Event-related brain potentials and visual attention in six-month-old infants

Mother-infant convergence of event-related potentials elicited by face and object processing

Prior work has provided conceptual support for developmental changes in face and object processing, such that: face processing, as captured by the N290 event-related potential (ERP) component in infancy, may develop into the N170 in adulthood; and motivated attention, as captured by the negative central (Nc) in infancy, may develop into the late positive potential (LPP). The present study examined these neural correlates in 12-month-old infants and their mothers (N = 33 dyads). Dyads completed a viewing task consisting of familiar and novel face and toy stimuli while electroencephalography was recorded. Results suggest that for mothers, the N170 was larger for faces than toys, regardless of familiarity, and the LPP was largest for familiar faces. In infants, the N290 was somewhat larger for faces than toys (p < .10); the Nc did not vary by condition. Adult ERPs demonstrated fair to good reliability; reliability of infant ERPs was lower and was influenced by looking behaviors. Intergenerational associations were strongest between the LPP and Nc, particularly when electrode and time window were taken into account. Refinement of data handling and ERP scoring procedures for infant ERPs are crucial next steps for estimation of intergenerational associations and further examination of developmental changes in face and object processing.

Brief Report: Preliminary Evidence of the N170 as a Biomarker of Response to Treatment in Autism Spectrum Disorder

Background: Autism Spectrum Disorder (ASD) is a neurodevelopmental disorder characterized by primary difficulties in social function. Individuals with ASD display slowed neural processing of faces, as indexed by the latency of the N170, a face-sensitive event-related potential. Currently, there are no objective biomarkers of ASD useful in clinical care or research. Efficacy of behavioral treatment is currently evaluated through subjective clinical impressions. To explore whether the N170 might have utility as an objective index of treatment response, we examined N170 before and after receipt of an empirically validated behavioral treatment in children with ASD. Method: Electroencephalography (EEG) data were obtained on a preliminary cohort of preschool-aged children with ASD before and after a 16-week course of PRT and in a subset of participants in waitlist control (16-weeks before the start of PRT) and follow-up (16-weeks after the end of PRT). EEG was recorded while participants viewed computer-generated faces with neutral and fearful affect. Results: Significant reductions in N170 latency to faces were observed following 16 weeks of PRT intervention. Change in N170 latency was not observed in the waitlist-control condition. Conclusions: This exploratory study offers suggestive evidence that N170 latency may index response to behavioral treatment. Future, more rigorous, studies in larger samples are indicated to evaluate whether the N170 may be useful as a biomarker of treatment response.

Face-sensitive brain responses in the first year of life

Cortical areas in the ventral visual pathway become selectively tuned towards the processing of faces compared to non-face stimuli beginning around 3 months of age and continuing over the first year. Studies using event-related potentials in the EEG (ERPs) have found an ERP component, the N290, that displays specificity for human faces. Other components, such as the P1, P400, and Nc have been studied to a lesser degree in their responsiveness to human faces. However, little is known about the systematic changes in the neural responses to faces during the first year of life, and the localization of these responses in infants' brain. We examined ERP responses to pictures of faces and objects in infants from 4.5 months through 12 months in a cross-sectional study. We investigated the activity of all the components reported to be involved in infant face processing, with particular interest to their amplitude variation and cortical localization. We identified neural regions responsible for the component through the application of cortical source localization methods. We found larger P1 and N290 responses to faces than objects, and these components were localized in the lingual and middle/posterior fusiform gyri, respectively. The amplitude of the P400 was not differentially sensitive to faces over objects. The Nc component was different for faces and objects, was influenced by the infant's attentional state, and localized in medial-anterior brain areas. The implications of these results are discussed in the identification of developmental ERP precursors to face processing.

P300 development from infancy to adolescence

This article provides an overview of P300 research from infancy through adolescence. First, a brief historical overview is provided highlighting seminal studies that began exploration of the P300 component in developmental groups. Overall, these studies suggest that the P300 can be detected in children and appears to reflect similar cognitive processes to those in adults; however, it is significantly delayed in its latency to peak. Second, two striking findings from developmental research are the lack of a clear P300 component in infancy and differential electrophysiological responses to novel, unexpected stimuli in children, adolescents, and adults. Third, contemporary questions are described, which include P300-like components in infancy, alteration of P300 in atypically developing groups, relations between P300 and behavior, individual differences of P300, and neural substrates of P300 across development. Finally, we conclude with comments regarding the power of a developmental perspective and suggestions for important issues that should be addressed in the next 50 years of P300 research.

Early behavioral intervention is associated with normalized brain activity in young children with autism

OBJECTIVE

A previously published randomized clinical trial indicated that a developmental behavioral intervention, the Early Start Denver Model (ESDM), resulted in gains in IQ, language, and adaptive behavior of children with autism spectrum disorder. This report describes a secondary outcome measurement from this trial, EEG activity.

METHOD

Forty-eight 18- to 30-month-old children with autism spectrum disorder were randomized to receive the ESDM or referral to community intervention for 2 years. After the intervention (age 48 to 77 months), EEG activity (event-related potentials and spectral power) was measured during the presentation of faces versus objects. Age-matched typical children were also assessed.

RESULTS

The ESDM group exhibited greater improvements in autism symptoms, IQ, language, and adaptive and social behaviors than the community intervention group. The ESDM group and typical children showed a shorter Nc latency and increased cortical activation (decreased α power and increased θ power) when viewing faces, whereas the community intervention group showed the opposite pattern (shorter latency event-related potential [ERP] and greater cortical activation when viewing objects). Greater cortical activation while viewing faces was associated with improved social behavior.

CONCLUSIONS

This was the first trial to demonstrate that early behavioral intervention is associated with normalized patterns of brain activity, which is associated with improvements in social behavior, in young children with autism spectrum disorder.

Developmental change in the ERP responses to familiar faces in toddlers with autism spectrum disorders versus typical development

Individuals with autism spectrum disorder (ASD) show differences in face processing abilities from early in development. To examine whether these differences reflect an atypical versus delayed developmental trajectory, neural responses to familiar and unfamiliar faces in twenty-four 18- to 47-month-old children with ASD were compared with responses of thirty-two 12- to 30-month-old typically developing children. Results of 2 experiments revealed that neural responses to faces in children with ASD resembled those observed in younger typically developing children, suggesting delayed development. Electrophysiological responses to faces were also related to parent report of adaptive social behaviors for both children with ASD and typical development. Slower development of the face processing system in ASD may be related to reduced self-directed "expected" experience with faces in early development.