Introduction

The thought-action fusion (TAF) is a tendency of individuals to blindly establish causal relations between their own thoughts and external reality.1 Many studies have investigated to reveal a reason of transition from normal to abnormal obsessive thought with TAF mechanism.2,3 Despite knowledge of amygdala involvement in fear and anxiety, its contribution to the pathophysiology of OCD remains controversial. In the current study, we used TAF task to reveal amygdala function related to anxiety and mindfulness effect in OCD.

Subjects and Methods

A total of sixty-two participants (30 OCD, 32 healthy controls, all men) were recruited for this study. The mean age of all subjects was 25.13±6.98 (OCD) and 23.22±1.62 (control) years and right-handed in accordance with the Edinburgh handedness scale. All participants received written informed content and the study protocol was approved by the Institutional Review Board at Kyungpook national University Hospital. During the functional magnetic resonance acquisition, participants evaluated how bad they feel about the following typed sentence with a Likert scale form 1(very little) to 4(very much) using MR convertible button box : “I hope that … will soon be in a car accident”. Participants were instructed to complete this sentence by filling the name of a close (close condition) or neutral (neutral condition) person to them. Functional image data were obtained the 3.0T GE 750W scanner with 24ch head coil (EPI, TR = 2000ms, TE = 30ms, FOV = 23cm, acquisition matrix = 64 X 64, no gap). The 3D T1-weighted fast spoiled gradient echo were used for structural imaging acquisition. fMRI data processing and statistical analyses used SPSS, SPM12, and CONN tool. In fMRI data within-group analysis, brain activation maps for each condition analyzed by one-sample t-test. The SPM{t} was thresholded at P<0.01, false discovery rate (FDR) corrected for multiple comparisons across the whole brain. The differences of PPI between the group were analyzed by two-sample t-test (P<0.01, p-uncorrected).

Results and Discussion

In one-sample t-test, the OCD group showed salience network activation without amygdala in both conditions. By comparison, the HC showed greater salience network activation including amygdala in both condition (Figure 1). Behavior performance of the TAF task showed significant differences between control and OCD (Figure 2). In the close condition, the OCD group used more time to response than the control group. In both condition, the control group reported more negative feeling to both conditions than the OCD group. In PPI, we identified brain regions that were functionally connected with the amygdala with other salience network ROI analyses. There were no greater PPI regions in OCD group compared with HC. In particular, the HC showed greater positive amygdala PPI with putamen compared with OCD group when a person with a close relationship entered the negative sentence (Figure 3). Based on our findings, the present study suggests that OCD might have a dysfunction to decision making for negative emotional situation.

Conclusion

We found that the dysfunction to decision making for negative situation might have negative influence in the formation and maintenance of obsessive thoughts and behavior.

Acknowledgements

No acknowledgement found.