Strengths and limitations The present study benefited from a large sample relative to the fMRI literature. It extends the literature by simultaneously examining
anxious apprehension and anxious arousal, as opposed to examining only one anxiety type or ignoring the distinction. Given that these anxiety types are correlated, inferences based on the measurement of only one anxiety type may not reflect effects specific to that Inhibitors,research,lifescience,medical anxiety type. The study also benefited from statistically controlling comorbid depression, which often confounds studies of anxiety due to shared general distress. Additionally, the present study examined habituation at the level of Syk inhibitor neural activation, which can reveal effects that may cancel out at the level of behavior. However, present findings should be interpreted in the context of some limitations. First, although the present study purposefully
chose Inhibitors,research,lifescience,medical stimuli that would not elicit an extremely strong fear response, in order to foster habituation, the stimuli may not be as relevant to pathological anxiety as stimuli that evoke a much stronger fear response (e.g., spiders for individuals with spider Inhibitors,research,lifescience,medical phobia). Second, it is unclear whether the stimuli used in the present investigation were experienced as threatening, and this may have limited the level of fear experienced by participants. Future research could explore a variety of stimuli that may engage fear
more strongly. Third, the present study interprets the observed habituation in Broca’s Inhibitors,research,lifescience,medical area as reflecting habituation in worry. However, it is possible that the activation in Broca’s area observed in the present study reflects processes other than, or in addition to, worry. For example, it is possible that Broca’s area activation better reflects Inhibitors,research,lifescience,medical engagement in processing of the specific word stimuli, rather than actual verbal rehearsal of worries. Even if true, engagement in word processing may still be driven by worry (e.g., worry about performing the task or word meaning), an inference that seems reasonable given that anxious apprehension moderated this activation. One possible method of differentiating between worry and word Oxymatrine processing specific to the stimuli would be to disentangle block-level and stimulus-specific variance, given that worry should be increased during negative blocks but not necessarily tied to specific stimuli. Although there is jitter in the presentation of words in the present study, the length of the jitter is small compared to the HRF, and the timing of the stimuli (2000 ± 225 msec) is approximately equal to the fMRI sampling rate (TR = 2 sec). In order to differentiate between these signals without aliasing, TR would have to be less than 1 sec or ITI greater than 4 sec.