Abstract Mirror writing is often produced by healthy children during early acquisition of literacy, and has been observed in adults following neurological disorders or insults. The neural mechanisms responsible for involuntary mirror writing remain debated, but in healthy children, it is typically attributed to the delayed development of a process of overcoming mirror invariance while learning to read and write. We present an unusual case of sudden-onset, persistent mirror writing in a previously typical seven-year-old girl.
Ann Neurol Oct;66 4: InExner first described a "graphic motor image center" in the middle frontal gyrus. Current psycholinguistic models of handwriting involve the conversion of abstract, orthographic representations into motor representations before a sequence of appropriate hand movements is produced.
Direct cortical stimulation and functional magnetic resonance imaging fMRI were used to study the human frontal areas involved in writing. Cortical electrical stimulation mapping was used intraoperatively in 12 patients during the removal of brain tumors to identify the areas involved in oral language sentence reading and naming and writing, and to spare them during surgery.
The fMRI activation experiment involved 12 right-handed and 12 left-handed healthy volunteers using word dictation without visual control and 2 control tasks. Direct cortical electrical stimulation of restricted areas rostral to the primary motor hand area Brodmann area [BA] 6 impaired handwriting in 6 patients, without disturbing hand movements or oral language tasks.
In 6 other patients, stimulation of lower frontal regions showed deficits combining handwriting with other language tasks. This area was anatomically matched to those areas that affected handwriting on electrical stimulation.Exner's area (EXA) is a language area, located just above Broca's area.
The functional role of EXA seems to be involved in both writing and reading. In , Exner postulated that the foot of the second convolution in the left . Jul 28, · This stage is mediated by Exner’s writing area of the frontal lobe. People with dysgraphia can often write on some level and may experience difficulty with other fine motor skills, such as tying.
It was indeed tempting, in decades following the discovery of the Broca area as a premotor region adjacent to the mouth region of the primary motor cortex, to hypothesize that, in the same manner, an area located rostral to the hand area (the Exner area) could be specifically involved in writing.
13, 15, 18, 27, 32 Nevertheless, this hypothesis. Exner's Writing Area is located within a small area along the lateral convexity of the left frontal lobe, and is adjacent to Broca's expressive speech area, and the primary and secondary areas controlling the movement of the hand and fine finger movements.
There is a growing body of evidence indicating a crucial role of Exner’s area in (hand-) writing symbolic codes such as letters and words. However, a recent study reported a patient with a lesion affecting Broca’s and Exner’s area, who suffered from severe peripheral . Exner's area in the superior premotor cortex is specifically recruited in writing, and is thought to store graphemes (Planton et al., , Potgieser et al., , Roux et al., ).
The left-lateralized Broca's area is engaged by .