Lecture
In the preceding chapters we showed the significance and role, for the normal course of the writing process, of the acoustic, phonemic, and articulatory-kinesthetic analysis of the sounds of a word, as well as of its dynamic, successive structure. Impairment of each of these structural components leads to an impairment of writing, but each time in a different way, depending on which of the above-listed forms of analysis (factors) is impaired. However, all these processes constitute, as it were, the content, the basis of the graphic signs — the letters — in which writing finds expression, the unit of which is not the articuleme or the phoneme, but the grapheme, each of which has its own written form and corresponds to a specific articuleme and phoneme.
The grapheme is a generalized, polymodal graphic image of the sound-letter. Its composition includes visual, acoustic, and motor components alike. The grapheme has two forms of expression — printed and handwritten letters, which differ sharply from one another in their optical image, and each form has, in addition, two subgroups of letters — capital (uppercase) and lowercase, which also differ from one another. The presence of such a variety of letter expressions for a single sound within one grapheme, together with its generalized character, makes the perception and recognition of the letter in reading, and the actualization of its image-representation in writing, a very difficult process, both in teaching children to write and in restoring writing in the optical forms of agraphia.
The articuleme, the phoneme, and the grapheme are in close interaction and constitute a hierarchical structure. In order to write a word, one must isolate all its sounds, relate them to the corresponding articulemes, actualize the corresponding visual image of the letter, and then translate this into the motor image and the required series of hand movements.
This whole process of writing a word, and the role of each of its structural components, their interdependence, and the difficulties of recoding the phoneme into the articuleme, and then into the grapheme and the corresponding hand movements, are revealed with particular clarity in teaching children to write at school and in its breakdown in brain lesions of differing etiology, both in children and in adults. In an adult, however, writing is a skill, proceeds in an automated mode, and becomes a means of written speech, carried out consciously and voluntarily. The grapheme, like the phoneme and the articuleme, can be impaired, and then writing is impaired, but no longer as a speech process.
The nonspeech forms of agraphia are associated with defects of the perceptual process of differing modality — visuospatial and visual. In the clinical picture of brain lesions, these kinds of agraphia occur within the syndrome of various forms of agnosia, and in these cases the connection with speech exists only on the basis of remote relations. The involvement of this link in the structure and course of writing is especially clearly represented during its formation in children. In the initial instruction of children in writing, difficulties connected with visual and visuospatial perception (or with the actualization of the image of the letter) are frequent and, as a rule, turn out to be persistent. Most often, children display what is known as "mirror writing," which is expressed in the fact that children confuse letters that are close in configuration and differ only in their spatial orientation. All of us have had occasion to observe this "mirror writing" in everyday life in children aged 5–7, which is accompanied by an inability to distinguish the left shoe from the right, the front of a shirt from the back, and so on.
It is precisely within the syndrome of spatial disorders that "mirror writing" occurs, in which children (and adult patients) write many letters as mirror images, letters that differ from one another only in their spatial characteristics (ш — т, Я — R, п — и, б — д etc.). "Mirror writing" is most often found in children with overt or "masked" signs of left-handedness. As studies by A.R. Luria, S.M. Blinkov, and others have shown, "mirror writing" most often arises with lesions of the inferior parietal regions of the cortex of the left hemisphere, since these brain systems mature completely later than other zones of the brain. Their independent entry into function is delayed, and therefore children need to be taught spatial analysis, spatial orientation in place, awareness of the spatial "body schema," and so on. Besides this, recoding a sound into a letter sign, and then the graphic execution (writing) of this sign, presents great difficulty for children. Differentiating letter signs that are close in their visual characteristics is not easy for children either (и — ш, с — е, ж etc.).
Thus we see that writing is not exhausted by an analysis of the sensory and motor composition of the word, as was still thought quite recently. It is also necessary to translate the sounds isolated from the spoken word into the graphic signs adequate to them — the graphemes. It is precisely in this link that writing is not infrequently impaired; this defect especially often delays and hinders the formation of writing in children. These difficulties are associated with a lesion or underdevelopment of specific zones of the cortex of the left hemisphere of the brain.
Which brain zones, then, provide the visual and visuospatial organization of writing? It is now known that the integration of visual experience and its spatial organization are associated with the inferior parietal and occipital zones of the left hemisphere of the brain, and a lesion of these areas of the brain leads to impairment of the optical and optic-spatial perception and image-representations of letters, which underlies impairments of writing of the optical type. These forms of agraphia arise with lesions of the cortex of the inferior parietal and parieto-occipital regions of the left hemisphere of the brain. The parieto-occipital regions of the brain constitute the apparatus that carries out integral visual perception, translating visual sensations into optical images, retaining these images, differentiating them, and, finally, realizing these generalized forms of visual and spatial cognition.
A lesion of the inferior parietal regions leads to impairment of the most complex forms of orientation in space, associated with the concept of "right — left," but does not affect the structural organization of visually perceived images. More severe cases occur with lesions of the parieto-occipital regions of the brain. A focus located within the occipital cortex does not cause an impairment of spatial orientation, but a much more severe and gross disturbance, which takes the form of optical estrangement of graphemes (this is a lesion of the occipital, and sometimes occipito-temporal, regions), manifested in an impairment of the optical images of letters. (Footnote: Tsvetkova L.S. Neuropsychological Rehabilitation of Patients. Moscow: Moscow University Press).
In patients the symptom of estrangement of the letter appears, of its connection with a specific sound, and they begin to search for the needed image, often substituting one letter for another that is close to it in graphic form. In this case the grapheme, too, breaks down, i.e., in patients only one sign of the grapheme may remain intact — either the printed or the handwritten one — owing to the breakdown of the generalized image of the letter.
The nature, mechanisms, and structure of the writing impairment in all these cases differ from the speech-related forms of agraphia described above, and the impairment here is based not on defects of the acoustic or kinesthetic analysis of sound, nor on defects of phonemes and articulemes, nor on impairment of the successive organization of the word, but on the breakdown of the optical and optic-spatial schemas of letters. The optical agraphias are considered within the syndrome of gnostic disorders.
In the clinical picture of the optical agraphias, three types of writing impairment are most often encountered — the optical, optic-spatial, and optic-mnestic forms of agraphia. The fourth type — the apractognostic type — is rare. The essence of all the optical agraphias lies in the fact that, in this case, the grapheme is impaired not as a speech unit, but as its visual and visuospatial image-representation. In addition, in all forms of optical agraphia the complex process of recoding a sound into a letter is impaired.
A lesion of the inferior parietal regions leads to defects (or an impairment) in the actualization of the visuospatial image and the grapheme, which constitutes the central mechanism of the writing impairment in ; optic-spatial agraphia. In these cases the patients retain the graphic image of the sound — the grapheme that needs to be written — but the perception and actualization of the spatial arrangement of the elements of the letter are impaired. Patients experience particular difficulty in writing letters that have a clear spatial orientation (и — п, е — э, б — д etc.), which constitutes the central defect in this form of writing impairment, occurring within the syndrome of disturbance of spatial perception and image-representations.
In the clinical picture of the writing impairment, literal spatial paragraphias come to the fore, along with searches for the needed letter, or conscious searches for the spatial arrangement of the needed elements of the letter when writing. Patients experience difficulties in orienting themselves in space — they cannot find their own ward, cannot correctly put on a shirt or a robe, and confuse "left" and "right," "bottom" and "top." Spatial acalculia, too, is not infrequently present within this syndrome.
In the psychological picture of the impairment, defects of spatial image-representations and impairments in coordinating the elements of letters in space when writing them come to the fore.
The central task of restorative learning of writing in these cases of agraphia is to restore visuospatial representations, the ability to orient oneself in space, awareness of the connection between the spatial orientation of a letter and its meaning, and so on.
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