The neuroradiological findings of children with developmental language disorder

PURPOSE: To investigate the general characteristics of glucose metabolism distribution and the functional deficit in the brain of children with developmental language delay (DLD), we compared functional neuroradiological studies such as positron emission tomography (PET) of a patient group of DLD children and a control group of attention- deficit hyperactivity disorder (ADHD) children. PATIENTS AND METHODS: Seventeen DLD children and 10 ADHD children under 10 years of age were recruited and divided into separate groups consisting of children less than 5 years of age or between 5 and 10 years of age. The PET findings of 4 DLD children and 6 control children whose ages ranged from 5 to 10 years were compared by Statistical Parametric Mapping (SPM) analysis. RESULTS: All of the DLD children revealed grossly normal findings in brain MRIs, however, 87.5% of them showed grossly abnormal findings in their PET studies. Abnormal findings were most frequent in the thalamus. The patient group showed significantly decreased glucose metabolism in both frontal, temporal and right parietal areas (p < 0.005) and significantly increased metabolism in both occipital areas (p < 0.05) as compared to the control group. CONCLUSION: This study reveals that DLD children may show abnormal findings on functional neuroradiological studies, even though structural neuroradiological studies such as a brain MRI do not show any abnormal findings. Frequent abnormal findings on functional neuroradiological studies of DLD children, especially in the subcortical area, suggests that further research with quantitative assessments of functional neuroradiological studies recruiting more DLD children and age-matched normal controls could be helpful for understanding the pathophysiology of DLD and other disorders confined to the developmental disorder spectrum.     

A systematic review and quantitative appraisal of fMRI studies of verbal fluency: role of the left inferior frontal gyrus

The left inferior frontal gyrus (LIFG) has consistently been associated with both phonologic and semantic operations in functional neuroimaging studies. Two main theories have proposed a different functional organization in the LIFG for these processes. One theory suggests an anatomic parcellation of phonologic and semantic operations within the LIFG. An alternative theory proposes that both processes are encompassed within a supramodal executive function in a single region in the LIFG. To test these theories, we carried out a systematic review of functional magnetic resonance imaging studies employing phonologic and semantic verbal fluency tasks. Seventeen articles meeting our pre-established criteria were found, consisting of 22 relevant experiments with 197 healthy subjects and a total of 41 peak activations in the LIFG. We determined 95% confidence intervals of the mean location (x, y, and z coordinates) of peaks of blood oxygenation level-dependent (BOLD) responses from published phonologic and semantic verbal fluency studies using the nonparametric technique of bootstrap analysis. Significant differences were revealed in dorsal-ventral (z-coordinate) localizations of the peak BOLD response: phonologic verbal fluency peak BOLD response was significantly more dorsal to the peak associated with semantic verbal fluency (confidence interval of difference: 1.9-17.4 mm). No significant differences were evident in antero-posterior (x-coordinate) or medial-lateral (y-coordinate) positions. The results support distinct dorsal-ventral locations for phonologic and semantic processes within the LIFG. Current limitations to meta-analytic integration of published functional neuroimaging studies are discussed.     

Response execution in lexical decision tasks obscures sex-specific lateralization effects in language processing: evidence from event-related potential measures during word reading

A common hypothesis about sex differences in language processing attributes these differences to a bilateral contribution of language-related brain areas in females and a left-hemispheric dominated activation in males. However, most imaging studies failed to find such a generalized lateralization effect and reported a left-lateralized activation in both sexes instead. In a previous semantic priming study, we found a sustained (approximately 190-640 ms) bilateral positivity in the ERP waveforms, which was larger for the female group. Word reading and lexical decision were confounded in that study. In the present study we used a delayed response to separate semantic processing from response selection and execution. The modification of the task design, together with a dense sensor array, showed that females developed a bilateral sustaining posterior positivity/frontal negativity during reading/semantic processing. In contrast, males showed an attenuated positivity at left posterior sites and an attenuated negativity at right frontal sites. This sex-specific lateralization effect disappeared during response processing, evoking a bilaterally distributed activation for both sexes (frontal negative and posterior positive), which was larger for the female subjects. We conclude that, at least under specific conditions, language processing evokes a bilateral activation in females and a lateralization effect in males. However, the processing of the response, which is dominated by a 'P300-like' component evoked by this process, evokes a larger activation in both sexes which obscures the sex-specific lateralization effect when semantic processing and response processing are not separated.     

Regional cerebral perfusion abnormalities in developmental language disorder

Objective A voxel based investigation of cerebral blood flow was conducted to identify brain functional differences during resting state between children with developmental language disorder (DLD) and normal controls. Method Using DSM–IV criteria, we selected 21 children with DLD.All children were examined by technetium–99m–HMPAO Brain SPECT. Using SPM analyses, we compared the SPECT images of children with DLD and those of 17 control subjects on a voxel by voxel basis using ANCOVA covarying for age. Results Reduced cerebral blood flow in the right putamen,the right inferior parietal cortex, and the left globus pallidus were found in children with DLD versus the controls. However, no area of increased cerebral blood flow was observed in children with DLD compared to the controls. Conclusion Though results should be interpreted cautiously, this study confirms the presence of functional defects in the basal ganglia and the inferior parietal lobe during the resting state of the brains of children with DLD. It also gives further evidence for functional deficits in basal ganglia as an important factor in the etiology of DLD.     

Working memory and proverb comprehension in adolescents with traumatic brain injury: a preliminary investigation

Primary objective: This study investigated the relationship between working memory and comprehension of low-familiarity proverbs in adolescents with traumatic brain injury (TBI).

Methods and procedures: Ten adolescents, aged 12-21 years who had suffered a TBI prior to the age of 10 years and 10 individually age-matched peers with typical development participated in the study. The participants listened to short paragraphs containing a proverb and interpreted the meaning of the proverb using a forced-choice task. In addition, participants engaged in a task that evaluated working memory ability. Main outcomes and results: Analysis revealed that individuals with TBI differed from their non-injured peers in their understanding of proverbs. In addition, working memory capacity influenced performance for all participants.

Conclusions: The importance of considering working memory when evaluating figurative language comprehension in adolescents with TBI is highlighted. Implications for future research, particularly with regard to varying working memory and task demands, are considered.     

Fast improvement of verbal memory function after left temporal tumour resection

CASE REPORT: A 7-y-old, right-handed girl presented at our clinic with complex partial seizures, behavioural problems and word-finding difficulties. Clinical examination was normal, but electroencephalogram revealed bilateral epileptic discharges in the temporal and paracentral leads. Magnetic resonance imaging showed an intracerebral mass in the left mesial temporal lobe in the areas of the gyrus temporooccipitalis medialis and gyrus parahippocampalis. Neuropsychological testing brought to light an above-average general intelligence, but the girl performed below average in verbal memory tests and average in figural memory tests. RESULTS: The tumour was completely removed by surgery. Neuropsychological testing 3 and 11 wk after tumour resection demonstrated above-average verbal learning and memory abilities and improved visual memory. The emotional disturbances, seizures and electroencephalogram abnormalities disappeared completely during the postoperative follow-up. CONCLUSION: After resection of a left temporal brain tumour, the patient was free of seizures, and neuropsychological functions recovered completely within weeks.     

Growth of infant communication between 8 and 12 months: a population study

AIM: To describe changes in infant prelinguistic communication skills between 8 and 12 months, and identify factors associated with those skills. METHODS: DESIGN: Parent questionnaire data for a prospective population-based cohort of infants in metropolitan Melbourne, Australia. PARTICIPANTS: 1911 infants born November 2002-August 2003. OUTCOME: Infant communication (Communication and Symbolic Behaviour Scales (CSBS)) at 8 and 12 months. Potential risk factors: sex; prematurity; multiple birth; sociodemographic indicators; maternal mental health, vocabulary and education; non-English speaking background; and family history of speech-language difficulties. Linear regression models were fitted to total standardised CSBS scores at 8 and 12 months. RESULTS: Social communication, especially the use of gesture, developed rapidly from 8 to 12 months. Female sex, twin birth, and family history were strongly associated with CSBS scores. The combined model accounted for 5% and 6% of the total variation at 8 and 12 months, respectively. CSBS score at 8 months strongly predicted CSBS score at 12 months (coefficient = 0.56, partial R(2) = 37.0). CONCLUSIONS: There is a dramatic increase in communication skills between 8 and 12 months, particularly the development of gesture, which (as in previous studies) predates and predicts future language development. Risk factors explained little variation in early communication trajectories and therefore, based on our findings, this developmental course is more likely to be biologically predetermined. Rather than focusing on risk factors, we suggest that language promotion activities in otherwise healthy young infants should either be universal or, if targeted, be based on the level of communication skills displayed.     

Attention development in 10-month-old infants selected by the WILSTAAR screen for pre-language difficulties

BACKGROUND: WILSTAAR comprises a programme for identifying and treating 8-10-month-old infants who are at risk of language and cognitive difficulties. It has been adopted by health trusts, and included in Sure Start intervention schemes, throughout the UK. This study addresses one of the main queries raised by critics of the programme, by providing evidence about the psychological abilities of infants who fail the WILSTAAR screening assessment. METHODS: Thirty 10-month-old infants who failed the screen ('at-risk' infants) and 30 gender- and age-matched infants who passed the screen ('not-at-risk' infants) were assessed using a standard, validated measure of attention, the Distractibility Task. RESULTS: The at-risk infants were found to have poorer focused attention, and were more distractible, than the not-at-risk infants. The not-at-risk infants were quicker in deducing that distractor slides included in the task were of little importance, spent more sustained periods of time in focused attention on toy play, and were quicker in learning to use the information available in the task. CONCLUSIONS: The findings contribute to knowledge about infants' psychological development and provide partial support for the thinking underlying WILSTAAR. Evidence was found to support concerns about the accuracy of the WILSTAAR screening assessment, and issues about the trade-off between assessment age and the inclusion of WILSTAAR in routine services are discussed.     

Discrimination of temporal synchrony in intermodal events by children with autism and children with developmental disabilities without autism

BACKGROUND: This project examined the intermodal perception of temporal synchrony in 16 young children (ages 4 to 6 years) with autism compared to a group of children without impairments matched on adaptive age, and a group of children with other developmental disabilities matched on chronological and adaptive age. METHOD: A preferential looking paradigm was used, where participants viewed non-linguistic, simple linguistic or complex linguistic events on two screens displaying identical video tracks, but one offset from the other by 3 seconds, and with the single audio track matched to only one of the displays. RESULTS: As predicted, both comparison groups demonstrated significant non-random preferential looking to violations of temporal synchrony with linguistic and non-linguistic stimuli. However, the group with autism showed an impaired, chance level of responding, except when presented with non-linguistic stimuli. CONCLUSIONS: Several explanations are offered for this apparently autism-specific, language-specific pattern of responding to temporal synchrony, and potential developmental sequelae are discussed.