title: The fine line between 'brave' and 'reckless': amygdala reactivity and regulation predict recognition of risk.
abstract: BACKGROUND
  High sensation-seekers (HSS) pursue novelty even at the cost of self-harm. When challenged, HSS are less anxious, show blunted physiological (cortisol, startle) and neurobiological (prefrontal-limbic) responses, and devalue aversive outcomes. Here, we investigate how these features interact under conditions of physical danger, in distinguishing between adaptive and maladaptive approaches to risk.
  
  
  METHODS
  We recruited a cohort of individuals who voluntarily sought out recreational exposure to physical risk, and obtained serial cortisol values over two time-locked days. On the 'baseline' day, we scanned subjects' brains with functional and structural MRI; on the 'skydiving day,' subjects completed a first-time tandem skydive. During neuroimaging, subjects viewed cues that predicted aversive noise; neural data were analyzed for prefrontal-limbic reactivity (activation) and regulation (non-linear complexity), as well as cortical thickness. To probe threat perception, subjects identified aggression for ambiguous faces morphed between neutral and angry poles.
  
  
  RESULTS
  Individuals with prefrontal-limbic meso-circuits with less balanced regulation between excitatory and inhibitory components showed both diminished cortisol/anxiety responses to their skydives, as well as less accurate perceptual recognition of threat. This impaired control was localized to the inferior frontal gyrus, with associated cortical thinning. Structural equation modeling suggests that sensation-seeking is primarily mediated via threat-perception, which itself is primarily mediated via neural reactivity and regulation.
  
  
  CONCLUSIONS
  Our results refine the sensation-seeking construct to provide important distinctions (brain-based, but with endocrine and cognitive consequences) between the brave, who feel fear but nonetheless overcome it, and the reckless, who fail to recognize danger. This distinction has important real-world implications, as those who fail to recognize risk are less likely to mitigate it.
authors.affiliation: Department of Biomedical Engineering, Stony Brook University School of Medicine, Stony Brook, NY 11794, USA; Department of Radiology, A. A. Martinos Center for Biomedical Imaging, Massachusetts General Hospital, Charlestown, MA 02129, USA. Electronic address: Lilianne.Strey@stonybrook.edu.
authors.forename: L R
authors.initials: LR
authors.lastname: Mujica-Parodi
authors.affiliation: Department of Psychology, Northern Michigan University, Marquette, MI 49855, USA.
authors.forename: Joshua M
authors.initials: JM
authors.lastname: Carlson
authors.affiliation: Department of Psychiatry, Columbia University College of Physicians and Surgeons, New York, NY 10032, USA.
authors.forename: Jiook
authors.initials: J
authors.lastname: Cha 차지욱
authors.affiliation: Department of Biomedical Engineering, Stony Brook University School of Medicine, Stony Brook, NY 11794, USA; Department of Applied Mathematics and Statistics, Stony Brook University, Stony Brook, NY 11794, USA.
authors.forename: Denis
authors.initials: D
authors.lastname: Rubin
mesh_terms: D000293:Adolescent; D000328:Adult; D000679:Amygdala / Q000502:physiology*; D001931:Brain Mapping; D005239:Fear / Q000502:physiology*; D005260:Female; D006801:Humans; D007091:Image Processing, Computer-Assisted; D008279:Magnetic Resonance Imaging; D008297:Male; D009434:Neural Pathways / Q000502:physiology*; D012309:Risk-Taking; D055815:Young Adult
keywords: Amygdala; Complexity; Cortisol; Fear; Limbic; Prefrontal cortex; Resilience; Sensation-seeking; Stress; chaos, fractal, power spectrum scale invariance