EEG has been central to investigations of the time course of various neural functions underpinning visual word recognition. Recently the steady-state visual evoked potential (SSVEP) paradigm has been increasingly adopted for word recognition studies due to its high signal-to-noise ratio. Such studies, however, have been typically framed around a single source in the left ventral occipitotemporal cortex (vOT). Here, we combine SSVEP recorded from 16 adult native English speakers with a data-driven spatial filtering approach—Reliable Components Analysis (RCA)—to elucidate distinct functional sources with overlapping yet separable time courses and topographies that emerge when contrasting words with pseudofont visual controls. The first component topography was maximal over left vOT regions with a shorter latency (approximately 180 ms). A second component was maximal over more dorsal parietal regions with a longer latency (approximately 260 ms). Both components consistently emerged across a range of parameter manipulations including changes in the spatial overlap between successive stimuli, and changes in both base and deviation frequency. We then contrasted word-in-nonword and word-in-pseudoword to test the hierarchical processing mechanisms underlying visual word recognition. Results suggest that these hierarchical contrasts fail to evoke a unitary component that might be reasonably associated with lexical access.

Autism Spectrum Disorder (ASD) is thought to reflect disrupted development of brain connectivity characterized by white matter abnormalities and dyscoordination of activity across brain regions that give rise to core features. But there is little consensus about the nature, timing and location of white matter abnormalities as quantified with diffusion-weighted MRI. Inconsistent findings likely reflect small sample sizes, motion confounds and sample heterogeneity, particularly different age ranges across studies. We examined the microstructural integrity of major white matter tracts in relation to age in 38 high functioning ASD and 35 typically developing (TD) participants, aged 8–25, whose diffusion-weighted scans met strict data-quality criteria and survived group matching for motion. While there were no overall group differences in diffusion measures, the groups showed different relations with age. Only the TD group showed the expected positive correlations of fractional anisotropy with age. In parallel, axial diffusivity was unrelated to age in TD, but showed inverse correlations with age in ASD. Younger participants with ASD tended to have higher fractional anisotropy and axial diffusivity than their TD peers, while the opposite was true for older participants. Most of the affected tracts – cingulum bundle, inferior and superior longitudinal fasciculi – are association bundles related to cognitive, social and emotional functions that are abnormal in ASD. The manifestations of abnormal white matter development in ASD as measured by diffusion-weighted MRI depend on age and this may contribute to inconsistent findings across studies. We conclude that ASD is characterized by altered white matter development from childhood to early adulthood that may underlie abnormal brain function and contribute to core features.

Objectives: Children with congenital heart disease are at high risk for developmental sequelae. Most studies focus on preoperative and intraoperative predictors of developmental impairment, with less attention to the postoperative period. The relationship between patient-related factors specific to the postoperative course in the PICU following cardiac surgery with long-term neurodevelopmental outcomes in adolescence was examined. Design: Retrospective chart review of patients previously recruited to a study describing their developmental outcomes in adolescence. Setting: Single tertiary care pediatric hospital in Canada. Patients: Eighty adolescents, born between 1991 and 1999, with congenital heart disease who required open-heart surgery before 2 years old. Measurements and Main Results: Several variables related to acuity of illness and complexity of postoperative course in the PICU were collected. Outcome measures included the Movement-Assessment Battery for Children-2 (motor), Leiter Brief Intelligence Quotient (cognition), and Strength and Difficulties Questionnaire (behavior). Analyses examined associations between PICU variables and long-term outcomes. Longer mechanical ventilation (β = –0.49; p = 0.013) and dopamine use (β = –14.41; p = 0.012) were associated with lower motor scores. Dopamine use was associated with lower cognitive scores (β = –14.02; p = 0.027). Longer PICU stay (β = 0.18; p = 0.002), having an open chest postoperatively (β = 3.83; p = 0.017), longer mechanical ventilation (β = 0.20; p = 0.001), longer inotrope support (β = 0.27; p = 0.002), hours on dopamine (β = 0.01; p = 0.007), days to enteral feeding (β = 0.22; p = 0.012), lower hemoglobin (β = –0.11; p = 0.004), and higher creatinine (β = 0.05; p = 0.014) were all associated with behavioral difficulties. Conclusions: Several important developmental outcomes in adolescents were associated with factors related to their postoperative course in the PICU as infants. Findings may highlight those children at highest risk for neurodevelopmental sequelae and suggest new approaches to critical care management following open-heart surgery, with the aim of mitigating or preventing adverse long-term outcomes.