Biology subjects

Bouchard, H. C.

Publications and source records attributed to Bouchard, H. C..

4 recordsLinked to original sources

bioRxiv2026

Concussion decreases brain signal variability

Sports-related concussion represents a major public health concern, with millions of cases diagnosed annually. Despite significant methodological advances in functional brain imaging, a clinically meaningful neuroimaging biomarker of concussion has yet to be established. This may be due in part to a reliance on traditional measures. For example, approaches examining mean activation across trials reduce responses to a single measure of central tendency and therefore fail to capture important individual differences. In contrast, blood oxygenation level dependent (BOLD) variability offers a promising new approach to measuring brain function, Specifically, it captures individual differences in the temporal variability in the BOLD signal over time. Further, it is sensitive to neural, vascular, and neurovascular coupling changes that accompany concussion. We collected baseline (prior to injury) and post-concussion (within 48 hours of injury) neuroimaging data in 56 collegiate athletes. Within this longitudinal dataset, we investigated changes in BOLD variability across multiple spatial scales. In addition, we examined their relationships with self-reported symptoms and cognitive performance. As expected, symptoms increased following concussion while computerized cognitive performance declined. BOLD variability decreased from baseline to post-concussion, particularly in the somatomotor and language networks. Moreover, changes in BOLD variability were related to changes in symptom reporting and cognitive performance. Together, these findings advance our understanding of how concussion affects brain function and highlight BOLD signal variability as a promising biomarker to aid ongoing efforts to improve the diagnosis and treatment of sports-related concussion.

neuroscience↗

bioRxiv2023

Is it sandbagging or is it just apathy? Baseline ImPACT and external validity indicators in collegiate athletes

ObjectiveBaseline cognitive testing is important for sport concussion management. Assessing baseline data for both the validity and reliability is vital to ensuring its utility. Stand-alone performance validity tests (PVT) and embedded validity indicators (EVI) (collectively called "validity measures" hereafter) are commonly used in neuropsychological testing and screening. This study further investigates efficient ways to assess validity of baseline cognitive testing. Methods231 NCAA athletes completed baseline assessment with ImPACT and one of two PVTs: Medical Symptom Validity Test or Rey Dot Counting Test. The relationship between scores on validity measures and cognitive performance, symptoms, and sleep was assessed. ResultsAthletes who failed two or more validity measures performed worse on the Visual Motor Speed Composite while athletes failing three or more measures performed worse on the Reaction Time Composite. Those athletes who failed validity measures and also reported poor sleep performed worse on both composites. Self-reported symptoms and hours of sleep were not independently associated with failing validity measures. Lastly, athletes with self-reported ADHD and/or LD were more likely to fail two+ validity measures (46% versus 27% of neurotypical athletes). ConclusionsConsistent with previous research, ImPACT Baseline++ only identified 1.7% of the samples data as invalid despite 4.8% of the dataset failing a combination of PVT and EVI and an additional 42.9% failing at least EVI alone. Results suggest that assessing validity on a continuum and using multiple validity measures may be useful to identify data validity that falls in the middle of the continuum. Public Significance StatementBaseline concussion testing is common and often mandated prior to sport participation, however, a baseline only has utility if it is both a reliable and valid representation of the athletes healthy and optimal functioning. This study adds to the growing body of literature demonstrating that baseline testing may frequently have questionable validity. It also provides support to the value of conceptualizing validity as a spectrum, rather than dichotomy and is the first to apply the concept to baseline concussion testing data.

animal behavior and cognition↗

bioRxiv2023

Concussion-related disruptions to hub connectivity in the default mode network are related to symptoms and cognition

Concussions present with a myriad of symptomatic and cognitive concerns; however, the relationship between these functional disruptions and the underlying changes in the brain are not yet well understood. Hubs, or brain regions that are connected to many different functional networks, may be specifically disrupted after concussion. Given the implications in concussion research, we quantified hub disruption within the default mode network (DMN) and between the DMN and other brain networks. We collected resting-state functional magnetic resonance imaging data from collegiate student-athletes (n = 44) at three timepoints: baseline (prior to beginning their athletic season), acute post-injury (approximately 48 hours after a diagnosed concussion), and recovery (after starting return-to-play progression, but prior to returning to contact). We used self-reported symptoms and computerized cognitive assessments collected across similar timepoints to link these functional connectivity changes to clinical outcomes. Concussion resulted in increased connectivity between regions within the DMN compared to baseline and recovery, and this post-injury connectivity was more positively related to symptoms and more negatively related to visual memory performance compared to baseline and recovery. Further, concussion led to decreased connectivity between DMN hubs and visual network non-hubs relative to baseline and recovery, and this post-injury connectivity was more negatively related to somatic symptoms and more positively related to visual memory performance compared to baseline and recovery. Relationships between functional connectivity, symptoms, and cognition were not significantly different at baseline versus recovery. These results highlight a unique relationship between self-reported symptoms, visual memory performance and acute functional connectivity changes involving DMN hubs after concussion in athletes. This may provide evidence for a disrupted balance of within- and between-network communication highlighting possible network inefficiencies after concussion. These results aid in our understanding of the pathophysiological disruptions after concussion and inform our understanding of the associations between disruptions in brain connectivity and specific clinical presentations acutely post-injury.

neuroscience↗

bioRxiv2021

Alcohol Use Disrupts Age-Appropriate Cortical Thinning in Adolescence: A Data Driven Approach

ObjectiveCortical thickness changes dramatically during development and is influenced by adolescent drinking. However, previous findings have been inconsistent and limited by region-of-interest approaches that are underpowered because they do not conform to the underlying heterogeneity from the effects of alcohol. MethodsAdolescents (n=657; 12-22 years at baseline) from the National Consortium on Alcohol and Neurodevelopment in Adolescence (NCANDA) who endorsed little to no alcohol use at baseline were assessed with structural MRI and followed longitudinally at four yearly intervals. Seven unique spatially covarying patterns of cortical thickness were obtained from the baseline scans by applying a novel data-driven method called non-negative matrix factorization (NMF). The cortical thickness maps of all participants longitudinal scans were projected onto vertex-level cortical patterns to obtain participant-specific coefficients for each pattern. Linear mixed-effects models were fit to each pattern to investigate longitudinal effects of alcohol consumption on cortical thickness. ResultsIn most NMF-derived cortical thickness patterns, the longitudinal rate of decline in no/low drinkers was similar for all age cohorts, among moderate drinkers the decline was faster in the younger cohort and slower in the older cohort, among heavy drinkers the decline was fastest in the younger cohort and slowest in the older cohort (FDR corrected p-values < 0.01). ConclusionsThe NMF method can delineate spatially coordinated patterns of cortical thickness at the vertex level that are unconstrained by anatomical features. Age-appropriate cortical thinning is more rapid in younger adolescent drinkers and slower in older adolescent drinkers.

neuroscience↗