Asunto(s)

RESUMEN

Cochlear implants (CI) are the most successful intervention for ameliorating hearing loss in severely or profoundly deaf children. Despite this, educational performance in children with CI continues to lag behind their hearing peers. From animal models and human neuroimaging studies it has been proposed the integrative functions of auditory cortex are compromised by crossmodal plasticity. This has been argued to result partly from the use of a visual language. Here we argue that 'cochlear implant sensitive periods' comprise both auditory and language sensitive periods, and thus cannot be fully described with animal models. Despite prevailing assumptions, there is no evidence to link the use of a visual language to poorer CI outcome. Crossmodal reorganisation of auditory cortex occurs regardless of compensatory strategies, such as sign language, used by the deaf person. In contrast, language deprivation during early sensitive periods has been repeatedly linked to poor language outcomes. Language sensitive periods have largely been ignored when considering variation in CI outcome, leading to ill-founded recommendations concerning visual language in CI habilitation.

Asunto(s)

RESUMEN

There has been substantial research interest in recent years in the relationship between the development of language and cognition, especially where dissociations can be seen between them. Williams syndrome, a rare congenital disorder characterized by a fractionation of higher cortical functions, with relatively preserved language but marked difficulties with visuospatial constructive cognition, has been extensively studied. The case of Heather, who is remarkably similar to the characteristic phenotype of Williams syndrome in physical appearance and cognitive abilities, but who is also congenitally deaf and a user of British Sign Language, provides the first opportunity to explore the consequences of specific visuospatial learning difficulties on the linguistic system when the language used is visuospatial. Heather shows a pattern of impaired drawing ability and visual form discrimination, but preserved ability to discriminate faces. She has a large vocabulary in British Sign Language, and overall presents a picture of relative competence in British Sign Language grammar. However, she shows specific deficits in those areas of British Sign Language which directly rely on spatial representations for linguistic purposes. A number of theories as to the nature of her impairments and those found in Williams syndrome are discussed, using models of the relationship between language and visuospatial cognition based on data from this unique case.

Asunto(s)

RESUMEN

Landau-Kleffner syndrome (LKS) is an acquired aphasia which begins in childhood and is thought to arise from an epileptic disorder within the auditory speech cortex. Although the epilepsy usually subsides at puberty, a severe communication impairment often persists. Here we report on a detailed study of a 26-year old, left-handed male, with onset of LKS at age 5 years, who is aphasic for English but who learned British Sign Language (BSL) at age 13. We have investigated his skills in different language modalities, recorded EEGs during wakefulness, sleep, and under conditions of auditory stimulation, measured brain stem auditory-evoked potentials (BAEP), and performed functional MRI (fMRI) during a range of linguistic tasks. Our investigation demonstrated severe restrictions in comprehension and production of spoken English as well as lip-reading, while reading was comparatively less impaired. BSL was by far the most efficient mode of communication. All EEG recordings were normal, while BAEP showed minor abnormalities. fMRI revealed: 1) powerful and extensive bilateral (R > L) activation of auditory cortices in response to heard speech, much stronger than when listening to music; 2) very little response to silent lip-reading; 3) strong activation in the temporo-parieto-occipital association cortex, exclusively in the right hemisphere (RH), when viewing BSL signs. Analysis of these findings provides novel insights into the disturbance of the auditory speech cortex which underlies LKS and its diagnostic evaluation by fMRI, and underpins a strategy of restoring communication abilities in LKS through a natural sign language of the deaf (with Video)

Asunto(s)

RESUMEN

Does the lateral temporal cortex require acoustic exposure in order to become specialized for speech processing? Six hearing participants and six congenitally deaf participants, all with spoken English as their first langugage, were scanned using functional magnetic resonance imaging while performing a simple speech-reading task. Focal activation of the left lateral temporal cortex was significantly reduced in the deaf group compared with the hearing group. Activation within this region was present in individual deaf participants, but varied in location from person to person. Early acoustic experience may be required for regions within the left temporal cortex in order to develop into a coherent network with subareas devoted to specific speech analysis functions.

Asunto(s)

Asunto(s)

RESUMEN

In a previous study we used functional magnetic resonance imaging (fMRI) to demonstrate activation in auditory cortex during silent speechreading. Since image acquisition during fMRI generates acoustic noise, this pattern of activation could have reflected an interaction between background scanner noise and the visual lip-read stimuli. In this study we employed an event-related fMRI design which allowed us to measure activation during speechreading in the absence of acoustic scanner noise. In the experimental condition, hearing subjects were required to speechread random numbers from a silent speaker. In the control condition subjects watched a static image of the same speaker with mouth closed and were required to subvocally count an intermittent visual cue. A single volume of images was collected to coincide with the estimated peak of the blood oxygen level dependent (BOLD) response to these stimuli across multiple baseline and experimental trials. Silent speechreading led to greater activation in lateral temporal cortex relative to the control condition. This indicates that activation of auditory areas during silent speechreading is not a function of acoustic scanner noise and confirms that silent speechreading engages similar regions of auditory cortex as listening to speech.

Asunto(s)

RESUMEN

Can face actions that carry significance within language be perceived categorically? We used continua produced by computational morphing of face-action images to explore this question in a controlled fashion. In Experiment 1 we showed that question--type--a syntactic distinction in British Sign Language (BSL)--can be perceived categorically, but only when it is also identified as a question marker. A few hearing non-signers were sensitive to this distinction; among those who used sign, late sign learners were no less sensitive than early sign users. A very similar facial-display continuum between "surprise" and "puzzlement" was perceived categorically by deaf and hearing participants, irrespective of their sign experience (Experiment 2). The categorical processing of facial displays can be demonstrated for sign, but may be grounded in universally perceived distinctions between communicative face actions. Moreover, the categorical perception of facial actions is not confined to the six universal facial expressions.

Asunto(s)

Asunto(s)

RESUMEN

Many explanations have been put forward for the observed preference of mothers to cradle babies on the left side. These include handedness, the importance of the maternal heartbeat, left breast sensitivity, socio-psychological factors, and advantages in monitoring the infant. We propose that protection and facilitation of affective communication is at the core of cradling; and explore the relation between left-cradling and the role of the right hemisphere in early mother-infant interaction. Left-cradling not only directs maternal communication to the infant's right hemisphere but also facilitates affective feedback to the maternal right brain. The underlying neuro-linguistic mechanisms proposed in this article may be important in the early course of child language development and may also serve to illuminate our understanding of the evolution of human language.

Asunto(s)

RESUMEN

21 patients with rheumatoid arthritis of the wrist diagnosed according to the criteria of the American Rheumatism Association were examined by dynamic MRT before and after the i.v. injection of Gd-DTPA (0.1 mmol/kg). The results were correlated with the clinical and radiological findings. The increased signal intensity of the pannus was 1.17 +/- 0.45%/sec and this differed significantly (p < 0.001) from bone marrow (0.16 +/- 0.11%/sec) and from muscle (0.25 +/- 0.16%/sec). Blood sedimentation rate correlated with the gradient of synovial proliferation (p < 0.05). There were no further statistically significant correlations between the clinical, radiological and MRT findings and the change in signal intensity from synovial proliferation as shown by dynamic MRT.

Asunto(s)

RESUMEN

To obtain functional studies of the cervical spine, a device has been developed which allows MRI examinations to be carried out in five different degrees of flexion. T1 and T2* weighted FFE sequences were used. Dynamic functional MRI was performed on 5 normals and 31 patients (5 disc herniation, 4 whiplash injuries, 6 spinal canal stenoses, 14 laminectomies and spinal fusions, 2 rheumatoid arthritis). The relationship of the spinal cord to the bony and ligamentous components in different degrees of flexion was particularly well shown in whiplash injury, spinal stenosis and postoperative situations.

Asunto(s)

Asunto(s)