The theory of Neurobiology

From the beginning of my work with deafblind children, I was interested in the medical aspects that played such an important role in their development. Confronted early in my career with all the problems of children with CRS (Congenital Rubella Syndrome), I saw the enormous impact the Rubella virus has when it enters an embryo early in pregnancy. It arrests the growth of cells, and affects numerous aspects of the child’s development.

The same can be said of children with concurrent vision and hearing impairments due to genetic dysfunction. I’ve discussed Usher Syndrome and CHARGE Syndrome, which are each caused by the dysfunction of a particular gene.

As a behavioural scientist, I am particularly interested in the brain. What does a virus (e.g. rubella, cytomegalovirus), a particular gene, lack of oxygen, or severe prematurity do to a child’s brain? Does it cause intellectual delay, autism, hyperactivity, or motor problems? If so, can something be done to minimize the effects?

These questions brought me to the intriguing problem of the role of nature/predisposition (e.g. the child’s genetic and physical constitution) and the influence of nurture/environment (e.g. education) on this predisposition.

We know how a normally developing baby interacts with his/her environment and how this process enhances the growth of the central nervous system (CNS). We also know that in cases where these interactions were of a low quality, or did not take place at all (e.g. because of severe neglect), the brain did not mature to its full potential.

In this regard, the studies of children who lived in extreme circumstances (alone in the woods, raised by wolves, etc.) are very worthwhile reading (e.g. the Wild Boy of Aveyron. If you would like to read more about this boy, please click here).

 

The Wild Boy of Aveyron

In these cases, with adequate intervention, the children’s rapid development was surprising. A well-known example of this is the success of therapy with Rumanian orphans, who had lived in severely deprived circumstances during the critical period of their development.

Does this also provide hope for children who are born deafblind? According the latest U.S. Deaf-Blind Census, over two thirds of this population is intellectually disabled. One reason for this is deprivation of adequate input during the critical period of brain formation.

What kind of therapeutic plan should be developed to compensate for this? I spoke earlier about the importance of cochlear implants, or other auditory and visual aids, to minimize sensory losses. I also mentioned the importance of early tactile interaction.

Are there specific principles for enhancing brain maturation? In 1997, I wrote an article with Margot Klomperg and Cathy Nelson called "Strategies in Deafblind Education based on Neurological Principles", which can be downloade here. We stated that the most basic element of learning was attention, “waking up” the child from his drowsy state and making him/her ready for sensory stimuli. This means stimulating the brain’s activation system, called the Reticular Activating System (RAS).

Reticular Activating System (RAS)

The RAS can be activated by a mismatch. After a child has gone through a routine several times (e.g. putting on a bib → sitting on mother’s lap→ drinking), and this routine is interrupted or changed (e.g. mother doesn’t have the milk bottle), the RAS will activate and direct the child’s attention toward specific stimuli (e.g. the missing bottle). (For another example, see the The Road to Symbolization: the case of Gerda, earlier in this chapter.)

This orienting response is extremely important in the learning process. There is some neurobiological evidence that this process enhances synaptic growth. Synapses allow neurons to form interconnected circuits within the CNS. Thus, they are crucial to the biological computations that underlie perception and thought.

 

Synapses

For many years, I felt that stress was very detrimental to outgrowth of the neural network. There is evidence-based research that supports this idea.

When a chain of reactions (a routine) is repeated over and over again, it becomes integrated in the hippocampus, the memory system. The stimuli becomes less novel, and the orienting response is diminished. In other words, the brain gets used to it. It habituates to the stimuli. This process is extremely important in learning, and is a predictor of cognitive development.

I also became interested in an area of the brain called the amygdala, which, like the hippocampus, deals with memory, but particularly with memory of fearful and stressful situations. Both the amygdala and the hippocampus play very important roles in the emotional life of a human being, and both are part of  the limbic system. I have recently produced, along with four co-authors, a DVD about the limbic system called "Let's Talk Limbic". It looks at the role of emotional well-being in the life of a person with multiple sensory impairment.

The previous menntioned DVD is produced by Jan van Dijk, Cathy Nelson, Arno de Kort, Johannes Fellinger & Rick van Dijk. The full name of the DVD is "Let's talk Limbic, The role of the emotional brain in the well-being of persons with multiple sensory impairment" (2010). It can be obtained via the webshop of this site.

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