Raj received her Ph.D. in Human Development and Designated Emphasis in Translational Research from the University of California, Davis in 2019, where she was a TL1 Pre-Doctoral Clinical Research Training Scholar and supported by the UC Davis School of Medicine and the NIH National Center for Advancing Translational Sciences. In her graduate work, Raj assessed how inter-individual differences in key developmental aspects of adolescence (i.e., puberty, psychopathology, and the brain) inform one another to contribute to our understanding of heterogeneous risk mechanisms and opportunities for targeted interventions. Specifically, Raj characterized associations between pubertal timing, structural and functional network properties in the brain, and internalizing symptoms. Raj also examined topographical signatures in white matter tracts as they reflect the history of depressive symptoms in adolescent girls, and patterns of functional connectivity, revealed by neural biotyping, as they forecast future internalizing symptoms in at-risk adolescents. As a post-doctoral researcher in the SNAP lab, Raj is extending her work by studying the effects of early life stress on the development of large-scale structural and functional brain circuits to understand when and in whom neurobiological alterations arise and confer risk for depression and suicidal ideation. The goal of this research is to guide person-centered approaches to detect vulnerability for, and predict the course of depression.
Boards, Advisory Committees, Professional Organizations
Early Career Director, Association for Clinical and Translational Science (2019 - Present)
Doctor of Philosophy, University of California Davis (2019)
Bachelor of Science, University of California Davis (2012)
Ph.D., University of California, Davis, Human Development - Designated Emphasis in Translational Research (2019)
B.S., University of California, Davis, Psychology (Emphasis: Biology) (2012)
Neural Responses to Implicit Forms of Peer Influence in Young Adults.
Young adults are acutely sensitive to peer influences. Differences have been found in neural sensitivity to explicit peer influences, such as seeing peer ratings on social media. The present study aimed to identify patterns of neural sensitivity to implicit peer influences, which involve more subtle cues that shape preferences and behaviors. Participants were 43 young adults (MAge = 19.2 years; 24 males) who underwent functional magnetic resonance imaging while completing a task used to assess neural responses to implicitly "socially tagged" symbols (previously judged by peers as liked vs. not liked, thus differing in apparent popularity) vs. novel symbols that carried no social meaning (not judged by peers). Results indicated greater activity in brain regions involved in salience detection (e.g., anterior cingulate cortex) and reward processing (e.g., caudate) to socially tagged vs. novel symbols, and particularly to unpopular symbols. Greater self-reported susceptibility to peer influence was related to more activity in the insula and caudate when viewing socially tagged vs. novel symbols. These results suggest that the brain is sensitive to even subtle cues varying in level of peer endorsement and neural sensitivity differed by the tendency to conform to peers' behaviors particularly in regions implicated in social motivation.
View details for DOI 10.1080/17470919.2021.1911843
View details for PubMedID 33820483
Heart rate variability moderates the effects of COVID-19-related stress and family adversity on emotional problems in adolescents: Testing models of differential susceptibility and diathesis stress.
Development and psychopathology
The COVID-19 pandemic is a unique period of stress, uncertainty, and adversity that will have significant implications for adolescent mental health. Nevertheless, stress and adversity related to COVID-19 may be more consequential for some adolescents' mental health than for others. We examined whether heart rate variability (HRV) indicated differential susceptibility to mental health difficulties associated with COVID-19 stress and COVID-19 family adversity. Approximately 4 years prior to the pandemic, we assessed resting HRV and HRV reactivity to a well-validated stress paradigm in 87 adolescents. During the pandemic, these adolescents (ages 13-19) reported on their health-related stress and concerns about COVID-19, family adversity related to COVID-19, and their recent emotional problems. The association between COVID-19 stress and emotional problems was significantly stronger for adolescents who previously exhibited higher resting HRV or higher HRV reactivity. For adolescents who exhibited lower resting HRV or HRV augmentation, COVID-19 stress was not associated with emotional problems. Conversely, lower resting HRV indicated vulnerability to the effect of COVID-19 family adversity on emotional problems. Different patterns of parasympathetic functioning may reflect differential susceptibility to the effects of COVID-19 stress versus vulnerability to the effects of COVID-19 family adversity on mental health during the pandemic.
View details for DOI 10.1017/S095457942100033X
View details for PubMedID 34099071
Higher Executive Control Network Coherence Buffers Against Puberty-Related Increases in Internalizing Symptoms During the COVID-19 Pandemic.
Biological psychiatry. Cognitive neuroscience and neuroimaging
Early pubertal maturation has been posited to be a biopsychosocial risk factor for the onset of internalizing psychopathology in adolescence; further, early-maturing youths exhibit heightened reactivity to stressful events. School closures and enforced social distancing, as well as health and financial uncertainties, during the COVID-19 pandemic are expected to adversely affect mental health in youths, particularly adolescents who are already at risk for experiencing emotional difficulties. The executive control network (ECN) supports cognitive processes required to successfully navigate novel challenges and regulate emotions in stressful contexts.We examined whether functional coherence of the ECN, measured using resting-state functional magnetic resonance imaging 5 years before the pandemic (T1), is a neurobiological marker of resilience to increases in the severity of internalizing symptoms during COVID-19 in adolescents who were in more advanced stages of puberty at T1 relative to their same-age peers (N = 85, 49 female).On average, participants reported an increase in symptoms from the 3 months before pandemic to the 2 most recent weeks during the pandemic. We found that early-maturing youths exhibited greater increases in internalizing symptoms during the pandemic if their ECN coherence was low; in contrast, relative pubertal stage was not associated with changes in internalizing symptoms in adolescents with higher ECN coherence at T1.These findings highlight the role of the functional architecture of the brain that supports executive functioning in protecting against risk factors that may exacerbate symptoms of internalizing psychopathology during periods of stress and uncertainty.
View details for DOI 10.1016/j.bpsc.2020.08.010
View details for PubMedID 33097469
- Neural connectivity biotypes: Associations with internalizing problems throughout adolescence Psychological Medicine 2020
Brain network connectivity and the heterogeneity of depression in adolescence: A precision mental health perspective
Journal of Child Psychology and Psychiatry
View details for DOI 10.1111/jcpp.13250
Sex Differences in Pubertal Associations with Fronto-accumbal White Matter Morphometry: Implications for Understanding Sensitivity to Reward and Punishment
View details for DOI 10.1016/j.neuroimage.2020.117598
Greater age-related changes in white matter morphometry following early life stress: Associations with internalizing problems in adolescence.
Developmental cognitive neuroscience
2020; 47: 100899
Early life stress (ELS) is associated with increased risk for internalizing disorders and variations in gray matter development. It is unclear, however, whether ELS affects normative age-related changes in white matter (WM) morphology, and if such maturational differences are associated with risk for internalizing psychopathology. We conducted comprehensive interviews in a cross-sectional sample of young adolescents (N = 156; 89 F; Ages 9-14) to assess lifetime exposure to stress and objective cumulative ELS severity. We used diffusion-weighted imaging to measure WM fixel-based morphometry and tested the effects of age and ELS on WM fiber density and cross-section (FDC), and associations between WM FDC and internalizing problems. Age was positively associated with FDC in all WM tracts; greater ELS severity was related to stronger age-WM associations in several association tracts connecting the frontal lobes with limbic, parietal, and occipital regions, including bilateral superior and inferior longitudinal and uncinate fasciculi (UF). Among older adolescents with greater ELS severity, a higher UF FDC was associated with fewer internalizing problems. Greater ELS severity predicted more mature WM morphometry in tracts implicated in emotion regulation and cognitive processing. More phenotypically mature UF WM may be adaptive against internalizing psychopathology in adolescents exposed to ELS.
View details for DOI 10.1016/j.dcn.2020.100899
View details for PubMedID 33340790
Girls' brain structural connectivity in late adolescence relates to history of depression symptoms
JOURNAL OF CHILD PSYCHOLOGY AND PSYCHIATRY
Girls' depressive symptoms typically increase in adolescence, with individual differences in course and severity being key risk factors for impaired emotional functioning in young adulthood. Given the continued brain white matter (WM) maturation that occurs in adolescence, the present study tested whether structural connectivity patterns in late adolescence are associated with variation in the course of depression symptom severity throughout adolescence.Participants were girls (N = 115) enrolled in a multiyear prospective cohort study of risk for depression. Initial depression severity (intercept) at age 10 and change in severity (linear slope) across ages 10-19 were examined in relation to WM tractography collected at age 19. Network-based statistic analyses were used to identify clusters showing variation in structural connectivity in association with depressive symptom intercept, slope, and their interaction.Higher initial depressive severity and steeper positive slope (separately) were associated with greater structural connectivity between temporal, subcortical socioaffective, and occipital regions. Intercept showed more connectivity associations than slope. The interaction effect indicated that higher initial symptom severity and a steeper negative slope (i.e., alleviating symptoms) were related to greater connectivity between cognitive control regions. Moderately severe symptoms that worsened over time were followed by greater connectivity between self-referential and cognitive regions (e.g., posterior cingulate and frontal gyrus).Higher depressive symptom severity in early adolescence and increasing symptom severity over time may forecast structural connectivity differences in late adolescence, particularly in pathways involving cognitive and emotion-processing regions. Understanding how clinical course relates to neurobiological correlates may inform new treatment approaches to adolescent depression.
View details for DOI 10.1111/jcpp.13184
View details for Web of Science ID 000504406900001
View details for PubMedID 31879977
Girls' pubertal development is associated with white matter microstructure in late adolescence
2018; 181: 659–69
Patterns of pubertal maturation have been linked to vulnerability for emotion dysregulation disorders in girls, as well as white matter (WM) development, suggestive of a potential mechanism between pubertal maturation and emotional health. Because pubertal processes begin at varying ages (i.e., status, timing) and proceed at varying rates (i.e., tempo), identifying individual differences in the pubertal course associated with subsequent WM microstructure development may reveal clues about neurobiological mechanisms of girls' emotional well-being. In a prospective cohort study of 107 girls, we examined associations between pubertal status at age 9, pubertal timing and tempo from ages 9-15, and WM microstructure at age 19. Tract-based spatial statistics revealed that girls with more advanced pubertal status at age 9, specific to gonadal-related physical changes, had higher fractional anisotropy, and lower mean diffusivity (MD) and radial diffusivity in tracts relevant to cognitive control and emotion regulation (e.g., the superior longitudinal fasciculus, external capsule, and uncinate fasciculus). Additionally, girls with earlier pubertal timing showed lower MD in the left anterior cingulum bundle. Tempo was unrelated to WM measures. These findings implicate specific aspects of pubertal maturation in subsequent neural signatures, suggesting possible neuroendocrine mechanisms relevant to emotional development. Future work incorporating longitudinal neuroimaging in parallel with pubertal measures may contribute to the understanding of individual variation in pubertal course and WM development.
View details for DOI 10.1016/j.neuroimage.2018.07.050
View details for Web of Science ID 000445165600058
View details for PubMedID 30056197
View details for PubMedCentralID PMC6296475
Reward-Related Brain Activation, Resting-State Functional Connectivity, and White Matter Morphology Link Early Life Stress and Internalizing Symptoms in Adolescence
ELSEVIER SCIENCE INC. 2021: S28
View details for Web of Science ID 000645683800071
Early Life Stress Predicts Depressive Symptoms in Adolescents During the COVID-19 Pandemic: The Mediating Role of Perceived Stress
Frontiers in Psychology
View details for DOI 10.3389/fpsyg.2020.603748
- EARLY-LIFE STRESS DIFFERENTIALLY AFFECTS WHITE MATTER TRACTS IN MALES AND FEMALES DURING EARLY PUBERTY: ASSOCIATIONS WITH INTERNALIZING AND EXTERNALIZING PROBLEMS ELSEVIER SCIENCE INC. 2020: S320
Modulation of reward-related neural activation on sensation seeking across development
2017; 147: 763–71
Sensation seeking is a personality construct associated with an increased propensity for engaging in risk-taking. Associations with deleterious outcomes ranging from mental health impairments to increased mortality rates highlight important public health concerns related to this construct. Although some have suggested that increased neural responsivity to reward within the ventral striatum (e.g., nucleus accumbens) may drive sensation seeking behaviors, few studies have examined the neural mechanisms associated with stable individual differences in sensation seeking across development. To address this issue, the current study used functional magnetic resonance imaging to examine the association between neural responding to reward and stable patterns of sensation seeking across a three-year follow-up period among healthy adolescents and young adults (N = 139). Results indicated that during early adolescence (~ages 10-12), increased reactivity to reward within the nucleus accumbens (NAcc) was associated with lower levels of sensation seeking across a three-year follow-up. In middle adolescence (~ages 12-16), there was no evidence of a relationship between NAcc reactivity and sensation seeking. However, during the transition from late adolescence into adulthood (~ages 17-25), heightened reward-related reactivity in the NAcc was linked to increased sensation seeking. Findings suggest that the neural mechanisms underlying individual differences in trait-like levels of sensation seeking change from early to late adolescence.
View details for DOI 10.1016/j.neuroimage.2016.12.020
View details for Web of Science ID 000394560600065
View details for PubMedID 27956207
View details for PubMedCentralID PMC5303670
An Integrative Model of the Maturation of Cognitive Control
ANNUAL REVIEW OF NEUROSCIENCE, VOL 38
2015; 38: 151–70
Brains systems undergo unique and specific dynamic changes at the cellular, circuit, and systems level that underlie the transition to adult-level cognitive control. We integrate literature from these different levels of analyses to propose a novel model of the brain basis of the development of cognitive control. The ability to consistently exert cognitive control improves into adulthood as the flexible integration of component processes, including inhibitory control, performance monitoring, and working memory, increases. Unique maturational changes in brain structure, supported by interactions between dopaminergic and GABAergic systems, contribute to enhanced network synchronization and an improved signal-to-noise ratio. In turn, these factors facilitate the specialization and strengthening of connectivity in networks supporting the transition to adult levels of cognitive control. This model provides a novel understanding of the adolescent period as an adaptive period of heightened experience-seeking necessary for the specialization of brain systems supporting cognitive control.
View details for DOI 10.1146/annurev-neuro-071714-034054
View details for Web of Science ID 000358485000008
View details for PubMedID 26154978
View details for PubMedCentralID PMC5661874