U. Bellugi et al. (1999) - Duke-UNC Brain Imaging and Analysis Center

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P ERSPECTIVES ON DISEASEU. Bellugi et al. – Linking cognition and the brainWilliams syndrome is rare, occurring in an estimatedone in 20 000 to one in 30 000 live births. Diagnosticcharacteristics include specific facial and physical features:a constellation of cardiovascular difficulties,which include supravalvular aortic stenosis (SVAS);failure to thrive in infancy; transient neonatal hypercalcemia;delayed language and motor milestones,and abnormal sensitivities to classes of sounds (hyperacusis).It has been recently found that in well over95% of the individuals who have been diagnosed clinicallywith WMS, there is a submicroscopic deletion ofone copy of perhaps 20 contiguous genes, whichinclude the gene for elastin, among others, on chromosome7. The deletion of one copy of elastin hasprovided a new genetic marker for WMS (Refs 11,12).Cognitive profile of WMSCognitive deficitsA hallmark of WMS is the dissociation between language(which is a strength in adolescents and adults)and spatial cognition (which is profoundly impaired),as shown in Fig. 1A. There are consistent cognitivedeficits in WMS: in general, standard Full Scale IQscores range from 40–100, with means of around 60(Refs 2,13; Fig. 1B). Many individuals with WMS findaspects of general problem solving difficult; most arenot able to achieve independent living 14 and typicallyexperience difficulty when dealing with money or balancinga checkbook. However, within the context oftheir intellectual impairments, individuals with WMSdisplay characteristic ‘peaks’ and ‘valleys’ in specificcognitive abilities. Complex expressive language abilitiesare relatively strong, spatial cognition is disproportionatelyimpaired (particularly at the level of globalorganization) and face-processing abilities are remarkablystrong. From studies across different populations, acharacteristic WMS cognitive profile is emerging 2,6,8,15 .Expressive language abilitiesOne striking aspect of the WMS profile is thestrength in language abilities in adolescence andadulthood, in contrast to the overall impairment seenin cognitive abilities. Although in the earliest stages oflanguage development, children with WMS show significantdelay 16 , once language is acquired, this abilitytends to become a relative strength in their cognitiveprofile. When adolescents and adults with WMS andDown syndrome (DNS), both syndromes of mentalretardation that are genetically based, are matched inage and Full Scale IQ, the differences in language skillsare evident at all levels (phonological, lexical, morphologicaland syntactic, as well as at levels ofprosody, discourse and narrative). For example, adolescentswith WMS score significantly higher on measuresof receptive word knowledge than on measures ofgeneral cognitive functioning, and perform dramaticallybetter than their counterparts with DNS(Ref. 17). On a word-fluency test, which asks subjectsto name all the animals they can in 60 seconds, adolescentsand adults with WMS score similarly to normalindividuals at the same mental age. Moreover, theresponses of the WMS group might include manyatypical examples (for example, chihuahua, ibex, condor)as well as typical ones (Fig. 1C). As part of a basisfor their language strengths, short-term memory forspeech sounds or phonological working memory, aform of memory that is relevant to language learningand comprehension, is relatively preserved in theWMS population 6,18,19 . The strength in verbal memoryseen in WMS is apparent when contrasted withanother domain, that of spatial memory. Individualswith WMS show far better verbal memory than spatialmemory, whereas individuals with DNS exhibit theopposite pattern (Fig. 1D) 2,20 .In general, compared with age-matched and FullScale IQ-matched subjects with DNS, the subjects withWMS perform far better on a wide variety of grammarprobes (reversible passives, negation, tag questions,sentence repetition, sentence completion, sentencecorrection, conditionals, etc.; see Fig. 1E) 2,3,17 . Thus,language at all levels in older individuals with WMSis a remarkable strength, in light of the level of cognitivedeficits that they have generally 17 . In fact, becausetheir language abilities are often at a level that ishigher than their overall cognitive abilities, individualswith WMS might be perceived to be more capablethan they really are. Although the domain of languageis a strength of individuals with WMS, there are cluesthat language might develop in somewhat differentways than in normal children. Morphological errorsabate more slowly in children with WMS than in normalchildren (but far more rapidly than in DNS) 21 anderrors show some differences from those produced bynormal children 6,15,22,23 . Studies are now showing thatthere are proportionately far more errors in the use ofspatial prepositions and in the use of language aboutspace by WMS individuals than found in the normaldevelopment (for example, when describing a pictureof an apple in a bowl during an experimental task,WMS individuals made errors such as ‘The apple isaround the bowl’, ‘The bowl is in the apple’ or ‘Theapple without the bowl’) 23 .There are controversial issues raised by the researchon WMS concerning the relationship between languageand cognition, which are still a matter ofdebate 10,22–25 . Some researchers consider the syndrometo be a remarkable example of the modularity of languageas a system that is separate from general cognitiveabilities. Others argue that as adults with WMS aresaid to function in some ways at the five- to sevenyear-oldlevel, there is a sufficient substrate of cognitiveabilities for the development of complex syntax,and that, thus, WMS does not represent a dissociationbetween language and general cognitive functions.There are unresolved issues about the relationshipbetween syntax and semantics, and about the intactnessof levels of language in WMS (Ref. 18), yetresearchers agree generally that language (for example,morphology and syntax) is a relative strength inWMS, which is apparently different from other syndromesthat can involve mental retardation 2,6,17,18,24 .Abnormally high linguistic affectA distinctive facet of the language abilities of individualswith WMS is their ability to use their heightened linguisticskills to engage others socially. Many individualswith WMS display a strong impulse towards social contact21,26 and affective expression, although their socialbehavior is not always appropriate 27,28 . The intersectionof language behavior and social engagement in individualswith WMS has been investigated through a series ofnarrative tasks in which subjects are asked to tell a storyfrom a wordless picture book 21,26 . Figure 1F shows examplesof the expressive language found in subjects withWMS compared to subjects with DNS (Ref. 2). The mostobvious distinction between subjects with WMS, and198 TINS Vol. 22, No. 5, 1999
U. Bellugi et al. – Linking cognition and the brain P ERSPECTIVES ON DISEASEAeareye headnosemouthElephantdrawingbodyElephant descriptionAnd what an elephant is it is one of theanimals. And what the elphant does, it livesin the jungle. It can also live in the zoo. Andwhat it has, it has long gray ears, fan ears,ears that can blow in the wind. It has a longtrunk that can pick up grass, or pick up hay...If they're in a bad mood it can be terrible... Ifthe elephant gets mad it could stomp; itcould charge. Sometimes elephants cancharge. They have long tusks. You don'twant an elephant as a pet. You want a cat ora dog or a bird...BCount20161284020 40 60 80 100 120 140 160Wechsler Full Scale IQCWords produced12840WMS DNS NCUncommonwordsCommonwordsWord fluency (60 s test): 'Name all the animals you can'WMS: brontosaurus, `tryrandon',dinosaurs, ibex, brontosaurusrex, elephant, dog, cat, lion,baby hippopotamus, whale, bull,yak, zebra, puppy, kitten, tiger,koala, dragonDNS: dogs, cats, fish, bird, fishDFree recall6420DigitspanCorsiblocksCorsi-blocksapparatusWMSDNSE% CorrectGrammar Context100806040200WMS DNS WMS DNSExperimenter question:'What if you were a bird?'DNS 1: Bird seeds.DNS 2: You'd be strong.DNS 3: I don't fly.DNS 4: I not a bird, you have wing.DNS 5: Fly in the air.WMS 1: You could fly, you could havebabies, fly north or south, east or west.WMS 2: Good question. I'd fly through theair being free.WMS 3: I would fly through the air and soarlike an airplane and dive through trees likea bird and land like a bird.WMS 4: I would fly through the air wheremy parents would never find me. Birds wantto be independent.WMS 5: I would fly and if I liked a boy, Iwould land on his head and start chirping.FWMS age 17, Full Scale IQ = 50Once upon a time when it was dark at night...theboy had a frog. The boy was looking at thefrog...sitting on the chair, on the table, and the dogwas looking through...looking up to the frog in a jar.That night he sleeped and slept for a long time, thedog did. But, the frog was not gonna go to sleep.And when the frog went out...the boy and the dogwere still sleeping. The next morning it wasbeautiful in the morning. It was bright and the sunwas nice and warm. Then suddenly when heopened his eyes...he looked at the jar and then suddenly the frog wasnot there. The jar was empty. There was no frog to found (whispered).DNS age 18, Full Scale IQ = 55The frog is in the jar. The jar is on the floor. The jar on the floor. That' sit. The stool is broke. The clothes is laying there.Fig. 1. Unusual language and cognitive profiles in Williams syndrome (WMS). A characteristic of WMS is the dissociation between languageand space. (A) shows a drawing and description of an elephant by a teenager with WMS, Full Scale IQ of 49, Verbal IQ of 52 and PerformanceIQ of 54. Note the difference between the impoverished drawing and grammatically complete language. (B) Wechsler Full Scale IQs range from40 to 100 in WMS and are reasonably normally distributed, with a mean IQ of approximately 60 (solid line; SD 11). Broken line shows populationdistribution of Full Scale IQs (mean 100; SD 11). (C) On a semantic fluency task, subjects with WMS give the same number of commonresponses but significantly more uncommon infrequent responses (for example, ibex, yak, dragon) than either matched subjects with Downsyndrome (DNS) or normal subjects matched for mental age (NC; n 10 in each group). The double dissociation between verbal and spatialshort-term memory is shown in (D): age-matched and Full Scale IQ-matched individuals with WMS (n 10) and DNS (n 9) demonstrate adifferential ability to remember a list of numbers in order (Digit Span) versus remembering location and order of blocks (Corsi blocks) 2 . (E)Individuals with WMS perform significantly better than individuals with DNS (age-matched and Full Scale IQ-matched) in syntactic processingtasks (for example, conditional sentences) on both grammar and content (for example, ‘Good question. I’d fly through the air being free.’). Normalcontrol results are shown by the broken line. (F) Individuals with WMS use more affective prosody, more audience ‘hookers’ and more linguisticaffective devices than do normals or individuals with DNS at any age. Subjects are asked to tell a story from a wordless picture book and the WMSsubjects tend to be dramatic story tellers. The figure shows samples of a story-telling task by age-matched and Full Scale IQ-matched individualswith WMS and DNS. The WMS individual shown is 17 years old, Full Scale IQ 50, Verbal IQ 54 and Performance IQ 55; the DNS individualshown is 18 years old, Full Scale IQ 54, Verbal IQ 59 and Performance IQ 53 (Ref. 2). (D) and (F) reproduced, with permission,from Ref. 2.subjects with DNS and age-matched normal controls, isin the use of narrative enrichment devices during thisstory-telling task by subjects with WMS. The enrichmentdevices (addition of affective qualities) are not found inthe pictures themselves, but are added to the narrative bythe subject as linguistic affect. Individuals with WMSshow an abundance of affectivity in both prosody andlexical devices and appear to be able to manipulate affectivelinguistic devices for the purposes of storytelling 21,26,29,30 . Affective prosody was measured by notinghow frequently paralinguistic affective expression wasused, including pitch change, vocalic lengthening andTINS Vol. 22, No. 5, 1999 199
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U. Bellugi et al. (1999) - Duke-UNC Brain Imaging and Analysis Center

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