Socioeconomic Inequalities Affect Brain Responses of Infants Growing Up in Germany.

Developmental changes in functional neural networks are sensitive to environmental influences. This EEG study investigated how infant brain responses relate to the social context that their families live in. Event-related potentials of 255 healthy, awake infants between six and fourteen months were measured during a passive auditory oddball paradigm. Infants were presented with 200 standard tones and 48 randomly distributed deviants. All infants are part of a longitudinal study focusing on families with socioeconomic and/or cultural challenges (Bremen Initiative to Foster Early Childhood Development; BRISE; Germany). As part of their familial socioeconomic status (SES), parental level of education and infant's migration background were assessed with questionnaires. For 30.6% of the infants both parents had a low level of education (≤10 years of schooling) and for 43.1% of the infants at least one parent was born abroad. The N2-P3a complex is associated with unintentional directing of attention to deviant stimuli and was analysed in frontocentral brain regions. Age was utilised as a control variable. Our results show that tone deviations in infants trigger an immature N2-P3a complex. Contrary to studies with older children or adults, the N2 amplitude was more positive for deviants than for standards. This may be related to an immature superposition of the N2 with the P3a. For infants whose parents had no high-school degree and were born abroad, this tendency was increased, indicating that facing multiple challenges as a young family impacts on the infant's early neural development. As such, attending to unexpected stimulus changes may be important for early learning processes. Variations of the infant N2-P3a complex may, thus, relate to early changes in attentional capacity and learning experiences due to familial challenges. This points towards the importance of early prevention programs.

Altered gamma and theta oscillations during multistable perception in schizophrenia.

OBJECTIVE: Coherent object perception in patients with schizophrenia is known to be impaired. Oscillatory brain dynamics constitute a fundamental mechanism for the coordinated communication of neural circuits. Such dynamics have been proposed to reflect impaired spatio-temporal integration of sensory and cognitive processes during object perception in schizophrenia. METHOD: EEG recordings of patients with schizophrenia (n = 23) and control participants (n = 23) were examined. Presented were either an ambiguous (multistable) stimulus, endogenously inducing switching between two perceptual alternatives, or a slightly modified unambiguous control stimulus, during which perceptual reversals were triggered by a minor change in the stimulus configuration. Event-related amplitude modulation induced by perceptual reversals was analyzed for theta (3-8 Hz) and gamma band oscillations (28-48 Hz). RESULTS: Patients displayed increased reaction times and more errors when indicating unambiguous reversals. The patients´ amplitude enhancement of theta oscillations was diminished in both task conditions. During the control task were gamma amplitudes larger in patients than in healthy participants. CONCLUSION: The results indicate that impairments in generating coherent percepts are reflected in alterations of multiple frequency bands and time windows. Changes in gamma band oscillations may reflect the patients' impairments in perceptuo-cognitive integration processes. Diminished theta amplitude modulation in patients further emphasize diminished top-down cognitive control during perceptual reversals. SIGNIFICANCE: This study provides insight into how theta and gamma oscillations underlie changes in object perception, and thereby possibly the generation of core symptoms, in schizophrenia. This paper is dedicated to Prof. Dr. Erol Basar, a pioneer in research on oscillatory braindynamics. He was tireless in his effort to understand brain functions and integratedphilosophy, physics, biology and psychology in his research. His vision on how informationis coded in brain networks inspired many researchers in the last 40 years. With him, we not only lose an exceptional researcher, but also a supportive academic teacher and mentor with a persistent, prolific enthusiasm for international and collaborative projects.

Novelty N2-P3a Complex and Theta Oscillations Reflect Improving Neural Coordination Within Frontal Brain Networks During Adolescence.

Adolescents are easily distracted by novel items than adults. Maturation of the frontal cortex and its integration into widely distributed brain networks may result in diminishing distractibility with the transition into young adulthood. The aim of this study was to investigate maturational changes of brain activity during novelty processing. We hypothesized that during adolescence, timing and task-relevant modulation of frontal cortex network activity elicited by novelty processing improves, concurrently with increasing cognitive control abilities. A visual novelty oddball task was utilized in combination with EEG measurements to investigate brain maturation between 8-28 years of age (n = 84). Developmental changes of the frontal N2-P3a complex and concurrent theta oscillations (4-7 Hz) elicited by rare and unexpected novel stimuli were analyzed using regression models. N2 amplitude decreased, P3a amplitude increased, and latency of both components decreased with age. Pre-stimulus amplitude of theta oscillations decreased, while inter-trial consistency, task-related amplitude modulation and inter-site connectivity of frontal theta oscillations increased with age. Targets, intertwined in a stimulus train with regular non-targets and novels, were detected faster with increasing age. These results indicate that neural processing of novel stimuli became faster and the neural activation pattern more precise in timing and amplitude modulation. Better inter-site connectivity further implicates that frontal brain maturation leads to global neural reorganization and better integration of frontal brain activity within widely distributed brain networks. Faster target detection indicated that these maturational changes in neural activation during novelty processing may result in diminished distractibility and increased cognitive control to pursue the task.