Dystypia in acute stroke not attributable to aphasia or neglect

[Dystypia in a patient with subcortical ischemic stroke]

A 58-year-old, right-handed man noticed difficulty in typing and speech. On day 3 after onset, the day of admission, he had frontal lobe dysfunction including verbal fluency impairment and impairment of recent memory, although he did not have apraxia or visual agnosia. Moreover, he had difficulty typing in romaji, especially words containing contracted or double consonant sounds, although he was able to do this before onset by visually checking the keyboard. He had mild dysgraphia. MRI showed an infarct in the genu and posterior limb of the left internal capsule. SPECT revealed low-uptake lesions in the left frontal lobe. In the present case, we consider that the subcortical infarction disrupted the network between the thalamus and frontal lobe, resulting in dystypia due to difficulty with recalling romaji spelling.

Case Report: Globus Pallidus Internus (GPi) Deep Brain Stimulation Induced Keyboard Typing Dysfunction

Introduction:Typing on a keyboard requires complex collaboration between visuospatial/procedural memory, language, and motor function. The impaired ability to type, independent of motor deficits, apraxia, or aphasia has been coined “dystypia.”

Case Presentation: A 68-year-old woman with a history of blepharospasm, oromandibular, and segmental dystonia underwent bilateral pallidal deep brain stimulation (DBS) because of a waning response to botulinum toxin therapy. Following DBS, she discovered she no longer “remembered” how to type fluidly and had to “hunt and peck” for letters on the keyboard. This issue persisted at a 2-year follow-up. The patient underwent serial typing tests with the DBS ON vs. OFF. Post-operative lead reconstruction was performed using Lead-DBS. The volume of tissue activation (VTA) modeling was combined with whole-brain tractography.

Results: Typing improved when the device was switched to the DBS OFF state. Cortical mapping revealed strong modulation of the right angular gyrus, left calcarine fissure, and left cuneus. There was also activation of bilateral supplemental motor areas and superior parietal gyri.

Discussion: Shared lesion topography analysis of dystypia cases in the literature has suggested the involvement of the superior longitudinal fasciculus (SLF). The SLF involves the superior parietal lobe, angular gyrus, supramarginal gyrus, and arcuate fasciculus. Our patient’s connectivity pattern suggested SLF involvement. The improvement in OFF state typing and her imaging together suggested that the dystypia in her case was a stimulation-induced side effect.

Conclusion: Dystypia is a rare side effect of Globus Pallidus Internus (GPi) DBS therapy and may be associated with SLF involvement.

Differential impacts of different keyboard inputting methods on reading and writing skills

Nowadays, typewriting has become an important mode of written communication. A report that typewriting may hinder Chinese children's reading development has sparked substantial concern about whether typing on electronic devices would increase the rate of reading disorders, wherein children used a pronunciation-based input system that associates alphabet letters with phonemes in standard Chinese (Putonghua) and may conflict with the traditional visuomotor-based learning processes for written Chinese. If orthographic-based input methods that require good awareness of the orthographic structure of characters are used, different outcomes might be observed. This study examined the impact of participants' experience in different typewriting methods on the literacy abilities of fluent Chinese-English bilingual readers. We found that orthographic-based typewriting measures correlated positively with Chinese reading measures, whereas pronunciation-based typewriting measures did not correlate with Chinese reading measures but correlated positively with English reading and spelling performance. Orthographic-based typewriters also performed better than pronunciation-based typewriters in Chinese reading and dictation when their age, typewriting skills and pre-University language ability were statistically controlled. Our findings based on two contrastive writing systems suggest that typewriting methods that tally with the learning principles of a writing system should be used to promote and preserve literacy skills in the digital era.

Writing in the air: A visualization tool for written languages

The present study investigated interactions between cognitive processes and finger actions called “kusho,” meaning “air-writing” in Japanese. Kanji-culture individuals often employ kusho behavior in which they move their fingers as a substitute for a pen to write mostly done when they are trying to recall the shape of a Kanji character or the spelling of an English word. To further examine the visualization role of kusho behavior on cognitive processing, we conducted a Kanji construction task in which a stimulus (i.e., sub-parts to be constructed) was simultaneously presented. In addition, we conducted a Kanji vocabulary test to reveal the relation between the kusho benefit and vocabulary size. The experiment provided two sets of novel findings. First, executing kusho behavior improved task performance (correct responses) as long as the participants watched their finger movements while solving the task. This result supports the idea that visual feedback of kusho behavior helps cognitive processing for the task. Second, task performance was positively correlated with the vocabulary score when stimuli were presented for a relatively long time, whereas the kusho benefits and vocabulary score were not correlated regardless of stimulus-presentation time. These results imply that a longer stimulus-presentation could allow participants to utilize their lexical resources for solving the task. The current findings together support the visualization role of kusho behavior, adding experimental evidence supporting the view that there are interactions between cognition and motor behavior.

The Neural Basis of Typewriting: A Functional MRI Study

To investigate the neural substrate of typewriting Japanese words and to detect the difference between the neural substrate of typewriting and handwriting, we conducted a functional magnetic resonance imaging (fMRI) study in 16 healthy volunteers. All subjects were skillful touch typists and performed five tasks: a typing task, a writing task, a reading task, and two control tasks. Three brain regions were activated during both the typing and the writing tasks: the left superior parietal lobule, the left supramarginal gyrus, and the left premotor cortex close to Exner’s area. Although typing and writing involved common brain regions, direct comparison between the typing and the writing task revealed greater left posteromedial intraparietal cortex activation in the typing task. In addition, activity in the left premotor cortex was more rostral in the typing task than in the writing task. These findings suggest that, although the brain circuits involved in Japanese typewriting are almost the same as those involved in handwriting, there are brain regions that are specific for typewriting.