Dislessie acquisite Deficit di lettura dopo una lesione

Dislessie acquisite Deficit di lettura dopo una lesione cerebrale

Dislessie acquisite: approcci neurologici Alessia parieto-occipitale (o alessia con agrafia) - associata a sintomi afasici Alessia occipitale (o alessia senza agrafia) Alessia frontale (o alessia letterale)

Jules Dejerine (1849 -1917) J. Déjerine, Sur un cas de cécité verbale avec agraphie suivi d’autopsie, in : , vol. 3, 1891, pp. 197– 201. J. Déjerine, Contribution à l’étude anatomo-pathologique et clinique des différentes variétés de cécité verbale, in: , vol. 4, 1892, pp. 61– 90. J. Déjerine, J. Tinel, Un cas d’aphasie de Broca, in: , vol. 16, 1908, pp. 691 -694.

Dislessie acquisite: approccio cognitivo Analisi degli errori di lettura Errori semantici (via - strada) Errori visivi (banale - banane) Sostituzione di parole funzione (questo- quello) Errori morfologici (entrano - entrando) Errori di lessicalizzazione: viornale - giornale

n n n A syndrome is a collection of symptoms that tend to occur together. Cognitive neuropsychologists don't use the concept of syndrome in their theorizing because, if the kinds of modular models of cognition favoured in cognitive neuropsychology are even roughly correct, the number of different possible syndromes of impairment in any domain of cognition is gigantic. So the probability of ever seeing two patients with the same syndrome (i. e. exactly the same pattern of preserved and impaired components of a particular cognitive processing system) is essentially zero. However, syndrome labels do have their uses. Firstly, they are convenient shorthand terms that can convey to other people a quick though only approximate idea of what impairments a patient has. Secondly, it has turned out that in any domain of cognition that is unexplored from a cognitive-neuropsychological point of view, a good way to begin such exploration is to try to identify some basic broadly-defined syndromes, even if this way of thinking will subsequently be abandoned as impairments in this domain become better understood That's what happened with respect to reading, the first domain to be studied in detail by cognitive neuropsychologists. The first paper on the cognitive neuropsychology of reading was published in Neuropsychologia in 1966 by Marshall and Newcombe; it was on the particular syndrome of acquired dyslexia known as deep dyslexia. They followed this up with a paper on three syndromes of acquired dyslexia (deep dyslexia, surface dyslexia, and visual dyslexia); this was published in the Journal of Psycholinguistic Research in 1973. A fourth syndrome of acquired dyslexia was first described in 1979, by Beauvois and Derouesne in the Journal of Neurology, Neurosurgery and Psychiatry. And in 1982 in the Quarterly Journal of Experimental Psychology, Patterson and Kay discussed a fifth syndrome which they called letter-by-letter reading; it is also known as pure alexia, and had in fact first been described about a century ago by the French neurologist Dejerine, though he and subsequent authors had not approached this acquired dyslexia in a cognitive-neuropsychological way (that is, they had not attempted to relate it to models of normal reading).

Syndromes of acquired dyslexia n n n n n A third use for the syndrome concept is that it is a good device for teaching material about acquired dyslexia; a good way of organizing basic knowledge of the area. So what I will do here first is to describe the general features of these five syndromes of acquired dyslexia so as to make it clear what they are like and how they differ from eachother. Having provided an overview of the basic characteristics of each of these acquired dyslexias, I will then go on to discuss how each relates to the model of language processing we are using; it will be at that point that we will move away from the concept of syndrome and adopt the real cognitive-neuropsychological approach. That approach is, of course, to treat each patient as a unique case, but to try to relate every patient to the model, by asking: can we see how all the patient's symptoms could arise from damage to specific components of the model, with all the other components being intact. Ellis and Young's "Human Cognitive Neuropsychology" has an excellent basic chapter on acquired dyslexia which you should read at this point. * Deep Dyslexia. * Surface Dyslexia. * Phonological Dyslexia. * Pure alexia (Letter-by-letter reading). * Visual Dyslexia. * Neglect Dyslexia.

Explaining the different patterns of acquired dyslexia in relation to a model of normal reading. n n Here is a model of the processes skilled readers use to read single words and nonwords aloud and to understand the meanings of single words. If any of the boxes or arrows in this diagram are not functioning normally, then reading will be abnormal in some way. So we could try to understand different patterns of acquired dyslexia by trying to work out which boxes and/or arrows have been affected by brain damage in each of these cases. This works very well for some kinds of acquired dyslexia, but less well for others.

Deep dyslexia n n Introduction The first systematic study of deep dyslexia was by Marshall and Newcombe (1966), although the condition had been sporadically mentioned in the neuropsychological literature at least since 1931. Marshall and Newcombe (1973) and Shallice and Warrington (1975) also published early systematic studies. An entire book on deep dyslexia was published in 1980 (Coltheart, Patterson and Marshall, 1980), and much work on deep dyslexia has appeared since then.

The symptoms of deep dyslexia. n n n n All patients so far reported with deep dyslexia have had extensive left-hemisphere damage sufficient to produce aphasia (normally Broca's aphasia) and normally also a left hemiparesis. This acquired dyslexia is identified by the occurrence of semantic errors in reading aloud. Single words are presented, without context and without time pressure, for reading aloud; even in this simple situation the deep dyslexic will often produce a reading response that is related in meaning to the stimulus word but may be quite different from it in spelling and pronunciation, such as reading the word canary as "parrot". Although the semantic error in reading aloud is the key symptom of deep dyslexia, many other reading symptoms are also seen in this form of acquired dyslexia (for review see Coltheart, 1980 a, 1987 a). Deep dyslexics generally show all of the following symptoms in reading-aloud tasks: * Semantic errors, such as "tartan" read as "kilt" or"anchor" read as "boat". * Visual errors: a visual error in reading is when the response shares many letters with the stimulus, such as quarrel read as "squirrel" or angel read as "angle". * Morphological errors: a morphological error in reading is when a prefixed or suffixed word is read with the root of the word correct but the prefix or suffix wrong, such as running read as"runner" or unreal read as "real". * Concreteness effect: concrete (highly-imageable) words such as tulip or green are much more likely to be successfully read than abstract (difficult-to-image) words such as idea or usual. * Function words such as and, the or or are very poorly read. * Nonwords such as vib or ap cannot be read aloud at all. * Spelling/writing may be impossible; if it is at all possible, then it usually shows the spelling equivalent of the above 6 symptoms.

Deep dyslexia as left-hemisphere reading. n n n n Cognitive neuropsychologists seek to understand cases of acquired dyslexia by investigating how one could selectively damage a component or some components of a model of reading so that the model would exhibit the same symptoms as the patient. For deep dyslexia, this was attempted by Morton and Patterson (1980, 1987) as follows: First, since nonword reading is completely abolished in deep dyslexia, the letter-to-sound rules system must have been abolished. Second, since word reading is much less than 100% accurate, the direct connection from the Orthographic Input Lexicon to the Phonological Output Lexicon must be impaired. Take function words, for example. The deep dyslexic can recognize these as words (since visual lexical decision performance with such words can be very good) and can produce them (since the usual error response to a function word is another function word). Hence the problem in reading them must be a disconnection between recognition and production. Third, since reading is worse for abstract words than for concrete words, there must also be an impairment of the Semantic System that is worse for abstract than for concrete words. Fourth, the Semantic System must be impaired in such a way that semantic errors occur e. g. that "parrot" and "canary" are not successfully distinguished in the semantic system. Fifth, since sometimes the deep dyslexic will correctly understand a printed word but make a semantic error in reading it aloud, the connection between the Semantic System and the Phonological Output Lexicon must be damaged in such a way that a correct semantic representation yields an incorrect (semantically related) reading response. Sixthly, there must be damage to whatever the syntactic system is that is used for processing prefixes and suffixes, to account for morphological errors in reading affixed words.

Deep dyslexia as left-hemisphere reading n The argument is that if the model has these 6 kinds of damage its reading will exhibit all the symptoms of deep dyslexia. A problem with this argument is that if these are really six different ways in which the reading system can be damaged, then one would expect to see patients with forms of acquired dyslexia that represent subsets from this set of six forms of damage. For example, there would be no reason why someone should not just have the first five impairments: that would mean we should see cases of acquired dyslexia where there are semantic errors but no morphological errors; similarly. when all but the third form of damage is present, we would see semantic errors but no advantage for concrete words. Patterns like these have never been observed. For that, and other, reasons an alternative theoretical account of deep dyslexia was proposed by Coltheart(1980, 1987) and Saffran, Bogyo, Schwartz and Marin (1980, 1987). They proposed that deep dyslexia was unique amongst the acquired dyslexias in that these patients are not reading with a damaged version of the normal reading system which is in the left hemisphere. Instead, they cannot use the left hemisphere at all for reading. Their reading is carried out by a separate reading system, located in the right hemisphere.

Deep dyslexia as right-hemisphere reading. n n Coltheart (1980 b, 1987 b) and Saffran, Bogyo, Schwartz and Marin(1980, 1987) supported their arguments that reading in deep dyslexia was carried out by a right-hemisphere reading system by pointing out a number of resemblances between deep dyslexic reading and what was then known about language in the right hemisphere: there was evidence, from split-brain patients, of poor syntax in the right hemisphere (which would impair processing of function words and affixes), and there was evidence from experiments with lateralized presentation of words to intact subjects of a concrete word superiority with right-hemisphere (left visual field)presentation. There was also Gott's report of a young girl who had learned to read but then had a left-hemispherectomy, after which semantic errors appeared in her reading aloud of single words. However, there was much that was inadequate about this evidence. For example, the well-studied split-brain patients all had bilateral brain damage from birth, so one cannot safely generalize from their hemispheres to the hemispheres of people who had intact brains in adulthood prior to the damage that caused deep dyslexia. Similarly, Gott's patient exhibited an encephalopathy at an age earlier than that at which language lateralization would have been complete, so she too is not a completely satisfactory source of evidence. More recently, however, two much more satisfactory pieces of evidence have emerged.

Deep dyslexia as right-hemisphere reading n n n n Patterson, Vargha-Khadem and Polkey (1987) report a study of a person who first exhibited signs of a left-hemisphere abnormality at 13 and had a left hemispherectomy at age 15. Given her age, it is likely that language development in the two hemispheres would have reached maturity. Prior to the onset of her left-hemisphere symptoms she was a normal reader for her age. After hemispherectomy she displayed all the major symptoms of deep dyslexia: * Semantic errors (arm -> "finger", pigeon -> "cockatoo") * Visual errors (bush -> "brush", frost -> "forest") * Morphological errors (duck -> ducks", smoke -> "smoking") * Very poor reading of function words * Nonword reading impossible. Michel, Henaff and Intrilligator (1996) report the case of a 23 -year-old man who as a result of neurosurgery was left with a lesion of the posterior half of the corpus callosum. He was able to resume his college studies in accountancy after recovering from surgery. Michel et al studied his reading by briefly presenting words to the left hemisphere (i. e. in the right visual hemifield) or the right hemisphere (left visual hemifield), with these results: n * Right visual hemifield: Words were read rapidly, and with 100% accuracy. Judgement of whether two words rhymed or not was 94% accurate. * Left visual hemifield: o Numerous semantic errors such as bijou -> "perle", poulet -> "garlic". o Concrete words read better than abstract words. o Function words poorly read. o Nonword reading virtually impossible. o At chance on judging whether two words rhymed. n These two studies would seem to provide conclusive evidence for the right-hemisphere interpretation of deep dyslexia. n n n

Treatment In deep dyslexia, the brain damage is extensive, the reading impairment is severe, and the patient is aphasic as well as dyslexic. Nevertheless, the condition responds to appropriate and intensive treatment; this has been demonstrated by de Partz (1986).

References n Coltheart, M. (1980 a, 1987 a). Deep dyslexia: A review of the syndrome. In Deep Dyslexia. op cit. n Coltheart, M. (1980 b, 1987 b) Deep dyslexia: A right-hemisphere hypothesis. In Deep Dyslexia. op. cit. n n n Coltheart, M. , Patterson, K. and Marshall, J. C. (Eds): Deep Dyslexia. London: Routledge and Kegan Paul, 1980 (Second Edition 1987). De Partz, M. P. (1986) Re-education of a deep dyslexic patient: Rationale of the method and results. Cognitive Neuropsychology, 3, 149 -177. Marshall, J. C. and Newcombe, F. (1966) Syntactic and semantic error sin paralexia. Neuropsychologia, 4, 169 -176. Marshall, J. C. and Newcombe, F (1973) Patterns of paralexia: A psycholinguistic approach. Journal of Psycholinguistic Research, 2, 175 -199. Michel, F. , Henaff, M. A. and Intriligator, J. (1996) Two different readers in the same brain after a posterior callosal lesion. Neuro. Report, 7, 786 -788. n Morton, J. and Patterson, K. (1980, 1987) In Deep Dyslexia. Op cit. n Patterson, K. , Vargha-Khadem, F. and Polkey, C. (1987) Reading with one hemisphere. Brain, 112, 39 -63. n n n Saffran, E. , Bogyo, L. C. Schwartz, M. F. and Marin, O. S. M. (1980, 1987). Does deep dyslexia reflect right-hemisphere reading? In Deep Dyslexia, Op. cit. Shallice, T. and Warrington, E. K. (1975) Word recognition in a phonemic dyslexic patient. Quarterly Journal of Experimental Psychology, 27, 187 -199. Weekes, B. , Coltheart, M. and Gordon, E. Deep dyslexia and right-hemisphere reading - A regional cerebral blood flow study. Aphasiology, 1997, 1139 -1158.

Introduction n Surface dyslexia was first described by Marshall and Newcombe (1973), and subsequently by Shallice, Warrington and Mc. Carthy (1983). An entire book on surface dyslexia was published in 1985 (Patterson, Marshall and Coltheart, 1985), and a number of other studies of surface dyslexia have appeared since then. Surface dyslexia also occurs as a form of developmental dyslexia i. e. as a specific pattern of difficulty in learning to read, in children without any sign of neurological abnormality.

The symptoms of surface dyslexia n n n About three-quarters of the words of English are regular words. This term refers to words which obey the standard spelling-to-sound rules of English: words like new, jetty or howl. The remaining 25% or so of words are irregular words, also referred to as exception words; such words contain at least one violation of English spelling-to-sound words. Examples are sew, pretty and bowl. The defining symptoms of surface dyslexia are: * Exception words are less often read correctly than regular words matched to the exception words on word frequency, number of letters, etc. ; * When an exception word is misread, the error is generally a regularization error i. e. the pronunciation given is the one specified by the rules. For example, pretty is read as if it rhymed with "jetty", and bowl is read as if it rhymed with "howl".

Parole regolari • 1 • 2 • 3 • 4 • 5 • 6 • 7 • 8 • 9 • 10 • 11 • 12 • 13 • 14 • 15 • 16 • 17 • 18 • 19 • 20 • 21 • 22 • 23 • 24 • 25 • 26 • 27 • 28 • 29 • 30 take free market effort plant middle check drop luck navy chicken context weddind smog tail victor weasel mist infest curb nerve pump peril radish brandy stench ditty marsh flannel cord frequenza 611 260 155 145 125 118 88 59 47 37 37 35 32 1 24 23 1 14 1 13 12 11 8 8 7 1 1 4 4 6 irregolari come sure island answer blood pretty break lose soul iron colonel routine ceiling quay bowl regime meringue shoe indict pint gauge tomb choir debris cough brooch beret yacht bouquet wolf frequenza 630 264 167 152 121 107 88 58 47 43 37 35 31 0 23 23 0 14 0 13 12 11 8 8 7 0 0 4 4 6

Non-Parole • 1 • 2 • 3 • 4 • 5 • 6 • 7 • 8 • 9 • 10 • 11 • 12 • 13 • 14 • 15 gop teg nad lif sut stet mulp prin nint gren thim chut sith phot giph • 16 • 17 • 18 • 19 • 20 • 21 • 22 • 23 • 24 • 25 • 26 • 27 • 28 • 29 • 30 hoil toud gead doil roin gurdet torlep tadlen latsar polmex tashet sothep miphic lishon dethix

ail - ale air - err aisle - I'll all - awl ate - eight bail - bale bait - bate ball - bawl balm - bomb band - banned bard - barred baron - barren base - bass bask - Basque be - bee beach - beech bear - bare beat - beet beer - bier bird - burred birr - burr blew - blue bloc - block board - bored bold - bowled boor - bore boos - booze born - bourne bough - bow brake - break bread - bred broach - brooch broom - brume grate - great groan - grown guessed - guest hail - hale hair - hare hay - hey heal - heel - he'll hear - here heard - herd hi - high him - hymn hoarse - horse hole - whole hour - our I - eye browse - brows brut - brute but - butt buy - bye Cain - cane capital - capitol cast - caste cede - seed ceiling - sealing cell - sell cellar - seller chard - charred sew - so shear - sheer shoe - shoo sighs - size sight - site - cite sign - sine slow - sloe cheap - cheep check - Czech chews - choose chilli - chilly coarse - course collard - collared cored - cord creak - creek cue - queue curd - Kurd dam - damn dane - deign days - daze dear - deer die - dye doe - dough done - dun Ernest - earnest ewe - yew - you faint - feint fair - fare feat - feet file - phial find - fined flea-flee flew - flue - flu flour - flower foul - fowl four - fore frays - phrase frees-freeze-frieze gait - gate gilt - guilt gored - gourd in - inn knap - nap knave - nave knead - need knew - new knot - not know - no knows - nose leak - leek led - lead liar - lyre lie - lye light - lite links - lynx loan - lone maid-made mail - male main - mane maize - maze mall - maul manner - manor mews - muse might - mite moor - more morning - mourning mote - moat muscle - mussel nay - neigh night - knight none - nun one - won or - ore pail - pale pain - pane

Homophones: spelling fun Is it "deer" or "dear"? Speaking of which or witch? A dog has a tail. A story's a tale. The postman brings the mail. , A boy's a male. A knight wears shining armour, at night we sleep (and speaking of wears, wares are also the goods sold in shops and … Where are you going? ) I have some chocolate. I make the sum of three plus three. You say "bye" to your friends after school. You buy a loaf of bread. We go by the pharmacy on our way downtown. I carry a pail of water. Mary is as pale as a ghost. The police go to the site of a crime. Teachers often cite the words of Shakespeare. We're in sight of the Statue of Liberty.

The theoretical interpretation of surface dyslexia n Because the nonlexical route reads by applying letter-sound rules, it will misread words that don't obey those rules; indeed, it will produce regularization errors with such words. Therefore, according to the model, correct reading aloud of exception words depends upon the lexical reading route. Hence damage to the lexical route will result in surface dyslexia: nonwords (and regular words) will still be read correctly, but exception words will often result in regularization errors.

n Since the lexical route has a number of different components, there a number of different ways in which it can be damaged so as to produce surface dyslexia, and so any two patients with surface dyslexia may have quite different patterns of damage in the lexical route. Two examples of such damage are (a) damage to entries in the Orthographic Input Lexicon and (b) damage to entries in the Phonological Output Lexicon. If the word pretty has been lost from the Orthographic Input Lexicon, it won't be recognized lexically, so will be read nonlexically and so will be regularized. If it has been lost from the Phonological Output Lexicon, it will be recognized when it is seen, but its pronunciation won't be retrieved from the Phonological Output Lexicon, so will have to be generated nonlexically - so again a regularization error will occur.

n In some of the early studies of surface dyslexia, the disorder was not pure, in the sense that reading by the nonlexical route was not completely intact. Doubts were therefore raised about the interpretation of surface dyslexia in terms of a model with separate lexical and nonlexical pathways. However, pure cases were eventually discovered: MP (Bub, Cancelliere and Kertesz, 1985) and KT (Mc. Carthy and Warrington, 1986). Both of these patients were poor at reading exception words, especially when these were of low frequency, and virtually all of their errors were regularization errors; critically, the accuracy and even the speed of their reading of nonwords was within normal limits. So they represent two pure cases.

n Both of these patients had semantic impairments. KT's was a progressive semantic deterioration. In other patients with "semantic dementia" (progressive loss of semantic knowledge due to progressive atrophy of temporal lobes), surface dyslexia is also often seen (which is why the NART can be inappropriate as a test for estimating premorbid intelligence). In these cases, the surface dyslexia is presumed to be due to an impairment of entries in, or access to, the Phonological Output Lexicon that accompanies the semantic impairment (so, as suggested in discussions in PSYP 811, a lexical decision task such as Baddeley's "Spot the Word" test, with low frequency words, might be better than the NART for estimating premorbid intelligence).

Developmental surface dyslexia n Holmes (1973), Coltheart, Byng, Masterson, Prior and Riddoch (1983) and Temple and Marshall(1983) have described cases of developmental surface dyslexia, and Castles and Coltheart (1994) have shown that this form of developmental dyslexia is not uncommon. These are children who have no trouble with the phonic side of reading and quickly learn to sound out words by letter-sound rules; their particular problem in learning to read is in developing a big enough sight vocabulary. They recognize by sight many fewer words than other children their age who are making normal progress in learning to read. Hence many exception words which the normal children can read aloud correctly will be regularized by the developmental surface dyslexic.

Surface dyslexia n Surface dyslexia: if brain damage has deleted words from the visual word recognition system, the reading aloud will have to rely on letter-to-sound rules. In that case, regular words will still be read correctly but irregular words won't.

Word visual analysis parser word detectors (input logogens) semantic system Phonological word representations (output logogens) response buffer “Word” translator retranslate blender

pint p int analisi 1. deaf 2. deaf d d /pint/ /p/ /int/ decodifica eaf ea f assemblaggio “nessuna traduzione” /d/ /i/ /f/ riparsing /dif/ “nessuna parola” --> retranslate (lexical check) 3. deaf d ea f /d/ /e/ /f/ /def/

Treatment n Both acquired and developmental surface dyslexia have been successfully treated, in small-scale single-case studies, by a mnemonic technique aimed at restoring or introducing whole words to the Orthographic Input Lexicon (see Byng and Coltheart, (1986), Coltheart and Byng (1989) and Weekes and Coltheart (1996) for work on the treatment of acquired surface dyslexia).

References n Byng, S. , and Coltheart, M. (1986) Aphasia therapy research: methodological requirements and illustrative results. In Nilsson, I. G. , and Hjelmquist, E. (Eds. ), Communication and Handicap: Aspects of Psychological Compensation and Technical Aids. Amsterdam: North-Holland Publishing. n Castles, A. and Coltheart, M. Varieties of developmental dyslexia. Cognition, 1993, 47, 149 -180. n Coltheart, M. Varieties of developmental dyslexia. Cognition, 1987, 27, 97 -101. n n n n Coltheart, M. and Byng, S. (1989) A treatment for surface dyslexia. In Seron, X. (Ed. ). Cognitive Approaches in Neuropsychological Rehabilitation. London: Lawrence Erlbaum Associates Ltd. Coltheart, M. , Byng, S. , Masterson, J. , Prior, M. , and Riddoch, M. J. Surface dyslexia. Quarterly Journal of Experimental Psychology, 1983, 35 A, 469 -495. Holmes , J. M. (1973) Dyslexia: A neurolinguistic study of traumatic and developmental dyslexia. Unpublished Ph. D. thesis, University of Edinburgh. Marshall, J. C. and Newcombe, F. (1973) Patterns of paralexia: A psycholinguistic approach. Journal of Psycholinguistic Research, 2, 175 -199. Patterson, K. , Marshall, J. C. and Coltheart, M. (Eds): Surface Dyslexia: Cognitive and Neuropsychological Studies of Phonological Reading. London: Lawrence Erlbaum Associates, 1985 Temple, C. M. and Marshall, J. C. (1983) A case study of developmental phonological dyslexia. British Journal of Psychology, 74, 517 -533. Weekes, B. , and Coltheart, M. (1996) Surface dyslexia and surface dysgraphia: Treatment studies and their theoretical implications. Cognitive Neurospychology, 13, 277 - 315