Limitations and constraints on generalizability
somatic disorders, anxiety, interoceptive dysfunction, Thomas, RVT
EVENTS, BRAIN, CORTEX
The IEAT should be improved by introducing a circle motion to the Passive Interoception condition, as the stationary target described here led to a motion confound between passive interoception and the other four experimental conditions. In its current form, Passive Interoception showed relative deactivation in the middle temporal (MT or V5) region of the visual cortex, which is well-established for its sensitivity to motion (Additionally, while we corrected for both respiration frequency and RVT, we did not measure PSeveral constraints on generalizability are also apparent. We present unexpected and exploratory findings from a small sample; replication is therefore needed, especially given the paucity of studies in this area. The community sample may also not generalize to people with clinical conditions associated with interoceptive dysfunction, nor advanced contemplative practitioners with extensive interoceptive training. Respiration is also only one of many interoceptive signals that each vary in their reportability and controllability, and so may possess distinct neural dynamics. Multimodal interoceptive research is needed to determine the generalizability of the patterns discussed here, to clarify the impact of active reporting versus passive engagement, the role sensory signal salience, and the influence of participant expertise/dysfunction.A further limitation to the present findings is that all practices were conducted with eyes-open, which may be dissimilar to many meditation practices. Following repeated evidence that opening one’s eyes decreases the functional connectivity between the SLN and the DMN, it was theorized that reducing the connectivity between these networks reflects an orientation to external rather than internal events (In conclusion, relative to Exteroception, Interoception of the breath reduced somatomotor and prefrontal activity, offset by enhanced connectivity between the ACC and the DAN. Greater self-reported interoceptive awareness was linked to sparing of the ACC and language processing regions from this deactivation pattern. Together, these processes may allow sensory signals from the body to be better discerned. The ACC deactivation observed in the IEAT paradigm may serve as a candidate biomarker of individual differences in interoceptive processing, one that distinguishes adaptive representations engendered by contemplative training from the avoidance and catastrophizing observed in anxiety and somatic disorders. Larger, more diverse samples and replication of effects are needed to test these emerging ideas.Acknowledgments: We thank Natalie Koh and Sophie Xie for their coordination and data collection efforts and to Dr. Thomas Grabowski, Dr. Chris Gatenby, and Liza Young at the Integrated Brain Research Center at the University of Washington for their collaboration.