Abstract
Although unconscious processing is a key element of mental operation, its neural correlates have not been established. Also, clinical observations suggest that unconscious processing may be involved in the pathophysiology of post-traumatic stress disorder (PTSD), but the neurobiological mechanisms underlying such impairments remain unknown. The purpose of the present study was to examine putative mechanisms underlying unconscious processing by healthy participants and to determine whether these mechanisms may be altered in PTSD patients. Twenty patients with PTSD and 27 healthy individuals were administered a validated wheel of fortune-type gambling task during functional magnetic resonance imaging (fMRI). Unconscious processing was elicited using unconscious contextual framing of the zero monetary outcomes as “no loss,” “no gain” or as “neutral.” Brief passive visual processing of the “no loss” vs. “no gain” contrast by healthy participants yielded bilateral frontal-, temporal- and insular cortices and striatal activations. Between-group comparison revealed smaller activity in the left anterior prefrontal-, left dorsolateral prefrontal-, right temporal- and right insular cortices and in bilateral striatum in PTSD patients with the left dorsolateral prefrontal cortex activity been more pronounced in those with greater PTSD severity. These observations implicate frontal-, temporal-, and insular cortices along with the striatum in the putative mechanisms underlying unconscious processing of the monetary outcomes. Additionally, our results support the hypothesis that PTSD is associated with primary cortical and subcortical alterations involved in the above processes and that these alterations may be related to some aspects of PTSD symptomatology.
Highlights
Arising outside of conscious awareness (Dijksterhuis, 2004), unconscious processing constitutes a key element of mental function (Bargh, 2019) that has evolved beyond immediate survival to support an instantaneous and effortless responsivity to internal and external stimuli (Greenwald et al, 1996)
Twenty patients diagnosed with Post-traumatic stress disorder (PTSD) as determined by the Structured Clinical Interview for DSM-IV-TR Axis I Disorders (First et al, 2002) and Clinician-Administered PTSD Scale (CAPS) (Weathers et al, 2001) and 27 healthy individuals were included in this study after the procedures were fully explained and written informed consent was given
Our observations support the thesis that an extended set of brain regions including frontal, temporal, and insular cortices along with the striatum may be involved in the mediation of unconscious processing inherent in contextual framing
Summary
Arising outside of conscious awareness (Dijksterhuis, 2004), unconscious processing constitutes a key element of mental function (Bargh, 2019) that has evolved beyond immediate survival to support an instantaneous and effortless responsivity to internal and external stimuli (Greenwald et al, 1996). Failure of the rational override contributes to cognitive/perceptual biases (Greenwald and Banaji, 1995) as well as to impulsive and potentially disadvantageous decisions and behavioral choices (Dijksterhuis, 2004; Koob and Volkow, 2016). In addition to PTSD’s association with unconscious threatrelated physiologic and behavioral responses manifested in anxiety and in conditioned fear (Elman and Borsook, 2018), there are clinical and even diagnostic features of PTSD itself that point to unconscious biases. Automatic “negative alterations in cognitions” is another key PTSD component (Hassin et al, 2006) encoded in the “D” diagnostic criteria e.g., negative thoughts and assumptions (American Psychiatric Association, 2013). Unconscious processing’s neural correlates in PTSD patients are unknown
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