants such as polychlorinated biphenyls (PCBs) are also well known. In addition many maternal diseases (e.g., rubella, syphilis, gonorrhea) are known to have harmful effects. Acquired Immune Deficiency Syndrome (AIDS) is a growing threat to newborn babies that is of particular current concern.
Clearly many of the findings produce much controversy because they are related to sensitive economic, social, and political issues. Indeed caution is appropriate since ethical considerations do not permit research that would provide dear conclusions. such as studies in which pregnant women would be intentionally exposed to any o! these conditions. We thus must rely on animal studies, the results of which may not hold for humans, and on investigations humans under natural (uncontrolled) conditions. Interpretation of the impact of particular teratogens in such instances is difficult since exposure to any one teratogen car be associated with exposure to others, a well as to other potentially harmful effect: such as poor prenatal rare, malnutrition , and other factors associated with substance abuse and poverty (cf. Gonzalez and Campbell, 1994; Niccols, 1994). These other factors can influence outcome prenatally and during the child's subsequent development.
Since a wide variety of potential teratogens exist (Kopp and Kaler, 1989), it may not be entirely possible to avoid exposure. Indeed; as women increasingly enter the workplace they increase their risk of expo¬sure to toxic agents. However, a pregnant woman does have some control over her environment; she can take special care not toexpose herself to disease and to obtain treatment if a disease is contracted. In addition to teratogens, several other variables such as age of the mother and maternal stress have been associated with infant death and developmental difficulties (Kopp, 1994).

perinatal and later influences. It is important to note that nervous system damage may also occur during or after birth. At birth, experiences such as excessive medication given to the mother, unusual delivery, and anoxia (lack of oxygen) may result in damage to the newborn. There is evidence to suggest that the frequency of some perinatal complications is greater in lower SES children. Furthermore, as noted in previous article, perinatal complications and SES factors have an interactive effect on the infant's subsequent development (e.g., Liaw and Brooks-Gunn, 1994).
Postnatal damage may occur as a result of experiences such as accident, illness, malnutrition, or accidental poisoning. Exposure of children to lead, even at relatively low levels, is one example of accidental poisoning that has received considerable attention and would appear to have negative impact on processes such as attention and cognitive development (e.g., Fergusson, Horwood, and Lynskey, 1993; Tesman and Hills, 1994).
Regardless of when biological insult occurs, both the site and the severity of brain damage help determine the nature of the difficulties. A precise description of the relationship between damage and dysfunction cannot always be made, however. Thus, the link between brain damage and psychopathology is unclear and in many ways controversial (cf. Taylor and Fletcher, 1990).
One of the major concerns of those who work with children is whether problems arising from brain damage can be remediated. A controversial issue is whether the child's immature central nervous system is highly "plastic," that is, more likely to recover after injury, than is the adult system. The issue is a complex one (Fletcher, 1988; Huttenlocher, 1994; Thatcher, 1994). Although there is sometimes remarkable recovery of function in children that is not achieved in adults, younger age u sometimes not associated with better outcomes and age or timing of injury is only one factor affecting recovery. Size, location, and progression of the lesion, severity of the insult, secondary complications such as infection, and type and degree of environmental stimulation are some others. An emphasis on plasticity encourages efforts to develop lost or unachieved functioning, but it may have some negative consequences. Frustration for the child, parent, and teacher may result when complete plasticity is assumed but is not realized. The assumption that the young brain is highly plastic may also lead to imprecise forms of intervention. On the other hand, identification of loss and realistic expectations for recovery can lead to advances in our understanding and to improved remediation.