Sign Language Aphasia Research Articles

Experience of The Rehabilitation for Sign Language Aphasia due to The Damage of The Right Brain in A Left-handed Deaf Japanese Signer

Experience of The Rehabilitation for Sign Language Aphasia due to The Damage of The Right Brain in A Left-handed Deaf Japanese Signer

Neural basis of action understanding: Evidence from sign language aphasia

Background: The neural basis of action understanding is a hotly debated issue. The mirror neuron account holds that motor simulation in fronto-parietal circuits is critical to action understanding including speech comprehension, while others emphasise the ventral stream in the temporal lobe. Evidence from speech strongly supports the ventral stream account, but on the other hand, evidence from manual gesture comprehension (e.g., in limb apraxia) has led to contradictory findings.Aims: Here we present a lesion analysis of sign language comprehension. Sign language is an excellent model for studying mirror system function in that it bridges the gap between the visual–manual system in which mirror neurons are best characterised and language systems which have represented a theoretical target of mirror neuron research.Methods & Procedures: Twenty-one life-long deaf signers with focal cortical lesions performed two tasks: one involving the comprehension of individual signs and the other involving comprehension of signed sentences (commands). Participants’ lesions, as indicated on MRI or CT scans, were mapped onto a template brain to explore the relationship between lesion location and sign comprehension measures.Outcomes & Results: Single sign comprehension was not significantly affected by left hemisphere damage. Sentence sign comprehension impairments were associated with left temporal–parietal damage. We found that damage to mirror system related regions in the left frontal lobe were not associated with deficits on either of these comprehension tasks.Conclusions: We conclude that the mirror system is not critically involved in action understanding.

Sign language aphasia from a neurodegenerative disease

While Alois Alzheimer recognized the effects of the disease he described on speech and language in his original description of the disease in 1907, the effects of Alzheimer’s disease (AD) on language in deaf signers has not previously been reported. We evaluated a 55-year-old right-handed congenitally deaf woman with a 2-year history of progressive memory loss and a deterioration of her ability to communicate in American Sign Language, which she learned at the age of eight. Examination revealed that she had impaired episodic memory as well as marked impairments in the production and comprehension of fingerspelling and grammatically complex sentences. She also had signs of anomia as well as an ideomotor apraxia and visual-spatial dysfunction. This report illustrates the challenges in evaluation of a patient for the presence of degenerative dementia when the person is deaf from birth, uses sign language, and has a late age of primary language acquisition. Although our patient could neither speak nor hear, in many respects her cognitive disorders mirror those of patients with AD who had normally learned to speak.

Sign language aphasia due to left occipital lesion in a deaf signer

Localization of sign language production and comprehension in deaf people has been described as similar to that of spoken language aphasia. However, sign language employs a visuospatial modality through visual information. We present the first report of a deaf signer who showed substantial sign language aphasia with severe impairment in word production due to a left occipital lesion. This case may indicate the possibility of other localizations of plasticity.

Sign language aphasia following right hemisphere damage in a left-hander: A case of reversed cerebral dominance in a deaf signer?

Recent lesion studies have shown that left hemisphere lesions often give rise to frank sign language aphasias in deaf signers, whereas right hemisphere lesions do not, suggesting similar patterns of hemispheric asymmetry for signed and spoken language. We present here a case of a left-handed, deaf, life-long signer who became aphasic after a right-hemisphere lesion. The subject exhibits deficits in sign language comprehension and production typically associated with left hemisphere damaged signers. He also exhibits evidence of local versus global deficits similar to left-hemisphere lesioned hearing patients. This case represents reversed lateralization for sign language and also may represent reversed lateralization for visuo-spatial abilities in a deaf signer.

Aphasia in a user of British Sign Language: Dissociation between sign and gesture

This paper reports a single case investigation of “Charles”, a Deaf man with sign language aphasia following a left CVA. Anomia, or a deficit in sign retrieval, was a prominent feature of his aphasia, and this showed many of the well‐documented characteristics of speech anomia. For example, sign retrieval was sensitive to familiarity, it could be cued, and there were both semantic and phonological errors. Like a previous case in the literature (Corina, Poizner, Bellugi, Feinberg, Dowd, & O'Grady‐Batch, 1992), Charles demonstrated a striking dissociation between sign and gesture, since his gesture production was relatively intact. This dissociation was impervious to the iconicity of signs. So, Charles' sign production showed no effect of iconicity, and gesture production was superior to sign production even when the forms of the signs and gestures were similar. The implications of these findings for models of sign and gesture production are discussed.

Early dissociation of verbal and nonverbal gestural ability in an epileptic deaf child

Studies of sign language aphasia in deaf adults have provided the evidence for two separable verbal and nonverbal manual gesture systems. We report a congenitally deaf child with a idiopathic focal epilepsy of childhood who showed specific language impairment in French sign language. The child's amazing performances in miming or sketching pictures she was unable to sign support the notion of an early dissociation of the two gestural systems.

Early dissociation of verbal and nonverbal gestural ability in an epileptic deaf child

Studies of sign language aphasia in deaf adults have provided the evidence for two separable verbal and nonverbal manual gesture systems. We report a congenitally deaf child with a idiopathic focal epilepsy of childhood who showed specific language impairment in French sign language. The child's amazing performances in miming or sketching pictures she was unable to sign support the notion of an early dissociation of the two gestural systems.

Hemispheric Organization of Local- and Global-Level Visuospatial Processes in Deaf Signers and Its Relation to Sign Language Aphasia

Previous work has shown that deficits in the production and perception of signed language are linked to left hemisphere damage but not right hemisphere damage in deaf lifelong signers, whereas severe deficits in nonlinguistic visuospatial abilities are more frequent following right hemisphere damage than left hemisphere damage in this population. In the present study we investigated the extent to which sign language deficits in deaf individuals can be dissociated from more subtle visuospatial deficits commonly associated with left hemisphere damage in the hearing/speaking population. A group of left- or right-lesioned deaf signers were asked to reproduce (1) two line drawings (a house and an elephant) and (2) four hierarchical figures. Drawings were scored separately for the presence of local vs global features. Consistent with data from hearing patients, left hemisphere-damaged deaf subjects were significantly better at reproducing global-level features, whereas right hemisphere-damaged deaf subjects were significantly better at reproducing local-level features. This effect held for both types of stimuli. Local-level performance in the LHD group did not correlate with performance on sign language tasks, suggesting that language deficits in LHD deaf signers are in fact linguistic specific.

The neural organization of language: evidence from sign language aphasia

To what extent is the neural organization of language dependent on factors specific to the modalities in which language is perceived and through which it is produced? That is, is the left-hemisphere dominance for language a function of a linguistic specialization or a function of some domain-general specialization(s), such as temporal processing or motor planning? Investigations of the neurobiology of signed language can help answer these questions. As with spoken languages, signed languages of the deaf display complex grammatical structure but are perceived and produced via radically different modalities. Thus, by mapping out the neurological similarities and differences between signed and spoken language, it is possible to identify modality-specific contributions to brain organization for language. Research to date has shown a significant degree of similarity in the neurobiology of signed and spoken languages, suggesting that the neural organization of language is largely modality-independent.

The basis of the neural organization for language: evidence from sign language aphasia.

The basis of the neural organization for language: evidence from sign language aphasia.

The role of the left frontal operculum in sign language aphasia

The role of the left frontal operculum in sign language aphasia

The Role of the Left Frontal Operculum in Sign Language Aphasia

The Role of the Left Frontal Operculum in Sign Language Aphasia

The role of the left frontal operculum in sign language aphasia

Abstract Broca's area has long been implicated in aspects of speech production. But does this region play a role in the production of signed language in prelingually deaf individuals? In this report, we describe our findings in a patient, congenitally deaf and a native user of American Sign Language, who suffered an ischemic infarct involving the left frontal operculum. Our patient presented with an acute expressive aphasia that subsequently resolved, and a chronic deficit predominantly characterized by frequent phonemic-like paraphaslas. We conclude that the left frontal operculum does, in fact, play a role in the production of signed language.

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.

Impurity scattering of warm holes in germanium and silicon

Each year in the United States roughly 80,000 persons suffer an acquired aphasia (Brody, 1992). Some small percentage of these cases involves deaf individuals whose primary means of communication is a visual-manual language; in the United States, this is likely to be American Sign Language (ASL). Studies of sign language aphasia have advanced our understanding of the contributions of symbolic, motoric, and linguistic processes in human language. Importantly, these studies have helped alert the medical profession to the potential effects of this malady in the deaf population. This chapter provides an overview of the effects of left-and right-hemisphere damage in users of signed languages, and explores the theoretical implications of these findings. One aim of this chapter is to document the current status of the field and to foreshadow issues that are likely to be of interest in future studies.