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Biomedical subjects

U Bellugi

Publications and source records attributed to U Bellugi.

64 records · Page 4Linked to original sources
PubMed1979

Language: perspectives from another modality.

Human languages have been forged in auditory-vocal channels throughout evolution. This paper examines the formal properties of a communication system that has developed in the absence of speech: the sign language of the deaf. The objective is to investigate to what extent the overall form and organization of language is determined by the articulatory and perceptual modality in which it has developed (its transmission system) and to what extent its form and organization represent more fundamental aspects of the human mind (intellect). Experimental and linguistic evidence is brought to bear on the analysis of the sign: studies of coding and processing of signs in memory; of slips of the hand; of historical change in signs over time; the heightened use of language in poetry and wit. American Sign Language differs dramatically from English and other spoken languages in the mechanisms by which its lexical units are modified. For the form of its morphological processes, the mode in which the language develops appears to make a crucial difference. Finally, the issue of cerebral specialization with respect to a visual-manual language is addressed.

Dominance, Cerebral↗
PubMed1976

Two faces of sign: iconic and abstract.

In this paper, we show that the total range of the communication system of the deaf is considerably enriched but at the same time rendered more difficult to analyze, because pantomime and other spontaneous nonsign representations occur in the same mode as regular ASL signs in deaf discourse. We note that the rarification of what was originally nonsign depiction is clearly an important source of regular ASL signs. We show that criteria can be established that would distinguish the clear cases of pantomime from the regular ASL signs. Nonetheless, there remain a sizable number of regular ASL signs which, although they are neither pantomimic nor otherwise freely mimetic, still appear to retain an iconic cast. We show that very few ASL signs are actually transparent; that is, a nonsigner cannot guess the meaning of a sign in the absence of further information. On the other hand, many signs are iconic in the sence that nonsigners, when given the sign and its meaning, show considerable agreement in how the two are related. More important in terms of language and its users is the significance of iconicity for deaf signers themselves. This paper shows that while in special circumstances the deaf do play on iconic elements of certain signs for special effects, iconicity plays no observable role in the coding of signs in short-term memory. The abstract formational parameters definitely dominate. We further note that it is the abstract system and not purely iconic aspects that have determined observed historical changes in the form of ASL signs. We interpret this as indicating the deeper structural significance of the abstract formational level. Finally, we show that very widespread and productive grammatical processes, especially suited for a visual-gestural language, override the iconic aspects of signs also at the synchronic structural level.

Concept Formation↗
PubMedDate not supplied

Neurologic features of Williams and Down syndromes.

Eight patients with Williams syndrome and 6 with Down syndrome, matched for age and full-scale IQ, underwent detailed neurologic testing as part of a large multidisciplinary research center study. Williams syndrome patients were small for gestational age and often had histories of failure-to-thrive and feeding problems as infants. Half of the Williams syndrome patients had epilepsy. On neurologic testing, Williams syndrome patients had greater difficulty with gross and fine motor coordination, oromotor skills, and cerebellar function than did those with Down syndrome. The neurologic distinctions between these 2 groups may reflect an underlying, as yet undefined, metabolic defect in Williams syndrome.

Adolescent↗
PubMedDate not supplied

Enlarged cerebellar vermis in Williams syndrome.

Williams syndrome (WMS) is a rare genetic disorder characterized by relative preservations of language ability and facial processing despite deficits in overall intelligence, problem solving, and visuospatial processing. Subjects with WMS also display hypersocial behavior and excessive linguistic affect during conversations and when giving narratives. Neuroimaging studies have shown global reductions in the brain volumes of subjects with WMS compared with normal controls, but with preservations in cerebellar volume. This study examines the neuroanatomic structure of the cerebellar vermis in 20 subjects with WMS and 20 age- and gender-matched controls via high-resolution magnetic resonance imaging. The vermis was divided into lobules I-V, VI-VII, and VIII-X. Lobules VI-VII and VIII-X were both relatively enlarged in the WMS group, and after adjusting for the smaller size of the WMS brain, the posterior vermis was significantly larger in WMS (Mann-Whitney z-value=4.27; P<0.001). Given that reductions in posterior vermis size have been implicated in flattened affect and autistic features, increased vermis size in subjects with WMS may be related to the hypersociality and heightened affective expression characteristic of individuals with this genetic condition.

Adult↗
PubMedDate not supplied

Sign language aphasia during left-hemisphere Amytal injection.

Although it has been established that the left cerebral hemisphere subserves spoken language, the nature of brain organization for sign language remains relatively unexplored. The issue is especially important because sign language displays the complex linguistic structure of spoken languages, but conveys it through manipulation of visuo-spatial relations, thereby exhibiting properties for which the hemispheres of hearing individuals show opposing specializations. We had the unique opportunity to study a hearing signer proficient in American sign language (ASL), during the left intracarotid injection of a barbiturate (the Wada test), and before and after a right temporal lobectomy. The subject was a strong right-hander. Neuropsychological and anatomical asymmetries suggested left cerebral dominance for auditory-based language. Emission tomography revealed lateralized activity of left Broca's and Wernicke's regions for spoken language. The Wada test, during which all left language areas were rendered inoperative, caused a marked aphasia in both English and ASL. After partial ablation of the right temporal lobe, the abilities to sign and understand signing were unchanged. These data add further support to the notion that anatomical structures of the left cerebral hemisphere subserve language in a visuo-spatial as well as an auditory mode.

Adult↗
PubMedDate not supplied

Neuropsychological studies of linguistic and affective facial expressions in deaf signers.

For deaf users of American Sign Language (ASL), facial behaviors function in two distinct ways: to convey affect (as with spoken languages) and to mark certain specific grammatical structures (e.g., relative clauses), thus subserving distinctly linguistic functions in ways that are unique to signed languages. The existence of two functionally different classes of facial behaviors raises questions concerning neural control of language and nonlanguage functions. Examining patterns of neural mediation for differential functions of facial expressions, linguistic versus affective, provides a unique perspective on the determinants of hemispheric specialization. This paper presents two studies which explore facial expression production in deaf signers. An experimental paradigm uses chimeric stimuli of ASL linguistic and affective facial expressions (photographs of right vs. left composites of posed expressions) to explore patterns of productive asymmetries in brain-intact signers. A second study examines facial expression production in left and right brain lesioned deaf signers, specifying unique patterns of spared and impaired functions. Both studies show striking differences between affective and linguistic facial expressions. The data indicate that for deaf signing individuals, affective expressions appear to be primarily mediated by the right-hemisphere. In contrast, these studies provide evidence that linguistic facial expressions involve left hemisphere mediation. This represents an important finding, since one and the same muscular system is involved in two functionally distinct types of facial expressions. For hearing persons, the right-hemisphere may be predominant in affective facial expression, but for deaf signers, hemispheric specialization for facial signals is influenced by the purposes those signals serve. Taken together, the data provide important new insights into the determinants of the specialization of the cerebral hemispheres in humans.

Affect↗