Validating a new methodology for optical probe design and image registration in fNIRS studies

Functional near-infrared spectroscopy (fNIRS) is an imaging technique that relies on the principle of shining near-infrared light through tissue to detect changes in hemodynamic activation. An important methodological issue encountered is the creation of optimized probe geometry for fNIRS recordings. Here, across three experiments, we describe and validate a processing pipeline designed to create an optimized, yet scalable probe geometry based on selected regions of interest (ROIs) from the functional magnetic resonance imaging (fMRI) literature. In experiment 1, we created a probe geometry optimized to record changes in activation from target ROIs important for visual working memory. Positions of the sources and detectors of the probe geometry on an adult head were digitized using a motion sensor and projected onto a generic adult atlas and a segmented head obtained from the subject's MRI scan. In experiment 2, the same probe geometry was scaled down to fit a child's head and later digitized and projected onto the generic adult atlas and a segmented volume obtained from the child's MRI scan. Using visualization tools and by quantifying the amount of intersection between target ROIs and channels, we show that out of 21 ROIs, 17 and 19 ROIs intersected with fNIRS channels from the adult and child probe geometries, respectively. Further, both the adult atlas and adult subject-specific MRI approaches yielded similar results and can be used interchangeably. However, results suggest that segmented heads obtained from MRI scans be used for registering children's data. Finally, in experiment 3, we further validated our processing pipeline by creating a different probe geometry designed to record from target ROIs involved in language and motor processing

The Neural Recruitment of Executive Function in Monolingual versus Bilingual Preterm-born Children: An FNIRS Study

Premature-birth is defined by the World Health Organization as birth less than 37 weeks. These children are particularly susceptible deficiencies in executive functioning (EF) as compared to term-born children. It has yet to be explored whether bilingualism might also give an edge to preterm-born-children (PBC) in EF. The present study aims to fill this gap by examining the EF of bilingual versus monolingual preterm-born children in Miami-Dade County. All 16 children were right-handed, ages 6-7, and born before 35 weeks. Results showed that both groups performed about the same on the Dimensional Change Card Sort (DCCS) and Go/No Go (GNG) task in terms of accuracy, however, the bilingual-PBC were over two times as fast in response as the monolingual group in the Go-trial suggesting faster information processing ability. Preliminary fNIRS analysis did not reveal a statistically significant difference in the brain activity over a broad area of the frontal lobe

Examining Perceptual and Categorical Influences on Visual Working Memory

Visual working memory (VWM) refers to the limited capacity storage of visual information used for behaviors like problem-solving, planning, or reasoning. VWM is a crucial component of cognition, and individual differences in capacity during childhood have been linked to outcomes in academic achievement, fluid intelligence, and socioemotional development. VWM increases in capacity and precision throughout development. Very few studies have investigated what factors influence changes in VWM abilities in preschool-aged children. The first goal of this study was to examine VWM precision development in this age-range. This was accomplished by administering a delayed estimation task. In this task, children touched a color wheel to indicate the color of an item in memory from a two-item array. Mixture modeling was used to measure the likelihood of reporting the target color and precision of the color represented in memory. The second goal of this project was to investigate the underlying neural, perceptual, and categorical mechanisms of VWM development. To measure perceptual mechanisms, children completed a discrimination task where they touched a color wheel to indicate the color of a visually presented color. For categorical mechanisms, children completed production and comprehension tasks for colors. To assess comprehension, children touched a color wheel to indicate the location of ‘blue’ and ‘green’. Lastly, for production, children provided ‘blue’ or ‘green’ labels for stimuli that were randomly sampled between canonical blue and green color values. Forty-four children aged 36-48 months completed these tasks across two sessions, as well as nine adults. Results showed deactivation across the delayed estimation and discrimination tasks in left postcentral gyrus, as well as activation for both in right middle temporal gyrus. In addition, right inferior gyrus was more strongly activated for the discrimination task, and left inferior frontal gyrus was more strongly activated for the delayed estimation task. Activation during both tasks was associated with behavioral measures such as the location of children’s color category boundary during production, suggesting a relationship between VWM precision and perceptual and categorical mechanisms

Early adversity in rural India impacts the brain networks underlying visual working memory

There is a growing need to understand the global impact of poverty on early brain and behavioural development, particularly with regard to key cognitive processes that emerge in early development. Although the impact of adversity on brain development can trap children in an intergenerational cycle of poverty, the massive potential for brain plasticity is also a source of hope: reliable, accessible, culturally-agnostic methods to assess early brain development in low resource settings might be used to measure the impact of early adversity, identify infants for timely intervention, and guide the development and monitor the effectiveness of early interventions. Visual working memory (VWM) is an early marker of cognitive capacity that has been assessed reliably in early infancy and is predictive of later academic achievement in Western countries. Here, we localized the functional brain networks that underlie VWM in early development in rural India using a portable neuroimaging system, and we assessed the impact of adversity on these brain networks. We recorded functional brain activity as young children aged 18-207 weeks performed a visual working memory task. Brain imaging results revealed localized activation in the frontal cortex, replicating findings from a midwestern US sample. Critically, children from families with low maternal education and income showed weaker brain activity and poorer distractor suppression in canonical working memory areas in the left frontal cortex. Implications of this work are far-reaching: it is now cost-effective to localize functional brain networks in early development in low-resource settings, paving the way for novel intervention and assessment methods

Evaluating motion processing algorithms for use with functional near-infrared spectroscopy data from young children

Motion artifacts are often a significant component of the measured signal in functional near-infrared spectroscopy (fNIRS) experiments. A variety of methods have been proposed to address this issue, including principal components analysis (PCA), correlation-based signal improvement (CBSI), wavelet filtering, and spline interpolation. The efficacy of these techniques has been compared using simulated data; however, our understanding of how these techniques fare when dealing with task-based cognitive data is limited. Brigadoi et al. compared motion correction techniques in a sample of adult data measured during a simple cognitive task. Wavelet filtering showed the most promise as an optimal technique for motion correction. Given that fNIRS is often used with infants and young children, it is critical to evaluate the effectiveness of motion correction techniques directly with data from these age groups. This study addresses that problem by evaluating motion correction algorithms implemented in HomER2. The efficacy of each technique was compared quantitatively using objective metrics related to the physiological properties of the hemodynamic response. Results showed that targeted PCA (tPCA), spline, and CBSI retained a higher number of trials. These techniques also performed well in direct head-to-head comparisons with the other approaches using quantitative metrics. The CBSI method corrected many of the artifacts present in our data; however, this approach produced sometimes unstable HRFs. The targeted PCA and spline methods proved to be the most robust, performing well across all comparison metrics. When compared head to head, tPCA consistently outperformed spline. We conclude, therefore, that tPCA is an effective technique for correcting motion artifacts in fNIRS data from young children

The Development and Relation of Working Memory and Fluid Intelligence in Middle and Late Childhood: A Neurocognitive Developmental Perspective

Working memory (WM) und fluid intelligence (Gf) are both key abilities in many cognitive development areas. Previous studies showed that both constructs are substantially related. However, WM consists of different aspects and it is not clear which of these aspects underlies this relation. Moreover, previous studies investigating the development of the neural basis of verbal WM have neglected the fact that WM and Gf are related. Accordingly, the main goal of the two studies presented in this dissertation was to gain a deeper understanding of the relation between WM and Gf. In addition, we aimed to investigate how age and Gf combine to affect WM performance and WM-related brain activity in middle and late childhood. The main question addressed in this umbrella paper was driven by the question of how Gf and WM develop, which was incorporated in both studies. The results revealed that WM and Gf improve with increasing age. Moreover, results showed that different WM aspects promote the development of WM as well as of Gf. However, also individual differences in Gf seem to foster the development in WM. Hence, the relation between WM and Gf seems to go in both directions. In addition, neural results revealed an age-by-Gf interaction effect on WM-related brain activation, indicating that also functional brain differences contribute to the development of WM and Gf. The results are discussed in terms of neural efficiency and in terms of theoretical and practical implications

Exploring the Effects of Response Type in a Visual Working Memory Task: An fNIRS Study

Visual working memory (VWM) allows us to hold visual information in mind to be manipulated for a task. Previous research shows that performance varies based on factors such as stimulus modality and number of distractors. This study aimed to explore the effect of response type on VWM performance in 4.5- and 5.5-year-olds. A single-item probe color change detection task and a cued recall with labeling task were administered. The tasks were identical in structure until the response phase of the trial. Neural data were collected using functional near-infrared spectroscopy. Both tasks used set-sizes 1-3 and six canonical colors (red, orange, yellow, green, blue, purple). All children were given the change detection task first. Behavioral analyses show a main effect of set size for both the change detection task, F(2, 618) = 85.37, p \u3c .001, and the cued recall task, F(2, 711) = 131.19, p \u3c .001, with a significant decrease in performance as set size increased. Moreover, VWM capacity was estimated to be higher in the change detection task (k4=2.12, k5=2.36) compared to the cued recall task (k4=1.18, k5=1.84) (p \u3c .001). When we look at the neural data, both tasks activated bilateral temporal and parietal cortices. Comparing same and different response in the change detection task, we saw a distinct network of activation for both in the 5-year-old group but not the 4-year-old group, suggesting a developmental shift in neural activity. The cued recall task elicited decreased activation patterns in the 5-year-old group in frontal and temporal regions which suggest a need for a greater amount of neural resources due to greater difficulty in the younger age group

Brain imaging and human nutrition: which measures to use in intervention studies?

The present review describes brain imaging technologies that can be used to assess the effects of nutritional interventions in human subjects. Specifically, we summarise the biological relevance of their outcome measures, practical use and feasibility, and recommended use in short- and long-term nutritional studies. The brain imaging technologies described consist of MRI, including diffusion tensor imaging, magnetic resonance spectroscopy and functional MRI, as well as electroencephalography/magnetoencephalography, near-IR spectroscopy, positron emission tomography and single-photon emission computerised tomography. In nutritional interventions and across the lifespan, brain imaging can detect macro- and microstructural, functional, electrophysiological and metabolic changes linked to broader functional outcomes, such as cognition. Imaging markers can be considered as specific for one or several brain processes and as surrogate instrumental endpoints that may provide sensitive measures of short- and long-term effects. For the majority of imaging measures, little information is available regarding their correlation with functional endpoints in healthy subjects; therefore, imaging markers generally cannot replace clinical endpoints that reflect the overall capacity of the brain to behaviourally respond to specific situations and stimuli. The principal added value of brain imaging measures for human nutritional intervention studies is their ability to provide unique in vivo information on the working mechanism of an intervention in hypothesis-driven research. Selection of brain imaging techniques and target markers within a given technique should mainly depend on the hypothesis regarding the mechanism of action of the intervention, level (structural, metabolic or functional) and anticipated timescale of the intervention's effects, target population, availability and costs of the technique

The Development of Attention Systems and Working Memory in Infancy

In this article, we review research and theory on the development of attention and working memory in infancy using a developmental cognitive neuroscience framework. We begin with a review of studies examining the influence of attention on neural and behavioral correlates of an earlier developing and closely related form of memory (i.e., recognition memory). Findings from studies measuring attention utilizing looking measures, heart rate, and event-related potentials (ERPs) indicate significant developmental change in sustained and selective attention across the infancy period. For example, infants show gains in the magnitude of the attention related response and spend a greater proportion of time engaged in attention with increasing age (Richards and Turner, 2001). Throughout infancy, attention has a significant impact on infant performance on a variety of tasks tapping into recognition memory; however, this approach to examining the influence of infant attention on memory performance has yet to be utilized in research on working memory. In the second half of the article, we review research on working memory in infancy focusing on studies that provide insight into the developmental timing of significant gains in working memory as well as research and theory related to neural systems potentially involved in working memory in early development. We also examine issues related to measuring and distinguishing between working memory and recognition memory in infancy. To conclude, we discuss relations between the development of attention systems and working memory