Poster group
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poster
Children affected by Williams' syndrome typically have difficulty with tasks involving spatial cognition, yet have relatively spared language skills and facial recognition. We are using visuomotor and visuospatial tests to relate the pattern of abilities and deficits in children with WS to current neurobiological models of brain structure and function.Firstly, we have investigated the extent to which children with Williams' syndrome have difficulty in planning simple, goal-directed movements. In the Handle Rotation task children are asked to grip and turn a handle to point to a coloured mouse on a clock face. In the Bar Task, children are asked to pick up a wooden bar, and to put the end of it into a coloured hole. We observed whether children chose a grip which would lead to a comfortable hand position at the end of the action. Typically developing children show an increase in the proportion of 'end-state comfort' grips between 6 and 8 years of age, as do children with DCD (Smyth et al, 1997). A majority of children with WS selected a preferred grip orientation at the start of the movement, leading to an awkward wrist position in certain end-states, implying immaturity of motor planning.Secondly, Atkinson et al (1996) have proposed that a deficit in dorsal stream visual processing may contribute to the visuo-spatial difficulties found in WS. We are testing this hypothesis using two tasks designed to compare the ability to make a perceptual judgement (a 'ventral stream' function) with the use of vision to control action (a 'dorsal stream' function). In the Shapes task children are asked to indicate which slot an irregular wooden shape will fit in to. They then pick up the same shape between the thumb and forefinger. A video record makes it possible to test whether the finger grip points on the object are appropriately guided by shape information. In the Squares task, children are first asked to choose from a range of squares the one which matches a target square. They are then asked to pick up the target square and the width of finger opening is measured using the Elite motion tracking system. These experiments will help determine how far visuo-motor difficulties experienced by children with WS are due to a specific deficit or a developmental delay in visual processing streams specialised for the control of action, and/or in the planning of action based on spatial information.References:Atkinson JA, King J, Braddick OJ, Nokes L, Anker S, and Braddick F (1997). A specific deficit of dorsal stream function in Williams' syndrome. NeuroReport, 8, 1919-1922.Smyth MM and Mason UM (1997) Planning and execution of action in children with and without developmental co-ordination disorder. J.Child Psychol Psychiat Vol 38 No 8 pp 1023-1027
poster
Children with Williams Syndrome show an uneven profile ofneuropsychological development, with sparing of some aspects of linguisticcompared to visuo-spatial function. We have considered five possibleneuroscientific models relating brain development to functional deficits inspatial cognition. These are that the WS visuospatial, visuocognitive andvisuomotor deficits are:1. a consequence of sensory visual deficits (strabismus, amblyopia) veryearly in life.2. related to dysfunction of the dorsal cortical stream in parietal lobe3. related to both parietal and frontal lobe dysfunction.4. related to competition between development of the dorsal and ventralcortical streams (parietal versus temporal lobe development). 5. related to poor development of right hemisphere relative to lefthemisphere function.Our programme, studying over 100 WS infants and young children (age 6months- 14 years), has included orthoptic and refractive examination,stereo and acuity testing, tests of visual attention, ABCDEFV (AtkinsonBattery of Child Development for Examining Functional Vision) visuo-spatialcognition (block construction, WPPSI object assembly, Hood spatial tubestest), and language tests (BPVS. TROG, our UK adapted Macarthur LanguageInventory). Strabismus, stereo deficit and marked refractive errors aremuch more common in the WS group than in normal populations. However, nosignificant association was found between the severity of these sensoryvision problems and the deficit on visuo-spatial tests. This suggests thatmodel 1, with a causal link between sensory visual loss and spatialcognitive deficits, is unlikely to be correct, although both types ofdeficit are present in many WS children. We have further investigated hypotheses 2 and 3 above in WS. We havemeasured visuo-motor deficits (Henderson ABC battery),and designed markertasks to dissociate dorsal from ventral visual stream functioning (the'postbox' task comparing visuo-manual and matching responses to an orientedslot) and the 'motion versus form coherence' test. Many young WS childrenshow marked deficits on the dorsal compared to the ventral stream tasks. These findings can be related to structural MRI results on two very youngWS children, where we have found characteristic structural changes incerebellum and abnormal white matter development within the parietal lobe.We have investigated frontal function with age-appropriate executivefunction tests in which the child has to inhibit a familiar response ('Anot B with delay' test of object permanence, the Russell detour box test,'Day-Night' Stroop test, and developed a new counter-pointing task(analogous to the Anti-saccade task) . Many WS children show deficits onthese tests, especially where the response has a spatial component,suggesting that hypothesis 3 of both parietal and frontal lobeabnormalities may apply.The challenge now is to not only relate these problems to underlying braincircuitry but to gauge the plasticity of these modules, so that successfulrehabilitation and treatment programmes can be developed Acknowledgments to Medical Research Council programme grant G7908507 andWS Foundation, UK.
poster
We are addressing patterns of continuity among diadic, triadic and attachment relations in a longitudinal study of social and cognitive development. 10 infants with Down's syndrome and 25 typically-developing comparison infants were assessed for their attachment security using the Strange Situation (Ainsworth et al., 1978). The organization of early mother-infant relations was assessed at the start of the study using the Still-face paradigm (Tronick et al., 1978). Further assessments were conducted in the intervening period to track the development of aspects of secondary intersubjectivity such as joint attention, social referencing and requesting behaviour. We have found differences in maternal behaviour towards infants with Down's syndrome in the first phase of the Still-face and we have found evidence for a continuity between patterns of primary intersubjectivity and the emergence of patterns of joint relating to events and objects external to the dyad, subject to cognitive constraints. Findings from the three sets of assessments (primary intersubjectivity, secondary intersubjectivity and attachment) will be used to present a preliminary model of the developmental factors affecting attachment security in infants with Down's syndrome and to examine the commonality of this model with developmental processes in typically-developing infants.Research supported by the Economic and Social Research Council (grant no. R000236722) and the Open University Research Committee.
poster
In a longitudinal study, 10 infants with Down's syndrome were assessed at 6, 12 and 18 months of age, and 20 typically developing infants were assessed at 4, 7 and 10 months, to provide CA and MA matched group comparisons. Over this period, visual attention regulation was assessed in a set of social perception experiments using preferential-looking and habituation/dishabituation paradigms: perception of Causality (Leslie & Keeble, 1987), Rationality (Gergely et al., 1995) and Point-Light Displays (Bertenthal et al., 1987). In addition, qualities of social relating and engagement were assessed using measures of face-to-face interaction and of secondary intersubjectivity. We have found associations between patterns of early mother-infant interaction and the subsequent emergence of joint attention. This presentation will expand on these findings, report on links between infants' attention regulation and the qualities of early mother-infant interactions, and consider how these relate to later joint attention. It is proposed that an infant's general attentional capacities may determine to some extent their mother's directive role in interactions and that cognitive, attentional and social-relational constraints mutually influence the development of joint attention in infants with and without Down's syndrome. A preliminary model of how these factors interact will be presented.Research supported by the Economic and Social Research Council (grant no. R000236722) and the Open University Research Committee.
poster
Attention plays a major role in the development of normal infants. Oneaspect of attention,sustained attention, occurs after orienting, and reflects informationprocessing. Ruff andLawson (1991) claim that there is a general developmental trend towardsgreater sustainedattention with increasing age. The effects of low attention in infancy areboth detrimental andcumulative (Lawson and Ruff, 1989), and have been linked with severalconditions whichresult in impaired learning, such as hyperactivity and prematurity.Parental and teacher reportssuggest that children with Williams syndrome (WS) exhibit attentionproblems, and AttentionDeficit Hyperactivity Disorder is often diagnosed in school age WSchildren. However, therehave been no empirical investigations of attention in WS. Both adults andchildren with Downsyndrome (DS) are often reported as exhibiting poorer general attentionthan normal controls,but similar to that shown in non-DS mentally delayed groups matched on IQ(e.g. Fisher1970).The aim of the present study was to investigate sustained attention ininfants with Williamsand Down syndromes, in order to determine if attention deficits reported inolder children withWS are present from an early age, if they differ from deficits of attentionin children with DS,and whether attention deficits in both groups was more indicative ofdelayed or atypicaldevelopment of attention systems. 4 groups were tested; WS, DS, CA(chronological agematched controls) aged from 24 to 36 months, and MA (mental age matchedcontrols,matched on the Bayley Scales of Infant Development II), aged from 11 to 20months. Thechildren were videotaped during play sessions in the lab with 6 toys, eachof which lasted for45 seconds. Sessions with three of the toys were subsequently coded bytrained coders, basedon the system developed by Ruff (e.g. Ruff and Lawson, 1990), whichidentifies periods ofsustained attention on the basis of a number of measures. WS infants hadsignificantly longerperiods of sustained attention than DS infants, but did not differ from CAor MA infants. TheDS group had significantly fewer periods of sustained attention than the MAgroup. Thispattern of results suggests that infants with Williams syndrome do not showimpaireddevelopment of sustained attention, while DS infants are impaired both interms of frequencyand duration of periods of sustained attention. Results are discussed inrelation to the reportedattention problems in older WS children, and how attention interacts withother cognitiveabilities and impairments in WS and DS.
poster
Adolescents and adults with Williams syndrome (WS) display unusually good language compared to their other non-verbal skills and to other syndromes with equivalent IQ. However, young children with WS are seriously delayed in language onset and early linguistic development. It is therefore essential to explore whether impairments in their pre-verbal communication skills can explain why language onset is so late. Clues to such impairments came from a study by Bertrand, Mervis, Rice and Adamson (1993) on a small sample of WS infants. Their results suggested that, unlike typically developing infants, those with WS 1) pay more attention to faces than to objects, and 2) show a pattern in which referential pointing post-dates rather than precedes spoken language. Furthermore, it has been shown that in normal development there is a strong relationship between joint attention skills, referential pointing and subsequent language development. It is therefore crucial to ascertain whether the pattern of development in infants with WS is the same. Study 1 tested 16 infants with WS, aged between 17 and 45 months, on the Early Social Communication Scales (Mundy & Hogan, 1996). This test measures three forms of pre-verbal communication skill: social interaction (e.g., social referencing), joint attention, and requesting. The study had three aims: 1) to investigate these skills in WS infants compared to MA- and LA- matched controls (matched on the Bayley-II and the Reynell); 2) to explore the relationship between pre-verbal skills and leve1 of language development, as measured on the Reynell and the MacArthur Communication Development Inventory; and 3) to further assess the hypothesis that infants with WS pay significantly more attention to faces than to objects. Surprisingly, given the adult phenotype, the WS group showed less social referencing than the control groups. The results are analysed in comparison to other disorders (autism and Down syndrome) which have shown syndrome-specific patterns of deficit. Study 2 tested the same WS infants and controls and investigated the comprehension and production of referential pointing. Pointing was assessed using a procedure devised for normal infants by Butterworth et al, (1997) in which children face an array of dolls which can be operated by the experimenter to move and speak, In half the trials (comprehension of pointing), the experimenter pointed at a given doll and the extent to which the child looked at the correct doll was recorded. In the other half (production of pointing), one of the dolls started to move and speak and measurement was taken of the child's pointing behaviour, as well as social referencing. Our aims were to assess: 1) the levels of successful production and comprehension of pointing; and 2) the relationship between these skills and level of language development. The WS infants produced less pointing and less social referencing than the controls, but showed equivalent comprehension skills. The full analysis of the results will help us to situate Williams syndrome in terms of whether the trajectory from pre-verbal communication to language shows a developmental delay or developmental deviance.
poster
This study takes a cross-syndrome and cross-domain approach to atypicaldevelopment. It demonstrates that infant performance on two tasksassessing language and number cannot be derived from the adult phenotypicaloutcome. Adults with Williams Syndrome (WS) have seriously impaired numberskills but relatively good language, whereas adults with Down Syndrome (DS)are impaired in both domains. Two experiments were conducted to ascertainwhether the pattern of abilities in infancy reflect those seen in the adultendstate.Experiment 1 assessed single word comprehension using a visual preferenceparadigm. 15 infants with WS, 22 infants with DS, 17 mental age-matchedcontrols, and 17 chronological age-matched controls were tested. The taskmeasured whether infants would look longer at a picture that isaccompanied by its verbal label than at one which is not labelled. It waspredicted that if initial states can be directly inferred from endstates,then the performance of infants with WS should resemble the CA- matchedcontrols, and be well in advance of the DS group who should perform likethe MA-controls. All the groups looked longer at the matching stimuli, butthe performance of both the DS and WS groups was delayed to an equivalentdegree, and matched the behaviour of the MA controls. The similaritybetween the DS and WS infant groups did not parallel the difference seen inthe adult phenotypes.Experiment 2 was a test of sensitivity to numerical changes in a series ofdisplays of everyday objects. 13 infants with WS, 22 with DS, 16MA-matched and 14 CA-matched infants took part. Infants were familiarisedto pairs of stimuli containing arrays of changing sets of 2 objects ofdifferent sizes and in different configurations. In the test phase, theywere shown a pair with one stimulus containing 2 objects and the other 3objects. If during familiarisation, the infants had become sensitive to theconstant numerosity (2) of each of the displays, then they should looksignificantly longer when in the test phase one of the pair displayed a newnumerosity. This is despite the fact that both displays had new objects.Given the impairments in number in adulthood for both DS and WS, it waspredicted that if initial states can be directly derived from endstates,then infants from both syndromes would show impairment on this task. TheWS, MA- and CA-matched controls looked significantly longer at the newnumerosity. There was no such difference for the DS group. The results showthat despite their serious impairment in number in the endstate, in infancyWS subjects perform normally and look like their chronologicallyage-matched controls. The difference between the DS and WS infant groupsdid not parallel the similarity seen in the adult phenotypes.These cross-syndrome studies indicate that infant profiles cannot bederived from the pattern of abilities in the endstate. It is thereforecrucial to characterise the infant state, in order to fully understand thedevelopmental trajectories of different atypical groups.Sarah Paterson 1,2., Janice Brown 1,2. , Marisa Gsodl 1, Mark H.Johnson 3.& Annette Karmiloff-Smith 1.1.Neurocognitive Development Unit, Institute of Child Health, 30 GuilfordStreet, London WC1N 1EH. 2. Dept of Psychology, University College London& 3. Centre for Brain & Cognitive Development, Birkbeck College, London.
poster
The aim of this paper is to investigate the specificity of language deficit in DS children and adolescents. This research could be of interest not only for effective intervention strategies in this impaired population but also to establish different patterns of language development within mental retardation and to shape our models of normal language development. Twelve Spanish-speaking DS children and adolescents aged between 6 and 18 were videotaped. Each subject was taped every three months throughout a year in a spontaneous conversation setting with the investigator that also included narrative tasks. Tapes were transcribed and analysed using the tools from CHILDES (MacWhinney, 1995; Diez-Itza, Macwhinney & Snow, 1999). The CHIP program (Sokolov and MacWhinney, 1990) allowed a special study of linguistic imitation. Further analyses were conducted in all linguistic levels, and measures of phonological, morphological, syntactic, semantic, and discourse levels were obtained. Comparisons with our previous research on language development of spanish William Syndrome children were also made. Results show remarkable individual differences as well as typical developmental patterns in language development that could be associated with DS. Discussion focuses on the degree of individual linguistic variation and its predictors, the underlying causes of specific language patterns and the developmental course of language acquisition at different ages.
poster
Downs Syndrome (DS) is characterized by global delays in a number of domains(cognitive, communicative, motor ability). In particular, linguistic skillsare impaired, and a number of studies have indicated that DS children'sperformance on language tasks is worse than that expected on the basis oftheir mental age (e.g., Chapman, 1995). In addition to specific problemswith verbal production, it has been documented that children with DS usecommunicative gestures for an extended period of time. Previous research has emphasized the importance of gesture in earlycommunicative development (e.g., Bates et al., 1979). These studies havereported that gestures are used frequently during the first two years oflife and may play a transitional role in the language acquisition process.The aim of this study is to compare early word and gesture use in childrenwith DS and in typically-developing children in order to investigatepotential differences in the relationship between gestural and verbalcommunication in early language development.Ten children from upper-middle class families participated in this study.The five children with DS (3 boys and 2 girls) had an average chronologicalage of 47.6 months, an average mental age of 22.4 months, and an averagelanguage age of 18 months. Each child with DS was matched with a normallydeveloping child on the basis of gender and language age (mean age 17.7months). Children were videotaped for 30 minutes as they interactedspontaneously with their mothers. All communicative and intelligible gestures and words were transcribed fromthe videotapes. Data analyses focused on: a) overall production of gesturesand words (i.e., gesture and word tokens); b) the size of children'sgestural and verbal repertoires (i.e., gesture and word types); and c)production and informational content of gesture + word combinations.Analyses revealed no differences between children in the two groups on anyof the measures considered, with one exception. Children with DS hadsignificantly smaller gestural repertoires than their language age-matchedpeers. Interestingly, however, there was no reliable difference between thetwo groups in the overall use of gesture. A second set of analyses carriedout within the group of children with DS examined the relationship betweengestural and verbal communication. Children with DS communicatedsignificantly more frequently with gestures than with words during theobservation. Such an asymmetry was not observed within the group oflanguage age-matched control children, who tended to produce words andgestures with equal frequency.Taken together, these findings suggest that in addition to thewell-documented global delays in language observed in children with DS,there may also be some differences in the course of early communicativedevelopment. The results are further discussed in terms of theirimplications for understanding the organization of the developinggesture-language system and for language intervention programs.