Title: Unpleasantness and Fear in Interoception
Authors: Ceunen, Erik
Issue Date: 20-Apr-2015
Abstract: _________________________________________Interoceptive fear (IF) is the apprehension of bodily sensations. IF is relevant to a number of psychiatric and somatoform disorders, in which fear learning to bodilysensations has been hypothesized to play an important role. Although IFconditioning (IFC) is of relevance to understanding the etiology of these disorders, thus far research has hardly addressed the basic fear response topography to experimentally induced interoceptive sensations.Human fear can be measured through self-report inquiring about subjective fear, unpleasantness, arousal, sense of control (dominance), and the extent to which an aversive event is expected (expectancy). A validated psychophysiological measure for the motivational intensity, i.e. for arousal, is skin conductance. Eye blink startle is modulated by motivational direction (pleasant vs unpleasant) and is used to measure it. Duringunpleasantness and fear, startle magnitudes are generally potentiated compared to emotionally neutral and pleasant states. The primary aim of this doctoral project was to find out whether the human eyeblink startle paradigm can be used to measure defensive response mobilization elicited by aversive interoceptive stimulation. To this purpose, a two-step approach was used: in a first step the concept of interoception was critically reviewed, while in a second step a series of empiricalstudies were conducted.The review on interoception traced the development of the concept to its modern day usage. This review proposes to consider interoception as the phenomenological perception of the state of the body, irrespective of how this perception is formed and whetherit is accurate or not. Labels are suggested for specific components of interoception that allow to classify sensations as similar or distinct.In the first study, participants adopted a flexed, an upright, and an extended posture. The reasoning was that postures can influence emotions, and thus perhaps impact startle. Also, differences in startle hadpreviously been observed in gastrointestinal (commonly associated with a flexed posture) vs respiratory (extended posture) stimulation. Study 1found startle magnitude to be higher during the extended posture, due to negative affectivity associated with that posture.In a second study, healthy participants were exposed to a cold pressor test (CPT), loaded breathing, and inhalation of CO2-enriched air. Startle amplitudes during interoceptive stimulation were decreased relative to when there was no stimulation. Respiratory stimuli showed a linearly decreasing slope during prolonged stimulation, while the CPT evoked a quadratic pattern.In the third study we observed a potentiated startle during painful esophageal stimulation in women, but not in men. In the fourth study, we used esophageal stimulation to establish a homoreflexive interoceptive conditioning paradigm in which a non-painful esophageal stimulus (conditioned stimulus, CS) preceded a painful esophageal stimulus (unconditioned stimulus, US) in a paired, but not in an unpaired group. Compared to the latter, participants from the paired group learned to fear the CS, as reflected in their US-expectancy ratings and skin conductance response. Women in the paired group also showed a trend towards increased startle in response to the CS (relative to a safe period). This response disappeared again during the extinction phase; on the other hand,in the extinction phase men in the paired group showed higher startle amplitudes during the CS.In summary, our findings indicate that during aversive interoceptive stimulation, there is quite some unexpected variability in startle responding that does not uniformly fit the usually observed pattern of exteroceptive fear potentiated startle. Known modulatory influences on startle that could explain the results are arousal and orientation of attention. Alternative explanations for the observed startle refer to the defense cascade model of Lang and colleagues,and the perceptual-defensive-recuperative model of Bolles and Fanselow._________________________________________
Table of Contents: Table of Contents

On the origin of interoception 1
1. Introduction 2
1.1 Scope of relevance 2
1.2. Communicating on interoception 4
2. History of a concept 6
2.1. Etymology 6
2.2 Semantic evolution 7
3. Aspects of interoception 11
3.1. Exogenous versus endogenous origins 11
3.2 Visceroceptor, visceroceptive, visceroception – a reference to efferent innervation 13
3.3 The homeostatic afferent pathways and early CNS processing of homeostasis 19
3.4 Interoception as integrated percept 21
4. Conclusions 25

Interoceptive fear and its measurement 27
Interoceptive stimuli 28
Fear and unpleasantness 31

Aims 35
3.1 Review: On the origin of interoception 35
3.2 Study 1: Effect of seated trunk posture 36
3.3 Study 2: Effects of cold pain and respiratory stimulation on startle in women 36
3.4 Study 3: Effect of visceral pain on startle 37
3.5 Study 4: Visceral fear learning 37

Effect of Seated Trunk Posture on Eye Blink Startle and Subjective Experience: Comparing Flexion, Neutral Upright Posture, and Extension of Spine 41
1. Introduction 42
2. Materials and Methods 44
2.1. Participants 44
2.2. Ethics Statement 44
2.3. Sitting postures 44
2.4. Self-report measures 46
2.5. Somatic reflex measurement and processing 46
2.6. Procedure 47
2.7. Data analysis 48
3. Results 49
3.1. Manipulation check 49
3.2. Eye Blink Startle 49
3.3. Self-report 50
4. Discussion 51

Atypical modulation of startle in women in face of aversive bodily sensations 55
1. Introduction 56
2. Materials and Methods 59
2.1. Participants 59
2.2. Stimuli and Apparatuses 59
2.3. Procedure 62
2.4. Data analysis 63
3. Results 65
3.1. Eye blink EMG 65
3.2. Self-report 66
4. Discussion 66

Visceral pain modulates startle differently in men and women 71
1. Introduction 72
2. Methods 73
3. Data Analysis 76
3.1 Manipulation check 76
3.2 Eye blink startle. 76
3.3 Skin Conductance Levels 78
3.4 Evaluative judgments 79
4. Results 79
4.1 Manipulation check 79
4.2 Eye blink startle 80
4.3 Skin Conductance Levels 82
4.4 Evaluative judgments 82
5. Discussion 83

Visceral fear learning as a mechanism of gastro-intestinal specific anxiety 87
1. Introduction 88
2. Methods 90
2.1. Participants 90
2.2. Stimuli 91
2.3. Measures 92
2.4. Procedure 93
3. Data reduction and analysis 96
4. Results 97
4.1. US-expectancy 97
4.2. SCRs 99
4.3. Startle eye blink EMG 100
5. Discussion 101
5.1. Pre-exposure and Acquisition 102
5.2. Extinction 103
5.3. Linear effects on startle 104
5.4. Gender differences 105
5.5. Limitations 107

General Discussion and Conclusions 111
1 Overview of studies and their aims 112
2. Startle modulation 114
Study 1: Effect of seated trunk posture 114
Study 2: Cold pain and respiratory stimulation 115
Study 3: Visceral pain 115
Study 4: Visceral fear learning 115
3. Possible modulatory influences on startle 116
4. Skin Conductance 120
5. Fear and unpleasantness ratings 121
6. Limitations and future research 122

References 125

Appendix 147
Publication status: published
KU Leuven publication type: TH
Appears in Collections:Health Psychology

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