Functional and Structural Optical Brain Imaging

Eunice Kennedy Shriver National Institute Of Child Health & Human Development

Investigators

Linked publications, trials & patents

Abstract

Utilizing Functional near-infrared spectroscopy (fNIRS) in conjunction with complementary neuroimaging techniques, we investigated cortical activation in two distinct cohorts: 1) a group of healthy volunteers, and 2) infants and children, both with and without developmental disorders. The primary aim of the first cohort was to validate fNIRS findings through comparison with previous results obtained from fMRI and EEG studies, while the focus of the second cohort was to comprehensively explore the typical and atypical developmental trajectories in infants and children, including those at elevated risk for developmental disorders. Before conducting fNIRS studies within these cohorts, our research endeavors began with a comprehensive analysis of existing fNIRS literature, focusing on neural activity in both adults and infants. Specifically, we systematically reviewed and critiqued the methodological and analytic approaches that have been used to study the mirror neuron network (MNN) in healthy adults using fNIRS. This endeavor results in the publication in Frontiers in Human Neural Science (Condy et al., 2021). Additionally, we engaged in an exhaustive assessment of contemporary fNIRS findings pertaining to the tracking of neurodevelopmental trajectories in infants and children, encompassing those with or without developmental disorders. The outcomes of this review article have been submitted to Frontiers in Psychiatry and are presently undergoing the final stages of revision (Su et al., 2023 in press). In relation to the adult cohort, we successfully conducted a pilot study encompassing 30 healthy volunteers, aimed at assessing the viability of employing fNIRS for the study of the MNN. The culmination of our endeavors revealed compelling outcomes. Specifically, our findings highlight parietal regions, including the bilateral superior parietal lobule (SPL), bilateral inferior parietal lobule (IPL), the right supra-marginal region (SMG), and the right angular gyrus (AG) as potential candidate regions within the human MNN. Furthermore, we effectively demonstrated the paradigm's capacity to discern variations in subclinical levels of autistic traits, presenting an avenue for subsequent exploration in clinical populations characterized by challenges in action comprehension and representation, notably autism spectrum disorders (ASD). The outcomes of this investigation were disseminated in the Plos One journal in August 2021 (Miguel et al., 2021). Subsequent to this, a supplementary analysis utilizing a connectivity approach has been undertaken, and the results stemming from this endeavor have been documented in the Journal of Brain Science (Nguyen et al., 2021). Notably, our findings revealed significant interplay between various brain regions during action execution, with distinct region-to-region connections within the left hemisphere manifesting while participants executed actions with their right hand. These connections included interactions within the left precentral, left postcentral, left inferior parietal regions, as well as between the left supramarginal and left angular regions. To comprehensively delineate the MNN utilizing concurrent EEG and fNIRS signals, we developed a multimodal multiset data-fusion analysis, strategically leveraging the strengths of each neuroimaging modality, that is, the EEG's exceptional temporal resolution and the fNIRS's superior spatial resolution. In this pursuit, we harnessed the well-established Mu suppression phenomenon as an indicator of MNN activation in EEG-related neural activity. By synergistically employing EEG and fNIRSeach modality contributing its unique attributeswe achieved a more refined understanding of MNN development. Specifically, we applied a structured sparse multiset CCA (ssmCCA) model to our merged dataset, revealing congruent activity patterns during both action execution and observation across designated regions of interest. These results underscored heightened brain activity within the left hemisphere's paracentral, precentral, and inferior and superior parietal regions during motor action execution. This is the first report that fused distinct brain metrics (hemodynamic response function and electrical activity) to characterize the MNN in the human brain, leading to a publication in Scientific Reports journal (Dashtestani et al., 2022). Subsequent to our in-depth exploration of brain activity patterns during action execution and observation, we ventured into investigating the imagination condition in relation to both action execution and observation. Within our paradigm, the incorporation of action imagination was also analyzed using the established ssmCCA method. The intrinsic value of introducing this dimension lies in the belief that motor cognitive abilities hinge on and are cultivated through the mechanisms of mental rehearsal and re-enactment of action execution. Our findings indicated the pivotal role of the left parietal inferior region as the primary contributor within the imagination condition. Concurrently, additional brain regions within the left hemisphere exhibited activation during the motor imagery task, mirroring the patterns witnessed during execution and observation conditions. Despite the relatively limited literature on action imagination, our outcomes harmonize with existing studies, validating the notion that both action observation and imagination stimulate the same sensory-motor cortical network that underpins the execution of the corresponding action. One plausible explanation for these consistent brain activity patterns across the three conditions is attributed to the internal rehearsal of action, reinforcing the intrinsic connection between observation, imagination, and execution. These pivotal insights have led to a recent publication in the Scientific Reports journal (Su et al., 2023) In addition to our exploration of the MMN network, we are currently engaged in the simultaneous collection of fNIRS and EEG data from healthy volunteers, a venture aimed at both validating and delving into the neural network linked to dual task performance. Specifically, our study entails tasking healthy volunteers with cognitive exercises, namely the Flanker vs Reverse Flanker tasks, while maintaining their balance across different positionsSitting, Standing, and Tandem Stance. Notably, we also embarked on an investigation into the impact of acute physical activity, specifically a one-minute sit-to-stand task, on dual task performance and neural activity within our cohort of healthy volunteers. Drawing on insights garnered from previous research and our pilot data, our expectations revolve around observing a decline in performance coupled with heightened prefrontal activity during cognitive tasks conducted in more challenging stances. Moreover, we anticipate observing improved cognitive performance, accompanied by associated alterations in neural activity, following an acute bout of physical activity. For our second cohort, our collaboration with Dr. Thurm (NIMH) and Dr. Fox (UMD) has continued, steadfastly pursuing the investigation of the developmental trajectory of the mirror neuron network (MNN) spanning infancy to adulthood. The MNN's intricate connections with the emergence of sophisticated social behaviors in typical human infants form the crux of our exploration. Building upon our earlier endeavors, data collection involving adult pilots who engaged in motor observation, execution, and imagination paradigmsconcurrently measured through multi-modal EEG and fNIRS systemshas been successfully completed.