Monthly Archives: March 2011
Biological and Environmental Factors as Predictors of Language Skills in Very Preterm Children at 5 Years of Age
Conclusions: Results support the role of both biological and environmental factors in the evolution of language difficulties and highlight the need to consider these factors in the follow-up of preterm infants.
Predicting Persistence of and Recovery from Stuttering by the Teenage Years Based on Information Gathered at Age 8 Years
Conclusions: Persistence and recovery at teenage can be predicted from information that can be collected at around age 8 years with sensitivity and specificity of ∼80%.
Racial Disparities in Community Identification of Autism Spectrum Disorders Over Time; Metropolitan Atlanta, Georgia, 2000–2006
Conclusion: NHB children were less likely than NHW children to have been identified with less severe ASDs, which might have prevented or delayed intervention services that would have catered to their needs. This study illustrates the need for continued professional education, particularly concerning milder ASDs in minority groups.
Functional equivalence of the National Adult Reading Test (NART) and Schonell reading tests and NART norms in the Dynamic Analyses to Optimise Ageing (DYNOPTA) project
This study investigates the functional equivalence of two measures of irregular word pronunciation—National Adult Reading Test (NART) and Schonell—which are popular instruments used to assess verbal neurocognitive functioning and to estimate premorbid IQ. We report norms for the NART in a pooled sample from 3 Australian population-based studies of adults aged 65-103 years. Norms were stratified by sex and age left school in 5-year age groups. The NART and the Schonell had a strong linear relation, allowing for the imputation of NART scores based on Schonell performance within 1 study. Neither measure was sensitive to the effects of sex after adjusting for the effects of age and education. Early school leavers performed worse on both measures. Data pooling enables greater precision and improved generalizability of NART norms than do methods that use single older adult samples.
Mapping feature-sensitivity and attentional modulation in human auditory cortex with functional magnetic resonance imaging
Feature-specific enhancement refers to the process by which selectively attending to a particular stimulus feature specifically increases the response in the same region of the brain that codes that stimulus property. Whereas there are many demonstrations of this mechanism in the visual system, the evidence is less clear in the auditory system. The present functional magnetic resonance imaging (fMRI) study examined this process for two complex sound features, namely frequency modulation (FM) and spatial motion. The experimental design enabled us to investigate whether selectively attending to FM and spatial motion enhanced activity in those auditory cortical areas that were sensitive to the two features. To control for attentional effort, the difficulty of the target-detection tasks was matched as closely as possible within listeners. Locations of FM-related and motion-related activation were broadly compatible with previous research. The results also confirmed a general enhancement across the auditory cortex when either feature was being attended to, as compared with passive listening. The feature-specific effects of selective attention revealed the novel finding of enhancement for the nonspatial (FM) feature, but not for the spatial (motion) feature. However, attention to spatial features also recruited several areas outside the auditory cortex. Further analyses led us to conclude that feature-specific effects of selective attention are not statistically robust, and appear to be sensitive to the choice of fMRI experimental design and localizer contrast.
from the European Journal of Neuroscience
Recent studies have implicated anatomical differences in speech-relevant brain regions of adults who stutter (AWS) compared to normally fluent adults (NFA). The present study focused on the region of the corpus callosum (CC) which is involved in interhemispheric processing between the left and right cerebral hemispheres. Two-dimensional segmentation of area and voxel based morphometry were used to evaluate the corpus callosum. Results revealed that the rostrum and anterior midbody of the CC was larger in AWS than NFA. In addition, the overall callosa area was larger in AWS than NFA. The group comparison of white matter volume showed a cluster of increased white matter volume predominantly encompassing the rostrum across the midline portion in AWS. These results potentially reflect anatomical changes associated with differences in the hemispheric distribution of language processes that has been reported previously in AWS.
from the Journal of Communication Disorders
Older and younger readers read sentences in which target words were masked 40 to 60 ms after fixation onset. Masking only the target word caused more disruption than did masking each word in the sentence, and this effect was stronger for the younger readers than for the older readers. Although older readers had longer eye fixations than did younger readers, the results indicated that the masking effect was comparable for the 2 groups. However, for both groups, how long the eyes remained in place was strongly influenced by the frequency of the fixated word (even though it had been rapidly replaced by the mask and was no longer there when the eyes did move). This is compelling evidence that for both older and younger readers, cognitive/lexical processing has a very strong influence on when the eyes move in reading.
from Psychology and Aging
The impact of sensory acuity, processing speed, and working memory capacity on auditory working memory span (L-span) performance at 5 presentation levels was examined in 80 young adults (18–30 years of age) and 26 older adults (60–82 years of age). Lowering the presentation level of the L-span task had a greater detrimental effect on the older adults than on the younger ones. Furthermore, the relationship between sensory acuity and L-span performance varied as a function of age and presentation level. These results suggest that declining acuity plays an important explanatory role in age-related declines in cognitive abilities.
from Psychology and Aging
The present study addresses three questions regarding age differences in working memory: (1) whether performance on complex span tasks decreases as a function of age at a faster rate than performance on simple span tasks; (2) whether spatial working memory decreases at a faster rate than verbal working memory; and (3) whether the structure of working memory abilities is different for different age groups. Adults, ages 20–89 (n = 388), performed three simple and three complex verbal span tasks and three simple and three complex spatial memory tasks. Performance on the spatial tasks decreased at faster rates as a function of age than performance on the verbal tasks, but within each domain, performance on complex and simple span tasks decreased at the same rates. Confirmatory factor analyses revealed that domain-differentiated models yielded better fits than models involving domain-general constructs, providing further evidence of the need to distinguish verbal and spatial working memory abilities. Regardless of which domain-differentiated model was examined, and despite the faster rates of decrease in the spatial domain, age group comparisons revealed that the factor structure of working memory abilities was highly similar in younger and older adults and showed no evidence of age-related dedifferentiation.
from Psychology and Aging
Numerous studies have shown that imitating observed actions belongs to the same category of processes involved in planning and executing actions. New competencies may be acquired by actually executing a task or by executing a task after having seen how to do it. The performance of thirty dyslexic children was compared with that of an age- and gender-matched group of thirty normally reading children on tasks of learning a visuo-motor sequence by observation or by trial and error. The children observed an actor detecting a visuo-motor sequence and then performed the task reproducing either the previously observed sequence or a new one (Learning by Observation), or detected a sequence by trial and error (Learning by Doing), or first performed the task by trial and error and then performed it after an observational training (Learning by Observation after Doing). Results demonstrate that the dyslexic children were severely impaired in learning a sequence by observation, were able to detect a sequence by trial and error, and became as efficient as normal readers in reproducing an observed sequence after a task of learning by doing. Thus, the impaired ability to learn by observation could be reversed by agentive experience that supplied dyslexic children with a powerful learning mechanism, which enabled them to efficiently transfer action information across modalities. The beneficial effect of practice on the ability to learn by observation could provide dyslexic children a useful chance to acquire new cognitive abilities through more tuned teaching approach.
Normal language acquisition is a process that unfolds with amazing speed primarily in the first years of life. However, the refinement of linguistic proficiency is an ongoing process, extending well into childhood and adolescence. An increase in lateralization and a more focussed productive language network have been suggested to be the neural correlates of this process. However, the processes underlying the refinement of language comprehension are less clear. Using a language comprehension (Beep Stories) and a language production (Vowel Identification) task in fMRI, we studied language representation and lateralization in 36 children, adolescents, and young adults (age 6–24 years). For the language comprehension network, we found a more focal activation with age in the bilateral superior temporal gyri. No significant increase of lateralization with age could be observed, so the neural basis of language comprehension as assessed with the Beep Stories task seems to be established in a bilateral network by late childhood. For the productive network, however, we could confirm an increase with age both in focus and lateralization. Only in the language comprehension task did verbal IQ correlate with lateralization, with higher verbal IQ being associated with more right-hemispheric involvement. In some subjects (24%), language comprehension and language production were lateralized to opposite hemispheres.
from Brain and Language
Initiating and responding to joint attention bids in children with autism: A review of the literature
Joint attention is a skill that involves coordinating the attention of at least two individuals towards an object or event. Although it is seen as a critical skill in early child development, it is frequently absent in children with autism and has been linked to poorer language outcomes for those children. As a result, multiple interventions have been developed to teach children with autism to respond to, and initiate, bids for joint attention. These interventions, however, differ widely both in terms of procedures used and in whether they focus on teaching children to respond to, or initiate, bids for joint attention. This literature review was conducted to document research gaps and intervention similarities between joint attention intervention studies for children with autism. The specific intent of this review was to determine whether researchers teach responding and initiating separately or sequentially, describe the extent to which procedures differ among studies, and identify whether social or non-social consequences are used during joint attention training. Implications for the treatment of joint attention deficits are discussed and recommendations to both researchers and practitioners are provided.
Speakers generally outperform signers when asked to recall a list of unrelated verbal items. This phenomenon is well established, but its source has remained unclear. In this study, we evaluate the relative contribution of the three main processing stages of short-term memory – perception, encoding, and recall – in this effect. The present study factorially manipulates whether American Sign Language (ASL) or English is used for perception, memory encoding, and recall in hearing ASL-English bilinguals. Results indicate that using ASL during both perception and encoding contributes to the serial span discrepancy. Interestingly, performing recall in ASL slightly increased span, ruling out the view that signing is in general a poor choice for short-term memory. These results suggest that despite the general equivalence of sign and speech in other memory domains, speech-based representations are better suited for the specific task of perception and memory encoding of a series of unrelated verbal items in serial order through the phonological loop. This work suggests that interpretation of performance on serial recall tasks in English may not translate straightforwardly to serial tasks in sign language.
Progressive mitochondrial myopathy, deafness, and sporadic seizures associated with a novel mutation in the mitochondrial tRNASer(AGY) gene
We sequenced the mitochondrial genome from a patient with progressive mitochondrial myopathy associated with deafness, sporadic seizures, and histological and biochemical features of mitochondrial respiratory chain dysfunction. Direct sequencing showed a heteroplasmic mutation at nucleotide 12262 in the tRNASer(AGY) gene. RFLP analysis confirmed that 63% of muscle mtDNA harboured the mutation, while it was absent in all the other tissues. The mutation is predicted to influence the functional behaviour of the aminoacyl acceptor stem of the tRNA. Several point mutations on mitochondrial tRNA genes have been reported in patients affected by encephalomyopathies, but between them only four were reported for tRNASer(AGY).
from the Journal of the Neurological Sciences
The role of the left anterior temporal lobe in language processing revisited: Evidence from an individual with ATL resection
Various hypotheses about the role of the anterior temporal lobe (ATL) in language processing have been proposed. One hypothesis is that it binds the semantic/conceptual properties of words, functioning as a hub for linking modality-specific conceptual properties of objects. This hypothesis predicts that damage to ATL would give rise to impaired conceptual knowledge of all categories. A related school of hypotheses assumes that the left ATL is critical for lexical retrieval, with different sub-regions potentially important for different categories of items. We examined these hypotheses by studying a case of surgical resection of left ATL due to a low-grade glioma (LGG). Thorough language assessments performed four months after the operation revealed the following profile: the patient showed intact conceptual knowledge for all categories of items tested using both accuracy and response latency measures; he suffered from name retrieval deficits for proper names (people and place names) and artifacts (including tools), but showed no name retrieval difficulties for animate things. This pattern of results challenges both target hypotheses about the role of ATL in language processing tested here.