Neural correlates of fear: insights from neuroimaging

Figures & data

Figure 1 A schematic diagram depicting different brain regions and their involvement in specific fear processes (red), and more general role in cognitive/affective processing (blue).

Note: The brain is organized into functional networks, with the salience network thought to regulate dynamic changes in other networks, principally the default mode network, which represents the brain at rest (networks are specified in green).
Abbreviation: PTSD, posttraumatic stress disorder.

Figure 2 (A) Fear faces time-locked to distinct parts of the cardiac cycle were judged as more intense at systole on the heart beat relative to systole between heart beats. (B) Observing these fear faces induced a fear reaction in the brain that was also modulated by the cardiac cycle (eg, enhanced amygdala activation at systole), indicating that the contagion of fear responses is altered by bodily context. (C) Attentional capture of fear faces was exaggerated at systole, as demonstrated using the attentional blink paradigm to present fear faces at the cusp of conscious awareness.

Notes: The red circle denotes FWE corrected cluster in right amygdala 32 0 -24. *Denotes significant effect of heart-timing for fear stimuli only.

Figure 3 Brain and body interact to affect the perception and expression of fear.

Notes: Physiological signals from the body can alter the fear signal in the brain: patients with pure autonomic failure (PAF) had a reduced neural expression of fear in left (L) amygdala (A) and insula (B) during a fear-conditioning task. Y pertains to co-ordinates.

Figure 4 (A and B) Fear-conditioning and -extinction procedures can be used to demonstrate deficits in the retention of safety information over time in patients with PTSD relative to combat control participants.

Notes: Using a fear-conditioning procedure in the scanner, a light was paired with a shock to form a CS⁺. Compared to a CS^- (different-colored light never followed by shock), the CS⁺ elicited a fear signal in the brain with activation of the amygdala and insula, as demonstrated in both PTSD patients and combat control participants (A). Extinction (repeated presentation of the CS⁺ in the absence of shock) led to a reduction in this fear signal. However, the next day, when both PTSD patients and combat control participants returned to the lab, combat control participants were able to retain this safety information, while PTSD patients displayed an enhanced fear signal in the amygdala to the CS⁺ relative to control participants (B), demonstrating that this safety information was not retained over time in this patient population.
Abbreviations: PTSD, posttraumatic stress disorder; CS, conditioned stimulus; CS⁺, CS with shock; CS^-, without a shock.