Archive for the ‘dyslexia’ Category
dyslexia is not one thing 4: the left and the right
a one-sided view (the left) of the parts of the brain involved in language and reading processing
Canto: So we’re still looking at automaticity, and it’s long been observed that dyslexic kids have trouble retrieving names of both letters and objects from age three, and then with time the problem with letters becomes more prominent. This means that there just might be a way of diagnosing dyslexia from early problems with object naming, which of course starts first.
Jacinta: And Wolf is saying that it may not be just slowness but the use of different neural pathways, which fMRI could reveal.
Canto: Well, Wolf suggests possibly the use of right-hemisphere circuitry. Anyway, here’s what she says re the future of this research:
It is my hope that future researchers will be able to image object naming before children ever learn to read, so that we can study whether the use of a particular set of structures in a circuit might be a cause or a consequence of not being able to adapt to the new task of literacy (Wolf, p181).
So that takes us to the next section: “An impediment in the circuit connections among the structures”.
Jacinta: Connections between. And if we’re talking about the two hemispheres, the corpus callosum could’ve provided a barrier, as it does with stroke victims…
Canto: Yes, connections within the overall reading circuit, which involves different parts of the brain, can be more important for reaching automaticity than the brain regions themselves, and a lot of neuroscientists are exploring this connectivity. Apparently, according to Wolf, three forms of disconnections are being focussed on by researchers. One is an apparent disconnection ‘between frontal and posterior language regions, based on underactivity in an expansive connecting area called the insula. This important region mediates between relatively distant brain regions and is critical for automatic processing’ (Wolf, p182). Another area of disconnection involves the occipital-temporal region, also known as Brodmann area 37, which is activated by reading in all languages. Normally, strong, automatic connections are created between this posterior region and frontal regions in the left hemisphere, but dyslexic people make connections between the left occipital-temporal area and the right-hemisphere frontal areas. It also seems to be the case that in dyslexics the left angular gyrus, accessed by good beginning readers, doesn’t effectively connect with other left-hemisphere language regions during reading and the processing of phonemes.
Jacinta: And it’s not just fMRI that’s used for neuro-imaging. There’s something called magnetoencephalography (a great word for dyslexics) – or MEG – that gives an ‘approximate’ account of the regions activated during reading, and using this tool a US research group found that children with dyslexia were using a completely different reading circuitry, which helps explain the underactivity in other regions observed by other researchers.
Canto: And leads to provocative suggestions of a differently arranged brain in some people. Which takes us to the last of the four principles: ‘a different circuit for reading’. In this section, Wolf begins by recounting the ideas of the neurologists Samuel T Orton and Anna Gillingham in the 1920s and 1930s. Orton rejected the term ‘dyslexia’, preferring ‘strephosymbolia’. Somehow it didn’t catch on, but essentially it means ‘twisted symbols’. He hypothesised that in the non-dyslexic, the left-hemisphere processes identify the correct orientation of letters and letter sequences, but in the dyslexic this identification was somehow hampered by a problem with left-right brain communication. And decades later, in the 70s this hypothesis appeared to be validated, in that tests on children in which they were given ‘dichotic tasks’ – to identify varied auditory signals presented to different ears – revealed that impaired readers didn’t use left-hemisphere auditory processes in the same way as average readers. Other research showed that dyslexic readers showed ‘right-hemisphere superiority’, by which I think is meant that they favoured the right hemisphere for tasks usually favoured by the left.
Jacinta: Yes, weakness in the left hemisphere for handling linguistic tasks. But a lot of this was dismissed, or questioned, for being overly simplistic. You know, the old left-brain right-brain dichotomy that was in vogue in popular psychology some 30 years ago. Here’s what Wolf, very much a leading expert in this field, has to say on the latest findings (well, circa 2010):
In ongoing studies of the neural of typical reading, the research group at Georgetown University [a private research university in Washington DC] found that over time there is ‘progressive disengagement’ of the right hemisphere’s larger visual recognition system in reading words, and an increasing engagement of left hemisphere’s frontal, temporal, and occipital-temporal regions. This supports Orton’s belief that during development the left hemisphere takes over the processing of words (Wolf, p185).
Canto: Yes, that’s ‘typical reading’. Children with dyslexia ‘used more frontal regions, and also showed much less activity in left posterior regions, particularly in the developmentally important left-hemisphere angular gyrus’. Basically, they used ‘auxiliary’ right-hemisphere regions to compensate for these apparently insufficiently functional left regions. It seems that they are using ‘memory’ strategies (from right-hemisphere structures) rather than analytic ones, and this causes highly predictable delays in processing.
Jacinta: A number of brain regions are named in this explanation/exploration of the problems/solutions for dyslexic learners, and these names mean very little to us, so let’s provide some – very basic – descriptions of their known functions, and their positions in the brain.
Canto: Right (or left):
The angular gyrus – which, like all other regions, is worth looking up on google images as to placement – is in a sense divided in two by the corpus callosum. Described as ‘horseshoe-shaped’, it’s in the parietal lobe, or more specifically ‘the posterior region of the inferior parietal lobe’. The parietal lobes are paired regions at the top and back of the brain, the superior sitting atop the inferior. The angular gyrus is the essential region for reading and writing, so it comes first.
The occipital-temporal zone presumably implies a combo of the occipital and temporal lobes. The occipital is the smallest of the four lobes (occipital, temporal, parietal, frontal), each of which is ‘sided’, left and right. The junction of these two lobes with the parietal (TPO junction) is heavily involved in language processing as well as many other high-order functions.
Jacinta: Okay, that’ll do. It’s those delays you mention, the inability to attain automaticity, which characterises the dyslexic, and it appears to be caused by the use of a different brain circuitry, circuitry of the right-hemisphere. Best to quote Wolf again:
The dyslexic brain consistently employs more right-hemisphere structures than left-hemisphere structures, beginning with visual association areas and the occipital-temporal zone, extending through the right angular gyrus, supramarginal gyrus, and temporal regions. There is bilateral use of pivotal frontal regions, but this frontal activation is delayed (Wolf, p186).
Canto: The supramarginal gyrus is located just in front of and connected to the angular gyrus (a gyrus is anatomically defined as ‘a ridge or fold between two clefts on the cerebral surface in the brain). These two gyri, as mentioned above, make up the inferior parietal lobe.
Jacinta: Wolf describes cumulative research from many parts of the world which tends towards a distinctive pattern in dyslexia, but also urges skepticism – the human brain’s complexity is almost too much for a mere human brain to comprehend. No two brains are precisely alike, and there’s unlikely to be a one-size-fits all cause or treatment, but explorations of this deficit are of course leading to a more detailed understanding of the brain’s processes involving particular types of object recognition, in visual and auditory terms.
Canto: It’s certainly a tantalising field, and we’ve barely touched on the surface, and we’ve certainly not covered any, or very much of the latest research. One of the obvious questions is why some brains resort to different pathways from the majority, and whether there are upsides to offset the downsides. Is there some clue in the achievements of people known or suspected to be have been dyslexic in the past? I feel rather jealous of those researchers who are trying to solve these riddles….
References
Maryanne Wolf, Proust and the squid: the story and science of the reading brain, 2010
https://www.kenhub.com/en/library/anatomy/angular-gyrus
https://academic.oup.com/brain/article/126/9/2093/367492
dyslexia is not one thing 3: problems with automaticity
Q Canto: So the next hypothesised basic source of dyslexia is ‘a failure to achieve automaticity’, that’s to say the sort of rapid, more or less unconscious processing of sounds into letters and vice versa, which probably means effective connection between brain regions or structures.
Jacinta: Perhaps because one of the structures is somehow internally dysfunctional.
Canto: wYes, and it often begins with vision. Researchers have found that many dyslexic individuals couldn’t separate two rapidly succeeding visual flickers as clearly as other individuals – an apparent processing problem. Similar research with dyslexic children found that, though they could identify stimuli initially as well as the non-dyslexic, they fell behind with added complexity and speed. This occurred more or less equally whether the stimuli were aural or visual. The connections just didn’t come ‘naturally’ to them.
Jacinta: So what about the connection between language – I mean speech, which is tens of thousands of years old – and reading and writing, a much newer development for our brains to deal with? Do dyslexic people have problems with processing good old speech? Are they slower to learn to talk?
Canto: Yes, a good question. Wolf describes research in which children with dyslexia in a number of languages, including English, ‘were less sensitive to the rhythm in natural speech, which is partly determined by how the sounds in words change through stress and ‘beat patterns’’ (Wolf, p177). Others have found breakdowns in processing in various motor tasks involving hearing and seeing. That’s to say, in the automaticity of such tasks. One psychologist who studies dyslexic children found an extensive range of problems with processing speed, especially a time gap or asynchrony between visual and auditory processing, and this observation has become commonplace.
Jacinta: But does this relate specifically to learning to speak? I’ve heard that Einstein was slow at that as a child.
Canto: Yes it’s said that he didn’t learn to speak full sentences before the age of five. But here we’re just talking about ‘naming speed’, and how it appears to use the same neurological structures as reading, as problems with one is predictive of problems with the other.
Jacinta: And the problem isn’t so much with naming per se, but the speed, the gap.
Canto: Yes, the lack of automaticity. Neurologists working in this field have developed ‘rapid automised naming’ (RAN) tasks which have become the most effective predictors of reading performance, regardless of language. Wolf herself has developed a refinement, rapid alternating stimulus (RAS), which, as the name suggests, gives more weight to attention-switching automaticity. Here’s an interesting quote from Wolf:
If you consider that the whole development of reading is directed toward the ability to decode so rapidly that the brain has time to think about incoming information, you will understand the deep significance of those naming speed findings. In many cases of dyslexia, the brain never reaches the highest stages of reading development, because it takes too long to connect the earliest parts of the process. Many children with dyslexia literally do not have time to think in the medium of print.
Jacinta: It makes me think of the unconscious, but not the Freudian one. A processing that you don’t have to think about. So that you can think about the info, not the form that encapsulates it.
Canto: Yes, and none of this explains why some have these problems with automaticity – which brings us back to neurology. Are dyslexic individuals using a different circuit from the rest of us, and does this explain their skills and abilities in other areas? Remember the names – Einstein, da Vinci, Gaudi, Picasso… not that dyslexia guarantees genius or anything…
Jacinta: Yes, far from it, I’d say, but it’s a fascinating conundrum.
Canto: So, neurology. And this takes us to how the ‘reading brain’, a very new phenomenon, evolutionarily speaking, came into being. fMRI images appear to confirm hypotheses that the brain ‘uses older object recognition pathways in the occipital-temporal zone (area 37) to name both letters and objects’ (Wolf, p179). It’s a process described as ‘neuronal recycling’. And it takes us to brain regions associated with particular tasks. For example, the left occipital-temporal area is apparently more associated with object naming, a much older task, evolutionarily speaking, than letter naming, and one that takes up more cortical space. The more streamlined, specialised use of this region for letters, and the development of automaticity for that purpose, is a prime example of our much-vaunted neuroplasticity.
Jacinta: What they’ve called RAN is always faster for letters than objects – that’s perhaps because letters are a small, even quite tiny subset of the near-infinite set of objects.
Canto: Yes, and here I’m going to quote a difficult passage by Wolf at some length, and then try, with your help, to make sense of it:
…culturally invented letters elicit more activation than objects in each of the other ‘older structures’ (especially temporal-parietal language areas) used for reading in the universal reading brain. This is why measures of naming speed like RAN and RAS predict reading across all known languages. It is also why, side-by-side, the brain images of the object- and letter-naming tasks are like comparative evolutionary photos of a pre-reading and post reading brain (Wolf, p181).
Jacinta: So this is a bit confusing. Culturally invented letters are new, evolutionarily speaking. And there are older language structures used for reading. Repurposed? Added onto? A bit of renovation? And what exactly is ‘the universal reading brain’?
Canto: Good question, and a quick internet research reveals much talk of a ‘universal reading network’. Here’s a fascinating abstract from a 2020 study, some ten years after the publication of Wolf’s book. It’s entitled “A universal reading network and its modulation by writing system and reading ability in French and Chinese children”:
Are the brain mechanisms of reading acquisition similar across writing systems? And do similar brain anomalies underlie reading difficulties in alphabetic and ideographic reading systems? In a cross-cultural paradigm, we measured the fMRI responses to words, faces, and houses in 96 Chinese and French 10-year-old children, half of whom were struggling with reading. We observed a reading circuit which was strikingly similar across languages and consisting of the left fusiform gyrus, superior temporal gyrus/sulcus, precentral and middle frontal gyri. Activations in some of these areas were modulated either by language or by reading ability, but without interaction between those factors. In various regions previously associated with dyslexia, reading difficulty affected activation similarly in Chinese and French readers, including the middle frontal gyrus, a region previously described as specifically altered in Chinese. Our analyses reveal a large degree of cross-cultural invariance in the neural correlates of reading acquisition and reading impairment.
So this research, like no doubt previous research, identifies various brain regions associated with reading ability and impairment, and finds that the same automacity, or lack thereof, is associated with the same regions, such as the middle frontal gyrus, in both alphabetic and ideographic reading systems. I think this is further confirmation of the research work Wolf is citing. Of course, I don’t know much about these brain regions. A course in neurology is required.
Jacinta: But what Wolf appears to be saying in that earlier quote is that you can get brain images (via fMRI) of object naming (older brain) tasks and put them side by side with images of letter naming tasks (younger brain), and it’s like seeing the results of evolution. Sounds a bit much to me. I suppose you can see a different pattern. Isn’t fMRI based on the magnetism of iron in the blood?
Canto: Yes yes. This is complex, but of course it’s true that the neural networking required for reading and writing is much more recent than that for language – and remember that of the 7000 or so languages we know of, only about 300 have a written form, which suggests that the Aborigines, before whities arrived, and the Papua-New Guineans, who have about 700 different languages on their island, were unable to even be dyslexic, or were all dyslexic without knowing it, or giving a flying fuck about it, because they had no writing, and no wiring for reading it.
Jacinta: So it would be interesting, then, to scan the brains of those language users – and there are no humans who aren’t language users – who don’t have writing. Take for example the Australian Aborigines, who became swamped by white Christian missionaries determined to ‘civilise’ them, more or less overnight in evolutionary terms, through teaching them to read and write. And then would’ve been characterised as backward for not picking up those skills.
Canto: That’s an interesting point, but it’s the same even in ‘cradles of civilisation’ such as Britain, where the vast majority were illiterate, and encouraged to be so, 500 years ago. At that time the printing press was a new-fangled device, church services were mostly conducted in Latin, and it was convenient to keep the peasantry in ignorance and in line. And yet, when it became more convenient to have a literate population, the change appears to have been relatively seamless, dyslexia notwithstanding. So it seems that, from a neurological perspective, little change was required.
Jacinta: Yes, that’s a good point, and it points to brain plasticity. Curiouser and curiouser – so it’s not so much about evolution and genes, but relatively rapid neural developments…. to be continued…
References
M Wolf, Proust and the squid, 2010
dyslexia is not one thing 2: structural deficits
the human brain- a very very rough guide
Jacinta: So we’re going to look at earlier ideas about dyslexia, before the recent revolution in neurology, if that’s not being too hyperbolic. These ideas tended to focus on known systems, before there were well-identified or detailed neural correlates. ‘Word-blindness’ was an early term for dyslexia, highlighting the visual system. This was partly based on the 19th century case of a French businessman and musician who, after a stroke, could no longer read words or musical notes or name colours. A second stroke worsened the situation considerably, eventually causing his death.
Canto: An autopsy revealed that the first stroke had damaged the left visual area and part of the corpus callosum, which connects the two hemispheres. It appears that what the man was seeing with his right hemisphere was not able to be ‘backed up’ by the left visual area, and/or connected to the left language area. The second stroke struck mainly the angular gyrus, a complex and vital integrating and processing region towards the back of the brain.
Jacinta: Yes, and before we go on, what we’re doing here is looking in more detail at the four potential sources of dyslexia set down at the end of the previous post. So in this post we’re focusing on 1. a developmental, possibly genetic, flaw in the structures underlying language or vision.
Canto: Right, so there’ll be three more dyslexia posts after this. So this ‘Monsieur X’ case was one of ‘classic alexia’ or acquired dyslexia, and marked an important step forward in mapping regions in relation to the visual and processing aspects of language. Norman Geschwind described it as ‘disconnection syndrome’, when two brain regions essential to a function, in this case written language, are cut off from each other.
Jacinta: The auditory cortex became an important focus in the twentieth century, as researchers noted a problem with forming ‘auditory images’ – which sounds like a problem everyone would have! More specifically it means not being able to translate the images made by letters and phonemes into sounds.
Canto: Yes, so that a word like ‘come’ (which is actually quite complex – the hard ‘k’ followed by an ‘o’ which, orally, is neither the typically short nor long version, followed finally by the silent ‘e’ which has some quite strange effect on the previous vowel) would be quite a challenge. Perhaps the real surprise is that we have no trouble with it.
Jacinta: Yes, I prefer cum myself, but that’s a bit off-topic. Anyway, psycholinguistics, much derived from the work of Noam Chomsky, which came into prominence from the 1970s, tended to treat dyslexia more as specifically language-based rather than audio-visual. Taking this perspective, researchers found that ‘reading depended more on the linguistically demanding skills of phonological analysis and awareness than on sensory-based auditory perception of speech sounds’ (Wolf, p173). This was evidenced by the way impaired-reading children treated ‘visual reversal’ in letters (e.g p and q, b and d). They were able to draw the letters accurately, but had great trouble saying them (sounding them). This appears to be a spoken language problem, which carries over to writing.
Canto: Indeed, it highlighted a problem, which apparently had nothing to do with intelligence, or basic perception, but was more of a specific perception-within-language thing:
These children cannot readily delete a phoneme from the beginning or end of a word, much less from the middle, and then pronounce it; and their awareness of rhyme patterns (to decide whether two words like ‘fat’ and ’rat’ rhyme or not) develops much more slowly. More significantly, we now know that these children experience the most difficulties learning to read when they are expected to induce the rules of correspondence between letters and sounds on their own.
Phonological explanations of dyslexia have resulted in a lot of effective remedial work in recent decades, and a library of research in the field of reading deficits.
Jacinta: Yes, these are called structural hypotheses, noting deficits in awareness of phonemic structure, and phoneme-grapheme correspondences. And these deficits presumably have their home in specific neural regions and wiring. The executive processes of the frontal lobes may be at play, in terms of organised attention, the fixing of memory and the monitoring of comprehension, but also the more ‘basic’ processes of the cerebellum, involving timing and motor coordination. And co-ordination between these regions may also be an issue.
Canto: And, as Wolf points out, these structural hypotheses have sheeted home problems to so many brain regions – the frontal executive function region, the speech region close by, the central auditory region, the language and language/visual integration regions, the posterior visual cortex and the cerebellum – that it would be fair to say that ‘many of the collective hypothesised sources of dyslexia mirror the major component structures of the reading brain’ (Wolf, p176).
Jacinta: Which sounds pretty serious. Why is it happening? And why not for others…?
References
M Wolf, Proust and the squid: the story and science of the reading brain
https://www.kenhub.com/en/library/anatomy/angular-gyrus
dyslexia is not one thing, apparently
Canto: So I’ve been reading Proust and the squid, by Maryanne Wolf, a book I bought back in 2010, when it was published, and apparently read at the time, though I remember very little about it. Did I really read it? I suspect I didn’t finish it. Anyway, it’s subtitled Science and the reading brain, and since we do a lot of reading, mostly still in the old-fashioned way (stuff written on paper), the subject is of obvious interest.
Jacinta: Yes, it’s interesting to reflect that though writing, of various types, came into being four to five thousand years ago, it’s only in the last few centuries that reading has become anything like universally adopted. And our brains have had to adapt to reading…
Canto: Yes, think of reading to ourselves, in a language that’s based on sound. Which not all languages are, if I’m not mistaken. So I imagine that non-phonological languages (is that a meaningful term?) use the brain in a different way…
Jacinta: It’s more complicated than that – for example, there’s a difference between phonetics and phonemics, in which the letter ‘t’ is sounded differently depending on its place within a word and what letters surround it, for example in ‘th’ words, and that phoneme is sounded differently, for example in ‘the’ and in ‘beneath’, if you listen carefully. We generally don’t notice these differences until they’re pointed out to us. And the English language is full of them. Phonemes can be divided into allophones, as they’re called. But getting back to dyslexia…
Canto: Well, first it needs to be made clear that dyslexia has nothing to do with lack of intelligence. Both Einstein and Leonardo da Vinci, the names most often trotted out as examples of genius, were likely dyslexic, or maybe I should say they suffered from some form of dyslexia – because it’s really really complex and multi-faceted, and seems to involve right-left brain differences. The last two chapters of Wolf’s book, ‘Dyslexia’s puzzle and the brain’s design’ and ‘Genes, gifts and dyslexia’, are fiendishly difficult for someone like me, with very little background in neurology, but fascinating, and I think it’ll take several posts to cover not only what’s in the book but the ongoing research since it was written.
Jacinta: Yes that reminds me of Sapolsky’s statement in Behave, that more neurological papers have been published in the 21st century than in all previous centuries combined – and that book was published five years ago.
Canto: Well, it’s not surprising, it’s a burgeoning area of research, looking for neural co-ordinates for various disabilities, proficiencies, tendencies… As well as genetic correlations. And epigenetic too, maybe. Anyway, to begin somewhere, Wolf describes a hypothesis that derives from the thinking of a famous and apparently prophetic 20th century neurologist, Norman Geschwind:
The genes that form the basis for a strengthened right hemisphere could have been highly productive in preliterate societies, but when these same genes are expressed within a literate society, they put structures in the right hemisphere in charge of the precise, time-based functions of reading. These functions would then be performed in the unique ways of the right hemisphere, rather than in the more precise, time-efficient ways of the left hemisphere. In the case of reading, that situation would lead inevitably to difficulties.
M Wolf, Proust & the squid: the story and science of the reading brain, pp205-6
Now, I had no idea that the left hemisphere was more precise and time-efficient than the right…
Jacinta: But this quote doesn’t quite make sense to me. We’re all descended from pre-literate societies after all, so with ‘highly productive right hemispheres’. And then, when literacy came along – what? The right hemisphere took on these ‘precise, time-based functions of reading’ in its ‘unique way’, when it would’ve been better to use the left hemisphere, which is better adapted for the purpose, apparently. Wouldn’t this make us all a bit dyslexic?
Canto: Yes, maybe that’s the point. But there’s also no doubt that the reading brain – which may one day become obsolete in the digital and post-digital world – has transformed our society more or less completely. So having serious reading/writing deficits can be a major problem, perhaps especially for highly intelligent people who might feel the disadvantage more.
So dyslexia, as the word suggests, is a broad and negative term which essentially covers all deficiencies in grasping and producing written text. Wolf presents, inter alia, the definition of The International Dyslexia Association:
Dyslexia is a specific learning disability that is neurological in origin. It is characterised by difficulties with accurate and/or fluent word recognition and by poor spelling and decoding abilities. These difficulties typically result from a deficit in the phonological component of language that is often unexpected in relation to other cognitive abilities and the provision of effective classroom instruction. Secondary consequences may include problems in reading comprehension and reduced reading experience that can impede growth of vocabulary and background knowledge.
Note that the only reference to causes here is that it’s ‘neurological in origin’.
Jacinta: Well mention has been made about right and left sides of the brain – does it get any more specific?
Canto: Of course – but as one researcher points out, dyslexia isn’t a reading disorder, as there are no reading centres in the brain. It’s rather a disorder in one or more regions of the brain that have been co-opted for reading and writing. Wolf describes a pyramid of nested connections regarding the disorder. First we observe a behavioural problem, in the act of getting words wrong in reading and writing, or an abnormal slowness and struggle in gaining proficiency in acquiring those skills. Next comes the observation of a pattern of disability, such as seeing/writing/speaking particular letters or phonemes incorrectly. Then there’s the connection between these deficits and neural structures. The next step is homing in on particular neurons and neural circuits, and finally taking this back to the level of particular genes.
Jacinta: But there aren’t any specific genes are there?
Canto: Well, not in the sense of genes for height or eye colour, or even language, which may go back to the earliest Homo sapiens. Literacy is a cultural invention. To quote Wolf:
Across all written languages, reading development involves: a rearrangement of older structures to make new learning circuits; a capacity for specialisation in working groups of neurons within these structures for representing information; and automaticity – the capacity of these neuronal groups and learning circuits to retrieve and connect this information at nearly automatic rates.
M Wolf, Proust and the squid, p 170
Genes aren’t specifically mentioned here – but neurologists are understandably asking whether this ‘rearrangement of older structures’, and possible failures in this rearrangement, have a genetic basis, just as the development of language itself presumably has (though this development too is shrouded in mystery). Wolf goes on to outline four ‘potential basic sources for dyslexia’. I’m going to set them down here because, frankly, I barely understand them. See what you make of them.
- a developmental, possibly genetic, flaw in the structures underlying language or vision (e.g. a failure of working groups to learn to specialise within those structures)
- a problem achieving automaticity – in retrieving representations within given specialised working groups, or in the connections among structures in the circuits, or both
- an impediment in the circuit connections between and among these structures
- the rearrangement of a different circuit altogether from the conventional ones used for a particular writing system
Jacinta: Hmmm. I don’t know what she means by ‘working groups’ – of neurons? The fourth one is the only one that I half comprehend. That some forms of dyslexia have harnessed a different circuit which isn’t quite as effective but gets there in the end? Or not?
Canto: Yes, on reflection I half-comprehend the others, and see them as rather connected. For example, failure to achieve automaticity sounds similar to having an impediment in the connections. With some it feels seamless – or doesn’t feel anything at all. I can’t remember ever learning to read or having problems with it, and loved school spelling bees, being very good at them. Anyway, Wolf elaborates on each of these four principles, and I think we should try to follow them in the next blog post. We’ll be better human beings for the process, I’m sure. Because, difficult though it is, I’ve found this to be one of the most intriguing and stimulating books I’ve read for some time.
Jacinta: Okay, let’s go for it.
References
Maryanne Wolf, Proust & the squid: the story and science of the reading brain, 2010
Click to access memorialminute_geschwind_norman.pdf
https://en.wikipedia.org/wiki/Origin_of_language