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Wednesday, March 19, 2014

Brain Plasticity and learning

It is known that during development the architecture of brain associative and progressive connections are susceptible to modifications from the experience, however these changes become be apparently stationed in adulthood. Eventually, progressive connections also seem to lose plasticity while the synapses of associative connections remain one susceptibility for experience-dependent changes. The persistent adaptability of reciprocal connections is probably the key to the acquisition of skills that are generated due to patterns perceptual and engines throughout the life (Aguilar 2003; Díaz-Arribas, Pardo-Hervas, Tabares-Lavado, Rios-lago, Maestú, 2006). 

Yo-Yo Ma
At this sense, it will be the individual and surrounding external influences which decide in the end, what should be the lattice of synaptic networks that are formed. Thus for example, in string musicians, the area of the cortex which governs the fingering hand is greater than the hand that does not have so much execution; fingers most used  will have more cortex space. Another example of connections that can be developed is in the people who read Braille, whom visual cortex is activated when they felt the prominences of the writing with their fingers (Aguilar, 2005).

This is a possible explanation about why some behaviors should be developed early as swimming, walking or the speech, but once the adjustments have been made and neural trimming is obvious, what do we have?. Some authors explains of the functional maturity that occurs when surplus neuronal connections have been removed and plasticity begins to decline, the process depends on the survival of the more suitable connections, thus the so-called critical period of development ends when the neuronal removal process has come to the point is that only a few synapsis, if some remain, thay might still have competitive interaction.

However, it is not only environmental stimulation which can cause long-lasting modifications in neurodevelopment. An example of this can be found with stimulation such as tactile stimulation, postnatal, maintained in soft and permanent manner for some time after the birth (consistent touch manipulation) exerts beneficial effects in the form of a less emotional reactivity, for example is less likely to stress, greater learning ability in emotional situations. While that when stimulation is inconsistent because you drill them touch have been irregular in form and frequency, children have greater emotional reactivity and see reduced its capacity for some learning.

This could mean  that environment is able to modify the function and brain structure, in such a way that the experience has consequences at different levels of integration more or less enduring. This is especially true during the early stages of life in which the brain development in which experience has one greater importance, if possible, since it not only facilitates patterns, but it should be noted that the modification of a function is not always accompanied by modification of the structure, and this should have it present especially when the brain is subjected to incisive and constant disturbances that impede the expression of adaptive processes in all fullness (Flores, 2005).

So it has been speculated that rapid learning of infants, especially during critical periods, reflects the exploitation of the large number of synapses available at that time, some of which not be connected soon will be removed or pruned. Being so, when surplus cells have been removed and the number of neurons that innervate is adjusted, then the flexibility and plasticity of this early phase of life seems to decline (Patchev, Rodrigues, Sousa, Spengler and Almeida, 2014).
           Even though there are several examples reported on the changes of environment on cognitive development, the study on environmental enrichment is one that most have been reproduced and applied to the teaching and learning models in particular. This model, applied to animals, usually rodents, which were put cage larger than usual, and with the largest number of inhabitants per cage. The cages are placed toys of forms and various colours that are exchanging systematically; stairs, casters are included and there are difficulties in access to food that also varies in texture and flavor.

A classical study exlained that animals that have been subjected to this type of stimulation during various time periods (usually 1 or 2 months after weaning) presented substantial synaptic differences compared to peers who live in standard conditions, in this sense, is the first to better perform tests which require a complex learning, are more proficient in tests assessing memory space viso and short-term memory, and may even show late signs of aging. These results of a cognitive nature are accompanied by neuroanatomical changes, such as the increase of thickness of the cerebral cortex, the increase in the number of dendritic spines and the increase in the number and size of synapses, as well as increasing the process of neurogenesis. 

At the neurochemical level, also shown an increase in the expression of some genes that have to do with neural development, and changes in the operation of the signalling pathways intra-neuronal that are activated in response to different neurochemicals stimuli. By what the moral of the whole research can be summarized that the experiences, which can be understood as learning, school or not, create brain patterns that allow long-term, create new brain connections, which can help others coming and consolidate (Lois y Álvarez Buylla, 1992; Álvarez Buylla and Garcia, 2002; Bredy, Lin, Wei, Baker-Andersen, Mattick, 2011). 


 Aguilar, F. (2003 b) Plasticidad cerebral: parte 1. Rev Med IMSS. 41(1) 55-64.

Aguilar, F. (2005) Razones biológicas de la plasticidad cerebral y la restauración neurológica. Revista Plasticidad y Restauración Neurológica. Vol. 4 Num.1. 5-6.

Álvarez Buylla, A. & García Verdugo, J.M. (2002) Neurogenesis in adult subventricular zone. Journal of neuroscience. 22 (3) 629 - 634.

Bredy, TW., Lin, Q., Wei, W., Baker-Andersen, D., & Mattick, JS. (2011) MicroRNA regulation of neural plasticity and memory. Neurobiology of Learning and Memory. 96 (1) 89-94.

Díaz-Arribas, M., Pardo-Hervás, P., Tabares-Lavado, M., Ríos-Lago, M. y Maestú, F. (2006) Plasticidad del sistema nervioso central y estrategias de tratamiento para la reprogramación sensoriomotora: comparación de dos casos de accidente cerebrovascular isquémico en el territorio de la arteria cerebral media. Rev Neurol. 42 (3): 153-158.

Flores, J. (2005) Atención temprana en el síndrome de Down: Bases neurobiológicas  Rev Síndrome de Down 20: 132-142.

Lois, C. and Álvarez Buylla, A. (1992) Proliferating subvetricular zone cells in the adult mammalian forebrain can differentiate into neurons and glia. Proceedings of the National Academy of Science of the United States of America .90; 2074-2077.

Patchev, AV., Rodrigues, AJ., Sousa, N., Spengler, D., and Almeida, OFX. (2014) The future is now: early life events preset adult behavior. Acta Physiologica. 210 (1) 46-57.

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