Poster #16 - Differential brain activity as a function of cortisol reactivity during a stress task

• In Event: 3-206 - Poster Session 13
  In Poster Session: PS 13 Section - Biological Processes: Neuroscience and Genetics

Integrative Statement

Background. The hypothalamic-pituitary-adrenal (HPA) axis, which produces the stress hormone cortisol, is among the most studied stress systems in developmental research. The Trier Social Stress Test (TSST), is the laboratory stress task that most reliably produces a cortisol response, but still does not elicit a cortisol response in all participants (Hostinar, Johnson, & Gunnar, 2015; Kirschbaum, Pirke, & Hellhammer, 1993). The neural systems involved in the cortisol response have been examined in adults using the Montreal Imaging Stress Test (MIST, Dedovic and colleagues 2005, 2009) and involve the anterior insula, ventral anterior cingulate cortex and ventrolateral and dorsomedial prefrontal cortex. No one has examined the neural response that corresponds to HPA axis activation in children or adolescents, in part because no imaging task, including the MIST, reliably elicits a response in a sufficient number of youth. Here we report on a new task, the Minnesota Imaging Stress Test in Children (MISTiC), a modified version of the TSST appropriate for imaging and the neural response of 11-13 yr olds who do and do not show a cortisol response.

Procedures: Twenty-four adolescent participants, ages 11-13 years (M = 12.73 years) completed the MISTiC). Participants were first asked to give a speech about themselves as if introducing themselves to a new class and to complete a series of multiple choice math problems in front of a pair of judges, all while lying in an MRI scanner. After a delay, participants completed another set of math problems, this time with no judges present. A series of 9 saliva samples were collected before, during, and after scanning to assess participants’ cortisol responses to the task. Area under the curve was calculated as a measure of each individual’s cortisol reactivity and the median split was used to create two groups, responders (those who showed a physiological response to the task) and non-responders (those who did not). Four participants were excluded due to excessive head motion or incomplete data. We examined the distribution of fMRI activity during the math portions of the MISTiC (math problems vs. blank problems).

Results and Discussion. Significant differences in brain activation were found between groups when comparing judged math performance to unjudged math. Cortisol responders exhibited greater activity in the hypothalamus, a crucial component of the HPA axis, and in bilateral middle frontal gyrus (p’s < 0.005). Similar effects were found when using area under the curve as a continuous measure of stress reactivity. Interestingly, when examining group-specific means, only the cortisol responders showed greater activation in areas associated with stress (e.g. OFC, dlPFC, and hypothalamus) during the judged vs the unjudged condition. Our results suggest differential brain function in adolescents who display a physiological stress response compared to those who do not, and begin to elucidate the neural activity that underlies neuroendocrine responses to psychosocial stress during adolescence.

Authors

• Max Herzberg, University of Minnesota
  Presenting Author

• Ruskin H. Hunt, University of Minnesota
  Non-Presenting Author

• Megan Gunnar, University of Minnesota
  Non-Presenting Author

• Kathleen M. Thomas, University of Minnesota
  Non-Presenting Author