Elena Plante

Normal fMRI Brain Activation Patterns in Children Performing a Verb Generation Task

Although much is known concerning brain-language relations in adults, little is known about how these functions might be represented during the developmental period. We report results from 17 normal children, ages 7-18 years, who have successfully completed a word fluency paradigm during functional magnetic resonance imaging at 3 Tesla. Regions of activation replicate those reported for adult subjects. However, a statistically significant association between hemispheric lateralization of activation and age was found in the children. Specifically, although most subjects at all ages showed left hemisphere dominance for this task, the degree of lateralization increased with age. This study demonstrates that fMRI can reveal developmental shifts in the pattern of brain activation associated with semantic language function.

Time course of word identification and semantic integration in spoken language.

The minimum duration signal necessary to identify a set of spoken words was established by the gating technique; most words could be identified before their acoustic offset. Gated words were used as congruous and incongruous sentence completions, and isolation points established in the gating experiment were compared with the time course of semantic integration evident in event-related brain potentials. Differential N400 responses to contextually appropriate and inappropriate words were observed about 200 ms before the isolation point. Semantic processing was evident before the acoustic signal was sufficient to identify the words uniquely. Results indicate that semantic integration can begin to operate with only partial, incomplete information about word identity. Influences of semantic constraint, word frequency, and rate of presentation are described.

Selection of Preschool Language TestsA Data-Based Approach

Clinicians are confronted with a wide range of norm-referenced tests designed to evaluate preschool language skills. This article approaches test selection from a data-based perspective. Twenty-one...

MRI findings in boys with specific language impairment

Magnetic resonance imaging scans of specifically language-impaired (SLI) boys were examined to determine whether atypical cerebral findings could be documented in children whose primary deficits were in language skills. Clinical examination of the scans failed to reveal any visually obvious lesions or abnormalities. In contrast, measurement of the scans revealed atypical perisylvian asymmetries in most of these subjects. The distribution of perisylvian asymmetries in SLI subjects was significantly different from the distribution in controls (p less than .01). Measurement of other brain regions revealed that extraperisylvian areas were occasionally deviant in individual SLI subjects; but no one region was consistently deviant across the SLI group. Thus, only atypical perisylvian asymmetries were linked to the language disorder. These neuroanatomical findings suggest that a prenatal alteration of brain development underlies specific language impairment.

A longitudinal functional magnetic resonance imaging study of language development in children 5 to 11 years old

Language skills continue to develop rapidly in children during the school‐age years, and the “snapshot” view of the neural substrates of language provided by current neuroimaging studies cannot capture the dynamic changes associated with brain development. The aim of this study was to conduct a 5‐year longitudinal investigation of language development using functional magnetic resonance imaging in healthy children.

Memory and executive function in older adults: relationships with temporal and prefrontal gray matter volumes and white matter hyperintensities

Forty-eight healthy adults aged 65-85 were recruited for structural magnetic resonance scans after an extensive neuropsychological battery that ensured a high degree of variability across the sample in performance on long-term memory tests, and on tests traditionally thought to rely on prefrontal cortex. Gray matter volumes were measured for three gyri in the frontal lobe (superior, middle, inferior), six gyri in the temporal lobe (superior, middle, inferior, fusiform, parahippocampal, and hippocampus), and the occipital lobe. Gray matter volumes declined across the age range evaluated, but with substantial regional variation--greatest in the inferior frontal, superior temporal, and middle temporal gyri but negligible in the occipital lobe. Both memory performance and executive function declined as the number of hyperintense regions in the subcortical white matter increased. Memory performance was also significantly correlated with gray matter volumes of the middle frontal gyrus (MFG), and several regions of temporal neocortex. However, the correlations were all in the negative direction; better memory performance was associated with smaller volumes. Several previous reports of significant negative correlations between gray matter volumes and memory performance are described, so that the possible reasons for this surprising finding are discussed.

Practical aspects of conducting large-scale functional magnetic resonance imaging studies in children

The potential benefits of functional magnetic resonance imaging (MRI) for the investigation of normal development have been limited by difficulties in its use with children. We describe the practical aspects, including failure rates, involved in conducting large-scale functional MRI studies with normal children. Two hundred and nine healthy children between the ages of 5 and 18 years participated in a functional MRI study of language development. Reliable activation maps were obtained across the age range. Younger children had significantly higher failure rates than older children and adolescents. It is concluded that it is feasible to conduct large-scale functional MRI studies of children as young as 5 years old. These findings can be used by other research groups to guide study design and plans for recruitment of young subjects. (J Child Neurol 2002;17:885—889).

Functional MRI of language lateralization during development in children.

Changes in the distribution of language function in the brain have been documented from infancy through adulthood. Even macroscopic measures of language lateralization reflect a dynamic process of language development. In this review, we summarize a series of functional MRI studies of language skills in children ages of five to 18 years, both typically-developing children and children with brain injuries or neurological disorders that occur at different developmental stages with different degrees of severity. These studies used a battery of fMRI-compatible language tasks designed to tap sentential and lexical language skills that develop early and later in childhood. In typically-developing children, lateralization changes with age are associated with language skills that have a protracted period of development, reflecting the developmental process of skill acquisition rather than general maturation of the brain. Normative data, across the developmental period, acts as a reference for disentangling developmental patterns in brain activation from changes due to developmental or acquired abnormalities. This review emphasizes the importance of considering age and child development in neuroimaging studies of language.

The Diagnostic Accuracy of Four Vocabulary Tests Administered to Preschool-Age Children.

This study examined the empirical evidence for using four vocabulary tests (Peabody Picture Vocabulary Test-III [Dunn & Dunn, 1997], Receptive One-Word Vocabulary Test [Gardner, 1985], Expressive Vocabulary Test [Williams, 1997], Expressive One-Word Vocabulary Test-Revised [Gardner, 1990]) to screen or identify specific language impairment (SLI) in preschool-age children. Tests were administered to 31 4- and 5-year-old children with SLI and 31 age-matched controls with normal language (NL). All children spoke General American English. Despite moderate to strong inter-test correlations, no test was a strong identifier of SLI. The group with SLI scored lower than the NL group on each test; however, the individual scores of children with SLI typically fell within the normal range. Vocabulary tests are frequently administered to determine whether a childs language skills require further evaluation (screening), as a method of identifying SLI in children, or simply to describe aspects of language functioning. These purposes for administering a vocabulary test require various forms of empirical evidence in support of their use. Our data support construct validity for the four vocabulary tests examined, but do not support their use for identification purposes. Clinicians must apply a degree of sophistication in evaluating the evidence presented for test validity relative to the purposes for which the test will be administered. Unfortunately, although many test manuals offer inter-test correlations or statistically significant group differences as evidence of construct validity, they often omit data that would support common clinical uses, such as screening or identification.

Cognitive Modules Utilized for Narrative Comprehension in Children: A Functional Magnetic Resonance Imaging Study

The ability to comprehend narratives constitutes an important component of human development and experience. The neural correlates of auditory narrative comprehension in children were investigated in a large-scale functional magnetic resonance imaging (fMRI) study involving 313 subjects ages 5-18. Using group independent component analysis (ICA), bilateral task-related components were found comprising the primary auditory cortex, the mid-superior temporal gyrus, the hippocampus, the angular gyrus, and medial aspect of the parietal lobule (precuneus/posterior cingulate). In addition, a right-lateralized component was found involving the most posterior aspect of the superior temporal gyrus, and a left-lateralized component was found comprising the inferior frontal gyrus (including Brocas area), the inferior parietal lobule, and the medial temporal gyrus. Using a novel data-driven analysis technique, increased task-related activity related to age was found in the components comprising the mid-superior temporal gyrus (Wernickes area) and the posterior aspect of the superior temporal gyrus, while decreased activity related to age was found in the component comprising the angular gyrus. The results are discussed in light of recent hypotheses involving the functional segregation of Wernickes area and the specific role of the mid-superior temporal gyrus in speech comprehension.