Simultaneous glucocorticoid and noradrenergic activity disrupts the neural basis of goal-directed action in the human brain.
Level 2 - randomized trial
Randomized controlled trial evaluating pharmacological stress hormone administration in humans
PubMed 22836250 · doi:10.1523/JNEUROSCI.1304-12.2012
What was done
Healthy participants were randomly administered hydrocortisone, the alpha-2 adrenoceptor antagonist yohimbine, or both before undergoing instrumental training for two distinct food rewards. One reward was subsequently devalued using sensory-specific satiety, followed by an instrumental extinction test. Functional magnetic resonance imaging (fMRI) was acquired during both instrumental training and extinction testing to assess brain activity during goal-directed versus habitual performance.
What was found
The abstract provides no numerical values, effect sizes, or test statistics. Directionally, simultaneous administration of hydrocortisone and yohimbine rendered instrumental behavior insensitive to outcome devaluation, indicating a shift to habitual control. Neither hydrocortisone nor yohimbine alone produced this behavioral shift. Neurally, the combined administration reduced the sensitivity of the orbitofrontal cortex and medial prefrontal cortex to changes in outcome value, whereas areas associated with habit learning showed no modulation.
Why it matters
This study provides mechanistic evidence in humans that the shift from goal-directed action to habit learning under acute stress requires concurrent activation of both glucocorticoid and noradrenergic systems, acting primarily by downregulating prefrontal goal-directed valuation circuits rather than upregulating habit systems.
Limits
The abstract does not report the total sample size, participant demographics, drug dosages, or quantitative statistical outputs. The study uses acute pharmacological administration in healthy subjects with food rewards, which may not capture chronic stress dynamics, real-world stressors, or clinical populations with stress-related disorders.