Emotion-induced changes in human medial prefrontal cortex: II. During anticipatory anxiety

Abstract

Regional cerebral blood flow (BF) was examined in the human medial prefrontal cortex (MPFC) with positron emission tomography during anticipatory anxiety. Transient anxiety was induced in normal subjects by having them anticipate a painful shock to the fingers of one hand. BF was decreased during anticipatory anxiety, relative to an eyes-closed resting condition, in two regions of the MPFC (Brodmann Areas 10/32 and 24/25). BF decreases in these areas were inversely correlated with anxiety self rating, such that the least anxious subjects exhibited the largest BF reductions, whereas the most anxious subjects showed no significant BF reduction or a slight increase. BF changes in MPFC and in the midbrain were correlated with each other and with anxiety self rating. These results are consistent with the hypothesis that BF reductions in MPFC, previously observed in cognitive tasks, reflect a dynamic balance between focused attention and subject anxiety and may occur from a functionally active baseline or default state. The characterization of such relationships within the human brain enables new insights into the integration of cognition and emotion.

Figure 1

Behavioral measurements (mean + SEM) obtained from 16 normal subjects during PET BF scans obtained before (Scan 1), during (Scan 2), and after (Scan 3) the anticipation of a painful shock to the hand. STAI refers to the STAI (21). During Scan 3 (anticipatory anxiety), all three measurements differed significantly (**, P < 0.000001; *, P < 0.0001) from baseline measurements (Scans 1 and 3). For the VAS, Scan 3 was significantly lower than Scan 1 (†, P < 0.05).

Figure 2

An averaged PET subtraction image overlaid on an averaged anatomical MRI image showing significant decreases in two MPFC regions, A and B. Left, anterior. x coordinates indicate distance from the midline in millimeters.

Figure 3

A covariance image indicating regions that varied with subject VAS ratings. The midbrain region referred to in the text is labeled C on slice x = 3. Regions A and B, seen in the averaged subtraction image (Fig. 1) are also seen in this covariance image.

Figure 4

Scatter plots of VAS used for the assessment of anxiety during the anticipation of an electric shock on the hand vs. BF change in the regions identified in the averaged subtraction (regions A and B, Fig. 2.) and covariance (region C, Fig. 3) images. The Blood Flow Change scale is a linear scale of normalized radioactive count differences.