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Wednesday, August 28, 2013

The importance of the environment in brain development

If we stops the study of learning stops only on genetic researches, thinking that we born born with immutable physical and cognitive structures, given from the moment of conception, we can believe environment is not so important, however, contemporary genetics and studies on the human genome, provide novel approaches to the source, and explain many pathologies, giving  more and more place to the experience of the individual and corners to a very precise place to initial genetic determinism that held  few years ago.
This suggests the possibility that brain superior functions are based on a biological substrate clearly designed by the genome, but the deployment and development of such capabilities of cognitive abilities need essentially the influence of the environment so much so that, without it, these functions may be severely truncated.

In this sense, it is known some regulatory genes susceptible to light only if they receive certain environmental signals, thereby greatly the generation of synaptic connections and neural routes are not provided in the basic design that are unique to each individual in relation to the experience.

But how does this relate with our brain?, well, as already mentioned, the human nervous system perceives, processes, stores and create behavior in response to information received from the environment, internal and external with the ultimate aim of ensuring the conservation of the species, that learning is as important as a means of stability, since the key brain capabilities level to develop skills for individual survival (Avaria, 2005).

At the end, our nervous system is the supporting material for knowledge, affection and behavior, along with genetics, and skills will be developed for adaptation in the middle which will make us more or less able to respond to the needs of the environment.

Of course is not possible to forget the role of our genetics heritage from parents, so there is something called genetic imprinting which is a phenomenon where certain genes are expressed in a way specific, for example, if a parent inherits more genes with certain features that the other is put in risk the brain and behavior of children, resulting in several possible syndromes.
Some research found out that gene expression plays an important role in brain development, in a way such that certain regions of the brain are almost entirely controlled by the genes of the mother and other regions, by the father (Wenner, 2009).

But once the environment comes in the sequential and orderly development of the nervous system gives rise to a fundamental concept, known as either critical periods and sensitive periods

This concept refers to the existence of determined moments in the maturation of the nervous system that establishes the conditions to achieve a particular function, what is really important in this aspect is that if the structures related to a function remain deprived of the necessary environmental influences for its development, this not will develop properly, even if these influences can exert their action at a later period. 

This knowledge came thanks to classical studies which showed that if it was blocking an eye of a kitten during their first weeks of life, this caused irreversible loss of vision in that eye due to the decrease in synaptic inputs to cortical neurons from thalamus (Hubel & Wiesel, 1970). 

These studies led to think that childhood was the only time critical development, but further investigations, particularly those carried out through neuroimaging, for example some at the University of California in los Angeles and at the National Institute of Mental Health in Maryland, allowed to observe a second stage of growth of gray matter just before puberty during which, our brain develops different to early adulthood. Analyses show that the maturity of the grey matter, is not signal the end of mental changes, but the ability to re settle and rearrange if same and that this occurs during adulthood as a signal of the continuing brain development for several years, being a reflection of the environmental interactions (Shreeve, 2005).  

This topic has received great attention, not only from the scientific community, but also on the part of the media and the community in general, developing related term of windows of opportunity, with important implications from the point of view of education, especially preschool. 

A well-studied aspect in this regard relates to the acquisition of language, since it is thought that learning a foreign language is only possible prior to puberty. However, studies with bilingual populations have shown that learning is possible, but it is  acquired with some grammatical errors and a notorious difficulty in the structuring of phrases, as well as an accent.

Positron Emission Tomography (PET) have shown that if a baby learns a second language, all linguistic activity is located in the same area of the brain, while those children who learn a second language later show two focuses of activity. Some studies in this respect have found in English speakers a curious decodification if the sounds R and L in separate parts of the brain, but these sounds are processed in the same part of the brain in those whose mother tongue is Asian because these languages do not distinguish between these phonemes (Kim, Relkin, Lee. Et all., 1997; Chugani, Phelp & Mazziotta, 1987).
In this sense, the possibility of inducing a greater number of connections and synapses through stimulation techniques has been subject of much debate.

One of the attempts that has received a lot of attention  called Mozart effect,  citing positive effects on cognitive abilities and therefore a better overall performance of the individual against multiple tasks. 

However, a recent review concluded that there is a specific improvement in the performance of visuospatial abilities after hearing some pieces by Mozart, but this effect has a short duration, no more than 10 to 15 minutes, which minimizes management commercial that promotes the rapid achievement of higher child intelligence (Avaria, 2005;  Rauscher & Shaw, 1995; Chanda, Levitin, 2013).
Other studies analyze the influence of the environment  and have focused on the development of gross motor skills, and what has been found is that this does not require so much stimulation from the environment, so the delay is usually due to biological causes, making it the exception to the idea of the environmental stimulation. 

While there is a normal variation in the acquisition of the development in gross motor development milestones, and the acquisition of the walking skills, this variation is lower than in other areas. This was demonstrated in a study in 404 children with retardation motor, at 18 months, a third of them children had failed to take 5 steps independently, and eventually presented a pathology (Avaria, 2005)

Studies of children with cerebral palsy, have allowed to observe the delay engine in any of its forms, while infants show cognitive delay, thus found with gross motor development within expected is not guarantee of normal cognitive development in the future.

Against, children with mental retardation, in general acquire progress independently at later ages that children with normal intelligence, but within each level of mental retardation, there are children walking to comparable to normal ages. In this sense, a study reported that only 62.2% of children with severe mental retardation and 38% of those who have moderate deficiency, walking after 12 months, showing that motor development may be apparently normal the first year of life, but cognitive retardation will be significant later in this population (Avaria, 2005).  

So we can say, different motor behaviors allow to relate the maturation of cognitive process and the brain connections product of environmental interaction, for example the use which makes the child's hands in relation to the exploration of the environment. 

The analyses that are made about the disappearance of primitive reflexes and maturation of visual function, when the nearby can be focused and achieved simultaneous information on the sight and touch, which establishes the basis of future skills visomotoras which gives opportunity that infant use your hands around three months together. It is so from the 3 to the 6 months baby gradually accomplished prehension voluntary and visually guided, first on the flat side and then in the middle line.

The acquisition of this skill, allows the study of the inter hemisferic-dominance (being right-handed or left-handed) which is not developed until after the first year, and is defined until after 2 years.

Therefore, the handling of objects reflects a progressive understanding of the world that surrounds the infant. At 9 months the child examines the objects in a systematic way, thanks to the ability to process non-sequential and simultaneous information how did before developing this skill.

 Of course this is very important as cognitive development, since around 9 months  will be handling the sense of permanence of objects that demonstrates the symbolic objects representation and causation from the Piagetian point of view, but confirm the consolidation of brain connections that allow such processing (Avaria, 2005;  Bloom, Beal & Kupfer, 2006).  

In regards to the development of the communication and language, this area is where the debate on the relative importance of biological and environmental mechanisms in its development has received greater attention. The question if cognitive abilities such as language are the result of structures and genetically coded and specific predispositions?. 

It is thus that the abilities that children acquire during the development are not only of maturation at the neurological level, but are largely the result of the interaction with the environment. The greater the stimulation that receives, more complete is the neurological organization and better expectations for cognitive skills. In that sense, importance early stimulation in early childhood (Ginarte, 2007).

But those who defend the genetic position can add one more aspect to the discussion,  and it is the role of the genetic influence, particularly the studies on the genetic imprint, since these studies are that the influence of paternal genetics plays a greater role in instinctive as feeding behaviors or look for couple, while the maternal genes are concentrated in the development of cognitive processes such as language and social behaviours (Wenner, 2009). 

The main response in this regard says: if the brains of children are innately predisposed to learn the language, with the proper exposure all children with normal brains must, without instruction, learning the language in a relatively uniform manner. 

If this hypothesis is correct, the capacity to acquire language should be both anatomically and functionally autonomous of other capabilities, and developing lesions or acquired can deteriorate, but does not stop the process of acquisition, on the other hand specifically preserve the ability to learn language. 

If we accept the position that learning of language ability is not innate, instruction should be required to learn it, the course of the acquisition should vary considerably in each person (perhaps depending on the quality of the instruction), and therefore there should be no critical period for the acquisition, or the functional or anatomical specificity of the language (Stromswold, 1995).

At this point, I can't avoid mention a classic study in  conducted around 1960 by Diamond, this experiment analyzed the changes in the structure of the nerve cells in the cerebral cortex of rats when they are exposed to what she calls an enriched environment or an environment depleted

 Rosenzweig (cited in Aguilar, 2003) conducted experimental studies in animals, with an idea of possible applications in human rehabilitation field. He proposed enriched environments in a model with rats, living in cages with a number of toys and other stimuli induce changes morphological, physiological, neurochemical and behavioral.

 This  was named as enriched environment if the rat had a large cage and access to objects with that play and explore and also socialize with other 12 rats. The objects had to be changed periodically so that the challenge was greater. The impoverished environment was a small cage with a single rat, without friends or toys (Diamond, 2001).

This experiment found out that animals exposed to the enriched environment had developed cerebral cortex thicker than rats that were in the impoverished environment. The dendritic branches in cerebral cortex had grown as a result of interacting with other rats and explore and play with objects, changes were observed primarily in visual, motor and the frontal area, associated with socializing. They also found low levels of neurochemicals associated with stress.

This study concludes that when nerve cells are stimulated by new experiences and exposure to the incoming information from the senses, it’s possible to grow dendritic branches. If rats continue in a rich in the right environment, the branches grow and this creates greater learning, while in an impoverished environment, these ramifications are pruning  to be lost. 

Diamond (2001) also found something that was not part of the original study, these same rats if were caressed, showed even larger number of neural connections in the area of the limbic system, which is associated with emotions, but also memory. 

They are such situations that make me think that genetics is so important when analyzing a learning problem, what should be the position to a child with Down Syndrome or a child with autism when they have a learning disability?, should we accept the idea of a genetic destiny?, can they learn?. should we believe the theory of enriched environment and say that genetics doesn't matter?. The function of the experience would be, in short, the alter of locally and selective gene expression pattern in charge of the organization and the functioning of a given brain region (Benitez - Burraco, 2006).

Some years ago I learned how to find the right medium of this dilemma. Someone asked during a conference: what is the difference between one and another position at the social level?.

 The answer is that if we accept the genetics, and I think most that most of people accept it, since we change our faces and our voices when we see a child adding a poor boy, he has Down syndrome. Only few persons will  see what this individual is, instead of seeing how this person can be, so we accept the genetic influence as important. 

But if we accept his Down's Syndrome but also this boy has capabilities that can come to be exploited, is to accept the position of the enriched environment.

My question is: How do I know if I have the skills to be high-level pianist if I've never have had the opportunity to be near a piano?. So we should ask: what can I do for this child? Instead of asking: what can this kid do?. It is seeing infants as human beings capable to grow and create and think, and not to fall into the Protocol of applying tons of tests to verify in a scientific way that children have a language problem, or which are not suitable for math or the arts. 

Therefore the vision of the neuroscientific posture is appealing to the brain and its ability to achieve neural connections, based on the skills that you already own to this meet that cost work or is even dreaming of having. Who was found with a good math teacher who managed, that for a moment, we thought that numbers were simple, even to me?. Neuroscience appeals to the principle of flexibility which is called plasticity, to develop skills from strategies that enable each individual better understand reality. 

Each brain develops, grows, learns, observes, understands differently. Some are based on visual clues, others are excellent for understanding the logical way to world mathematics. Some are good to be located geographically, while to others, we have the broken GPS. This is what makes wonderful brain, can be molded plus enjoy this learning, and learning in many ways. The children not only learn by repeating, learn again and again playing with a Nintendo game. Even if adults like or not, children's brains generate neural networks faster than us, take advantage of this window of opportunity is the difference between suffering in school and enjoy school. 

Some lessons require repetition, others require understanding of its usefulness, while others are based on direct experimentation. Cognitive goal tasks needs to recognize and apply the necessary strategies is perhaps the differences between this child cannot learn and this child learns differently .


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