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Cultural stimulation changes the organization of the human brain

November 18, 2002

The development of a neurosciences project on the influence of culture on the organization of the functions of the brain, by Alexandre Castro-Caldas, brings us a perspective of life-long evolution and adaptation, demonstrating the importance of knowledge acquired at school age.
The analysis of the acquisition and performance in the areas of reading and writing made it possible to corroborate that intellectual learning modifies the brain, improving for example capacities of abstraction and performance.

As such, it is possible to establish a relationship between the area of determined capacities and the development of certain regions of the brain; such has already been shown in the case of animals.

We can also say that the brain organizes itself in an adaptive form relative to exposure to richer and more diverse environments and that the verbal and physical expression of a person reveals their past.

The researcher and professor Alexandre Castro Caldas, from the Centro de Neurociencias in Lisbon, shows in a recent article the development of years of work, which started at the beginning of the 90s in the publication of various articles and books, both nationally and internationally, as well as others in the pipeline.

The age at which one learns to read ( normally at six years old ) is significant, as it deals with the maturing of certain structures in the brain, above all in the cortex regions with multimode association to the parietal lobe, crucial for reading and writing.

"The meeting of the process of maturity and exposure to appropriate stimulus moulds the system in such a way that we consider definitive. We can make the analogy with the process learning of how to read and write, considering it to be, like body growth, a journey with no return," says the author.

The demonstration that learning to read in childhood and as an adult produces different effects becomes important for the orientation of the selection of the people for the study of this phenomena.

The knowledge, since 1892, of regions of the brain whose injury provokes changes in reading and writing capacities, allows us to look for regions in the brain that can be influenced by the knowledge of these capacities. We know the involvement of the occipital lobes in the recognition of words; the corpus callosum as a transporter of visual information (dominantly from right to left) in the occipital cortex; the fundamental role of parietal lobes of both cerebral hemispheres; and the frontal lobe, particularly on the left, with a crucial role in accompanying of the reading process.

On the other hand, modern image methods such as Magnetic Resonance (MR) and Positron Emission Tomography (PET) help us to understand the structures that sustain the functions being studied.

Throughout the research people were selected and divided into groups of those who were illiterate and those with schooling. Three dimensions were studied.

The first dimension has to do with the capacity of individuals to integrate visual-perceptive information in the language system. The access to the denomination of representations of the real world was studied, from the concrete to the abstract.

Illiterate and educated people were confronted with exercises in which they were asked to name real objects, and photographs and drawings of those same articles.

The results demonstrated that the capacity to name objects was lower in illiterate people and this confirms the conclusions of other similar studies by other authors.

The second dimension is related to the transfer of information between two cerebral hemispheres that is done through the fibres that run through corpus callosum. In a comparative study of illiterate and educated women, the measurements of the corpus callosum in illiterate women were smaller; apparently they have fewer fibres in the interparietal sulcus. Measurement was done through the digitalisation of the image of the spinal chord of the corpus callosum, as it is seen in the Magnetic Resonance. The conclusion reached is that learning to read changes the way the two hemispheres relate to each other.

Another study in the pipeline, which also involves images by Magnetic Resonance, shows that, in calculus, unschooled people predominantly activate the right hemisphere and the formally educated the left hemisphere.

Finally, the capacity of individuals to deal with sub-lexical units of language was tested.

In published studies, the author and his collaborators verified significant differences between educated and illiterate people, in the carrying out of various verbal tasks (repetition of pseudo-words, association of word pairs according to their formal structure in comparison to the association based on the semantic structure, and evocation of words given the first phoneme).

Resorting to PET in the analysis of repetition of word series and pseudo-words series (meaning, a sequence of phonemes governed by identical rules to those used in Portuguese) demonstrates two situations. In the repetition of real words, the left hemisphere of those who could read and write was more active.

In the repetition of pseudo-words there was a marked difference: those with no schooling were unable to activate the cerebral structures necessary to complete the task correctly activating less than those educated individuals certain cerebral zones such as the hypothalamus, for example.

The research of the author and his collaborators continues, namely in the last dimension mentioned.

Observatório da CiÙncia e do Ensino Superior