Darren S. Kadis

Localization of Broca's area using verb generation tasks in the MEG: validation against fMRI.

Functional MRI (fMRI) is routinely used to non-invasively localize language areas. Magnetoencephalography (MEG) is being explored as an alternative technique. MEG tasks to localize receptive language are well established although there are no standardized tasks to localize expressive language areas. We developed two expressive language tasks for MEG and validated their localizations against fMRI data. Ten right-handed adolescents (μ=17.5 years) were tested with fMRI and MEG on two tasks: verb generation to pictures and verb generation to words. MEG and fMRI data were normalized and overlaid. The number of overlapping voxels activated in fMRI and MEG were counted for each subject, for each task, at different thresholding levels. For picture verb generation, there was 100% concordance between MEG and fMRI lateralization, and for word verb generation, there was 75% concordance. A count showed 79.6% overlap of voxels activated by both MEG and fMRI for picture verb generation and 50.2% overlap for word verb generation. The percentage overlap decreased with increasingly stringent activation thresholds. Our novel MEG expressive language tasks successfully identified neural regions involved in language production and showed high concordance with fMRI laterality. Percentage overlap of activated voxels was also high when validated against fMRI, but showed task-specific and threshold-related effects. The high concordance and high percentage overlap between fMRI and MEG activations confirm the validity of our new MEG task. Furthermore, the higher concordance from the picture verb generation task suggests that this is a promising task for use in the young clinical population.

Characterizing the Normal Developmental Trajectory of Expressive Language Lateralization Using Magnetoencephalography

To characterize the developmental trajectory for expressive language representation and to test competing explanations for the relative neuroplasticity of language in childhood, we studied 28 healthy children and adolescents (aged 5-19 years) participating in a covert verb generation task in magnetoencephalography. Lateralization of neuromagnetic responses in the frontal lobe was quantified using a bootstrap statistical thresholding procedure for differential beamformer analyses. We observed a significant positive correlation between left hemisphere lateralization and age. Findings suggest that adult-typical left hemisphere lateralization emerges from an early bilateral language network, which may explain the pediatric advantage for interhemispheric plasticity of language.

Quality of life in young adults who underwent resective surgery for epilepsy in childhood.

Purpose:  This study investigated quality of life (QOL) in young adults who had undergone epilepsy surgery before the age of 16 years. The contribution to QOL of seizure status in the prior year, sex, number of antiepileptic drugs, and mood were evaluated.

Psychosocial outcomes in children two years after epilepsy surgery: has anything changed?

Purpose: We prospectively explored psychosocial outcomes in children (7–18 years) 2 years after epilepsy surgery. This study built on our previous one that examined these children 1 year after surgery.

Relationship between speech motor control and speech intelligibility in children with speech sound disorders

UNLABELLED The current study was undertaken to investigate the impact of speech motor issues on the speech intelligibility of children with moderate to severe speech sound disorders (SSD) within the context of the PROMPT intervention approach. The word-level Childrens Speech Intelligibility Measure (CSIM), the sentence-level Beginners Intelligibility Test (BIT) and tests of speech motor control and articulation proficiency were administered to 12 children (3:11 to 6:7 years) before and after PROMPT therapy. PROMPT treatment was provided for 45 min twice a week for 8 weeks. Twenty-four naïve adult listeners aged 22-46 years judged the intelligibility of the words and sentences. For CSIM, each time a recorded word was played to the listeners they were asked to look at a list of 12 words (multiple-choice format) and circle the word while for BIT sentences, the listeners were asked to write down everything they heard. Words correctly circled (CSIM) or transcribed (BIT) were averaged across three naïve judges to calculate percentage speech intelligibility. Speech intelligibility at both the word and sentence level was significantly correlated with speech motor control, but not articulatory proficiency. Further, the severity of speech motor planning and sequencing issues may potentially be a limiting factor in connected speech intelligibility and highlights the need to target these issues early and directly in treatment. LEARNING OUTCOMES The reader will be able to: (1) outline the advantages and disadvantages of using word- and sentence-level speech intelligibility tests; (2) describe the impact of speech motor control and articulatory proficiency on speech intelligibility; and (3) describe how speech motor control and speech intelligibility data may provide critical information to aid treatment planning.

Self-reported symptoms of psychological well-being in young adults who underwent resective epilepsy surgery in childhood

Purpose:  This study investigated the relationship of childhood resective surgery for lesional epilepsy and recent seizure history on self‐reported symptoms of mood and psychological distress in young adults (aged 18–30).

Reading acceleration training changes brain circuitry in children with reading difficulties

Dyslexia is characterized by slow, inaccurate reading. Previous studies have shown that the Reading Acceleration Program (RAP) improves reading speed and accuracy in children and adults with dyslexia and in typical readers across different orthographies. However, the effect of the RAP on the neural circuitry of reading has not been established. In the current study, we examined the effect of the RAP training on regions of interest in the neural circuitry for reading using a lexical decision task during fMRI in children with reading difficulties and typical readers.

Pathology type does not predict language lateralization in children with medically intractable epilepsy

Purpose:  We examined potential differences in the effects of pathology type on language lateralization in pediatric epilepsy.

Characterizing Information Flux Within the Distributed Pediatric Expressive Language Network: A Core Region Mapped Through fMRI-Constrained MEG Effective Connectivity Analyses.

Abstract Using noninvasive neuroimaging, researchers have shown that young children have bilateral and diffuse language networks, which become increasingly left lateralized and focal with development. Connectivity within the distributed pediatric language network has been minimally studied, and conventional neuroimaging approaches do not distinguish task-related signal changes from those that are task essential. In this study, we propose a novel multimodal method to map core language sites from patterns of information flux. We retrospectively analyze neuroimaging data collected in two groups of children, ages 5–18 years, performing verb generation in functional magnetic resonance imaging (fMRI) (n = 343) and magnetoencephalography (MEG) (n = 21). The fMRI data were conventionally analyzed and the group activation map parcellated to define node locations. Neuronal activity at each node was estimated from MEG data using a linearly constrained minimum variance beamformer, and effective connectivity within canonical frequency bands was computed using the phase slope index metric. We observed significant (p ≤ 0.05) effective connections in all subjects. The number of suprathreshold connections was significantly and linearly correlated with participants age (r = 0.50, n = 21, p ≤ 0.05), suggesting that core language sites emerge as part of the normal developmental trajectory. Across frequencies, we observed significant effective connectivity among proximal left frontal nodes. Within the low frequency bands, information flux was rostrally directed within a focal, left frontal region, approximating Brocas area. At higher frequencies, we observed increased connectivity involving bilateral perisylvian nodes. Frequency-specific differences in patterns of information flux were resolved through fast (i.e., MEG) neuroimaging.

Changes in voice onset time and motor speech skills in children following motor speech therapy: Evidence from /pa/ productions

Abstract This study evaluated changes in motor speech control and inter-gestural coordination for children with speech sound disorders (SSD) subsequent to Prompts for Restructuring Oral and Muscular Phonetic Targets (PROMPT) intervention. We measured the distribution patterns of voice onset time (VOT) for a voiceless stop (/p/) to examine the changes in inter-gestural coordination. Two standardized tests were used (Verbal Motor Production Assessment for Children (VMPAC), GFTA-2) to assess the changes in motor speech skills and articulation. Data showed positive changes in patterns of VOT with a lower pattern of variability. All children showed significantly higher scores for VMPAC, but only some children showed higher scores for GFTA-2. Results suggest that the proprioceptive feedback provided through PROMPT had a positive influence on speech motor control and inter-gestural coordination in voicing behavior. This set of VOT data for children with SSD adds to our understanding of the speech characteristics underlying speech motor control. Directions for future studies are discussed.