Discovery of my own Mirror Writing!! left-handedness and brain asymmetric strangeness

So I just discovered something I wrote when I just started out writing - and my "gs" were backwards! My relative then said - it was because I was left-handed. So I googled it.
Mirror writing is an unusual script, in which the writing runs in the opposite direction to normal, with individual letters reversed,

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.

Let's see what strangeness we find!

 Eighty years ago in English elementary schools, about 0.48% of children mirror wrote when they used their left hand.... left‐handed mirror writing, often for a few letters, sometimes emerges for a brief transitional period.²³

so not a lot of us out there!!

 Compared with the 0.48% of normal elementary school children who mirror wrote, the frequency was 8% among children with learning disabilities; among the children with learning disabilities, 30% of left‐handed children mirror wrote, compared with about 2% of the right‐handed children.¹⁵

and it's more by innate left-handers

 The propensity for mirror writing among left‐handed school children was noted by Ireland²⁵ more than a century ago, and others have confirmed this. For reasons discussed earlier, the left‐handed tendency and accompanying mirror writing then become suppressed, only to re‐emerge when this suppression is overcome. An example is provided by Smetacek's¹⁷ patient referred to earlier. It has been repeatedly observed that it is those who are left‐handed, ambidextrous or who somehow believe they are inherently left‐handed, who retain their unusual left‐handed mirror writing facility—a facility, or advantage, that has been both confirmed^55,56 and refuted^57,58 in experimental studies in normal people.

 But what causes it?

No experimental data are available on the processes specifically subserving mirror writing, and we are therefore dependent on speculative possibilities suggested by other motor phenomena.

 normal suppression of ipsilateral motor pathways from the contralateral cortex via transcallosal pathways may be impaired.

 In other words - a higher level of brain cross-wiring is occurring.

ipsilateral pathways are likely to be implicated in motor recovery after stroke,^64,65 and could “drive” the left hand when mirror writing.

 transcallosal deactivation of contralateral crossed pathways.^71,72 Apart from mirror writing associated with callosal damage due to stroke and possibly head injury, it is also possible that left‐handed mirror writing normally disappears during childhood maturation, as a result of inhibition associated with callosal myelination which takes place at around the same time.

 Arguing against the involvement of the corpus callosum is the fact that congenital abnormalities of the corpus callosum, and callosotomy in either left handers⁷⁵ or right handers,⁷⁶ are not associated with mirror writing.

 Why not do MRIs while someone is mirror writing?

the natural script of the left hander, and this view remains compelling. The evidence that mirror writing is the natural script of the left hander arises from everyday observations that abductive movements are generally more natural, and also more accurate,⁷⁹ than adductive movements. Writing with a pen held in the left hand will therefore be more readily undertaken leftwards; the script, too, would then be reversed compared with the conventional rightward‐directed script—that is, mirrored.

Thus, mirror writing with the left hand is not a bizarre form of writing at all, but predictable, and presumably a form of writing that is normally suppressed or superseded by conventional writing in order to be read.

yeah

  In children, there is a tendency for very young, left‐handed school children to scan from right to left,⁸³ and oculomotor control when reading, at least in the early stages, may be a right‐hemisphere specialisation.⁸⁴ A right‐hemisphere bias to the control of eye movements when reading would favour leftwards reading and hence writing, and consequent conflict with the rightwards direction of writing (and reading) of Western languages—leading to the view that confusions are especially likely to occur when eye movements are controlled by one hemisphere and hand movements by the other.⁸⁵

 fascinating!

 Furthermore, those who retain normal cerebral function but, after injury, have to undertake left‐handed tasks, such as using a screwdriver or turning a door knob, sometimes do so in mirror fashion,²³ and people who have had limbs amputated occasionally experience phantom mirror movements of their missing limbs.⁸⁷ These examples show that mirroring seems to be an unselective feature of dextrous left‐handed movements—that is, mirror writing may simply represent a specific example of a mirror movement, both perhaps enlisting the same motor processes that were discussed earlier.

In other words - noncommutative phase movements are natural!

But does the brain work the same way?

 Evidence in animals⁹¹ and humans⁹² suggests that visual images are transferred across the corpus callosum in mirror image form.

 Nope! Debunked:

However, Corballis and Beale⁹⁴ tersely comment “Orton's theory is wrong”. They rightly point out that by implying that the dominant hemisphere would record events with the correct orientation and the non‐dominant hemisphere would record them in reversed orientation, the conclusion follows that whenever the dominant hemisphere was inactivated, mirror phenomena would necessarily emerge—and this clearly does not occur.

 This suggests that left handers may have intrinsically different patterns of cerebral organisation and facility for using different motor pathways, at least with respect to writing.

at LEAST that....

  Importantly, however, the languages involved are both phonetic (Hebrew) and ideographic (Japanese and Chinese),⁹⁸ indicating that it is the leftwards direction in which they are written, and hence the link with right‐hemispheric control of movement, rather than the structural or visuospatial aspects of the languages, which is important.

Exactly! Fascinating.

So that was 2007 - but 2011 brings us new research:

Breaking the symmetry: Mirror discrimination for single letters but not for pictures in the Visual Word Form Area

 Humans and primates can quickly recognize mirror images of previously exposed pictures. This spontaneous mirror invariance, though advantageous for visual recognition, makes it difficult to distinguish the orientation of letters (e.g. to differentiate a “b” from a “d”), and may result in classical mirror reading and writing errors in preschoolers. Mirror invariance must therefore be overcome during reading acquisition. The Visual Word Form Area (VWFA), a region in the ventral stream that develops with reading expertise, was previously shown to discriminate words from their mirror images in literate adults. Here we investigate whether this region underlies mirror-image discrimination at the most elementary level of the orthographic code, the single-letter level. Using an fMRI priming paradigm, we demonstrate that the VWFA distinguishes the left–right orientation of single letters in skilled readers, and yet exhibits mirror invariance for simple pictures of matched complexity. These results clarify how letter shapes, after reading acquisition, escape the process of mirror invariance which is a basic property of the ventral visual shape recognition pathway.

fascinating - so reading and writing is a kind of brain damage I think.

 the left fusiform visual word form area, a major site of learning during reading acquisition, simultaneously shows a maximal effect of mirror priming for pictures and an absence of mirror priming for words. Thus, learning to read recruits an area which possesses a property of mirror invariance, seemingly present in all primates, which is deleterious for letter recognition and may explain children's transient mirror errors.

The Cost of Blocking mirror reversals!

expert readers never completely “unlearn” the mirror-generalization process and still need to inhibit this heuristic to overcome mirror errors.

so it appears that this is more of a visual brain training than it is the physical movement control of writing. Turns out that the "letter" reading part of the brain cortex is based out of the "animal" reading part of the brain cortex versus their control of the "building" visual reading part of the brain cortex. So over time the letter reading is trained - but it's never HARD-wired - it has to be constantly conditioned to register only the one direction of the letter.

 

We have found that a particularly high prevalence of left-handed mirror writing has been reported among those whose native languages are traditionally written in a leftward direction, including Chinese, Japanese, and Hebrew. Innate left-handers and those whose languages are written leftward thus share an unusual facility for left-handed mirror writing, an observation that may have implications for understanding hemisphere specialization in relation to handedness.

Mirror Writing, Left-handedness, and Leftward Scripts

a surprisingly large number of reported left-handed mirror writers are those whose native languages have traditionally been written and read leftward.

This finding cannot be attributed to population differences in handedness. Left-handedness is no more frequent among Asians than Westerners, and right-handedness has predominated in all cultures for at least 5000 years. Both consonantal phonetic (Hebrew) and ideographic (Chinese and Japanese) languages are implicated.

This suggests that, although ideographic languages are extensively processed in the right hemisphere, it is less the structure and more the leftward direction of these languages that is important and that drives, or is driven by, the contralateral right hemisphere. In addition, as was postulated in the case of ancient Semitic mirror writing, it may well be not only the direction of writing itself but also the right hemisphere involvement in leftward direction of eye movements and the left visual fields that are important.¹² Consistent with the present hypothesis, left-handedness and its association with involvement of the right hemisphere in producing the script of the world’s most famous habitual mirror writer, Leonardo da Vinci, has been postulated on the basis of historical evidence.² The high prevalence of left-handed mirror writing in those whose languages are written leftward recalls the facility for mirror writing among innate left-handers. In both groups, there is a suggestion that the right hemisphere may have an important role in mediating left-handed mirror writing, and, in the case of left-handers, there is supporting evidence for greater right hemisphere or bilateral activation compared with right-handers.^13,14