Mirror phenomena in language and nonverbal activities--a case report

Mirror writing resulting from an egocentric representation disorder: a case report

Buchwald (1878 ) used the term 'mirror writing' to indicate writing in the reverse direction to what is normal in a particular language and in which the individual letters are also reversed. Cases of healthy individuals (i.e., Leonardo da Vinci and Lewis Carroll) as well as brain-damaged patients have been described in the literature. Here, we report the case of PM, a 70-year-old right-handed woman who showed right hemiplegia and mirror writing following a stroke in the left lenticular nucleus and internal capsulae. PM underwent a complete neuropsychological evaluation, which included copying, dictation and spontaneous writing in both hemispaces with both hands. She was also tested for topographical disorientation, visuo-spatial disorders and body schema deficits. We observed isolated mirror writing only when PM wrote with the left hand, without differences between hemispaces. She also showed a left-right disorientation, a body topological map disorder and an egocentric misrepresentation. The presence of mirror writing not confined to one hemispace and the co-presence of executive function disorders, as well as anosognosia, suggests damage to our patient's sub-cortical frontal network. As no previous interpretation fits with PM's symptoms, we hypothesize that mirror writing resulted from damage to her egocentric frame of reference. This hypothesis allows us to interpret the patient's array of disorders, including mirror writing, body topological map disorder, left-right confusion and egocentric representation.

Mirror-image discrimination and reversal in the disconnected hemispheres

Two callosotomized patients and 24 neurologically normal subjects performed simple binary discriminations between upright letters flashed in one or other visual field. Where discrimination of the letters F and R by name either showed a left-hemisphere advantage or no hemispheric effect, discrimination of whether the same letters were normal or backward showed a right-hemisphere advantage. These results suggest that discrimination of mirror-image letters depends on matching to an exemplar, for which the right-hemisphere is dominant, while letter naming depends on abstract category recognition. One commissurotomized patient, DDV, showed systematic left-right reversal of the letters in the left visual field, classifying the normal letters as reversed and reversed ones as normal, and persisted with this reversal when the letters were shown in free vision. This suggests that reversed exemplars of the letters may be laid down the right cerebral hemisphere. There was no such reversal in the other patient (DDC).

'Directional apraxia': a unitary account of mirror writing following brain injury or as found in normal young children

Mirror writing refers to the production of individual letters, whole words or sentences in reverse direction. Unintentional mirror writing has been observed in young children and brain-damaged people and interpreted as the manifestation of different cognitive impairments. We report on a mirror writing patient following left hemisphere stroke and the mirror writing phenomena in one sample of children learning to write. We propose a unitary account of mirror writing as the unavailability of the appropriate movement direction representation, either because the right configuration has yet to be specified fully (children learning to write) or because of its damage (acquired brain injury). For this reason, we propose that the lack of directional information relevant to writing be labelled 'directional apraxia'.

Mirror writing: neurological reflections on an unusual phenomenon

Mirror writing is an unusual script, in which the writing runs in the opposite direction to normal, with individual letters reversed, so that it is most easily read using a mirror. This writing is seen in healthy individuals; it is also associated with various focal lesions that most commonly involve the left hemisphere, as well as with certain diffuse cerebral disorders. Mirror writing is nearly always undertaken with the left hand, and left-handers, and those whose languages are written leftwards, have an unusual facility for this writing. Concerning possible underlying processes, the implications of using the left hand when writing are considered first. Motor pathways that may be important, the surrogate model of bimanual mirror movements and the contribution of the corpus callosum are then discussed. The reasons why left-handed writing is mirrored, and the factors that tend to inhibit mirroring, are outlined. After commenting on mirrored motor and visual engrams, the possibility that the right hemisphere may play an important part is entertained, and Leonardo da Vinci's unique, habitual mirror writing proves to be of unexpected relevance. Further investigations, ranging from epidemiological to functional imaging studies, may provide valuable insights into mirror writing.

Acquired mirror writing and reading: evidence for reflected graphemic representations

Mirror writing occurs when individual letters and whole word strings are produced in reverse direction. By analogy, mirror reading refers to the preference to read mirror reversed over normally written words. These phenomena appear rarely after brain damage and offer insight into the nervous system's organization of visual-spatial and visual-motor representations. We present the case of a 51-year-old patient with persistent mirror writing and reading following traumatic brain injury. She preferred to write in the mirror direction with either hand. She drew asymmetric pictures with the same directional bias as normal right-handed subjects, and she did not exhibit left-right confusion regarding other pictures. By contrast, on picture-word matching and lexical decision tasks, she was faster and more accurate with mirrored than normally written words. This pattern of performance suggests that her behavior was not accounted for by reflected motor programs, or by the mirroring of visual-spatial representations in general. Rather, we suggest that her behavior was produced by privileged access to mirrored graphemes. Furthermore, because she seemed better able to read irregular words in mirrored than in normal formats, we suggest that mirrored representations may exist at the whole word level and not simply at the letter level.