Corpus Callosum Disorders

Disorders of the corpus callosum are conditions in which the corpus callosum does not develop in a typical manner. Since these are disorders of brain structure, they can only be diagnosed by brain scan, including:

• Pre/postnatal sonogram (ultrasound)


• Computerized Axial Tomography (CT-scan or CAT scan)


• Magnetic Resonance Imaging (MRI)

The disruptions to the development of the corpus callosum occur during the 5th to 16th week of pregnancy. There is no single cause and many different factors can interfere with this development, including:

• Prenatal infections or viruses (for example, rubella)


• Chromosomal (genetic) abnormalities (for example, trisomy 8 and 18, Andermann syndrome, and Aicardi syndrome)


• Toxic metabolic conditions (for example, Fetal Alcohol Syndrome)


• Blockage of the growth of the corpus callosum (for example, cysts)

Disorders of the corpus callosum are not illnesses or diseases, but abnormalities of brain structure. Many people with these conditions are healthy. However, other individuals with disorders of the corpus callosum do require medical intervention due to seizures and/or other medical problems they have in addition to the disorder of the corpus callosum.

Estimates of the frequency of corpus callosum disorders vary greatly. Some suggest as many as 7 in 1000 children may have DCC, while others believe it may be as rare as 5 in a million. The rate of diagnosis of these disorders is likely to increase with greater access to the brain scanning technology listed above.

Physically, it is a condition that does not change. It will not get worse. Since the corpus callosum is already absent, it cannot regenerate or degenerate. Likewise, in partial ACC and hypoplasia, once the infant’s brain is developed, no new callosal fibers will emerge.

In that sense, disorders of the corpus callosum are conditions one must “learn to live with” rather than “hope to recover from.” Long-term challenges are associated with malformation of the corpus callosum, but this in no way suggests that individuals with DCC cannot lead productive and meaningful lives.


Behaviorally individuals with DCC may fall behind their peers in social and problem solving skills in elementary school or as they approach adolescence. In typical development, the fibers of the corpus callosum become more efficient as children approach adolescence. At that point children with an intact corpus callosum show rapid gains in abstract reasoning, problem solving, and social comprehension. Although a child with DCC may have kept up with his or her peers until this age, as the peer-group begins to make use of an increasingly efficient corpus callosum, the child with DCC falls behind in mental and social functioning. In this way, the behavioral challenges for individuals with DCC may become more evident as they grow into adolescence and young adulthood.

This is an overview of the behavioral characteristics, which are often evident in individuals with DCC.

•   Delays in attaining developmental milestones (for example, walking, talking, reading). Delays may range from very subtle to highly significant.

•   Clumsiness and poor motor coordination, particularly on skills that require coordination of left and right hands and feet (for example, swimming, bike riding, tying shoes, driving).

•   Atypical sensitivity to particular sensory cues (for example, food textures, certain types of touch) but often with a high tolerance to pain.

•   Difficulties on multidimensional tasks, such as using language in social situations (for example, jokes, metaphors), appropriate motor responses to visual information (for example, stepping on others’ toes, handwriting runs off the page), and the use of complex reasoning, creativity and problem solving (for example, coping with math and science requirements in middle school and high school, budgeting).

•   Challenges with social interactions due to difficulty imagining potential consequences of behavior, being insensitive to the thoughts and feelings of others, and misunderstanding social cues (for example, being vulnerable to suggestion, gullible, and not recognizing emotions communicated by tone of voice).

•   Mental and social processing problems become more apparent with age, with problems particularly evident from junior high school into adulthood.

•   Limited insight into their own behavior, social problems, and mental challenges.

These symptoms occur in various combinations and severity. In many cases, they are attributed incorrectly to one or more of the following: personality traits, poor parenting, ADHD, Asperger’s Syndrome, Nonverbal Learning Disability, specific learning disabilities, or psychiatric disorders. It is critical to note that these alternative conditions are diagnosed through behavioral observation.

In contrast, DCC is a definite structural abnormality of the brain diagnosed by an MRI. These alternative behavioral diagnoses may, in some cases, represent a reasonable description of the behavior of a person with DCC. However, they misrepresent the cause of the behavior.

Alcohol & Genes 

Alcohol dependence is a major global problem, associated with lower quality of physical and mental health, higher mortality and an enormous familial and social cost. Prevention strategies and treatment of this condition are therefore crucial. Success of psychosocial programs and pharmacological treatments has been frequently reported, but a better understanding of the etiology of this chronic disease is needed. For this purpose, the identification of associated factors in different populations is of great significance.

It has been clearly demonstrated by twin and adoption studies and supported by animal models that both genetic and environmental components play a substantial role in alcohol dependence. Heritability estimates range from 40 to 60%, depending on the specific analyzed sample.

Most research points to an association between alcohol dependence and genes related with alcohol metabolism, with neurotransmission of dopamine, GABA, serotonin, glutamate, endogenous opioids, and cannabinoids, signal transduction within the mesolimbic dopamine reward system, and stress response system, among others.

During pregnancy, there are several non-genetic factors that may have an important impact on vulnerability to alcohol dependence. Given that the Central Nervous System is developing throughout the entire pregnancy and that alcohol consumed by the mother can reach the fetus through the placental barrier, the brain of a baby is always vulnerable to harm caused by alcohol exposure. Children born to alcoholic mothers may inherit genetic susceptibility variants but at the same time they may be exposed to early effects of ethanol. Heavy alcohol exposure during pregnancy has been associated with mental retardation, epilepsy, attention deficit/ hyperactivity disorder, learning disabilities, and later on with substance abuse, anxiety, personality, affective and psychotic disorders, as well as with engagement in antisocial behaviors and school or work problems.

Furthermore, it has been shown that animals exposed to prenatal stress exhibit persisting modifications related to dopamine and glutamate transmission in limbic structures associated with dependence to alcohol and other substances. These alterations may later contribute to increase motivation to drink, to use large amounts of drugs of abuse or to relapse after periods of drug withdrawal. It was shown that after exposure to prenatal stress, male mice consumed more ethanol during alcohol reinforcement in adulthood.

Adolescence is a critical period for initiation of alcohol intake, experimentation, and establishment of regular drinking patterns. Substance use at this age is considered a risk factor for the development of later alcohol and other drug-related problems, as well as for externalizing disorders such as antisocial personality disorder. Alcohol use initiation is affected by environmental factors such as ethanol availability, parental attitudes, and peer pressure. It has been reported that heavy drinking during adolescence can have a negative impact on brain development. Moreover, dopaminergic and GABA systems undergo important changes during adolescence, and they can be affected by alcohol intake. Dopamine is implicated in the rewarding effects of ethanol, and GABA in its sedating effects and development of tolerance.

The way an adult copes with environmental challenges is notably influenced by early life experiences and by the familial environment he or she had as an infant, which affects neurodevelopmental behavior.

While environmental factors tend to have a crucial role in drinking habits in adolescence, adulthood may be characterized by a weaker effect of environment and a higher effect of genetic components.

It is probable that a complex set of gene–environment interactions determine the risk to alcohol dependence. Environmental factors that may affect this vulnerability appear at different stages from pregnancy to adulthood. 

References: Salud Mental; mar2011,Vol. 34 Issue 2, p157-166, 10p, 1 Diagram, 1 Chart-

Santiago Ramon y Cajal

 “The human brain is a world consisting of a number of explored continents and great stretches of unknown territory” - Santiago Ramón y Cajal.

Born on May 1, 1852, at Petilla de Aragón, Spain. As a boy he was apprenticed first to a barber and then to a cobbler. He himself wished to be an artist - his gift is evident in his published works. His father, however, who was Professor of Applied Anatomy in the University of Saragossa, persuaded him to study medicine, which he did. Later, he made drawings for an atlas of anatomy which his father was preparing, but was never published.

Santiago Ramón y Cajal is the father of modern neuroscience. After studying at the University of Zaragoza, he developed two nerve-specific stains, allowing him to differentiate neurons from other cells. He was awarded the Nobel Prize in 1906 for establishing the neuron as the basic unit of the nervous structure. Many of his illustrations are still used today.

Santiago Ramón y Cajal made fundamental contributions to the understanding of the nervous system, particularly through the neuron doctrine.

His first finding of a nerve cell, found with a rickety Verick microscope, was published in The Catholic Daily in Zaragoza. While convalescing from tuberculosis in 1884 he also became a skilled photographer. That year he was appointed to the chair of comparative anatomy at Valencia. In 1887 Ramón y Cajal was appointed to the chair of normal and pathological histology at Barcelona and, in 1892, to the chair of histology and pathological anatomy at Madrid, a position he held until his retirement in 1922. In 1900 he had been appointed director of the Investigaciones biológicas and the Instituto nacional de Higiene.

In 1920 King Alfonso XIII of Spain commissioned the construction of the Cajal Institute in Madrid, where Ramón y Cajal worked until his death. Among his many books concerning nervous structure is Estudios sobre la degeneración y regeneración del sistema nervioso, 2 vol. (1913–14; The Degeneration and Regeneration of the Nervous System).

 

Biological Psychology is the study of the physiological, evolutionary and developmental mechanisms of behavior and experience. The term biological psychology emphasizes that the goal is to relate biology to issues of psychology. It is more than a field of study; it is also a point of view. It holds that we think and act as we do because of certain brain mechanisms, which we evolved because ancient animals with these mechanisms survived and reproduced better than animals with other mechanisms.

It is a sister idea of Darwinism, the full concept of evolution and survival of the fittest amongst species. The human species is one that have prevailed the most, we can live in extreme cold temperatures as well as extremely hot temperatures, we have adapted and survived. Applying the theory of survival of the fittest every single day of our existence. 

Much of biological psychology concerns brain functioning. Brain functioning could give some biological explanations of behavior. To explain why humans don’t always know the reasons for their actions, there are some biological explanations that could resolve this issue and they fall into four categories.

First we have the physiological explanation; that relates a behavior to the activity of the brain and other organs. Then there is the ontogenetic explanation that describes how a structure or behavior develops, including the influences of genes, nutrition, experiences, and their interactions. Third it is an evolutionary explanation that reconstructs the evolutionary history of a structure or behavior. Finally we have the functional explanation that describes why a structure or behavior evolved as it did.

What biological psychology is trying to do is explain why and how the brain became conscious, in order to answer the mind – body problem.