Person:

Nelson, Charles

Background: Lead (Pb) and polychlorinated biphenyls (PCBs) are neurotoxic contaminants that have been related to impairment in response inhibition. Objectives: In this study we examined the neurophysiological correlates of the response inhibition deficits associated with these exposures, using event-related potentials (ERPs) in a sample of school-age Inuit children from Arctic Québec exposed through their traditional diet. Methods: In a prospective longitudinal study, we assessed 196 children (mean age, 11.3 years) on a visual go/no-go response inhibition paradigm. Pb, PCB, and mercury (Hg) concentrations were analyzed in cord and current blood samples. Hierarchical multiple regression analyses were conducted to examine the associations of contaminant levels to go/no-go performance (mean reaction time, percent correct go, percent correct no-go) and five ERPs [N2, P3, error-related negativity, error positivity (Pe), and correct response positivity (Pc)] after control for confounding variables. Results: Current blood Pb concentrations were associated with higher rates of false alarms and with decreased P3 amplitudes to go and no-go trials. Current plasma PCB-153 concentrations were associated with slower reaction times and with reduced amplitudes of the Pe and Pc response-related potentials. Hg concentrations were not related to any outcome on this task but showed significant interactions with other contaminants on certain outcomes. Conclusions: These results suggest that Pb exposure during childhood impairs the child’s ability to allocate the cognitive resources needed to correctly inhibit a prepotent response, resulting in increased impulsivity. By contrast, postnatal PCB exposure appears to affect processes associated with error monitoring, an aspect of behavioral regulation required to adequately adapt to the changing demands of the environment, which results in reduced task efficiency.:

3 experiments examined 7-month-old infants' ability to discriminate the facial expressions of happy vs. fear. Experiment 1 revealed that infants demonstrated discrimination of happy vs. fear expressions when posed by a single model but that this discrimination was affected by the order of stimulus presentation. In experiment 2 infants were shown 2 models posing the happing and fearful expressions and did not demonstrate generalization of the discrimination of happy versus fear across these models. The third and main experiment varied the test procedure. Here, infants demonstrated reliable generalized discrimination of the 2 expressions across different models. As in experiment 1, however, these results were constrained by the order in which the stimuli were presented. These consistent order effects were not due to the initial salience of the 2 expressions but, instead, appeared to reflect differential rates of habituation to happy vs. fear expressions.

Current research suggests that autism spectrum disorder (ASD) is characterized by asynchronous neural oscillations. However, it is unclear whether changes in neural oscillations represent an index of the disorder or are shared more broadly among both affected and unaffected family members. Additionally, it remains unclear how early these differences emerge in development and whether they remain constant or change over time. In this study we examined developmental trajectories in spectral power in infants at high- or low-risk for ASD. Spectral power was extracted from resting EEG recorded over frontal regions of the scalp when infants were 6, 9, 12, 18 and 24 months of age. We used multilevel modeling to assess change over time between risk groups in the delta, theta, low alpha, high alpha, beta, and gamma frequency bands. The results indicated that across all bands, spectral power was lower in high-risk infants as compared to low-risk infants at 6-months of age. Furthermore high-risk infants showed different trajectories of change in spectral power in the subsequent developmental window indicating that not only are the patterns of change different, but that group differences are dynamic within the first two years of life. These findings remained the same after removing data from a subset of participants who displayed ASD related behaviors at 24 or 36 months. These differences in the nature of the trajectories of EEG power represent important endophenotypes of ASD.

This paper provides an overview of the largest longitudinal investigation of institutionalized children less than 2 years old ever conducted. The Bucharest Early Intervention Project is an ongoing randomized controlled trial of foster placement as an alternative to institutionalization in abandoned infants and toddlers being conducted in Bucharest, Romania. In addition to describing the contexts in which this study is imbedded, we also provide an overview of the sample, the measures, and the intervention. We hope that the natural experiment of institutionalization will allow us to examine directly the effects of intervention on early deprivation. We hope it will provide answers to many of the critical questions that developmentalists have asked about the effects of early experience, the timing of deprivation, and the ameliorating effects of early intervention and provide clues to which underlying neurobiological processes are compromised by, and resilient to, dramatic changes in early experience.

Event-related potentials ~ERPs! were recorded to brief images of caregivers’ and strangers’ faces for 72 institutionalized children ~IG!, ages 7–32 months, and compared with ERPs from 33 children, ages 8–32 months,who had never been institutionalized. All children resided in Bucharest, Romania. Prominent differences in four ERP components were observed: early negative ~N170!, early positive ~P250!, midlatency negative ~Nc!, and positive slow wave ~PSW!. For all but the P250, the amplitude of these components was larger in the never instituionalized group than the institutionalized group; this pattern was reversed for the P250. Typical effects of the Nc ~amplitude greater to stranger vs. caregiver! were observed in both groups; in contrast, the IG group showed an atypical pattern in the PSW. These findings are discussed in the context of the role of experience in influencing the neural circuitry putatively involved in recognizing familiar and novel faces.

We sought to elucidate the behavioral and electrophysiological correlates of face processing, in adults and infants, by manipulating either the featural or configural information within the face. Two different experiments are reported. In these experiments, event-related potentials (ERPs) were recorded from the scalp while adult, 8-month-old, and 4-month-old participants completed configural-change and featural-change face tasks. The infants also completed a behavioral visual paired-comparison task with featural and configural face changes. ERP results reveal hemispheric differences in processing featural but not configural changes for the N170 in adults. Furthermore, featural and configural changes are processed differently within the right and left hemispheres. The right hemisphere N170 is significantly greater for configural compared to featural changes. The left hemisphere N170, however, exhibits the opposite effect. Infant data suggest that similar to adults, 8-month-old, but not 4-month-old participants, exhibit similar hemispheric differences between featural and configural changes for the P400 component. Behavioral results suggest increased sensitivity to both featural and configural face changes in 8-month-olds compared to 4-month-olds.

This study investigated the effects of early institutional care on memory and executive functioning. Subjects were participants in the Bucharest Early Intervention Project (BEIP) and included institutionalized children, children with a history of institutionalization who were assigned to a foster care intervention, and community children in Bucharest, Romania. Memory and executive functioning were assessed at the age of 8 years using the Cambridge Neuropsychological Test and Automated Battery (CANTAB). As expected, children with a history of early institutional care performed worse on measures of both visual memory and executive functioning compared to their peers without a history of institutional care. In comparing children randomly assigned to the foster care intervention with their peers who had continued care in the institution, initial comparisons did not show signifi cant differences on any of the memory or executive functioning outcomes. However, for one of the measures of executive functioning, after controlling for birth weight, head circumference, and duration of time spent in early institutional care, the foster care intervention was a signifi cant predictor of scores. These results support and extend previous fi ndings of defi cits in memory and executive functioning among school-age children with a history of early deprivation due to institutional care. This study has implications for the millions of children who continue to experience the psychosocial deprivation associated with early institutional care.

Two groups of Romanian children were compared on spectral power and coherence in the electroencephalogram (EEG)in early childhood. One group consisted of previously institutionalized children who had been randomly assigned to a foster care intervention at a mean age of 23 months. The second group had been randomized to remain in institutional care. Because of a policy of noninterference, a number of these children also experienced placement into alternative family care environments. There were minimal group differences between the foster care and institutionalized groups in EEG power and coherence across all measured frequency bands at 42 months of age. However, age at foster care placement within the foster care group was correlated with certain measures of EEG power and coherence. Earlier age at foster care placement was associated with increased alpha power and decreased short-distance EEG coherence. Further analyses separating age at placement from duration of intervention suggest that this effect may be more robust for EEG coherence than EEG band power. Supplementary analyses examined whether the EEG measures mediated changes in intellectual abilities within the foster care children, but no clear evidence of mediation was observed.

Background: Early psychosocial deprivation has profound effects on brain activity in the young child. Previous reports have shown increased power in slow frequencies of the electroencephalogram (EEG), primarily in the theta band, and decreased power in higher alpha and beta band frequencies in infants and children who have experienced institutional care. Methodology/Principal Findings: We assessed the consequences of removing infants from institutions and placing them into a foster care intervention on brain electrical activity when children were 8 years of age. We found the intervention was successful for increasing high frequency EEG alpha power, with effects being most pronounced for children placed into foster care before 24 months of age. Conclusions/Significance: The dependence on age of placement for the effects observed on high frequency EEG alpha power suggests a sensitive period after which brain activity in the face of severe psychosocial deprivation is less amenable to recovery

An essential aspect of infant language development involves the extraction of meaningful information from a continuous stream of auditory input. Studies have identified early abilities to differentiate auditory input along various dimensions, including the presence or absence of structural regularities. In newborn infants, frontal and temporal regions were found to respond differentially to these regularities (Gervain et al., 2008), and in order to examine the development of this abstract rule learning we presented 7- and 9-month-old infants with syllables containing an ABB pattern (e.g., “balolo”) or an ABC pattern (e.g., “baloti”) and measured activity in left and right lateral brain regions using near-infrared spectroscopy (NIRS). While prior newborn work found increases in oxyhemoglobin (oxyHb) activity in response to ABB blocks as compared to ABC blocks in anterior regions, 7- and 9-month-olds showed no differentiation between grammars in oxyHb. However, changes in deoxyhemoglobin (deoxyHb) pointed to a developmental shift, whereby 7-month-olds showed deoxyHb responding significantly different from zero for ABB blocks, but not ABC blocks, and 9-month-olds showed the opposite pattern, with deoxyHb responding significantly different from zero for the ABC blocks but not the ABB blocks. DeoxyHb responses were more pronounced over anterior regions. A grammar by time interaction also illustrated that during the early blocks, deoxyHb was significantly greater to ABC than in later blocks, but there was no change in ABB activation over time. The shift from stronger activation to ABB in newborns (Gervain et al., 2008) and 7-month-olds in the present study to stronger activation to ABC by 9-month-olds here is discussed in terms of changes in stimulus salience and novelty preference over the first year of life. The present discussion also highlights the importance of future work exploring the coupling between oxyHb and deoxyHb activation in infant NIRS studies.