Project Summary
Fragile X Syndrome (FXS), a rare monogenic neurodevelopmental disorder caused by a trinucleotide
expansion of the Fmr1 gene on the X chromosome. FXS is the most common inherited form of intellectual
disability (ID) and monogenic cause of autism spectrum disorder (ASD), characterized by sensory
hypersensitivities, executive dysfunction, learning difficulties, and social anxiety. Individuals with FXS also exhibit
increased functional connectivity (FC) abnormalities observed using electroencephalography (EEG) related to
cognitive impairments and behavioral features of FXS, with a high degree of heterogeneity (despite being
monogenic). Limited work has addressed these FC disruptions in frontoparietal, and temporal networks with no
studies directly assessing FC disruptions during a cognitive task. I hypothesize specific network connectivity
dynamics within frontoparietal and temporal regions in FXS will effectively parse higher-order behavioral features
of FXS from ID, with frontoparietal FC disruption related to the “control network” being more associated with both
ID and cognitive control (including cognitive/behavioral flexibility) and temporal “salience network” FC more
associated with other FXS features, particularly sensory hypersensitivity and anxiety. The long-term goal of this
proposal is to characterize functional disruptions in networks underlying ID and cognitive function as separate
from behavioral features of FXS to identify targets for intervention while using a cognitive task and address
heterogeneity in neural network performance underlying features core to FXS (e.g., hyperactivity, sensory
processing difficulties, anxiety). Experiments proposed in Aim 1 will use robust FC measures through a source
analysis to parse ID from other features of FXS to evaluate the effectiveness of using microstates as a proxy
and to explore the triple network hypothesis in FXS by assessing FC during a cognitive task. Aim 2 will utilize
data-driven methods to identify variable combinations from EEG to meaningfully distinguishing FXS from
individuals with developmental delay (DD), and parse cognitive ability/ID (defined by NIH Toolbox for ID and
nonverbal IQ) from other FXS features (i.e., anxiety, hyperactivity, sensory hypersensitivities). The proposed
project will have broad implications for ongoing efforts to evaluate neurophysiology in FXS and the development
of effective biomarkers for therapeutic applications, particularly taking the novel approach of addressing FC
during a cognitive task.