electroencephalogram (eeg) and electrocardiogram (ecg) sensor application for the caregiver for home-based eeg hyperscanning

Real-Life EEG and ECG Synchronization in Infant-Caregiver Interactions

With the simultaneous recording of brain activities from two or more interacting subjects, also known as hyperscanning, it has become possible to elucidate the neural basis of social interactions in their complex, bidirectional, and fast-paced dynamics1. This technique has shifted the focus from studying individuals in isolated, tightly controlled settings to examining more naturalistic interactions, such as parent-child interactions during free play2,3, puzzle-solving4, and cooperative computer games5,6. These studies demonstrate that brain activities synchronize during social interactions, i.e., show temporal similarities, a phenomenon termed interpersonal neural synchrony (INS). However, the great majority of hyperscanning studies have been confined to laboratory settings. While this allows for better experimental control, it may come at the expense of losing some ecological validity. Behaviors observed in the laboratory may not be representative of the participants&#39; typical everyday interactive behaviors due to the unfamiliar and artificial setting and the nature of the tasks imposed7.
Recent advances in mobile neuroimaging devices, such as electroencephalography (EEG) or functional near-infrared spectroscopy (fNIRS), alleviate these issues by removing the requirement for participants to remain physically connected to the recording computer. Thus, they allow us to measure participants&#39; brain activities while they interact freely in the classroom or in their homes8,9. The advantage of EEG compared to other neuroimaging techniques, such as fNIRS, is that it has an excellent temporal resolution, which makes it particularly suitable for investigating fast-paced social dynamics10. Yet, it comes with the caveat that the EEG signal is highly vulnerable to motion and other physiological and non-physiological artifacts11.
Despite this, the first studies have successfully implemented EEG hyperscanning set-ups in realistic environments and conditions. For instance, Dikker et al.12 measured the EEG signal of a group of students while they engaged in various classroom activities, including attending lectures, watching videos, and participating in group discussions. This study, along with other studies8,9, has predominantly utilized dry EEG electrodes to ease the process of conducting measurements in non-laboratory settings. Compared to wet electrodes, which require the application of conductive gel or paste, dry electrodes offer notable advantages in terms of usability. They have been shown to exhibit comparable performance to wet electrodes in adult populations and stationary conditions; however, their performance may decrease in motion-related scenarios due to increased impedance levels13.
Here, we present a working protocol to capture synchronized recordings from a low-density seven-channel liquid gel EEG system with a single lead electrocardiography (ECG) connected to the same wireless amplifier (sampling rate: 500 Hz)&#160;of infant-caregiver dyads in a home setting. While active electrodes were used for adults, passive electrodes were used instead for infants since the latter typically comes in the form of ring electrodes, thereby easing the process of gel application. Additionally, EEG-ECG recordings were synchronized to three cameras and microphones to capture the participants&#39; behaviors from different angles. In the study, 8-12-month-old infants and their caregivers engaged in a reading and play task while their EEG, ECG, and behaviors were recorded. To minimize the impact of excessive movement on EEG signal quality, the tasks were conducted in a table-top setting (e.g., utilizing the kitchen table and an infant highchair), requiring participants to remain seated throughout the interaction task. Caregivers were provided with three age-appropriate books and table-top toys (equipped with suction cups to prevent them from falling). They were instructed to read to their child for approximately 5 min, followed by a 10 min play session with the toys.
This protocol details the methods for collecting synchronized EEG-ECG, video, and audio data during the reading and play tasks. The overall procedure, however, is not specific to this research design but is appropriate for different populations (e.g., parent-child dyads, friend dyads) and experimental tasks. The method of synchronization of different data streams will be presented. Further, a basic EEG preprocessing pipeline based on Dikker et al.12 will be outlined, and EEG data retention rates and quality control metrics will be reported. Since the specific analytical choices depend on a variety of factors (such as task design, research questions, EEG montage), hyperscanning-EEG analysis will not be detailed further, but instead, the reader will be referred to existing guidelines and toolboxes (e.g.,14 for guidelines;15,16 for hyperscanning analysis toolboxes). Finally, the protocol discusses challenges and potential solutions for EEG-ECG hyperscanning in the home and other real-world settings.

Author Spotlight: Capturing Infant-Caregiver Interactions Through Synchronized Multimodal Data Collection

Home-Based EEG Hyperscanning for Infant-Caregiver Social Interactions

Our research aims to study how social interactions between infants and caregivers can impact the infant's learning and development. We have developed a comprehensive hyperscanning protocol to capture synchronized EEG, ECG, and behavioral recordings from infant-caregiver dyads during interactive play tasks in the family home. Unlike prior hyperscanning protocols, which have primarily been conducted in laboratory environments, our experiment is conducted in the home setting.One key experimental challenge is balancing the need for standardization across home environments, which can limit ecological validity, with the flexibility required to promote naturalistic interactions between participants. This protocol offers unique insights into addressing potential issues and critical considerations regarding the experimental setup, tasks, and data collection in home settings. Additionally, our protocol provides a detailed demonstration of the design and setup of the multimodal synchronization of EEG, ECG, video and audio data into a single timeline.

Electroencephalogram (EEG) and Electrocardiogram (ECG) Sensor Application for the Caregiver for Home-Based EEG Hyperscanning

To begin, store the amplifier for the caregiver in the back pocket of the EEG cap to minimize cable movement and reduce EEG noise. Before applying the cap, check that the amplifier is securely stored and connected. With gloves on and after obtaining the caregiver's permission, clean the caregiver's forehead using alcohol swabs containing 70%isopropyl alcohol.Part the hair on both sides at the top of the ear following the natural hairline to expose the caregiver's ear. To measure the caregiver's head circumference, place the measuring tape around the nasion over the crest of the inion and between left and right dragus. Now using a crown like hand gesture, stretch the EEG cap from the inside.Start placing the cap from the caregiver's forehead towards the back of their head. Then hold the straps without releasing the cap. Pull them down towards the chin and fasten the hook and loop ends.Remove any bangs or strands of hair from the caregiver's face to avoid discomfort or vision obstruction. Then smooth down the cap gently to ensure close contact of the electrodes with the scalp and to eliminate any wrinkles on the cap. Next, place the measuring tape over the electrodes at the midline and measure the distance from the nasion to the inion.Adjust the cap using the scrunch and release method if necessary. Then measure the distance between the left and right dragus to ensure that the CZ electrode is at the midpoint of this measurement. Begin by applying gel to the reference and ground electrodes then proceed to gel the remaining electrodes starting with those at the back.When applying gel to the caregiver, use a syringe with a longer, finer tip. Insert the syringe's tip into the electrode opening, and use the bottom curve to part the hair. Dispense small amounts of gel while withdrawing the syringe.While applying gel to the passive infant cap electrodes, fill all electrode openings with gel and then use the cotton tips to part the hair in a gentle left to right motion. To improve electrode contact, use light as an impedance reference guide or refer to EEG recording software readings. After achieving low impedance on all EEG electrodes, clean the soft area under the participant's left collarbone with alcohol wipes.Attach circular tape to the bottom of the ECG electrode and apply enough gel to cover the electrodes well. Place the electrode on the soft area under the left clavicle and secure it with white masking tape over the sensor.

Research

JoVE Journal

Neuroscience

Prior hyperscanning studies that record the brain activities of caregivers and children concurrently have primarily been conducted within the confines of ...