Biological studies of post-traumatic stress disorder

Abstract

Preface Posttraumatic stress disorder (PTSD) is the only major mental disorder for which a cause is considered to be known, viz., an event that involves threat to the physical integrity of oneself or others and induces a response of intense fear, helplessness, or horror. Although PTSD is still largely regarded as a psychological phenomenon, over the past three decades the growth of the biological PTSD literature has been explosive, and thousands of references now exist. Ultimately, the impact of an environmental event, such as a psychological trauma, must be understood at organic, cellular, and molecular levels. The present review attempts to present the current state of this understanding, based upon psychophysiological, structural and functional neuroimaging, endocrinological, genetic, and molecular biological studies in humans and in animal models.

Infralimbic cortex controls the activity of the hypothalamus–pituitary–adrenal axis and the formation of aversive memory: Effects of environmental enrichment

“…However, most pharmacological and lesion studies are limited to the dorsal part of the medial PFC or do not distinguish between the dorsal and ventral parts [5][6][7][8] and, therefore, the role played by the infralimbic cortex in the regulation of the HPA axis and corticosterone concentrations is still uncertain. A dysfunctional regulation of the HPA axis as well as other limbic areas by the infralimbic cortex (ventral medial PFC in humans) is associated with stress mal adaptation and stress-related disorders [9][10][11][12].…”

Evaluating web-based cognitive-affective remediation in recent trauma survivors: study rationale and protocol

“…Putative neural mechanisms underlying their pathogenic effect may involve a combination of a hyperactive emotional reactivity system coupled with dysfunctional regulatory circuitry in the frontal lobes (Etkin & Wager, 2007; Hayes, Hayes, & Mikedis, 2012; Pitman et al, 2012). Beyond the fronto-limbic circuitry, aberrations between and within (Sripada et al, 2012) the default mode network (DMN), salience network (SN), and the central executive network (CEN) were demonstrated in PTSD.…”

The role of automatic defensive responses in the development of posttraumatic stress symptoms in police recruits: protocol of a prospective study

“…Neurobiological models on the pathophysiology of PTSD describe enhanced activity and connectivity between core nodes of the salience network (SN), such as the amygdala, anterior insula and dorsal anterior cingulate cortex (dACC) (Hayes, Hayes, & Mikedis, 2012; Patel, Spreng, Shin, & Girard, 2012; Pitman et al, 2012). The SN is an intrinsic connectivity network directed at the detection of biologically relevant information in the environment (Seeley et al, 2007), showing increased engagement during the unconscious processing of trauma-related stimuli in PTSD patients, compared to healthy controls (Rabellino et al, 2015).…”

“…Especially the amygdala is important in fear learning, the detection of threat and orchestrating the expression of fear in coordination with the basal forebrain (Fox, Oler, Tromp, Fudge, & Kalin, 2015). Besides amygdala hyperactivity, PTSD has been associated with hyperactivity in prefrontal structures involved in fear expression, such as the dACC (Hayes et al, 2012; Pitman et al, 2012). Further, brainstem structures, such as the periaqueductal grey (PAG), are involved in physiological responses of automatic defensive mechanisms.…”

“…Not surprisingly, the predominant neurocircuitry model of PTSD postulates deficient inhibitory control of the ventromedial prefrontal cortex (vmPFC) over the fear response (Pitman et al, 2012; Rauch, Shin, & Phelps, 2006), characterized with hypo-activity of the vmPFC (Hayes et al, 2012; Patel et al, 2012), as well as diminished functional (Sripada et al, 2012) and structural (Koch et al, 2017) connectivity between the amygdala, vmPFC and hippocampus. Of note, the vmPFC and hippocampus are important nodes of the default mode network (DMN), which is an intrinsic connectivity network engaged during rest and involved in internally focused thought (Greicius, Krasnow, Reiss, & Menon, 2003).…”