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.
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)
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
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