Biology subjects

Valera, E. M.

Publications and source records attributed to Valera, E. M..

4 recordsLinked to original sources

bioRxiv2026

Cognitive reserve depends on cortical neurochemistry to predict memory after partner-inflicted brain injury

Memory problems are commonplace following brain injury (BI). However, it remains unclear why some report memory problems while others do not, especially following repeated neurotrauma. Cognitive reserve has been widely hypothesized to account for this variation, but testing this account has yielded inconsistent results and proven difficult, likely as it requires a sample spanning a wide range of BI burden with concurrent neuroimaging and cognitive measurement. Here, we combined a wide range of cognitive assessments with measures of neuronal health using magnetic resonance spectroscopy across three brain regions in 62 women who had experienced physical intimate partner violence. Partner-inflicted BI counts ranged from 0 to 420, yet we found that the number of BIs alone did not explain the variance in memory outcomes. Among a small subset with high BI exposure ([≥]10 BIs; n = 11), BI count explained 5% of the variance in delayed recall, the primary memory outcome, whereas cognitive reserve, inferred from a measure of premorbid functioning, explained almost half (unadjusted in-sample associations). In the full cohort, cognitive reserve predicted memory only among the most heavily injured participants. In a separate model, cognitive reserve predicted memory only when creatine-referenced total N-acetylaspartate, a marker of neuronal health, was lower in the posterior cingulate gyrus and dorsolateral prefrontal cortex. Ultimately, our findings provide behavioral and neurochemical evidence consistent with the cognitive reserve hypothesis and shed new light on why, despite a high burden of neurotrauma, memory may remain resilient.

neuroscience↗

bioRxiv2026

Neuroimaging of intimate partner violence can underrepresent the most affected survivors

Neuroimaging is becoming an increasingly prominent tool to understand intimate partner violence (IPV) and partner-inflicted brain injury (BI). Yet, by nature of IPV and partner-inflicted BI, those most affected may be the least likely to be eligible, participate, and produce usable data in neuroimaging studies. A critical question therefore remains of who is represented in neuroimaging research on IPV and related BI. Here, we examined representativeness at three major stages of neuroimaging sample construction using screening records from 352 women and a subsequent cohort of 207 enrolled women with lifetime exposure to physical IPV. At the eligibility stage, three in five women eligible for behavioral research were deemed ineligible for magnetic resonance imaging (MRI) at initial screening. At the participation stage, the 61 women who underwent resting-state functional MRI (fMRI) had more education, were more likely to be employed, and reported lower psychiatric and neurobehavioral symptom burden than enrolled women who did not undergo neuroimaging. Finally, at the quality-control stage following fMRI, motion-based exclusion disproportionately removed women who had sustained the most partner-inflicted BIs. Our findings empirically reveal that eligibility, participation, and quality control each bias the demographic, clinical, abuse, and BI burden represented in an fMRI sample, and therefore have key implications for generalizability. Measuring and reporting representation bias can help identify whose experiences are underrepresented in the evidence, and accordingly reduce the risk that IPV neuroimaging research understates the very harms it seeks to characterize.

neuroscience↗

bioRxiv2021

Generalizable prediction of stimulus-independent, task-unrelated thought from functional brain networks

Neural substrates of "mind wandering" have been widely reported, yet experiments have varied in their contexts and their definitions of this psychological phenomenon, limiting generalizability. We aimed to develop and test the generalizability, specificity, and clinical relevance of a functional brain network-based marker for a well-defined feature of mind wandering--stimulus-independent, task-unrelated thought (SITUT). Combining functional MRI (fMRI) with online experience sampling in healthy adults, we defined a connectome-wide model of inter-regional coupling--dominated by default-frontoparietal control subnetwork interactions--that predicted trial-by-trial SITUT fluctuations within novel individuals. Model predictions generalized in an independent sample of attention-deficit/hyperactivity disorder (ADHD) adults. In three additional resting-state fMRI studies (total n=1,115), including healthy and ADHD populations, we demonstrated further prediction of SITUT (at modest effect sizes) defined using multiple trait-level and in-scanner measures. Our findings suggest that SITUT is represented within a common pattern of brain network interactions across time scales, populations, and contexts.

neuroscience↗

bioRxiv2020

Two dominant brain states reflect optimal and suboptimal attention

Attention is not constant but fluctuates from moment to moment. Previous studies dichotomized these fluctuations into optimal and suboptimal states based on behavioral performance and investigated the difference in brain activity between these states. Although these studies implicitly assume there are two states, this assumption is not guaranteed. Here, we reversed the logic of these previous studies and identified unique states of brain activity during a sustained attention task. We demonstrate a systematic relationship between dynamic brain activity patterns (brain states) and behavioral underpinnings of sustained attention by explaining behavior from two dominantly observed brain states. In four independent datasets, a brain state characterized by default mode network activity was behaviorally optimal and a brain state characterized by dorsal attention network activity was suboptimal. Thus, our study provides compelling evidence for behaviorally optimal and suboptimal attentional states from the sole viewpoint of brain activity. We further demonstrated how these brain states were impacted by motivation, mind wandering, and attention-deficit hyperactivity disorder. Within-subject level modulators (motivation and mind wandering) impacted the optimality of behavior in the suboptimal brain state. In contrast, between-subject level differences (ADHD vs healthy controls) impacted the optimal brain state character, namely its frequency.

neuroscience↗