The Hypothesis of Unexplained Brain Damage and Learning Difficulties

The term learning disabilities refers to a complex and multidimensional phenomenon that affects many thousands of students. Due to the rich symptomatology of learning difficulties and the increased differences between individuals, it has not been possible to analyze all cases exclusively from the perspective of the neuropsychological approach. Aim. The aim of this study was to present research conducted in the context of theories on the brain function of people with learning disabilities. Supporting the hypothesis of brain dysfunction. Methodology: Literature review was carried out in the web, which referred to researches on Special Learning Disabilities and the brain function associated with them. Results: Review of the literature highlighted key points of the relationship between learning difficulties and brain function. Brain dysfunction and the cognitive functions produced emerged as one of the key factors involved in learning disabilities. Many of the theories developed around the problems of children with learning disabilities have focused on specific areas of the brain that may be dysfunctional. Conclusions: The difficulty of locating obvious brain damage in individuals who have been characterized as dyslexic leads to the strengthening of the hypothesis of the existence of a slight or minimal brain damage that cannot be easily diagnosed and strengthens the hypothesis of an unexplained brain damage that could be heterogeneous groups of learning disabilities.


ISSN: 2578-8868
Page 7 of 7 properly (Baillieux, et. al., 2008). Due to the rich symptomatology of learning difficulties and the increased differences between individuals, it has not been possible to analyze all cases exclusively from the perspective of the neuropsychological approach. Thus, in addition to neurobiological factors, there are three other known categories of factors: biochemical, genetic, and environmental. The biochemical factors that are being investigated for their contribution to the genesis of reading disorders and learning disorders in general, argue that biochemical disorders in a child's body cause these difficulties. For example, artificial colors and flavors in many foods that children consume (poor nutrition), eating conditions, the inability of the child's blood flow to synthesize a normal amount of vitamins, etc. Today, most professionals, of course, do not trust the hypothesis of biochemical imbalance as a major cause or treatment of learning disabilities (Park, & Lombardino, 2013). Genetic factors refer to heredity and the hypothesis that siblings and children of people with reading difficulties have a slightly higher than normal chance of developing reading problems. Although some research has identified a possible chromosomal region for the genetic transmission of phonological deficits that may predispose a child to future reading problems, different conclusions between genetic studies leave the field unclear at this time.
As for the environmental factors, they refer to the living of children in conditions of severe deprivation, early in the life of the child, to the limited exposure to highly effective teaching in school, and even to the quality of teaching. Other culprits that have been identified include an unwanted pregnancy, the father's alcoholism, an illegitimate childbearing, and divorce, which can cause learning difficulties (Baillieux, et. Al., 2008). However, although a large body of data shows that the learning problems of many students can be remedied with intensive and systematic teaching, it would be naive to think that learning disabilities are caused solely by inadequate teaching or psychological neglect (Park, & Lombardino, 2013). .

The one-factor and multi-factor approach
The theories that are valid today for learning disabilities, accept the neurological basis of special developmental learning disabilities and move around two axes, which at the same time classify them into two general categories. There are theoretical positions with which one tries to justify the learning difficulties in one dimension, ie they emphasize one main factor, and there are positions that use a multidimensional causal approach, ie they emphasize many factors. The one-factor approach, otherwise known as the neurological-biological perspective or medical model of interpreting the phenomenon that is basically one-factor, explores how the brain processes information and, consequently, the points at which children with learning disabilities differ from the whole to the learning processes (eg structure and function of the brain, etc.). It focuses, therefore, on specific areas or parts of the brain that are intertwined with the individual's language development (Renterıa, 2012).
Proponents of the neuro-biological perspective focus their scientific interest on the anatomy and function of the human brain, that is, the way the brain processes sensory information. However, there are disagreements about how functional impairment manifests itself and what are the functional processes that negatively affect the ability to read and write (Baillieux, et. Al., 2008). The existence of a neurological basis is a commonly accepted hypothesis and many studies have been conducted to determine the exact type of neurological disorder. Some scientists claim that dyslexia is due to brain damage, which is either inherited (developmental dyslexia) or caused by illness or injury (acquired dyslexia). People with developmental dyslexia show either underdevelopment of specific areas of the brain, problems in its general organization, or insufficient differentiation of the functions of the cerebral hemispheres. Also, many children experience insufficient dominance of the left cerebral hemisphere which contributes to the creative use of language (Lagarde, et. al., 2009). Causes of learning disabilities include minimal neurological dysfunction, slowing of neurological maturation of the brain, ectopic growth of neurons in the cerebral cortex, inhibition of left hemisphere growth, and compensatory development of right cerebral hemispheres, cerebral hemispheres and cerebral hemispheres. in the area of the temporal field (planum temporale), dysfunction in transnational cooperation, deficient development of directional function or even the incorrectly produced amount of neurotransmitters or malfunction in their use (Renterıa, 2012).
The multifactorial approach, or cognitive perspective or psychologicalpedagogical model of interpretation of the phenomenon that is based on the multifactorial, is registered in the field of cognitive psychology, which studies every form of human behavior that includes the element of internal representation and information processing.
Based on this, the relevant theoretical positions and researches mainly concern issues such as: perceptual and motor deficits (visual-auditory perception, sensory integration, eye movement), memory, verbalphonological processing, deficits in the syntactic, semantic and lexical function of language, observance correct sequence or series of written symbols (serialization) etc. This separation into a single-factor and a multifactorial approach is a common practice for classifying related research in the international literature. Each of these interpretive approaches consists of a set of hypotheses that concern individual aspects of the whole problem (Renterıa, 2012).

Theories
It is a fact that the group of disorders that has been researched the most from all special developmental learning difficulties, is that of dyslexic children. This is due to the increased incidence of the disorder but also to its centralized dimension, since it occurs primarily or secondarily with symptoms of hyperactivity, perceptual dysfunction and developmental insufficiency. This is why the term "dyslexia" is often used interchangeably with the term "learning disabilities". For these reasons, as well as the increased difficulty of finding bibliographic data for other specific developmental learning difficulties, more emphasis is placed on the causal theories of dyslexia. A fairly common view that prevails and is considered responsible for reading difficulties and dyslexia is that of cerebral dominance and pleurisy, and in particular the lack of dominance with a corresponding pleurisy picture. The term "ribbing" refers to the fact that the two sides of the brain perform different functions. The term "cerebral domination" refers to the correlation between the two hemispheres of the human brain and that one hemisphere dominates the other in terms of controlling the movements and functions of the body. In He himself hypothesized that there was a correlation between reading difficulty and a lack of cerebral dominance, and this led him to conclude: (a) that readers with reading difficulties tend to reverse and mirror the mental image of sensory information in the brain; (b) that the observed inversions and mirrors are associated with the symptom of lack of cerebral dominance, and c) that this lack of brain dominance refers to differences in the organization of the brain of children with dyslexia, which fatally differentiates them from normal readers. Bakker (1990), who investigated the asymmetry of the hemispheres of the brain in relation to the cognitive process and especially to the reading process, found that at younger ages there was high-frequency activity in the right hemisphere, while at the age of about 7-8 years this activity was transferred to the left hemisphere. This phenomenon seemed to be related to reading performance. He then examined whether some children's failure to read was due to a delayed or no transfer of cognitive activity to the reading hemisphere after early childhood. He therefore assumed that some children do not, at the appropriate age, switch to the use of the left hemisphere, in which case there is a failure in the side of the lingual function in the predominant hemisphere or a reversal of the cerebral asymmetry. The same hypothesis is supported by Hier et. al., (1978) in their studies, where 10 out of 24 cases of "dyslexia" were found with reversal of cerebral asymmetry. This means that tilting leads to a hemisphere that is less properly prepared to support language functions, which is a risk factor for developing reading difficulties (Lagarde, et. al., 2009). Witelson (1987) proposed an almost purely neurobiological approach to the child's tongue. He argued that the right hemisphere of the child with dyslexia is somewhat deficient in the sense that his programmatic specialization in non-linguistic subjects is not observed. For this reason, the left hemisphere undertakes to make up for the familiar deficit of the right. As a result, the left hemisphere has a deficit in an area that is programmatically responsible. Thus, the intrusion of the left into the role of the right hemisphere simply means that the execution of the tasks of the right is undertaken by both hemispheres, which is why people with dyslexia tend to show mixed dominance of the hemispheres of the brain.
Mixed dominance occurs in cases where a hemispheric dominance of one hemisphere has not been achieved, and this results in the creation of a symmetry, which is considered responsible for the onset of dyslexia. does not always mean that there is a defect in the general structure of the brain.
Hemispherical asymmetries are a fundamental principle in the functional organization of the human brain. As has already been said, a neurologically normal brain exhibits the right hemisphere's superiority Of these three, the deficits in phonological awareness have been argued to coexist with the deficits of dyslexic children in reading but also that the relationship between them is causal (Ball, 1993;Lagarde, et. al., 2009).
According to phonological awareness deficit theory, a deficit in a lowerorder (phonological) language function prevents the transition to higherorder processes and the ability to draw meaning from the text. The problem with this is that the "poor" reader cannot use his highest language skills to make sense until the written word is first decoded and recognized.
In other words, there is a problem first in decoding a word or a text and then in recognizing them (Kovelman, 2011;Shaywitz, 2001).
Although phonological awareness is more often recognized as a major However, in addition to the asymmetry of the temporal field and the damage to the parts of the cerebral cortex responsible for phonological processing mentioned above, research has revealed another area of the brain that may be responsible for the onset of learning disabilities.
Traditionally, cerebellar function has been associated with movement control and coordination, but recently it has emerged as an important role in higher cognitive functions such as attention, memory, learning, executive control, language and visual spatial functions. Schmahmann On the other hand, the observed deficits of children with dyslexia in auditory perception are also interesting. These deficits are not problems related to their acoustic acuity, but are involved with the stage of acoustic discrimination and acoustic coding. Studies show that reading problems stem from difficulties in processing and representing certain auditory abilities, which degrades the brain's ability to accurately participate in vital elements in the flow of speech. These difficulties impair a child's ability to match the sounds of speech with letters, a skill that is essentially particularly important for learning to read new words (Johnson, et. al., 2012).
Continuing the research, researchers of the problem of dyslexia investigated the possibility of a deficiency in the eye movement control systems of these children. Eye movement is a sensory indicator of a person's reading function. Javal (1879) was the first to report that in general readers do not observe a smooth flow of their eyes from left to right following the homonymous procedure and along the lines of the text.
On the contrary, the reader's eyes move by making, in a sequential way, fast and abrupt jumps, making pauses at the same time, that is, focusing on certain parts of the text (Bellocchi, et. al., 2012).
Most studies today agree on the link between visual acuity and ocular motor control during reading. Attention seems to affect saccadic programming, that is, the position where the eyes will land on a word. In addition, these visual processes associated with attention are strictly related to normal and deficient reading. At the biological level, these deficits are attributed to dysfunction of the large cell pathway, which is supposed to be involved in low-spatial-frequency processing and ocular control. In general, research data that have studied the visual systems involved in reading with particular reference to the possibility that the combined movements of the individual's eyes, their incorrect concentration and various motor deficits create difficulties in reading, showed that deficient readers at slow or delayed reading make eye movements that are smaller in size compared to normal readers, last longer and form a schematic representation similar to that of the normal reader (Bellocchi, et. al., 2012) Another issue that has preoccupied researchers with the etiology of dyslexia has to do with serialization and sequencing. Written language contains the element of order or sequence, and is therefore sequential, because its semantic rendering presupposes that its constituent elements, that is, letters and words, are arranged in a predetermined order.
According to Thomson (1977), written language is composed of a series of "arbitrary symbols" that must be combined in the correct order in order to produce existing and familiar words in the spoken language. The correct order of the components of the written language is necessary, because, otherwise, there may be a complete change of its content. For the neurological review of the etiological theories of learning disabilities it is worth noting one more hypothesis. The angular helix of the brain is the protrusions between the grooves of the cerebral cortex whose function is to transmit and correlate the information recorded by visual stimuli with the stored / recorded phonemes-sounds of the tongue.
It is, in other words, the area in the left hemisphere of the brain that is responsible for the written form of speech. It has been found that possible damage to the angular helix causes problems in reading and writing without at the same time affecting the person's speech. When a child has no learning difficulties, reads, the brain automatically correlates the symbols, which it sees on the book page, with the corresponding phonemes and puts them in the correct order to form the word. The brain of the child with special learning difficulties can not do this process properly and tries to read using other brain areas that serve the production of speech or its semantic processing. Therefore, in children with dyslexia, the Wernicke and angular helix areas -which are responsible for coding and decoding language and for writing, reading and understanding language -are malfunctioning or malfunctioning. While, on the contrary, the Broca area, the center of speech production, can be overworked.

Conclusions
As understood, based on the literature review, learning disabilities are a learning problem and learning is the result of a cognitive process and consequently of the coordinated function of the central nervous system.
For this reason, the neurological basis of learning disabilities is fully understood. Starting from a lesion at a nodal point in the brain, an obstruction to the normal function of this area can be created, which may be the dominant area of some cognitive function that contributes to learning. Result is a problem in the learning process, and therefore in its expression. The problem of learning disabilities must be examined comprehensively, in order to have a complete picture and to be able to make a correct and timely intervention. Most research on the etiology of special learning disabilities revolves around a neurophysiological basis.
Many of the theories developed around the various problems of children with learning disabilities have focused on specific areas of the brain that may be malfunctioning to substantiate their hypothesis. However, many times the brain findings are not localized and no specific damage can be detected focusing on an area of the brain. The difficulty of locating obvious brain damage in individuals who have been described as dyslexic has led to the strengthening of the hypothesis of the existence of a slight or minimal brain damage that cannot be easily diagnosed. This view has been modified by the hypothesis of mild or minimal brain dysfunction and reinforces the hypothesis of an undetectable brain injury, with the intention of covering heterogeneous groups of learning disabilities.