It is important to note that both writing and reading (written language) are closely related to hearing and speech (verbal language), and the capacities of oral and written language share many brain mechanisms (Redolar, 2007). The following post discusses a specific type of alteration in written language expression, dysgraphia.
In most people, the left cerebral hemisphere is responsible for the comprehension and production of oral and written language; however, the right hemisphere also possesses linguistic capabilities.
What is Dysgraphia?
From a clinical point of view, when discussing dysfunctions in written communication (reading and writing), the prefixes –a or –dys are often used depending on when the alteration occurs. Agraphia refers to the altered ability to write after a brain injury, and if the loss involves reading, it is called alexia. If the alteration involves a disruption in an individual’s normal development, reading alterations will be grouped under dyslexias, and writing alterations are referred to as dysgraphia (Redolar, 2007). Therefore, it is expected that behind this disorder there is a dysfunction in the development of processes and/or structures related to the acquisition of written language expression.
Writing involves a series of processes that, when correctly organized and sequenced, allow for the representation of the phonological, semantic, syntactic, and pragmatic characteristics of language. (Rosselli, Matute y Ardilla., 2010).
An alteration in one or more of these processes leads to a poor ability to compose texts, whether handwritten or typed, with grammatical and/or punctuation errors, as well as in sentence construction, poor paragraph organization, spelling errors, and excessively deficient handwriting.
According to the American Psychiatric Association (2003), written language expression disorder does not usually occur in isolation, but rather in conjunction with other learning disorders such as dyslexia or dyscalculia, and may also be accompanied by other language difficulties, perceptual or motor issues. Regarding its etiology, a single cause cannot be sought, as learning disorders (which include dysgraphia) depend on both genetic and environmental factors.
Regarding underlying neurological damage, studies conducted in adults with brain lesions have shown that the location of a specific brain lesion is related to the symptoms of agraphia (acquired writing disorder), which allows for inferences about which brain areas are involved in writing. However, it is not possible to locate a single specific cortical region in relation to writing given the complexity of this cognitive function. (Rosselli et al., 2010)
The Brain and the Writing Mechanism Process
To illustrate brain involvement in the main mechanisms of writing, Serratrice and Habib (1997) divide this process into three stages:
Brain Perception and Comprehension
The first is the brain’s perception and comprehension of the message to be written. This function is performed by the primary auditory cerebral cortex of both hemispheres and by the associative temporal cortex of the left hemisphere. When it comes to the comprehension of visual messages, visual areas (primary and specific associative visual areas) are involved.
Message Transcoding
The second stage of the process is message transcoding and is the most complex of the three. In it, integrative processes convert perceived messages into written forms (words). The areas involved are two regions of the associative cortex, known as the left temporo-parieto-occipital junction.
Message Transmission
In the last stage, the message is transmitted to the primary motor cortex to concretize movement. Many brain regions participate in conjunction with these areas, providing supplementary but indispensable information. For example, the hippocampus and the associative sensory cortex are essential for memory-related aspects, the right hemisphere for spatial aspects and the global vision of the written word, and the prefrontal areas for the executive functions involved (such as text planning, objective maintenance, and achievement, among others).
In conclusion, and despite the lack of total agreement, the hypothesis is that underlying these problems is fundamentally a language problem mediated by the left hemisphere (Rosselli et al., 2010).
The study of dysgraphia is extensively covered in the Master’s in Clinical Speech Therapy in Neurological Damage offered by ISEP. If you are interested, do not hesitate to request information!