Pure dysgraphia with relative sparing of lower-case writing

Progressive macrographia for block letter writing: A case study

"Macrographia", a relatively rare symptom generally following cerebellar diseases, consists of an abnormally large handwriting. The case reported in the present investigation shows several outstanding features. First, it is of the progressive variety, letters increase in size as one goes through the word towards the lower-right portion of space. Moreover, it is limited to one allographic variety, that is, block letters. This phenomenon is previously unreported, all allographic varieties being usually equally affected. Finally, no prominent cerebellar or basal ganglia abnormality could be demonstrated with structural MRI or PET. From a cognitive point of view, a peculiar combination of spatial attention, executive function and working memory deficits is proposed to account for the progressive misalignment and elongation of individual letters when specifically writing in block prints. From an anatomical perspective, the pattern of multifocal lesions, encompassing multiple cortical areas in both hemispheres and the corpus callosum, may support this multi-componential interpretation of the reported phenomenon.

A deficit in post-graphemic writing processes: Evidence for a graphomotor buffer

Post-graphemic writing processes transform abstract letter representations into representations of writing movements. We describe an individual with an acquired post-graphemic writing deficit. NGN is normal in spelling words aloud, but impaired in writing words to dictation, with most errors involving letter substitutions (e.g., RUMOR written as BUMOR). NGN's deficit affects graphic motor plans, which specify the writing strokes for producing letters. Analyses of writing speed, fluency, and stroke patterns suggest that NGN's errors result from incomplete motor-plan activation. NGN's error rate is high for the first letter in a word, and declines across subsequent positions. On the basis of this serial position effect and other results, we propose that post-graphemic writing mechanisms include a graphomotor buffer, a writing-specific working memory that holds activated graphic motor plans bound to specific serial positions. We suggest that NGN's graphomotor buffer is damaged such that early serial positions are affected most severely. Finally, we present results speaking to the roles and capabilities of the graphomotor buffer, and the structure of graphic motor plans.

Allographic agraphia: a case study

We report the case of patient MN, diagnosed with frontotemporal dementia, who exhibited a severe impairment in writing letters and words in upper-case print in the face of accurate production of the same stimuli in lower-case cursive. In contrast to her written production difficulties, MN was unimpaired in recognizing visually presented letters and words in upper-case print. We find a modest benefit of visual form cueing in the written production of upper-case letters, despite an inability to describe or report visual features of letters in any case or font. This case increases our understanding of the allographic level of letter-shape representation in written language production. It provides strong support for previous reports indicating the neural independence of different types of case and font-specific letter-shape information; it provides evidence that letter-shape production does not require explicit access to information about the visual attributes of letter shapes and, finally, it reveals the possibility of interaction between processes involved in letter-shape production and perception.

Post graphemic impairments of writing: the case of micrographia

Micrographia (MG), an acquired impairment of writing characterized by diminution of letter size, coupled with slowing and loss of accuracy, is most frequently observed in the course of degenerative disease of basal ganglia, such as Parkinson's Disease. Only a few cases of MG without concomitant extrapyramidal signs have been described, mostly following vascular lesion of the left basal ganglia. In this article we report an isolated pattern of MG following an extensive traumatic cerebral lesion centered in the left basal ganglia. The nature of this impairment is analyzed according to a cognitive model of writing and interpreted as a specific example of peripheral dysgraphia.

The impact of deep dysgraphia on graphemic buffer disorders

This article describes an investigation into the residual writing skills of a severely dysgraphic patient (DA). We found that they were powerfully influenced by a number of lexical variables (lexicality, frequency, imageability, length and geminates). His error pattern was characterized by semantic, lexical, substitution, deletion errors and fragment responses that preserved the first letter. Thus, DA's written spelling was characterized by both deep dysgraphic and graphemic output buffer effects. It is proposed that this pattern of performance represents a new"putative functional syndrome."

A case for case: handling letter case selection in written spelling

This study reports the unusual writing performance of a 72-year-old woman, Pp, who was unable to maintain her writing within a particular case, and made numerous case mixing errors (e.g. insTEAd). Her oral spelling was flawless, but when tested using a written spelling task (including words and non-words), a picture description task, a sentence writing task and a transcription task (from upper case to lower case, and vice versa), she showed a high proportion of case mixing errors, though spelling per se was correct. The problem, although less severe, was also present when spelling with letter cards. Despite a spared ability to select the correct letters in the stimulus, specify the correct number of letters and place them in the correct order, she had a specific problem in selecting the appropriate case. This impairment is indicative of peripheral dysgraphia. She appeared to have intact orthographic representations, but selection of the appropriate allographic codes for upper and lower case was impaired. Her longitudinal neuropsychological profile and MRI evidence suggest that Pp suffers from mild vascular dementia with more severe impairments in attentional functions. Her writing deficits may be accounted for by a model that incorporates an inhibitory mechanism, which is responsible for maintaining the appropriate case and inhibiting the inappropriate one, subsequent to case selection in writing. Failure of this mechanism would explain the pattern of case mixing shown by Pp.

Dissociation between word reading and word copying in a patient with left visual neglect

A patient with left visual neglect following a right hemisphere infarction is described. When presented with isolated words and nonwords, she made left neglect errors in reading aloud, but not in direct copying. This finding suggests a distinction between two ways of processing orthographic stimuli: depending on the task, the unit of processing can be the letter string or the single letter. In reading, the letter string is treated as a whole while in copying it is processed element-by-element. Left neglect differentially affects the processing of single words: in reading errors involve the left, initial letters, while in copying they involve the single letters, or the left part of the letters, independently of their position within the stimulus.

A dissociation between the ability to print and write cursively in lower-case letters

This paper reports the case of a patient with a peripheral spelling impairment who is much more severely impaired at writing in lower-case letters than in upper-case letters. This pattern can be observed when writing both words and single letters of the alphabet. Despite this, his problems in writing lower-case letters are no longer present when he is writing cursively. This case therefore indicates that the ability to print letters in lower-case can be selectively impaired in the absence of similar problems in printing upper-case letters or in writing lower-case letters cursively. In terms of the model of writing put forward by Ellis (1982, 1988), this suggests that allographic level representations for print handwriting styles can be functionally dissociated from allographic representations for cursive styles.

Acquired dysgraphia with selective damage to the graphemic buffer: a single case report

We describe one patient with acquired dysgraphia who showed spelling errors (mainly deletions and substitutions), both for words and non-words, across all output modalities (oral and written spelling, and delayed copying). Spelling accuracy was not affected by lexical factors, but was a function of word length. The patient's performance in oral and written tasks suggests the hypothesis of selective damage to the Graphemic Buffer.