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Neural predictors of trauma and stress-related disorders
Individuals differ in their likelihood of developing adverse posttraumatic outcomes such as PTSD, depression, and anxiety. Neuroimaging in the early aftermath of trauma may provide quantifiable brain targets that can a) help predict who is likely to develop these disorders and b) facilitate early intervention and treatment options for those susceptible. We use a multidimensional approach including multimodal magnetic resonance imaging (MRI), psychophysiological recording, and behavioral assessment to understand the neurobiology of PTSD susceptibility. Our work suggests that brain regions such as the prefrontal cortex, amygdala, and hippocampus play a key role in expression of PTSD symptoms after an individual has experienced a traumatic event (Harnett et al., 2021, Neuropsychopharmacology). More recent work suggests that how these regions interact with brain regions involved in processing visual information may be equally as important for understanding PTSD susceptibility after trauma (Harnett et al, 2022, Translational Psychiatry). |
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Neural mechanisms of cognitive-affective function
Emotions like fear can be beneficial for survival in certain situations. Our emotions can also influence our thoughts and behaviors. Importantly, traumatic and stressful situations can disrupt typical emotional and cognitive function which may be important for understanding the development of psychiatric conditions. A core component of our work is thus to investigate the neural mechanisms that mediate processes such as fear learning to better understand how certain disorders, like PTSD, may develop. We have primarily used Pavlovian conditioning (or classical conditioning) to understand brain regions involved in associative learning of cues that predict threat. Similar to our findings in PTSD susceptibility, our work - along with others - suggests threat learning that is dysregulated in PTSD is driven by a core neural circuit featuring the prefrontal cortex, amygdala, and hippocampus (Harnett et al., 2020, Experimental Neurology). |
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Neurobiological consequences of racial inequities
There are stark disparities in distribution of economic resources, exposure to stress, and psychiatric disorder prevalence by racial group within the United States. Although many of these factors are known to have direct effects on the brain, relatively limited research has investigated how the racial inequities in socioeconomic factors may lead to adaptive/deleterious changes in the brain for different groups. Given these factors are also directly related to the development of psychiatric disorders, understanding potentially racialized impacts on the brain is critical for developing generalizable neurobiological models of disease and equitable treatments. Our research leverages large-scale longitudinal data and original data collection to look at both a) potential race-related differences in neurobiology of psychiatric disorders and b) how racial structural inequities explain these differences. Our work suggests these deep-rooted inequities, that deprive many minoritized and marginalized individuals, contribute to desensitization to experimental threat that may confer an adaptive advantage in the face of later real-world trauma (Harnett et al., 2019, NeuroImage; Harnett et al., 2022, Psychological Medicine). Our collaborators have also begun to look at the direct effects of racial discrimination on both brain reactivity to threat (Fani et al., 2021, JAMA Psychiatry) and white matter microstructure (Fani et al., 2022, Biological Psychiatry: CNNI). |
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