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Biomedical subjects

U Bellugi

Publications and source records attributed to U Bellugi.

13 recordsLinked to original sources
PubMed1992

The linguistic basis of left hemisphere specialization.

In humans the two cerebral hemispheres of the brain are functionally specialized with the left hemisphere predominantly mediating language skills. The basis of this lateralization has been proposed to be differential localization of the linguistic, the motoric, or the symbolic properties of language. To distinguish among these possibilities, lateralization of spoken language, signed language, and nonlinguistic gesture have been compared in deaf and hearing individuals. This analysis, plus additional clinical findings, support a linguistic basis of left hemisphere specialization.

Adult↗
PubMed1992

Callosal morphology concurs with neurobehavioral and neuropathological findings in two neurodevelopmental disorders.

To integrate neuroimaging, neuropathologic, and neuropsychological findings, computer-assisted morphometry was applied to magnetic resonance images of the corpus callosum in adolescents with Down and Williams syndromes and in control subjects. Callosa of subjects with Down syndrome were distinctively rounded in form, consistent with Down syndrome brachycephaly. These callosa also showed decreased widths throughout their rostral fifth, which serves frontal lobe projections. This finding correlates with the hypocellularity and hypofrontality of neocortex in subjects with Down syndrome and with their neuropsychological profile of frontal lobe dysfunction. Callosa of subjects with Williams syndrome generally resembled control specimens, in congruence with their frontal lobe structure and better preserved frontal lobe function. These results represent a convergence of findings across levels of neuroscientific investigation.

Adolescent↗
PubMed1992

Acquisition of signs from American sign language in hearing individuals following left hemisphere damage and aphasia.

Three severely aphasic hearing patients with no prior knowledge of sign language were able to acquire competency in aspects of American Sign Language (ASL) lexicon and finger spelling, in contrast to a near complete inability to speak the English counterparts of these visuo-gestural signs. Two patients with damage in left postero-lateral temporal and inferior parietal cortices mastered production and comprehension of single signs and short meaningful sign sequences, but the one patient with damage to virtually all left temporal cortices was less accurate in single sign processing and was unable to produce sequences of signs at all. These findings suggest that conceptual knowledge is represented independently of the auditory-vocal records for the corresponding lexical entries, and that left anterior temporal cortices outside of traditional "language areas" are part of the neural network which supports the linkage between conceptual knowledge and linguistic signs, especially as they are used in the sequenced activations required for production or comprehension of meaningful sentences.

Adult↗
PubMed1992

Sensitivity to inflectional morphology in aphasia: a real-time processing perspective.

The present study investigates Broca's aphasics' sensitivity to morphological information in an on-line task. German is used as the test language because it is highly inflected. Results from two word monitoring experiments show first that Broca's patients like normal controls are sensitive to the presence of a contextually incorrect inflection. Contrary to normals, they are, however, not sensitive to the absence of an obligatory inflection even when its presence is syntactically highly constrained. Second, they reveal that Broca's aphasics are only sensitive to the presence of an incorrect inflection when it functions as a marker of lexical category (noun vs. verb) and not when it functions as a diacritical marker (second person singular vs. third person singular). The results are taken as evidence for the claim that Broca's aphasics are impaired in the ability to process the full syntactic information encoded in closed class elements in a fast, automatic, and obligatory way.

Adult↗
PubMed1992

Dissociation between linguistic and nonlinguistic gestural systems: a case for compositionality.

This paper addresses the issue of the separability of disorders of sign language from disorders of gesture and pantomime. The study of a left-lesioned deaf signer presents one of the most striking examples to date of the cleavage between linguistic signs and manual pantomime. The left-hemisphere lesion produced a marked sign language aphasia disrupting both the production and the comprehension of sign language. However, in sharp contrast to the breakdown of sign language, the ability to communicate in nonlinguistic gesture was remarkably spared. This case has important implications for our understanding of the neural mediation of language and gesture. We argue that the differences observed in the fractionation of linguistic versus nonlinguistic gesture reflect differing degrees of compositionality of systems underlying language and gesture. The compositionality hypothesis receives support for the existence of phonemic paraphasias in sign language production, illustrating structural dissolution which is absent in the production of pantomimic gesture. Understanding the neural encoding of compositional motoric systems may lead to a principled anatomical account of the neural separability of language and gesture. This case provides a powerful indication of the left hemisphere's specialization for language-specific functions.

Aphasia↗
PubMed1992

Fetal alcohol syndrome: a case report of neuropsychological, MRI and EEG assessment of two children.

Neuropsychological, neuroanatomical, and electrophysiological data are presented on two subjects with fetal alcohol syndrome (FAS). Both boys had intelligence quotients in the mentally deficient range and were found to have several other severe, specific deficits. Magnetic resonance imaging showed abnormalities of the corpus callosum, and reductions in the size of the basal ganglia and thalamic structures. No focal abnormalities were noted in the electroencephalogram records, although the electroencephalograms of both boys were moderately abnormal for their age group. A multidisciplinary approach to the study of FAS, hopefully will lead to a more unified concept of the disorder and perhaps indicate specific areas of vulnerability.

Adolescent↗
PubMed1992

Specific neurobehavioral profile of Williams' syndrome is associated with neocerebellar hemispheric preservation.

Previous work demonstrated enlargement of the neocerebellar vermis in Williams' syndrome (WS), despite diminished volumes in the cerebral hemispheres. We present the first in vivo volumetric study of any structure within the cerebellar hemispheres. Using MRI, we identified and reliably measured the neocerebellar tonsils in WS subjects; Down's syndrome (DS) subjects matched for age, IQ, and cerebral volume; and age-matched normal controls. WS tonsils were equal in size to control tonsils and larger than DS tonsils. In proportion to the cerebrum, WS tonsils were larger than controls'. These results coincide with the remarkable neuropsychological preservation of language and affect in WS, despite general cognitive impairment. They contrast with the neocerebellar vermal hypoplasia seen in autism, with its communicative and affective deficits. Additionally, two WS subjects showed Chiari type I malformations, but the average tonsillar position in WS was not found to be different than in controls.

Adolescent↗
PubMed1990

Anomalous brain morphology on magnetic resonance images in Williams syndrome and Down syndrome.

Quantitative studies of brain morphology in a group of subjects with Williams syndrome revealed a distinctive pattern of dysmorphology unlike that observed in another form of mental retardation. Down syndrome. Reduced cerebral size but normal cerebellar size was observed in Williams syndrome, in contrast to reductions in both brain components in Down syndrome. Examination of cerebellar vermal morphology suggested significantly increased area of neocerebellar vermal lobules in Williams syndrome, with low-normal size in the paleocerebellar vermal lobules. Thus, a highly selective effect on brain development appears to accompany Williams syndrome, with some brain subsystems, possibly later-developing ones, relatively spared.

Adolescent↗
PubMed1990

Neuropsychological, neurological, and neuroanatomical profile of Williams syndrome.

The general aim of our research is to understand the brain mechanisms that underlie language and cognition. In this paper, we present a new line of investigation which attempts to forge links between a specific neurodevelopmental disorder, a specific neuropsychological profile, and abnormal brain organization. We report on a dissociation between language and cognitive functions in Williams syndrome adolescents, in contrast to age- and IQ-matched Down syndrome adolescents. The Williams syndrome individuals exhibit an unusual fractionation of higher cortical functioning, with marked cognitive deficits, but selective sparing of syntax. Differences in spatial cognitive abilities in the 2 groups are investigated, showing peaks and valleys of abilities specific to Williams syndrome individuals. These neurobehavioral profiles are explored in light of new evidence regarding neurologic and neuroanatomical differences between the 2 matched groups of adolescents. Results from these combined studies should help clarify the neural systems that mediate language and cognitive functions.

Abnormalities, Multiple↗
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↗