FIGURE 4.

Scatterplots Displaying Significant Bivariate Relations Across All Subjects (N=61) Between Total Scores on the Clinician-Administered PTSD Scale (CAPS) and the Steepness of Positive and Negative Neural Gradients of Generalization in a Study of Neural Substrates of Overgeneralized Conditioned Fear^a

^a Bivariate relation between CAPS scores and the steepness of both positive neural gradients of generalization in the right anterior insula and negative neural gradients of generalization in the left ventral hippocampus/amygdala. The y-axis shows a measure of gradient steepness reflecting the degree to which generalization gradients deviated from linearity. Larger linear deviation scores reflect more shallow downward slopes from the conditioned danger cue (CS+) to the conditioned safety cue (CS−) in the case of positive gradients and more shallow upward slopes from CS+ to CS− in the case of negative gradients. Of note, linear deviation was reverse scored for negative gradients such that larger scores consistently indicated greater generalization whether the generalization gradient was negative or positive. As shown, increasing levels of generalization at both these neural loci are associated with increasing levels of PTSD symptom severity as measured by the CAPS.