A Within-subjects Experimental Protocol to Assess the Effects of Social Input on Infant EEG

Summary

This novel protocol is designed to assess the neural bases of social interaction in infants. The paradigm is designed to tease apart how various social inputs such as language, joint attention, and face-to-face interaction relate to infant neural activation. Infant EEG power is recorded during both social and nonsocial conditions.

Abstract

Despite the importance of social interactions for infant brain development, little research has assessed functional neural activation while infants socially interact. Electroencephalography (EEG) power is an advantageous technique to assess infant functional neural activation. However, many studies record infant EEG only during one baseline condition. This protocol describes a paradigm that is designed to comprehensively assess infant EEG activity in both social and nonsocial contexts as well as tease apart how different types of social inputs differentially relate to infant EEG. The within-subjects paradigm includes four controlled conditions. In the nonsocial condition, infants view objects on computer screens. The joint attention condition involves an experimenter directing the infant's attention to pictures. The joint attention condition includes three types of social input: language, face-to-face interaction, and the presence of joint attention. Differences in infant EEG between the nonsocial and joint attention conditions could be due to any of these three types of input. Therefore, two additional conditions (one with language input while the experimenter is hidden behind a screen and one with face-to-face interaction) were included to assess the driving contextual factors in patterns of infant neural activation. Representative results demonstrate that infant EEG power varied by condition, both overall and differentially by brain region, supporting the functional nature of infant EEG power. This technique is advantageous in that it includes conditions that are clearly social or nonsocial and allows for examination of how specific types of social input relate to EEG power. This paradigm can be used to assess how individual differences in age, affect, socioeconomic status, and parent-infant interaction quality relate to the development of the social brain. Based on the demonstrated functional nature of infant EEG power, future studies should consider the role of EEG recording context and design conditions that are clearly social or nonsocial.

Introduction

Social interactions are crucial for infant neural development ^1,2. Although recent research has begun to focus on the development of the social brain ^3,4, the neural processes involved in social engagement are not well understood. The goal of the reported method was to assess how infant electroencephalography (EEG) power, a measure of voltage released from neuronal communication, varies across controlled social and nonsocial contexts. This method allows for assessment of how specific aspects of social input differentially relate to neural activation an....

Protocol

All procedures were approved by the Boston University Institutional Review Board (IRB).

1. Recruitment

1. Identify potential participants through participant databases (if available), through publicly available state birth records, through online advertising, and through face-to-face recruitment events.
2. Call potential participants and invite them to participate in the study.
   1. Explain that the study is looking at social experiences and how they relate to brain development.
   2. Explain that a visit would involve using EEG to get a measure of the infant's brain activity using a stretchy cap made of soft spo....

Results

Infant Looking Behavior

Representative results are from 73 x 12-month old infants ¹². Conditions were effective in changing infants' looking behavior ¹⁶. In the social engagement condition, infants spent the majority of the time looking at the experimenter, as intended (on average, 60.06% of the time during the social engagement condition). Further, every infant looked at the experime.......

Discussion

First, it is critical that the net application is correct and that impedances are lowered. Second, it is important to explain to the parent what the EEG net application and paradigm will entail and how the parent can help calm the infant if they become fussy without speaking to or making eye contact with the infant, which would blur the lines between the social and non-social conditions. Further, instruct parents to keep infants from pulling on the net, which can affect the EEG data and cause damage to the net. Third, co.......

Materials

List of materials used in this article

Name	Company	Catalog Number	Comments
EEG Amplifier	EGI	N/A	We used a net amps 300 system. Contact EGI for more information or to purchase. https://www.egi.com/
EEG Sensor Nets	EGI	N/A	We used HDGSN 130 nets with 128 channels in pediatric sizes. Contact EGI for more information or to purchase. https://www.egi.com/clinical-division/geodesic-sensor-nets
EEG Recording Software	Netstation	N/A	Contact EGI for more information or to purchase. https://www.egi.com/clinical-division/net-station
EEG Recording Computer	Apple	N/A	An apple computer is required to run the Netstation software. The operating system just has to match the version of Netstation used.
Stimulus Presentation Computer	Dell	N/A	E-Prime 2.0 is compatible with PCs running Microsoft Windows XP SP3, Vista SP1, 7 SP1, 8/8.1 and 10
Stimulus Presentation Software - E-Prime 2.0 Professional Edition	Psychology Software Tools, Inc.	http://www.psychology-software-tools.mybigcommerce.com/e-prime-2-0-professional/
Stimulus Presentation Monitors	Dell	N/A	LCD monitors are appropriate.
Potassium Chloride	Sigma-Aldrich	http://www.sigmaaldrich.com/catalog/product/sigma/p9541?lang=en®ion=US
Pipettes	Karter Scientific Labware Manufacturing Co.	http://www.kartersci.com/7ml_ Volume_3ml_Graduated_ Transfer_Pipette_Karter_ p/206h2.htm
Disinfectant-Control 3 Disinfectent Germicide	Maril Products Inc	https://www.amazon.com/Control-Disinfectant-Germicide-Cntrl3-Concntr/dp/B007AZ37VC
EEG Processing Software	MATLAB	https://www.mathworks.com/products/matlab/
Data Analysis Software	SPSS	https://www.ibm.com/marketplace/cloud/statistical-analysis-and-reporting/purchase/us/en-us#product-header-top
Coding Software - The Observer XT	Noldus	http://www.noldus.com/
General Note: This equipment list includes what was used in the presented study, however other systems and products with the same capabilities are also appropriate.