Margriet A. Groen

Qualitative differences between conscious and nonconscious processing? On inverse priming induced by masked arrows

In general, both consciously and unconsciously perceived stimuli facilitate responses to following similar stimuli. However, masked arrows delay responses to following arrows. This inverse priming has been ascribed to inhibition of premature motor activation, more recently even to special processing of nonconsciously perceived material. Here, inverse priming depended on particular masks, was insensitive to contextual requirements for increased inhibition, and was constant across response speeds. Putative signs of motor inhibition in the electroencephalogram may as well reflect activation of the opposite response. Consequently, rather than profiting from inhibition of primed responses, the alternative response is directly primed by perceptual interactions of primes and masks. Thus there is no need to assume separate pathways for nonconscious and conscious processing.

Does cerebral lateralization develop? A study using functional transcranial Doppler ultrasound assessing lateralization for language production and visuospatial memory

In the majority of people, language production is lateralized to the left cerebral hemisphere and visuospatial skills to the right. However, questions remain as to when, how, and why humans arrive at this division of labor. In this study, we assessed cerebral lateralization for language production and for visuospatial memory using functional transcranial Doppler ultrasound in a group of 60 typically developing children between the ages of six and 16 years. The typical pattern of left‐lateralized activation for language production and right‐lateralized activation for visuospatial memory was found in the majority of the children (58%). No age‐related change in direction or strength of lateralization was found for language production. In contrast, the strength of lateralization (independent of direction) for visuospatial memory function continued to increase with age. In addition, boys showed a trend for stronger right‐hemisphere lateralization for visuospatial memory than girls, but there was no gender effect on language laterality. We tested whether having language and visuospatial functions in the same hemisphere was associated with poor cognitive performance and found no evidence for this “functional crowding” hypothesis. We did, however, find that children with left‐lateralized language production had higher vocabulary and nonword reading age‐adjusted standard scores than other children, regardless of the laterality of visuospatial memory. Thus, a link between language function and left‐hemisphere lateralization exists, and cannot be explained in terms of maturational change.

Associations between handedness and cerebral lateralisation for language: a comparison of three measures in children.

It has been known for many years that hand preference is associated with cerebral lateralisation for language, but the relationship is weak and indirect. It has been suggested that quantitative measures of differential hand skill or reaching preference may provide more valid measures than traditional inventories, but to date these have not been validated against direct measures of cerebral lateralisation. We investigated the associations of three different handedness assessments; 1) a hand preference inventory, 2) a measure of relative hand skill, and 3) performance on a reaching task; with cerebral lateralisation for language function as derived from functional transcranial Doppler ultrasound during a language production task, in a group of 57 typically developing children aged from 6 to 16 years. Significant correlations between cerebral lateralisation for language production and handedness were found for a short version of the inventory and for performance on the reaching task. However, confidence intervals for the correlations overlapped and no one measure emerged as clearly superior to the others. The best handedness measures accounted for only 8–16% of the variance in cerebral lateralisation. These findings indicate that researchers should not rely on handedness as an indicator of cerebral lateralisation for language. They also imply that lateralisation of language and motor functions in the human brain show considerable independence from one another.

Reliability of a novel paradigm for determining hemispheric lateralization of visuospatial function

In most individuals, language production and visuospatial skills are subserved predominantly by the left and right hemispheres, respectively. Functional Transcranial Doppler (fTCD) provides a noninvasive and relatively low-cost method for measuring functional lateralization. However, while the silent word generation task provides an accurate and reliable paradigm for investigating lateralization of language production, there is no comparable gold-standard method for measuring visuospatial skills. Thirty undergraduate students (19 females) completed a task of spatial memory while undergoing fTCD recording. Participants completed this task at two different time points, separated by between 26 to 155 days. The relative activation between hemispheres averaged across all participants was found to be consistent across testing sessions. This was observed at the individual level also, with a quantitative index of lateralization showing high reproducibility. These findings indicate that the use of the spatial memory task with fTCD is a robust methodology for examining laterality of visuospatial skills.

No population bias to left-hemisphere language in 4-year-olds with language impairment

Background. An apparent paradox in the field of neuropsychology is that people with atypical cerebral lateralization do not appear to suffer any cognitive disadvantage, yet atypical cerebral lateralization is more common in children and adults with developmental language disorders. This study was designed to explore possible reasons for this puzzling pattern of results. Methods. We used functional transcranial Doppler ultrasound (fTCD) to assess cerebral blood flow during language production in 57 four-year-olds, including 15 children who had been late-talkers when first seen at 20 months of age. We categorized cerebral lateralization as left, right or bilateral, and compared proportions with each type of laterality with those seen in a previously tested sample of children aged 6–16 years. We also compared language scores at 4 years for those with typical and atypical lateralization, and then looked at the association the opposite way: comparing those with typical or impaired language in terms of their cerebral lateralization. Results. The distribution of types of cerebral lateralization was similar for 4-year-olds to that seen in older children. Overall, cerebral lateralization was not predictive of language level. However, for children who had language difficulties at 20 months and/or 4 years (N = 21), there was no population bias to left-hemisphere language activation, whereas children without language problems at either age showed a pronounced bias to left-sided language lateralization. Nevertheless, many children with right hemisphere language had no indications of language difficulties, confirming that atypical cerebral asymmetry is not a direct cause of problems. Conclusions. We suggest that atypical lateralization at the individual level is not associated with language impairment. However, lack of lateralization at the population level is a marker of risk for language impairment, which could be due to genetic or non-genetic causes.

Lateralisation of auditory processing in Down syndrome: a study of T-complex peaks Ta and Tb

It has long been argued that abnormal cerebral lateralisation might underlie the language problems that characterise Down syndrome, but to date only behavioural evidence has been provided. We used the auditory event-related potentials Ta and Tb of the T-complex to investigate lateralised processing of speech (vowels) and non-speech (simple and complex tones) sounds in children with Down syndrome and age-matched typically developing children. We also explored associations with speech and language abilities. Although changes in the Ta and Tb in response to increases in stimulus complexity and ‘speechness’ were similar across group, the Tb peak was delayed in children with Down syndrome across conditions. In addition, marked differences in the patterns of lateralisation of Ta latency and Tb amplitude were observed in children with Down syndrome, in response to both speech and non-speech sounds. No associations were found between Ta and Tb characteristics and speech and language abilities in children with DS.

What Oral Text Reading Fluency Can Reveal about Reading Comprehension.

Text reading fluency – the ability to read quickly, accurately and with a natural intonation – has been proposed as a predictor of reading comprehension. In the current study, we examined the role of oral text reading fluency, defined as text reading rate and text reading prosody, as a contributor to reading comprehension outcomes in addition to decoding efficiency and language comprehension. One hundred and six Dutch primary school children from fourth grade participated in this study and were assessed on decoding efficiency, vocabulary, syntactic ability, reading fluency performance and reading comprehension skills. Regression analysis showed that text reading prosody, not text reading rate, explained additional variance in reading comprehension performance when decoding efficiency and language comprehension were controlled for. This result suggests that the inclusion of text reading prosody as an aspect of text reading fluency is justified and that a natural intonation is associated with better comprehension of what is read.

Where were those rabbits? A new paradigm to determine cerebral lateralisation of visuospatial memory function in children.

Highlights ► A child-friendly fTCD task to measure cerebral lateralisation of visuospatial memory. ► Strong positive correlations were found between the child and adult versions. ► No associations between lateralisation and task performance were found. ► It was a valid measure of cerebral lateralisation for visuospatial memory in children.

The role of speech prosody and text reading prosody in children's reading comprehension

BACKGROUND Text reading prosody has been associated with reading comprehension. However, text reading prosody is a reading-dependent measure that relies heavily on decoding skills. Investigation of the contribution of speech prosody - which is independent from reading skills - in addition to text reading prosody, to reading comprehension could provide more insight into the general role of prosody in reading comprehension. AIMS The current study investigates how much variance in reading comprehension scores is explained by speech prosody and text reading prosody, after controlling for decoding, vocabulary, and syntactic awareness. SAMPLE A battery of reading and language assessments was performed by 106 Dutch fourth-grade primary school children. METHODS Speech prosody was assessed using a storytelling task and text reading prosody by oral text reading performance. Decoding skills, vocabulary, syntactic awareness, and reading comprehension were assessed using standardized tests. RESULTS Hierarchical regression analyses showed that text reading prosody explained 6% of variance and that speech prosody explained 8% of variance in reading comprehension scores, after controlling for decoding, vocabulary, and syntactic awareness. Phrasing was the significant factor in both speech and text reading. When added in consecutive order, phrasing in speech added 5% variance to phrasing in reading. In contrast, phrasing in reading added only 3% variance to phrasing in speech. CONCLUSIONS The variance that speech prosody explained in reading comprehension scores should not be neglected. Speech prosody seems to facilitate the construction of meaning in written language.

The contribution of executive functions to narrative writing in fourth grade children

The present study investigated the contribution of executive functions to narrative writing in fourth grade children, and evaluated to what extent executive functions contribute differentially to different levels of narrative composition. The written skills of 102 Dutch children in fourth grade were assessed using a narrative picture-elicitation task. In addition, a large test battery assessing transcription skills, language skills and executive functions, was administered. The results showed that executive functions contributed both directly and indirectly to narrative composition. More specifically, analyses revealed that inhibition and updating, but not planning, contributed directly to the text length of the narrative, and indirectly, through handwriting, to the text length, syntactic complexity, and story content. The findings underscore the need to assess a variety of executive functions and support the idea that in developing writers executive functions also play a role in more complex written composition tasks, such as narrative writing.