The neural correlates of inhibitory control in 10-month-old infants: A functional near-infrared spectroscopy study

Inhibitory control development from infancy to early childhood: A longitudinal fNIRS study

The developmental period from infancy to early childhood is one of substantial change - in advancements in cognitive skills, such as early executive functions, but also in the maturation of the prefrontal and parietal cortices that parallel such advances. The current study aims to investigate the emergence and development of inhibitory control, a core executive function, from infancy to early childhood. We collected longitudinal functional near-infrared spectroscopy (fNIRS) data from the same sample of participants at 10-months, 16-months, and 3½ years of age whilst they completed the Early Childhood Inhibitory Touchscreen Task. In our previous publications, we reported that 10-month-old infants recruited right lateralised regions of the prefrontal and parietal cortex when inhibition was required. Despite no change in response inhibition performance, 16-month-olds recruited broader and bilateral regions of the prefrontal and parietal cortex. Results of the current study found that 3½-year-olds activated regions of the right inferior parietal cortex and the right inferior frontal gyrus when inhibition was required. Response inhibition performance was significantly improved by early childhood, yet there was commonality in the brain regions recruited at 16-months and 3½ years. This could suggest that these brain regions are fundamental neural indices of inhibitory control, even from toddlerhood.

Shared neural correlates of interference control and response inhibition in adolescence and young adulthood

Inhibitory control (IC) is the ability to inhibit dominant or automatic behaviours, responses or thoughts, to allow for the selection of appropriate goal-directed responses. IC is a core executive function and has been associated with specific brain regions, such as the right inferior frontal gyrus (IFG) but also with a broader fronto-parietal network similar to the multiple demand network, which is thought to support the elaboration and maintenance of structured mental programs across a range of tasks. Here, functional magnetic resonance imaging data were collected from different IC tasks within the same participants to investigate similarities and differences in brain activation between tasks and age groups. Adolescents (11-15 years-old, n = 34) and adults (18-26, n = 33) completed block-design numerical Stroop and simple and complex Go/No-go (GNG) tasks. Univariate analyses showed large overlapping fronto-parietal activation in the Stroop and complex GNG tasks, with more limited activation in the simple GNG task. When compared to adolescents, adults showed greater increases in activation in the right IFG in the Stroop task and in temporo-parietal and precentral clusters in the complex GNG task. High multivariate similarity was observed across fronto-parietal regions between complex GNG and Stroop tasks, and between simple and complex GNG tasks, but was much lower between Stroop and simple GNG tasks. Adults showed greater similarity between complex GNG and Stroop tasks, suggesting increased reliance on shared neural processes across tasks, rather than increased specialisation of brain networks to specific aspects of IC over development.

Test-retest reliability of functional near infrared spectroscopy during tasks of inhibitory control and working memory

Functional near-infrared spectroscopy (fNIRS) has become a well-established tool for neuroscience research and been suggested as a potential biomarker during clinical assessment in individuals with mental disorders. Biomarker need to be objective indications of biological processes which can be measured accurately and reproducibly. Despite various applications in clinical research, test-retest reliability of the fNIRS signal has not yet been evaluated sufficiently. To assess reliability of the fNIRS signal during tasks of executive functions, a group of 34 healthy subjects (13 male, 21 female) were tested twice for inhibitory control and working memory. On a group level results show a specific activation pattern throughout the two sessions, reflecting a task-related frontal network associated with the assessed cognitive functions. On the individual level the retest reliability of the activation patterns were considerably lower and differed strongly between participants. In conclusion, the interpretation of fNIRS signal on a single subject level is partially hampered by its low reliability. More studies are needed to optimize the retest reliability of fNIRS and to be applied on a routine basis in developmental research.

Oscillatory But Not Aperiodic Frontal Brain Activity Predicts the Development of Executive Control From Infancy to Toddlerhood

Executive control (EC) emerges in the first year of life, with the ability to inhibit prepotent responses (inhibitory control [IC]) and to flexibly readapt (cognitive flexibility [CF]) steadily improving. Simultaneously, electrophysiological brain activity undergoes profound reconfiguration, which has been linked to individual variability in EC. However, most studies exploring this relationship have used relative/absolute power and tasks that combine different executive processes. In addition, brain activity conflates aperiodic and oscillatory activity, which hinders the interpretation of the relationship between power and cognition. In the current study, we used the Early Childhood Inhibitory Touchscreen Task (ECITT) to examine the development of EC skills from 9 to 16 months in a longitudinal sample, and related performance of the task to resting-state EEG (rs-EEG) power, separating oscillatory and aperiodic activity. Our results showed improvement in IC but not in CF with age. In addition, alpha and theta oscillatory activity were concurrent (9-mo.) and longitudinal predictors of CF in toddlerhood, whereas the aperiodic exponent of the EEG signal did not contribute to EC. These findings demonstrate the relevance of oscillatory brain activity for cognitive development and provide an early brain marker for the early development of EC.

Forming Connections: Functional Brain Connectivity is Associated With Executive Functioning Abilities in Early Childhood

Functional magnetic resonance imaging (fMRI) studies with adults provide evidence that functional brain networks, including the default mode network and frontoparietal network, underlie executive functioning (EF). However, given the challenges of using fMRI with infants and young children, little work has assessed the developmental trajectories of these networks or their associations with EF at key developmental stages. More recently, functional near-infrared spectroscopy (fNIRS) has emerged as a promising neuroimaging tool which can provide information on cortical functional networks and can be more easily implemented with young children. Children (N = 207; n = 116 male; n = 167 White) had fNIRS data recorded at infancy, 3, 5, and 7 years of age while watching a 2-min nonsocial video. At 3, 5, and 7 years, children completed behavioral assessments and parents completed questionnaires to assess child EF abilities. Results showed that, although early functional brain network connectivity was not associated with later functional brain connectivity, EF was concurrently and longitudinally associated with functional connectivity levels in both networks. Overall, these results inform the understanding of early emerging neural underpinnings of regulatory abilities and point to considerable change in the composition of functional brain networks and a conservation of function across development.

Cognitive control in infancy: Attentional predictors using a tablet-based measure

Cognitive control is a predictor of later-life outcomes and may underpin higher order executive processes. The present study examines the development of early cognitive control during the first 24-month. We evaluated a tablet-based assessment of cognitive control among infants aged 18- and 24-month. We also examined concurrent and longitudinal associations between attentional disengagement, general cognitive skills and cognitive control. Participants (N = 60, 30 female) completed the tablet-task at 18- and 24-month of age. Attentional disengagement and general cognitive development were assessed at 5-, 8-, 12-, 18- and 24-month using an eye-tracking measure and the Mullen Scales of Early Learning (MSEL), respectively. The cognitive control task demonstrated good internal consistency, sensitivity to age-related change in performance and stable individual differences. No associations were found between infant cognitive control and MSEL scores longitudinally or concurrently. The eye-tracking task revealed that slower attentional disengagement at 8-month, but faster disengagement at 18-month, predicted higher cognitive control scores at 24-month. This task may represent a useful tool for measuring emergent cognitive control. The multifaceted relationship between attention and infant cognitive control suggests that the rapid development of the attentional system in infancy results in distinct attentional skills, at different ages, being relevant for cognitive control development.

Rates of family history of autism and ADHD varies with recruitment approach and socio-economic status

Family history (FH) of autism and ADHD is not often considered during the recruitment process of developmental studies, despite high recurrence rates. We looked at the rate of autism or ADHD amongst family members of young children (9 to 46 months) in three UK-based samples (N = 1055) recruited using different methods. The rate of FH-autism or FH-ADHD was 3%-9% for diagnosed cases. The rate was highest in the sample recruited through an online participant pool, which also consisted of the most socio-economically diverse families. Lower parental education and family income were associated with higher rates of FH-ADHD and lower parental education with increased FH-autism. Thus, recruitment strategies have a meaningful impact on neurodiversity and the conclusions and generalizations that can be drawn. Specifically, recruitment using crowdsourcing websites could create a sample that is more representative of the wider population, compared to those recruited through university-related volunteer databases and social media.

Irritability Moderates the Association between Cognitive Flexibility Task Performance and Related Prefrontal Cortex Activation in Young Children

The association between cognitive flexibility and related neural functioning has been inconsistent. This is particularly true in young children, where previous studies have found heterogenous results linking behavior and neural function, raising the possibility of unexplored moderators. The current study explored the moderating role of dimensional irritability in the association between cognitive flexibility task performance and prefrontal activation in young children. A total of 106 3- to 7-year-old children were recruited to complete a custom-designed, child-adapted, cognitive flexibility task, and 98 of them were included in the data analysis. The children's dorsolateral prefrontal cortex activation was monitored using functional near-infrared spectroscopy, and their levels of irritability were reported by parents using the MAP-DB Temper Loss subscale. Results indicated that the mean reaction time of the cognitive flexibility task was negatively correlated with concurrent prefrontal activation. No evidence was found for the association between task accuracy and prefrontal activation. Moreover, irritability moderated the association between the mean reaction time and prefrontal activation. Children high in irritability exhibited a stronger negative association between the mean reaction time and related prefrontal activation than children low in irritability. The moderating model suggested a novel affective-cognitive interaction to investigate the associations between cognitive task performance and their neural underpinnings.

Influence of the environment on the early development of attentional control

The control of visual attention is key to learning and has a foundational role in the development of self-regulated behavior. Basic attention control skills emerge early in life and show a protracted development along childhood. Prior research suggests that attentional development is influenced by environmental factors in early and late childhood. Although, much less information is available about the impact of the early environment on emerging endogenous attention skills during infancy. In the current study we aimed to test the impact of parental socioeconomic status (SES) and home environment (chaos) in the emerging control of orienting in a sample of typically-developing infants. A group of 142 (73 female) 6-month-old infants were longitudinally tested at 6, 9 (n = 122; 60 female) and 16-18 (n = 91; 50 female) months of age using the gap-overlap paradigm. Median saccade latency (mdSL) and disengagement failure (DF) were computed as dependent variables for both overlap and gap conditions. Also, composite scores for a Disengagement Cost Index (DCI) and Disengagement Failure Index (DFI) were computed considering mdSL and DF of each condition, respectively. Families reported SES and chaos in the first and last follow-up sessions. Using Linear Mixed Models with Maximum Likelihood estimation (ML) we found a longitudinal decrease in mdSL in the gap but not in the overlap condition, while DF decreased with age independently of the experimental condition. Concerning early environmental factors, an SES index, parental occupation and chaos at 6 months were found to show a negative correlation with DFI at 16-18 months, although in the former case it was only marginally significant. Hierarchical regression models implementing ML showed that both SES and chaos at 6 months significantly predicted a lower DFI at 16-18 months. Results show a longitudinal progression of endogenous orienting between infancy and toddlerhood. With age, an increased endogenous control of orienting is displayed in contexts where visual disengagement is facilitated. Visual orienting involving attention disengagement in contexts of visual competition do not show changes with age. Moreover, these attentional mechanisms of endogenous control seem to be modulated by early experiences of the individual with the environment.

Using preregistration as a tool for transparent fNIRS study design

Significance

The expansion of functional near-infrared spectroscopy (fNIRS) methodology and analysis tools gives rise to various design and analytical decisions that researchers have to make. Several recent efforts have developed guidelines for preprocessing, analyzing, and reporting practices. For the planning stage of fNIRS studies, similar guidance is desirable. Study preregistration helps researchers to transparently document study protocols before conducting the study, including materials, methods, and analyses, and thus, others to verify, understand, and reproduce a study. Preregistration can thus serve as a useful tool for transparent, careful, and comprehensive fNIRS study design.

Aim

We aim to create a guide on the design and analysis steps involved in fNIRS studies and to provide a preregistration template specified for fNIRS studies.

Approach

The presented preregistration guide has a strong focus on fNIRS specific requirements, and the associated template provides examples based on continuous-wave (CW) fNIRS studies conducted in humans. These can, however, be extended to other types of fNIRS studies.

Results

On a step-by-step basis, we walk the fNIRS user through key methodological and analysis-related aspects central to a comprehensive fNIRS study design. These include items specific to the design of CW, task-based fNIRS studies, but also sections that are of general importance, including an in-depth elaboration on sample size planning.

Conclusions

Our guide introduces these open science tools to the fNIRS community, providing researchers with an overview of key design aspects and specification recommendations for comprehensive study planning. As such it can be used as a template to preregister fNIRS studies or merely as a tool for transparent fNIRS study design.

We need to talk about validity - A commentary on "Six solutions for more reliable infant research" from the viewpoint of an early executive functions researcher

In their methodological article, "Six solutions for more reliable infant research", Byers-Heinlein, Bergmann and Savalei (2021) present compelling arguments for why developmental researchers should report and consider measures of reliability more frequently in their work. They also provide useful guidance on solutions to this "reliability crisis". In this commentary, I highlight a further methodological aspect that I think is key to successful and robust infancy research, that of construct validity. I also discuss recent reliability data from my own research on early executive function development, analyses which were directly inspired by the target article.

Highlights

Considering measurement reliability and effect sizes is important for robust infant research and for optimising infant tasks to measure group-level effects or individual differences.Construct validity - making sure that we measure what we think we are measuring - is also important.A robust effect at the group-level may not always restrict reliability - it depends on the amount of true variation between infants.