The role of executive functioning in memory performance in pediatric focal epilepsy.

OBJECTIVE: Learning and memory are essential for academic success and everyday functioning, but the pattern of memory skills and its relationship to executive functioning in children with focal epilepsy is not fully delineated. We address a gap in the literature by examining the relationship between memory and executive functioning in a pediatric focal epilepsy population. METHODS: Seventy children with focal epilepsy and 70 typically developing children matched on age, intellectual functioning, and gender underwent neuropsychological assessment, including measures of intelligence (Wechsler Abbreviated Scale of Intelligence [WASI]/Differential Ability Scales [DAS]), as well as visual Children's Memory Scale (CMS Dot Locations) and verbal episodic memory (Wide Range Assessment of Memory and Learning [WRAML] Story Memory and California Verbal Learning Test for Children [CVLT-C]). Executive functioning was measured directly (WISC-IV Digit Span Backward; Clinical Evaluation of Language Fundamentals, Fourth Edition (CELF-IV) Recalling Sentences) and by parent report (Behavior Rating Inventory of Executive Function [BRIEF]). RESULTS: Children with focal epilepsy had lower delayed free-recall scores than controls across visual and verbal memory tasks (p = 0.02; partial η2 = 0.12). In contrast, recognition memory performance was similar for patients and controls (p = 0.36; partial η2 = 0.03). Children with focal epilepsy demonstrated difficulties in working memory (p = 0.02; partial η2 = 0.08) and planning/organization (p = 0.02) compared to controls. Working memory predicted 9-19% of the variance in delayed free recall for verbal and visual memory; organization predicted 9-10% of the variance in verbal memory. Patients with both left and right focal epilepsy demonstrated more difficulty on verbal versus visual tasks (p = 0.002). Memory performance did not differ by location of seizure foci (temporal vs. extratemporal, frontal vs. extrafrontal). SIGNIFICANCE: Children with focal epilepsy demonstrated memory ability within age-level expectations, but delayed free recall was inefficient compared to typically developing controls. Memory difficulties were not related to general cognitive impairment or seizure localization. Executive functioning accounted for significant variance in memory performance, suggesting that poor executive control negatively influences memory retrieval.

Regional differences in the developmental trajectory of lateralization of the language network.

The timing and developmental factors underlying the establishment of language dominance are poorly understood. We investigated the degree of lateralization of traditional frontotemporal and modulatory prefrontal-cerebellar regions of the distributed language network in children (n = 57) ages 4 to 12--a critical period for language consolidation. We examined the relationship between the strength of language lateralization and neuropsychological measures and task performance. The fundamental language network is established by four with ongoing maturation of language functions as evidenced by strengthening of lateralization in the traditional frontotemporal language regions; temporal regions were strongly and consistently lateralized by age seven, while frontal regions had greater variability and were less strongly lateralized through age 10. In contrast, the modulatory prefrontal-cerebellar regions were the least strongly lateralized and degree of lateralization was not associated with age. Stronger core language skills were significantly correlated with greater right lateralization in the cerebellum.

Age of first words predicts cognitive ability and adaptive skills in children with ASD.

Acquiring useful language by age 5 has been identified as a strong predictor of positive outcomes in individuals with Autism Spectrum Disorders (ASD). This study examined the relationship between age of language acquisition and later functioning in children with ASD (n = 119). First word acquisition at a range of ages was probed for its relationship to cognitive ability and adaptive behaviors at 52 months. Results indicated that although producing first words predicted better outcome at every age examined, producing first words by 24 months was a particularly strong predictor of better outcomes. This finding suggests that the historic criterion for positive prognosis (i.e., "useful language by age 5") can be updated to a more specific criterion with an earlier developmental time point.

Brief report: a comparison of statistical learning in school-aged children with high functioning autism and typically developing peers.

Individuals with autism spectrum disorders have impairments in language acquisition, but the underlying mechanism of these deficits is poorly understood. Implicit learning is potentially relevant to language development, particularly in speech segmentation, which relies on sensitivity to transitional probabilities between speech sounds. This study investigated the relationship between implicit learning and current language abilities in school-aged children with high functioning autism and a history of language delay (n = 17) and in children with typical development (n = 24) using a well-studied artificial language learning task. Results suggest that high functioning children with autism (HFA) and TD groups were equally able to implicitly learn transitional probabilities from a lengthy stimulus stream. Furthermore, task performance was not strongly associated with current language abilities. Implications for implicit learning research in HFA are discussed.

Functional anatomy of listening and reading comprehension during development.

Listening and reading comprehension of paragraph-length material are considered higher-order language skills fundamental to social and academic functioning. Using ecologically relevant language stimuli that were matched for difficulty according to developmental level, we analyze the effects of task, age, neuropsychological skills, and post-task performance on fMRI activation and hemispheric laterality. Areas of supramodal language processing are identified, with the most robust region being left-lateralized activation along the superior temporal sulcus. Functionally, this conjunction has a role in semantic and syntactic processing, leading us to refer to this conjunction as "comprehension cortex." Different from adults, supramodal areas for children include less extensive inferior frontal gyrus but more extensive right cerebellum and right temporal pole. Broader neuroanatomical pathways are recruited for reading, reflecting the more active processing and larger set of cognitive demands needed for reading compared to listening to stories. ROI analyses reveal that reading is a less lateralized language task than listening in inferior frontal and superior temporal areas, which likely reflects the difficulty of the task as children in this study are still developing their reading skills. For listening to stories, temporal activation is stable by age four with no correlations with age, neuropsychological skills or post-task performance. In contrast, frontal activation during listening to stories occurs more often in older children, and frontal activation is positively correlated with better performance on comprehension questions, suggesting that the activation of frontal networks may reflect greater integration and depth of story processing.