title: Idle behaviors of the hippocampus reflect endogenous cortisol levels in youth.
abstract: OBJECTIVE
  Compelling evidence indicates that disruption in functional connectivity (FC) in brain networks underlies many psychiatric and developmental disorders. Current theory posits that biological (i.e., cortisol) and environmental (i.e., stress) experiences in early life are strong determinants in the development of functional brain systems and formative in the genesis of such disorders. The objective of this study was to examine the extent to which individual differences in cortisol concentrations during FC magnetic resonance imaging (MRI) would map onto variability in hippocampal to default mode network (DMN) connectivity in typically developing youth.
  
  
  METHODS
  Salivary cortisol and FC MRI data were collected concurrently in 33 scan-naive 7- to 15-year-old participants. Twenty-nine of these participants previously completed the Trier Social Stress Test. Hippocampal to DMN FC and endogenous cortisol variability during MRI were examined. A possible association between MRI cortisol and cortisol response to the Trier Social Stress Test during the preceding visit or a participant's ratings of anxiety during MRI was tested.
  
  
  RESULTS
  There were significant positive relations between MRI cortisol levels and measurements in the following 3 areas: hippocampal to DMN FC during the resting state, cortisol levels during the Trier Social Stress Test, and fear/anxiety ratings during MRI. Fear/anxiety ratings during MRI also related to self-reported anxiety on standardized measurements.
  
  
  CONCLUSIONS
  This study shows for the first time that FC of the hippocampus is altered with changing cortisol responsivity in youth. Altered FC during the resting state may represent altered alertness or monitoring resulting from variation in glucocorticoid function in youth, which carries implications for the effect of stress on response monitoring and decision making.
authors.affiliation: Merrill Palmer Skillman Institute for Child and Family Development, Wayne State University, Detroit, MI 48202, USA. moriah@wayne.edu
authors.forename: Moriah E
authors.initials: ME
authors.lastname: Thomason
authors.forename: Maria A
authors.initials: MA
authors.lastname: Tocco
authors.forename: Kelly A
authors.initials: KA
authors.lastname: Quednau
authors.forename: Andrea R
authors.initials: AR
authors.lastname: Bedway
authors.forename: Justin M
authors.initials: JM
authors.lastname: Carré
mesh_terms: D000293:Adolescent; D002648:Child; D063132:Connectome / Q000379:methods; D002658:Developmental Disabilities / Q000209:etiology* / Q000378:metabolism / Q000503:physiopathology; D005260:Female; D006624:Hippocampus / Q000503:physiopathology*; D006801:Humans; D006854:Hydrocortisone / Q000378:metabolism*; D008279:Magnetic Resonance Imaging; D008297:Male; D009415:Nerve Net / Q000503:physiopathology*; D012463:Saliva; D013315:Stress, Psychological / Q000378:metabolism / Q000503:physiopathology*
chemical_list: D006854:Hydrocortisone