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Ursula Bellugi
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Journal Articles
Publisher: Journals Gateway
Journal of Cognitive Neuroscience (2008) 20 (12): 2198–2210.
Published: 01 December 2008
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Despite decades of research, there is still disagreement regarding the nature of the information that is maintained in linguistic short-term memory (STM). Some authors argue for abstract phonological codes, whereas others argue for more general sensory traces. We assess these possibilities by investigating linguistic STM in two distinct sensory–motor modalities, spoken and signed language. Hearing bilingual participants (native in English and American Sign Language) performed equivalent STM tasks in both languages during functional magnetic resonance imaging. Distinct, sensory-specific activations were seen during the maintenance phase of the task for spoken versus signed language. These regions have been previously shown to respond to nonlinguistic sensory stimulation, suggesting that linguistic STM tasks recruit sensory-specific networks. However, maintenance-phase activations common to the two languages were also observed, implying some form of common process. We conclude that linguistic STM involves sensory-dependent neural networks, but suggest that sensory-independent neural networks may also exist.
Journal Articles
Publisher: Journals Gateway
Journal of Cognitive Neuroscience (2000) 12 (Supplement 1): 89–107.
Published: 01 March 2000
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Williams syndrome (WMS) is a most compelling model of human cognition, of human genome organization, and of evolution. Due to a deletion in chromosome band 7q11.23, subjects have cardiovascular, connective tissue, and neurode-velopmental deficits. Given the striking peaks and valleys in neurocognition including deficits in visual-spatial and global processing, preserved language and face processing, hypersociability, and heightened affect, the goal of this work has been to identify the genes that are responsible, the cause of the deletion, and its origin in primate evolution. To do this, we have generated an integrated physical, genetic, and transcriptional map of the WMS and flanking regions using multicolor metaphase and interphase fluorescence in situ hybridization (FISH) of bacterial artificial chromosomes (BACs) and P1 artificial chromosomes (PACs), BAC end sequencing, PCR gene marker and microsatellite, large-scale sequencing, cDNA library, and database analyses. The results indicate the genomic organization of the WMS region as two nested duplicated regions flanking a largely single-copy region. There are at least two common deletion breakpoints, one in the centromeric and at least two in the telomeric repeated regions. Clones anchoring the unique to the repeated regions are defined along with three new pseudogene families. Primate studies indicate an evolutionary hot spot for chromosomal inversion in the WMS region. A cognitive phenotypic map of WMS is presented, which combines previous data with five further WMS subjects and three atypical WMS subjects with deletions; two larger (deleted for D7S489L) and one smaller, deleted for genes telomeric to FZD9 , through LIMK1 , but not WSCR1 or telomeric. The results establish regions and consequent gene candidates for WMS features including mental retardation, hypersociability, and facial features. The approach provides the basis for defining pathways linking genetic underpinnings with the neuroanatomical, functional, and behavioral consequences that result in human cognition.
Journal Articles
Publisher: Journals Gateway
Journal of Cognitive Neuroscience (2000) 12 (Supplement 1): 1–6.
Published: 01 March 2000
Journal Articles
Publisher: Journals Gateway
Journal of Cognitive Neuroscience (2000) 12 (Supplement 1): 65–73.
Published: 01 March 2000
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Williams syndrome (WMS), a genetic condition resulting from a contiguous deletion on the long arm of chromosome 7, is associated with a relatively consistent profile of neurocognitive and neurobehavioral features. The distinctiveness and regularity of the profile of learning and behavioral characteristics in this genetic condition suggests that underlying neurobiological correlates may be identifiable. In this initial study, we report findings derived from a high-resolution neuroimaging study of 14 young adult subjects with WMS and an individually matched normal control group. Compared to controls, subjects with WMS were noted to have decreased overall brain and cerebral volumes, relative preservation of cerebellar and superior temporal gyrus (STG) volumes, and disproportionate volume reduction of the brainstem. Analyses also suggested that the pattern of cerebral lobe proportions in WMS may be altered compared to normal controls with a greater ratio of frontal to posterior (parietal+occipital) tissue. Assessment of tissue composition indicated that, relative to controls, individuals with WMS have relative preservation of cerebral gray matter volume and disproportionate reduction in cerebral white matter volume. However, within the cerebral gray matter tissue compartment, the right occipital lobe was noted to have excess volume loss. Combined with our growing knowledge of the function of genes in the commonly deleted region for WMS, more detailed information regarding the structure and function of the WMS brain will provide a unique opportunity for elucidating meaningful correlations amongst genetic, neurobiological, and neurobehavioral factors in humans.
Journal Articles
Publisher: Journals Gateway
Journal of Cognitive Neuroscience (2000) 12 (Supplement 1): 7–29.
Published: 01 March 2000
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The rare, genetically based disorder, Williams syndrome (WMS), produces a constellation of distinctive cognitive, neuroanatomical, and electrophysiological features which we explore through the series of studies reported here. In this paper, we focus primarily on the cognitive characteristics of WMS and begin to forge links among these characteristics, the brain, and the genetic basis of the disorder. The distinctive cognitive profile of individuals with WMS includes relative strengths in language and facial processing and profound impairment in spatial cognition. The cognitive profile of abilities, including what is ‘typical’ for individuals with WMS is discussed, but we also highlight areas of variability across the group of individuals with WMS that we have studied. Although the overall cognitive abilities (IQs) of individuals with WMS are typically in the mild-to-moderate range of mental retardation, the peaks and valleys within different cognitive domains make this syndrome especially intriguing to study across levels. Understanding the brain basis (and ultimately the genetic basis) for higher cognitive functioning is the goal we have begun to undertake with this line of interdisciplinary research.
Journal Articles
Publisher: Journals Gateway
Journal of Cognitive Neuroscience (2000) 12 (Supplement 1): 30–46.
Published: 01 March 2000
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Studies of abnormal populations provide a rare opportunity for examining relationships between cognition, genotype and brain neurobiology, permitting comparisons across these different levels of analysis. In our studies, we investigate individuals with a rare, genetically based disorder called Williams syndrome (WMS) to draw links among these levels. A critical component of such a cross-domain undertaking is the clear delineation of the phenotype of the disorder in question. Of special interest in this paper is a relatively unexplored unusual social phenotype in WMS that includes an overfriendly and engaging personality. Four studies measuring distinct aspects of hypersocial behavior in WMS are presented, each probing specific aspects in WMS infants, toddlers, school age children, and adults. The abnormal profile of excessively social behavior represents an important component of the phenotype that may distinguish WMS from other developmental disorders. Furthermore, the studies show that the profile is observed across a wide range of ages, and emerges consistently across multiple experimental paradigms. These studies of hypersocial behavior in WMS promise to provide the ground-work for crossdisciplinary analyses of gene-brain-behavior relationships.
Journal Articles
Publisher: Journals Gateway
Journal of Cognitive Neuroscience (2000) 12 (Supplement 1): 74–88.
Published: 01 March 2000
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The purpose of a neuroanatomical analysis of Williams Syndrome (WMS) brains is to help bridge the knowledge of the genetics of this disorder with the knowledge on behavior. Here, we outline findings of cortical neuroanatomy at multiple levels. We describe the gross anatomy with respect to brain shape, cortical folding, and asymmetry. This, as with most neuroanatomical information available in the literature on anatomical-functional correlations, links up best to the behavioral profile. Then, we describe the cytoarchitectonic appearance of the cortex. Further, we report on some histometric results. Finally, we present findings of immunocy-tochemistry that attempt to link up to the genomic deletion. The gross anatomical findings consist mainly of a small brain that shows curtailment in the posterior-parietal and occipital regions. There is also subtle dysmorphism of cortical folding. A consistent finding is a short central sulcus that does not become opercularized in the interhemispheric fissure, bringing attention to a possible developmental anomaly affecting the dorsal half of the hemispheres. There is also lack of asymmetry in the planum temporale. The cortical cytoarchitecture is relatively normal, with all sampled areas showing features typical of the region from which they are taken. Measurements in area 17 show increased cell size and decreased cell-packing density, which address the issue of possible abnormal connectivity. Immunostaining shows absence of elastin but normal staining for Lim-1 kinase, both of which are products of genes that are part of the deletion. Finally, one serially sectioned brain shows a fair amount of acquired pathology of microvascular origin related most likely to underlying hypertension and heart disease.
Journal Articles
Publisher: Journals Gateway
Journal of Cognitive Neuroscience (2000) 12 (Supplement 1): 47–64.
Published: 01 March 2000
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Williams Syndrome (WMS) is a genetically based disorder characterized by pronounced variability in performance across different domains of cognitive functioning. This study examined brain activity linked to face-processing abilities, which are typically spared in individuals with WMS. Subjects watched photographic pairs of upright or inverted faces and indicated if the second face matched or did not match the first face. Results from a previous study with normal adults showed dramatic differences in the timing and distribution of ERP effects linked to recognition of upright and inverted faces. In normal adults, upright faces elicited ERP differences to matched vs. mismatched faces at approximately 320 msec (N320) after the onset of the second stimulus. This “N320” effect was largest over anterior regions of the right hemisphere. In contrast, the mismatch/match effect for inverted faces consisted of a large positive component between 400 and 1000 msec (P500) that was largest over parietal regions and was symmetrical. In contrast to normal adults, WMS subjects showed an N320-mismatch effect for both upright and inverted faces. Additionally, the WMS subjects did not display the N320 right-hemisphere asymmetry observed in the normal adults. WMS subjects also displayed an abnormally small negativity at 100 msec (N100) and an abnormally large negativity at 200 msec (N200) to both upright and inverted faces. This ERP pattern was observed in all subjects with WMS but was not observed in the normal controls. These results may be linked to increased attention to faces in subjects with WMS and might be specific to the disorder. These results were consistent with our ERP studies of language processing in WMS, which suggested abnormal cerebral specialization for spared cognitive functions in individuals with WMS.
Journal Articles
Publisher: Journals Gateway
Journal of Cognitive Neuroscience (1995) 7 (2): 196–208.
Published: 01 April 1995
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Many species can respond to the behavior of their conspecifics. Human children, and perhaps some nonhuman primates, also have the capacity to respond to the mental states of their conspecifics, i.e., they have a “theory of mind.” On the basis of previous research on the theory-of-mind impairment in people with autism, together with animal models of intentionality, Brothers and Ring (1992) postulated a broad cognitive module whose function is to build representations of other individuals. We evaluate the details of this hypothesis through a series of experiments on language, face processing, and theory of mind carried out with subjects with Williams syndrome, a rare genetic neurodevelopmental disorder resulting in an uneven lin-guisticocognitive profile. The results are discussed in terms of how the comparison of different phenotypes (e.g., Williams syndrome, Down syndrome, autism, and hydrocephaly with associated myelomeningocele) can contribute both to understanding the neuropsychology of social cognition and to current thinking about the purported modularity of the brain.