Biomedical subjects

Ruth Campbell

Publications and source records attributed to Ruth Campbell.

22 records · Page 2Linked to original sources

PubMed2002

Speechreading circuits in people born deaf.

In hearing people, silent speechreading generates bilateral activation in superior temporal regions specialised for the perception of auditory speech [Science 276 (1997) 593; Neuroreport 11 (2000) 1729; Proceedings of the Royal Society London B 268 (2001) 451]. In the present study, FMRI data were collected from deaf and hearing volunteers while they speechread numbers and during a control task in which they counted nonsense mouth movements (gurns). Brain activation for silent speechreading in oral deaf participants was found primarily in posterior cingulate cortex and hippocampal/lingual gyri. In contrast to the pattern observed in the hearing group, deaf participants showed no speechreading-specific activation in left lateral temporal regions. These data suggest that acoustic experience shapes the functional circuits for analysing speech. We speculate on the functional role, the posterior cingulate gyrus may play in speechreading by profoundly congenitally deaf people.

Acoustics↗

PubMed2002

Neural systems underlying British Sign Language and audio-visual English processing in native users.

In order to understand the evolution of human language, it is necessary to explore the neural systems that support language processing in its many forms. In particular, it is informative to separate those mechanisms that may have evolved for sensory processing (hearing) from those that have evolved to represent events and actions symbolically (language). To what extent are the brain systems that support language processing shaped by auditory experience and to what extent by exposure to language, which may not necessarily be acoustically structured? In this first neuroimaging study of the perception of British Sign Language (BSL), we explored these questions by measuring brain activation using functional MRI in nine hearing and nine congenitally deaf native users of BSL while they performed a BSL sentence-acceptability task. Eight hearing, non-signing subjects performed an analogous task that involved audio-visual English sentences. The data support the argument that there are both modality-independent and modality-dependent language localization patterns in native users. In relation to modality-independent patterns, regions activated by both BSL in deaf signers and by spoken English in hearing non-signers included inferior prefrontal regions bilaterally (including Broca's area) and superior temporal regions bilaterally (including Wernicke's area). Lateralization patterns were similar for the two languages. There was no evidence of enhanced right-hemisphere recruitment for BSL processing in comparison with audio-visual English. In relation to modality-specific patterns, audio-visual speech in hearing subjects generated greater activation in the primary and secondary auditory cortices than BSL in deaf signers, whereas BSL generated enhanced activation in the posterior occipito-temporal regions (V5), reflecting the greater movement component of BSL. The influence of hearing status on the recruitment of sign language processing systems was explored by comparing deaf and hearing adults who had BSL as their first language (native signers). Deaf native signers demonstrated greater activation in the left superior temporal gyrus in response to BSL than hearing native signers. This important finding suggests that left- temporal auditory regions may be privileged for processing heard speech even in hearing native signers. However, in the absence of auditory input this region can be recruited for visual processing.

Adolescent↗

PubMed2002

High motion coherence thresholds in children with autism.

BACKGROUND: We assessed motion processing in a group of high functioning children with autism and a group of typically developing children, using a coherent motion detection task. METHOD: Twenty-five children with autism (mean age 11 years, 8 months) and 22 typically developing children matched for non-verbal mental ability and chronological age were required to detect the direction of moving dots in a random dot kinematogram. RESULTS: The group of children with autism showed significantly higher motion coherence thresholds than the typically developing children (i.e., they showed an impaired ability to detect coherent motion). CONCLUSIONS: This finding suggests that some individuals with autism may show impairments in low-level visual processing--specifically in the magnocellular visual pathway. The findings are discussed in terms of implications for higher-level cognitive theories of autism, and the suggestion is made that more work needs to be carried out to further investigate low-level visual processing in autism.

Adolescent↗

PubMedDate not supplied

Speechreading and its association with reading among deaf, hearing and dyslexic individuals.

Reading and speechreading are both visual skills based on speech and language processing. Here we explore individual differences in speechreading in profoundly prelingually deaf adults, hearing adults with a history of dyslexia, and hearing adults with no history of a literacy disorder. Speechreading skill distinguished the three groups: the deaf group were better speechreaders than hearing controls, who were better than the group with a history of dyslexia. The dyslexic group, while within range of hearing controls in terms of reading, nevertheless showed a residual deficit in speech/language processing when tested with silent speech. Within-group correlations suggested different associations between speechreading subtasks, reading and language skills. In particular, in the deaf and dyslexic groups, but not in the hearing controls, speechreading skill correlated with reading ability.

Adolescent↗