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There are three proposed cognitive subtypes of dyslexia: auditory, visual and attentional. Although dyslexia is not an intellectual disability, it is considered both a learning disability and a reading disability. Dyslexia and IQ are not interrelated, since reading and cognition develop independently in individuals who have dyslexia.
There are many definitions of dyslexia but no official consensus has been reached.
The World Federation of Neurology defines dyslexia as "a disorder manifested by difficulty in learning to read despite conventional instruction, adequate intelligence and sociocultural opportunity".
MedlinePlus and the National Institutes of Health define dyslexia as "a reading disability resulting from the inability to process graphic symbols".
The National Institute of Neurological Disorders and Stroke gives the following definition for dyslexia:
"Dyslexia is a brain-based type of learning disability that specifically impairs a person's ability to read. These individuals typically read at levels significantly lower than expected despite having normal intelligence. Although the disorder varies from person to person, common characteristics among people with dyslexia are difficulty with spelling, phonological processing (the manipulation of sounds), and/or rapid visual-verbal responding. In adults, dyslexia usually occurs after a brain injury or in the context of dementia. It can also be inherited in some families, and recent studies have identified a number of genes that may predispose an individual to developing dyslexia".Castles and Coltheart describe phonological and surface types of developmental dyslexia by analogy to classical subtypes of alexia (acquired dyslexia) which are classified according to the rate of errors in reading non-words. However, the distinction between surface and phonological dyslexia has not replaced the old empirical terminology of dysphonetic versus dyseidetic types of dyslexia. The surface/phonological distinction is only descriptive, and devoid of any aetiological assumption as to the underlying brain mechanisms (Galaburda and Cestnick 2003). Studies have, however, alluded to potential differential underlying brain mechanisms in these populations given performance differences (Cestnick et al.) . The dysphonetic/dyseidetic distinction refers to two different mechanisms; one that relates to a speech discrimination deficit, and another that relates to a visual perception impairment.
Signs and symptoms
The symptoms of dyslexia vary according to the severity of the disorder as well as the age of the individual.
Preschool-aged children
It is difficult to obtain a certain diagnosis of dyslexia before a child begins school, but many dyslexic individuals have a history of difficulties that began well before kindergarten. Children who exhibit these symptoms early in life have a higher likelihood of being diagnosed as dyslexic than other children. These symptoms include: delays in speechslow learning of new words not crawlingdifficulty in rhyming words, as in nursery rhymes low letter knowledge letter reversal or mirror writing (for example, "Я" instead of "R")
Early primary school children
Difficulty learning the alphabet or letters order Difficulty with associating sounds with the letters that represent them (sound-symbol correspondence) Difficulty identifying or generating rhyming words, or counting syllables in words (phonological awareness) Difficulty segmenting words into individual sounds, or blending sounds to make words (phonemic awareness) Difficulty with word retrieval or naming problemsDifficulty learning to decode written words Difficulty distinguishing between similar sounds in words; mixing up sounds in polysyllabic words (auditory discrimination) (for example, "aminal" for animal, "bisghetti" for spaghetti)
Older primary school children
Slow or inaccurate reading (although these individuals can read to an extent). Very poor spelling which has been called dysorthographia (orthographic coding)Difficulty reading out loud, reading words in the wrong order, skipping words and sometimes saying a word similar to another word (auditory processing disorder) Difficulty associating individual words with their correct meanings Difficulty with time keeping and concept of time when doing a certain task Difficulty with organization skills (working memory) Children with dyslexia may fail to see (and occasionally to hear) similarities and differences in letters and words, may not recognize the spacing that organizes letters into separate words, and may be unable to sound out the pronunciation of an unfamiliar word (auditory processing disorder).
Secondary school children and adults
Some people with dyslexia are able to disguise their weaknesses (even from themselves) and often do acceptably well — or better — at GCSE level (U.K. - at 16 years old). Many students reach higher education before they encounter the threshold at which they are no longer able to compensate for their learning weaknesses.One common misconception about dyslexia is that dyslexic readers write words backwards or move letters around when reading. In fact, this only occurs in a very small population of dyslexic readers. Dyslexic people are better identified by writing that does not seem to match their level of intelligence from prior observations. Additionally, dyslexic people often substitute similar-looking, but unrelated, words in place of the ones intended (what/want, say/saw, help/held, run/fun, fell/fall, to/too, etc.).
Comorbidities
Several learning disabilities often occur with dyslexia, but it is unclear whether these learning disabilities share underlying neurological causes with dyslexia. These disabilities include, but are not limited to: Cluttering— a speech fluency disorder involving both the rate and rhythm of speech, resulting in impaired speech intelligibility. Speech is erratic and nonrhythmic, consisting of rapid and jerky spurts that usually involve faulty phrasing. The personality of people with cluttering bears striking resemblance to the personalities of those with learning disabilities.Dysgraphia— a disorder which expresses itself primarily through writing or typing, although in some cases it may also affect eye–hand coordination direction or sequence oriented processes such as tying knots or carrying out a repetitive task. Dysgraphia is distinct from dyspraxia in that the person may have the word to be written or the proper order of steps in mind clearly, but carries the sequence out in the wrong order. Dyscalculia— a neurological condition characterized by a problem with learning fundamentals and one or more of the basic numerical skills. Often people with this condition can understand very complex mathematical concepts and principles but have difficulty processing formulas or even basic addition and subtraction.
Cause
The following theories should not be viewed as competing, but viewed as theories trying to explain the underlying causes of a similar set of symptoms from a variety of research perspectives and background.;Cerebellar theory The Cerebellar Theory asserts that a mildly dysfunctional cerebellum can cause dyslexia. The cerebellum contributes to motor control during the articulation of speech, and the Cerebellar Theory proposes that articulation problems can contribute to the phonological processing deficits that can cause dyslexia. The Cerebellum also contributes to the automatisation of learnt behaviors, which includes learning the grapheme–phoneme relationships when reading text.
;Evolutionary hypothesis This theory considers that reading is an unnatural act carried out by humans for an exceedingly brief period in our evolutionary history. It has been less than a hundred years that western societies promoted reading to the mass population and therefore the forces that shape our reading behavior have been weak. Many areas of the world still do not even have access to reading for the majority of the population.
;Magnocellular theory The Magnocellular theory attempts to unify the Cerebellar Theory, the Phonological Theory, the Rapid Auditory Processing Theory, and the Visual Theory. The Magnocellular theory proposes that the magnocellular dysfunction is not only restricted to the visual pathways but also includes auditory and tactile modalities.
;Naming speed deficit and double deficit theories The speed with which an individual can engage in the rapid automatized naming of familiar objects or letters is a strong predictor of dyslexia. Slow naming speed can be identified as early as kindergarten and persists in adults with dyslexia.
A deficit in naming speed is hypothesized to represent a deficit that is separate from phonological processing deficit. Wolf identified four types of readers: readers with no deficits, readers with phonological processing deficit, readers with naming speed deficit, and readers with double deficit (that is, problems both with phonological processing and naming speed). Students with double deficits are most likely to have some sort of severe reading impairment.
Distinguishing among these deficits has important implications for instructional intervention. If students with double deficits receive instruction only in phonological processing, they are only receiving part of what they need.
;Perceptual visual-noise exclusion hypothesis The concept of a perceptual noise exclusion deficit (impaired filtering of behaviorally irrelevant visual information in dyslexia or visual-noise) is an emerging hypothesis, supported by research showing that subjects with dyslexia experience difficulty in performing visual tasks (such as motion detection in the presence of perceptual distractions) but do not show the same impairment when the distracting factors are removed in an experimental setting. The researchers have analogized their findings concerning visual discrimination tasks to findings in other research related to auditory discrimination tasks. They assert that dyslexic symptoms arise because of an impaired ability to filter out both visual and auditory distractions, and to categorize information so as to distinguish the important sensory data from the irrelevant.
;Phonological deficit theory The phonological deficit theory proposes that people with dyslexia have a specific sound manipulation impairment, which affects their auditory memory, word recall, and sound association skills when processing speech. The phonological theory explains a reading impairment when using an alphabetic writing system which requires learning the grapheme/phoneme correspondence, the relationship between the graphic letter symbols and speech sounds which they represent.
;Visual theory The visual theory represents a traditional perspective of dyslexia, as being the result of a visual impairment creating problems when processing information from letters and words from a written text. This includes visual processing problems such as binocular, poor vergence, and visual crowding. The Visual Theory does not deny the possibility of alternative causes of dyslexia Logographic writing systems, notably Japanese and Chinese characters, have a purer direct relationship between the sound of a word and the representative visual symbols, which pose a different type of dyslexic difficulty. A disorder that occurs in between 12% and 24% of those with dyslexia. It can lead to problems with auditory memory and auditory sequencing. Many people with dyslexia have auditory processing problems including history of auditory reversals, and may develop their own logographic cues to compensate for this type of deficit. Auditory processing disorder is recognized as one of the major causes of dyslexia. Some children can acquire auditory processing disorder as a result of experiencing otitis media with effusion (glue ear, sticky ear, grommets) and other severe ear conditions. Developmental dyspraxia - Specific language impairment (SLI) - A developmental language disorder that can affect both expressive and receptive language. SLI is defined as a "pure" language impairment, meaning that is not related to or caused by other developmental disorders, hearing loss or acquired brain injury. A study by the Universities of Maastricht and Utrecht examined speech perception and speech production in 3-year-old Dutch children at familial risk of developing dyslexia. Their performance in speech sound categorization and their production of words was compared to that of age-matched children with SLI and typically developing controls. The results of the at-risk and SLI-group were highly similar. Analysis of the individual data revealed that both groups contained subgroups with good and poorly performing children. Their impaired expressive phonology seemed to be related to a deficit in speech perception. The findings indicate that both dyslexia and SLI can be explained by a multi-risk model which includes cognitive processes as well as genetic factors.
Experience of speech acquisition delays and speech and language problems can be due to problems processing and decoding auditory input prior to reproducing their own version of speech, and may be observed as stuttering, cluttering or hesitant speech.
History
Identified by Oswald Berkhan in 1881, the term 'dyslexia' was later coined in 1887 by Rudolf Berlin, an ophthalmologist practising in Stuttgart, Germany, from the Greek prefix δυσ- (dus-), "hard, bad, difficult" + λέξις (lexis), "speech, word". In 1896, W. Pringle Morgan published a description of a reading-specific learning disorder in the British Medical Journal titled "Congenital Word Blindness". During the 1890s and early 1900s, James Hinshelwood published a series of articles in medical journals describing similar cases of congenital word blindness. In his 1917 book Congenital Word Blindness, Hinshelwood asserted that the primary disability was in visual memory for words and letters, and described symptoms including letter reversals, and difficulties with spelling and reading comprehension. 1925 Samuel T. Orton determined that there was a syndrome unrelated to brain damage that made learning to read difficult. Orton's theory strephosymbolia described individuals with dyslexia having difficulty associating the visual forms of words with their spoken forms. Orton observed that reading deficits in dyslexia did not seem to stem from strictly visual deficits. He believed the condition was caused by the failure to establish hemispheric dominance in the brain. Orton later worked with the psychologist and educator Anna Gillingham to develop an educational intervention that pioneered the use of simultaneous multisensory instruction.
In contrast, Dearborn, Gates, Bennet and Blau considered a faulty guidance of the seeing mechanism to be the cause. They sought to discover if a conflict between spontaneous orientation of the scanning action of the eyes from right to left and training aimed at the acquisition of an opposite direction would allow an interpretation of the facts observed in the dyslexic disorder and especially of the ability to mirror-read. 1949 Research conducted under G. Mahec show that the phenomenon is clearly linked to the dynamics of sight as it disappears when the space between letters is increased, transforming the reading into spelling. This experience also explains the ability to mirror-read. 1968 Makita suggested that dyslexia was mostly absent among Japanese children. A 2005 study shows that Makita's claim of rarity of incidence of reading disabilities in Japan to be incorrect. In the 1970s a new hypothesis emerged: that dyslexia stems from a deficit in phonological processing or difficulty in recognizing that spoken words are formed by discrete phonemes. Affected individuals have difficulty associating these sounds with the visual letters that make up written words. Key studies suggested the importance of phonological awareness, 1979 Galaburda and Kemper, and Galaburda et al. 1985, reported observations from the examination of post autopsy brains of people with dyslexia. Their studies reporting observed anatomical differences in the language center in a dyslexic brain, taken with the similar work of Cohen et al. 1989, suggested abnormal cortical development, which was presumed to occur before or during the sixth month of foetal brain development. Cestnick and Coltheart (1999) demonstrated what these underlying deficits are in part, through unveiling different profiles of phonological versus surface dyslexics. Cestnick and Jerger (2000) and Cestnick (2001) further demonstrated distinct processing differences between phonological and surface dyslexics. 1994 From post autopsy specimens Galaburda et al., reported : Abnormal auditory processing in people with dyslexia suggests that accompanying anatomical abnormalities might be present in the auditory system. Supported the reported behavioral findings of a left hemisphere-based phonological defect in dyslexic individuals. The development of neuroimaging technologies during the 1980s and 1990s enabled dyslexia research to make significant advances. Positron emission tomography (PET) and functional magnetic resonance imaging (fMRI) studies have revealed the neural signature of adult normal reading (e.g. Fiez and Petersen, 1998; Turkeltaub et al., 2002 and phonological processing (e.g., Gelfand and Bookheimer, 2003; Poldrack et al., 1999). Employing various experimental approaches and paradigms (e.g., the detection or judgment of rhymes, nonword reading, and implicit reading), these studies have localized dysfunctional phonological processing in dyslexia to left-hemisphere perisylvian regions, especially for the alphabetic writing system (Paulesu et al., 2001; for review, see Eden and Zeffiro, 1998,). However, it has been demonstrated that in nonalphabetic scripts, where reading places less demands on phonemic processing and the integration of visual-orthographic information is crucial, dyslexia is associated with under activity of the left middle frontal gyrus (Siok et al., 2004). 1999 Wydell and Butterworth reported the case study of an English-Japanese bilingual with monolingual dyslexia. Suggesting that any language where orthography-to-phonology mapping is transparent, or even opaque, or any language whose orthographic unit representing sound is coarse (i.e. at a whole character or word level) should not produce a high incidence of developmental phonological dyslexia, and that orthography can influence dyslexic symptoms. 2003 Ziegler and colleagues claimed that the dyslexia suffered by German or Italian dyslexics is very similar to the one suffered by English dyslexics (readers of different—shallow versus deep orthographic systems), supporting the idea that the origin of dyslexia is mostly biological. 2007 Lyytinen et al. Researchers are seeking a link between the neurological and genetic findings, and the reading disorder. 2008 S Heim et al. in a paper titled "Cognitive subtypes of dyslexia" describe how they compared different sub-groups of dyslexics in comparison with a control group. This is one of the first studies not to just compare dyslexics with a non dyslexic control, but to go further and compared the different cognitive sub groups with a non dyslexic control group.
Neuroimaging
Modern neuroimaging techniques such as functional magnetic resonance imaging (fMRI) and positron emission tomography (PET) have produced clear evidence of structural differences in the brains of children with reading difficulties. It has been found that people with dyslexia have a deficit in parts of the left hemisphere of the brain involved in reading, which includes the inferior frontal gyrus, inferior parietal lobule, and middle and ventral temporal cortex.
That dyslexia is neurobiological in origin is supported by what Lyon et al. proclaimed as "overwhelming and converging data from functional brain imaging investigations" (2003, p. 3). The results of these studies suggest that there are observable differences in how the dyslexic brain functions when compared to the brain of a typical reader. Using fMRI, Shaywitz found that good readers show a consistent pattern of strong activation in the back of the brain with weaker activation in the front of the brain during reading tasks. In contrast, the brain activation pattern in dyslexics is the opposite during reading tasks—the frontal part of the brain becomes overactive with weaker activation in the back. Shaywitz points out "It is as if these struggling readers are using the systems in the front of the brain to try to compensate for the disruption in the back of the brain."
Brain activation studies using PET to study language have produced a breakthrough in understanding of the neural basis of language over the past decade. A neural basis for the visual lexicon and for auditory verbal short term memory components have been proposed, with some implication that the observed neural manifestation of developmental dyslexia is task-specific (i.e., functional rather than structural).
A University of Hong Kong study argues that dyslexia affects different structural parts of children's brains depending on the language which the children read.
A University of Maastricht (Netherlands) study revealed that adult dyslexic readers underactivate superior temporal cortex for the integration of letters and speech sounds.
Genetic
Molecular studies have linked several forms of dyslexia to genetic markers for dyslexia. Several candidate genes have been identified, including at the two regions first related to dyslexia: DCDC2 and KIAA0319 on chromosome 6, and DYX1C1 on chromosome 15.
A unifying theoretical framework of three working memory components provides a systems perspective for discussing past and new findings in a 12-year research program that point to heterogeneity in the genetic and brain basis and behavioral expression of dyslexia.
Controversy
In recent years there has been significant debate on the categorization of dyslexia. In particular, Elliot and Gibbs argue that "attempts to distinguish between categories of 'dyslexia' and 'poor reader' or 'reading disabled' are scientifically unsupportable, arbitrary and thus potentially discriminatory".While acknowledging that reading disability is a valid scientific curiosity, and that "seeking greater understanding of the relationship between visual symbols and spoken language is crucial" and that while there was "potential of genetics and neuroscience for guiding assessment and educational practice at some stage in the future", they conclude that "there is a mistaken belief that current knowledge in these fields is sufficient to justify a category of dyslexia as a subset of those who encounter reading difficulties".
See also
Child development History of the alphabet Learning theory (education) Linguistics List of people diagnosed with dyslexia Neurolinguistics Philosophy of language Writing system
References
External links
Etymology for dyslexia Cortexit Text Dispersant: Chrome Browser plugin assisting Dyslexia ;Research papers, articles and media
Auditory and Visual Dynamic Processing: Separate Influences in Reading? by Caroline Witton, Joel B. Talcott, Peter C. Hansen, Catherine J. Stoodley & John F. Stein Evaluating Alternative Solutions for Dyslexia by Professor Dorothy Bishop ;Organizations
International Dyslexia Association British Dyslexics Charity Dyslexia Action (UK) British Dyslexia Association European Dyslexia Association Dyslexia Research Trust
Category:Developmental dyslexia Category:Dyslexia Category:Neurology Category:Educational psychology Category:Human skills Category:Disability Category:Learning disabilities Category:Literacy Category:Reading Category:Special education Category:Writing Category:Greek loanwords
This text is licensed under the Creative Commons CC-BY-SA License. This text was originally published on Wikipedia and was developed by the Wikipedia community.
Name | Paul Westerberg |
---|---|
Background | solo_singer |
Birth name | Paul Westerberg |
Born | December 31, 1959 |
Origin | Minnesota, United States |
Instrument | Guitar, vocals, bass guitar, piano, drums |
Genre | Alternative rock |
Years active | 1979–present |
Label | Sire RecordsReprise RecordsVagrant RecordsFat Possum Records |
Associated acts | The Replacements |
The Replacements quickly made a name for themselves in the Twin Cities punk scene, largely thanks to Westerberg's songwriting. The band made several critically acclaimed albums for local label Twin/Tone before signing to Sire Records in 1985. Despite the jump to Sire, the Replacements never translated their critical success into commercial sales.
By 1990, the band had run its course. The 1990 Replacements album All Shook Down was for all intents and purposes a Westerberg solo project. There are numerous guest performers and the other three members of the band (including Slim Dunlap, who had replaced Bob Stinson three years earlier to tour in support of Pleased to Meet Me) made minimal contributions. Mars left the band during this project. After touring for the album (which was critically well-received) with replacement Replacements, Tommy and Paul went their separate ways.
Westerberg co-wrote the song "Backlash" with Joan Jett for her 1991 album Notorious, and played guitar with her on a video of the song. He also recorded a duet with Jett ("Let's Do It") for the Tank Girl soundtrack (1994).
1996 heralded his second solo album, the appropriately titled Eventually, which was tepidly received by critics and had modest sales. It did yield the alternative radio hit, "Love Untold". Westerberg parted ways with Reprise records and the following year chose to release songs that were more blues influenced and less slickly produced under the name Grandpaboy. An EP and single were released by indie label Soundproof/Monolyth Records. His third album Suicaine Gratifaction is a piano-driven, melancholy, and highly personal work. The album was released on Capitol Records in 1999. The label was undergoing reorganization, and failed to push the album. Westerberg appeared on a fifth season episode of The Larry Sanders Show (entitled "Larry's New Love") performing "Ain't Got Me" from Eventually. The episode first aired Wednesday, February 26, 1997. Westerberg also performed the song that same year on The Tonight Show hosted by Jay Leno.
Westerberg then quit the major label circuit and disappeared for three years before staging a major comeback in 2002. With new management and a new independent label, Vagrant Records, he released two records simultaneously, Stereo and Mono (Mono being released under his alter ego Grandpaboy). Stereo and Mono were recorded in Westerberg's basement studio. They were acclaimed as his best works since the Replacements, and Westerberg became increasingly prolific, releasing Dead Man Shake (as Grandpaboy), Come Feel Me Tremble, and Folker all within the next two years to critical success.
Westerberg contributed a cover of The Beatles' "Nowhere Man" for the 2002 soundtrack to the 2001 film I Am Sam. Additionally, "Lookin' Up in Heaven" appears on the Starbucks sampler Hear Music, Vol. 10: Reveal, "Outta My System" can be found on Hot Stove, Cool Music, Vol. 1, and the Vagrant Records sampler Another Year on the Streets, Vol. 3 features "As Far As I Know." All three compilations were released in 2004.
In December 2005, Westerberg reconvened with Tommy Stinson and Chris Mars to record two new songs for a compilation titled Don't You Know Who I Think I Was? - The Best of the Replacements, which was released in 2006.
In 2006, Westerberg took on the challenge of writing a collection of songs for the animated film Open Season. In all, the soundtrack includes eight new Westerberg originals. It is unique in that two of the songs were covered by other artists. The track "Wild As I Wanna Be" is performed by Deathray, whereas Pete Yorn performs "I Belong (Reprise)." In addition, Tommy Stinson is featured playing bass on the songs "Love You In The Fall" and "Right To Arm Bears." The soundtrack also includes the song "Good Day" from Westerberg's solo album Eventually. The album is rounded out by two non-Westerberg originals, Deathray's own "I Wanna Lose Control (Uh Oh)" and the Talking Heads' 1986 hit "Wild Wild Life."
Seen on stage playing a First Act production model guitar, Westerberg joined creative forces with the Boston based guitar manufacturer to create his signature edition PW580 in September 2006. Built with a red plaid pickguard, the guitar was designed to be "mean and lean".
On July 17, 2008 it was announced that on "June 49" (July 19) Paul Westerberg would release an album with 49 minutes' worth of music for 49 cents. The album, , was released on July 21, 2008. A few weeks after 49:00 was released, it was taken down from Amazon.com and TuneCore store. In its place, Westerberg released a song titled "5:05" (in reference to the fact that 49:00 was really 43:55 long, 5:05 shorter than 49:00). From the lyrical content of "5:05," it is believed that 49:00 was recalled due to copyright issues in the ending cover medley.
On August 27, 2008, Westerberg released two new songs, "3oclockreep" and "Finally Here Once" on TuneCore.
On September 13, 2008, another new song "Bored of Edukation" was released as an MP3 download on Amazon.com.
On December 24, 2008, Westerberg released three songs; "Always in a Manger," "Streets of Laredo," and "D.G.T." on tunecore.com for $0.74.
On September 22, 2009, Westerberg released an EP titled "PW & The Ghost Gloves Cat Wing Joy Boys" with six songs; "Ghost On The Canvas," "Drop Them Gloves," "Good As The Cat," "Love On The Wing," "Gimmie Little Joy," and "Dangerous Boys".
Category:1959 births Category:Living people Category:American rock singer-songwriters Category:American male singers Category:American rock guitarists Grandpaboy Category:Musicians from Minnesota Category:The Replacements members
This text is licensed under the Creative Commons CC-BY-SA License. This text was originally published on Wikipedia and was developed by the Wikipedia community.