You shall (not) pass: The relationships of neural gating of bodily sensations to bodily perception and state negative affect

Recurrent and debilitating symptoms such as pain and breathlessness in chronic health conditions represent a significant burden to the affected individuals and the society at large. How acute sensations transition into chronic complaints has been a central question in the field of health psychology, with popular and enduring models suggesting that negative affect, namely fear of symptoms and the general anxious predisposition, can affect how symptoms are processed and perceived. A candidate mechanism for distorted symptom perception is reduced neural gating, a phenomenon where the redundant sensations that would normally be suppressed, are allowed past the midbrain "gate", which is reflected as a less-suppressed response to redundant stimuli in scalp-recorded neural activity. Based on the previous research on the gating of auditory stimuli as a mechanism for over-perception in conditions such as schizophrenia, we hypothesized that neural gating of bodily sensations might serve a similar function in the transition from acute to chronic bodily symptoms. For neural gating to qualify as a plausible mechanism for over-perception, it should 1) relate to bodily perception and 2) be reduced by negative affect. We tested these hypotheses in healthy adults and in two bodily-related domains (respiratory and somatosensory) to investigate if these purported relationships are domain-specific or generalized across domains. In the first study, we tested whether neural gating of respiratory and somatosensory stimuli relates to the perception of brief and sustained bodily stimulation (Chapter 2). We found that only somatosensory gating predicted perception, across domains but in an unexpected direction (more gating à higher perception). We interpreted this relationship as potentially moderated by top-down attention to stimuli. The next study (Chapter 3) investigated whether neural gating relates to long-term perceptual habituation to sustained bodily stimulation. We found that respiratory gating was improved by the repeated experience of breathlessness, but found no relationships to habituation in either domain. We then turned to the modulation of neural gating by state negative affect. Chapter 4 reports a study in which neural gating was measured during both explicit safety or the (unpredictable) threat of pain or breathlessness. We found increased fear and perception during threat, but no effects of threat or its unpredictability on neural gating. The final study (Chapter