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Altered functional connectivity in the fear network of firefighters with repeated traumatic stress

  • Hyeonseok Jeong (a1), Shinwon Park (a2), Stephen R. Dager (a3), Soo Mee Lim (a4), Suji L. Lee (a2), Haejin Hong (a2), Jiyoung Ma (a5), Eunji Ha (a2), Young Sun Hong (a6), Ilhyang Kang (a5), Eun Hee Lee (a7), Sujung Yoon (a8), Jieun E. Kim (a9), Jungyoon Kim (a10) and In Kyoon Lyoo (a11)...



Firefighters are routinely exposed to various traumatic events and often experience a range of trauma-related symptoms. Although these repeated traumatic exposures rarely progress to the development of post-traumatic stress disorder, firefighters are still considered to be a vulnerable population with regard to trauma.


To investigate how the human brain responds to or compensates for the repeated experience of traumatic stress.


We included 98 healthy firefighters with repeated traumatic experiences but without any diagnosis of mental illness and 98 non-firefighter healthy individuals without any history of trauma. Functional connectivity within the fear circuitry, which consists of the dorsal anterior cingulate cortex, insula, amygdala, hippocampus and ventromedial prefrontal cortex (vmPFC), was examined using resting-state functional magnetic resonance imaging. Trauma-related symptoms were evaluated using the Impact of Event Scale – Revised.


The firefighter group had greater functional connectivity between the insula and several regions of the fear circuitry including the bilateral amygdalae, bilateral hippocampi and vmPFC as compared with healthy individuals. In the firefighter group, stronger insula–amygdala connectivity was associated with greater severity of trauma-related symptoms (β = 0.36, P = 0.005), whereas higher insula–vmPFC connectivity was related to milder symptoms in response to repeated trauma (β = −0.28, P = 0.01).


The current findings suggest an active involvement of insular functional connectivity in response to repeated traumatic stress. Functional connectivity of the insula in relation to the amygdala and vmPFC may be potential pathways that underlie the risk for and resilience to repeated traumatic stress, respectively.

Declaration of interest



Corresponding author

Correspondence: In Kyoon Lyoo, Ewha Brain Institute and Department of Brain and Cognitive Sciences, Ewha Womans University, 52 Ewhayeodaegil, Seodaemungu, Seoul, 03760, South Korea. E-mail:


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1Benedek, DM, Fullerton, C, Ursano, RJ. First responders: mental health consequences of natural and human-made disasters for public health and public safety workers. Annu Rev Public Health 2007; 28: 5568.
2Agaibi, CE, Wilson, JP. Trauma, PTSD, and resilience: a review of the literature. Trauma Violence Abuse 2005; 6: 195216.
3Lanius, RA, Bluhm, RL, Coupland, NJ, Hegadoren, KM, Rowe, B, Theberge, J, et al. Default mode network connectivity as a predictor of post-traumatic stress disorder symptom severity in acutely traumatized subjects. Acta Psychiatr Scand 2010; 121: 3340.
4Fragkaki, I, Thomaes, K, Sijbrandij, M. Posttraumatic stress disorder under ongoing threat: a review of neurobiological and neuroendocrine findings. Eur J Psychotraumatol 2016; 7: 30915.
5Hennig-Fast, K, Werner, NS, Lermer, R, Latscha, K, Meister, F, Reiser, M, et al. After facing traumatic stress: brain activation, cognition and stress coping in policemen. J Psychiatr Res 2009; 43: 1146–55.
6Jung, WH, Chang, KJ, Kim, NH. Disrupted topological organization in the whole-brain functional network of trauma-exposed firefighters: a preliminary study. Psychiatry Res 2016; 250: 1523.
7Reynaud, E, Guedj, E, Souville, M, Trousselard, M, Zendjidjian, X, El Khoury-Malhame, M, et al. Relationship between emotional experience and resilience: an fMRI study in fire-fighters. Neuropsychologia 2013; 51: 845–9.
8Reynaud, E, Guedj, E, Trousselard, M, El Khoury-Malhame, M, Zendjidjian, X, Fakra, E, et al. Acute stress disorder modifies cerebral activity of amygdala and prefrontal cortex. Cogn Neurosci 2015; 6: 3943.
9Shucard, JL, Cox, J, Shucard, DW, Fetter, H, Chung, C, Ramasamy, D, et al. Symptoms of posttraumatic stress disorder and exposure to traumatic stressors are related to brain structural volumes and behavioral measures of affective stimulus processing in police officers. Psychiatry Res 2012; 204: 2531.
10Shin, LM, Liberzon, I. The neurocircuitry of fear, stress, and anxiety disorders. Neuropsychopharmacology 2010; 35: 169–91.
11First, MB, Spitzer, RL, Gibbon, M, Williams, JBW. Structured Clinical Interview for DSM-IV-TR Axis I Disorders, Research Version. Biometrics Research, 2002.
12Eun, HJ, Kwon, TW, Lee, SM, Kim, TH, Choi, MR, Cho, SJ. A study on reliability and validity of the Korean version of Impact of Event Scale-Revised. J Korean Neuropsychiatr Assoc 2005; 44: 303–10.
13Cohen, S, Doyle, WJ, Skoner, DP, Rabin, BS, Gwaltney, JM. Jr Social ties and susceptibility to the common cold. JAMA 1997; 277: 1940–4.
14Oldfield, RC. The assessment and analysis of handedness: the Edinburgh inventory. Neuropsychologia 1971; 9: 97113.
15Whitfield-Gabrieli, S, Nieto-Castanon, A. Conn: a functional connectivity toolbox for correlated and anticorrelated brain networks. Brain Connect 2012; 2: 125–41.
16Behzadi, Y, Restom, K, Liau, J, Liu, TT. A component based noise correction method (CompCor) for BOLD and perfusion based fMRI. Neuroimage 2007; 37: 90101.
17Fair, DA, Cohen, AL, Power, JD, Dosenbach, NU, Church, JA, Miezin, FM, et al. Functional brain networks develop from a ‘local to distributed’ organization. PLoS Comput Biol 2009; 5: e1000381.
18DiGangi, JA, Tadayyon, A, Fitzgerald, DA, Rabinak, CA, Kennedy, A, Klumpp, H, et al. Reduced default mode network connectivity following combat trauma. Neurosci Lett 2016; 615: 3743.
19Guidotti, TL, Clough, VM. Occupational health concerns of firefighting. Annu Rev Public Health 1992; 13: 151–71.
20Ye, S, Kim, H, Jeong-Choi, K, Kim, JE, Park, S, Lee, Y, et al. Parkinson's disease among firefighters: a focused review on the potential effects of exposure to toxic chemicals at the fire scene. Korean J Biol Psychiatry 2017; 24: 1925.
21Etkin, A, Wager, TD. Functional neuroimaging of anxiety: a meta-analysis of emotional processing in PTSD, social anxiety disorder, and specific phobia. Am J Psychiatry 2007; 164: 1476–88.
22Waugh, CE, Wager, TD, Fredrickson, BL, Noll, DC, Taylor, SF. The neural correlates of trait resilience when anticipating and recovering from threat. Soc Cogn Affect Neurosci 2008; 3: 322–32.
23Singer, T, Critchley, HD, Preuschoff, K. A common role of insula in feelings, empathy and uncertainty. Trends Cogn Sci 2009; 13: 334–40.
24Immordino-Yang, MH, McColl, A, Damasio, H, Damasio, A. Neural correlates of admiration and compassion. Proc Natl Acad Sci U S A 2009; 106: 8021–6.
25Namkung, H, Kim, SH, Sawa, A. The Insula: an underestimated brain area in clinical neuroscience, psychiatry, and neurology. Trends Neurosci 2017; 40: 200–07.
26Menon, V, Uddin, LQ. Saliency, switching, attention and control: a network model of insula function. Brain Struct Funct 2010; 214: 655–67.
27Dunsmoor, JE, Prince, SE, Murty, VP, Kragel, PA, LaBar, KS. Neurobehavioral mechanisms of human fear generalization. Neuroimage 2011; 55: 1878–88.
28Ohman, A. The role of the amygdala in human fear: automatic detection of threat. Psychoneuroendocrinology 2005; 30: 953–8.
29Rabinak, CA, Angstadt, M, Welsh, RC, Kenndy, AE, Lyubkin, M, Martis, B, et al. Altered amygdala resting-state functional connectivity in post-traumatic stress disorder. Front Psychiatry 2011; 2: 62.
30Brown, VM, LaBar, KS, Haswell, CC, Gold, AL, Mid-Atlantic, MW, McCarthy, G, et al. Altered resting-state functional connectivity of basolateral and centromedial amygdala complexes in posttraumatic stress disorder. Neuropsychopharmacology 2014; 39: 351–9.
31van Wingen, GA, Geuze, E, Vermetten, E, Fernandez, G. Perceived threat predicts the neural sequelae of combat stress. Mol Psychiatry 2011; 16: 664–71.
32Milad, MR, Quirk, GJ. Neurons in medial prefrontal cortex signal memory for fear extinction. Nature 2002; 420: 70–4.
33Urry, HL, van Reekum, CM, Johnstone, T, Kalin, NH, Thurow, ME, Schaefer, HS, et al. Amygdala and ventromedial prefrontal cortex are inversely coupled during regulation of negative affect and predict the diurnal pattern of cortisol secretion among older adults. J Neurosci 2006; 26: 4415–25.
34Feng, P, Feng, T, Chen, Z, Lei, X. Memory consolidation of fear conditioning: bi-stable amygdala connectivity with dorsal anterior cingulate and medial prefrontal cortex. Soc Cogn Affect Neurosci 2014; 9: 1730–7.
35Rauch, SL, Shin, LM, Phelps, EA. Neurocircuitry models of posttraumatic stress disorder and extinction: human neuroimaging research--past, present, and future. Biol Psychiatry 2006; 60: 376–82.
36Shin, LM, Rauch, SL, Pitman, RK. Amygdala, medial prefrontal cortex, and hippocampal function in PTSD. Ann N Y Acad Sci 2006; 1071: 6779.
37Fox, MD, Greicius, M. Clinical applications of resting state functional connectivity. Front Syst Neurosci 2010; 4: 19.
38Koch, SB, van Zuiden, M, Nawijn, L, Frijling, JL, Veltman, DJ, Olff, M. Intranasal oxytocin normalizes amygdala functional connectivity in posttraumatic stress disorder. Neuropsychopharmacology 2016; 41: 2041–51.
39Fox, MD, Buckner, RL, Liu, H, Chakravarty, MM, Lozano, AM, Pascual-Leone, A. Resting-state networks link invasive and noninvasive brain stimulation across diverse psychiatric and neurological diseases. Proc Natl Acad Sci U S A 2014; 111: E436775.


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Altered functional connectivity in the fear network of firefighters with repeated traumatic stress

  • Hyeonseok Jeong (a1), Shinwon Park (a2), Stephen R. Dager (a3), Soo Mee Lim (a4), Suji L. Lee (a2), Haejin Hong (a2), Jiyoung Ma (a5), Eunji Ha (a2), Young Sun Hong (a6), Ilhyang Kang (a5), Eun Hee Lee (a7), Sujung Yoon (a8), Jieun E. Kim (a9), Jungyoon Kim (a10) and In Kyoon Lyoo (a11)...
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