How Do You Feel?

List of Figures and Plates ix
List of Boxes xi
Preface xiii
1AN INTRODUCTION TO INTEROCEPTION 1
2FEELINGS FROM THE BODY VIEWED AS EMOTIONS
Ideas from the lamina I projection map that add to the textbooks 16
An overview of the map 16
The central neural substrates for homeostasis 19
Textbook knowledge regarding touch 23
Textbook knowledge regarding pain and temperature 28
Irritating incongruities 31
Identification of the thermosensory pathway 33
Recognizing that temperature sensation is part of interoception 38
Viewing a thermosensory feeling as a homeostatic emotion 42
Thermal sensations become subjective feelings 45
Emergent ideas about feelings, moments, music, and time 46
Bivalent emotions in bicameral brains 50
3THE ORIGIN OF THE INTEROCEPTIVE PATHWAY
Homeostatic sensory fibers and the interoceptive dorsal horn 54
Finding lamina I spinothalamic neurons 55
Lamina I spinothalamic neurons are "labeled lines 62
Anomalous characteristics point to a new direction 71
Integrated lamina I activity generates thermoregulatory pain: the thermal grill 74
Identifying lamina I projections to autonomic neurons 82
Demonstrating that lamina I subserves homeostasis 90
The identification of homeostatic small-diameter sensory fibers 94
The development of the interoceptive dorsal horn 97
The interoceptive dorsal horn subserves homeostasis 101
The evolutionary origin of interoceptive and exteroceptive neurons 103
The homeostatic sensory system provides crucial vasoreceptive feedback 106
4INTEROCEPTION AND HOMEOSTASIS
Lamina I terminations at cardiorespiratory sites in the brainstem 111
An overview of lamina I projections to the brainstem 112
Lamina I terminations in the lower brainstem (medulla) 115
Lamina I terminations in the middle brainstem (pons) 118
Lamina I terminations in the parabrachial nucleus 119
Lamina I terminations in the periaqueductal gray (upper brainstem) 124
Summary 129
5THE INTEROCEPTIVE PATHWAY TO THE INSULAR CORTEX
Lamina I spinothalamic input to the thalamus and cortex in primates 130
My introduction to functional neuroanatomy 131
The significance of somatotopic organization 133
The lateral spinothalamic tract 134
Finding Waldo 135
The functional anatomical characteristics of the VMpo in the macaque monkey 139
The projection from the VMpo to the dorsal posterior insula in the macaque monkey 145
The organization of the dorsal posterior insula in the macaque monkey 150
The interoceptive pathway 155
The human VMpo 160
The human dorsal posterior insula 166
The human interoceptive cortex 170
Interoceptive touch 173
Summary, and an interoceptive perspective on cortical gyrification 175
6BODILY FEELINGS EMERGE IN THE INSULAR CORTEX
Interoceptive integration generates the feeling of being alive 182
The structure of the insular cortex 183
Posterior-to-mid-to-anterior processing of interoceptive activity 185
Multimodal integration in the mid-insula 188
Feelings from the body emerge first in the mid-insula 191
Homeostatic sentience 194
Interoceptive integration improves energy efficiency 197
The model of interoceptive integration and the generalization of feelings 199
Interoceptive feelings come to awareness in the anterior insula 203
Emotional feelings emerge and come to awareness in the anterior insula 206
The embodiment of emotional feelings 209
7FEELINGS ABOUT THOUGHTS, TIME, AND ME
Awareness emerges in the anterior insular cortex 216
The AIC is activated during cognitive activity 219
The model: Integration of cognitive feelings 221
Evidence that awareness is engendered in the AIC 223
Evidence that the AIC supports feelings about time 226
The model: Cinemascopic integration of moments of time 228
The model: The structural basis of awareness 235
The role of the AIC in the control of network activity 243
Evidence that the AIC is crucial for fluid intelligence 247
Evidence that the AIC optimizes energy utilization 249
Individual variability and maturation 251
Distorted feelings produce mental illness 254
8FEELINGS AND EMOTIONS ON BOTH SIDES OF THE BRAIN
The asymmetric forebrain 257
Ethological evidence of forebrain asymmetry 260
Neuroanatomical evidence of forebrain and AIC asymmetry 262
Clinical evidence of forebrain and AIC asymmetry 263
Physiological evidence of forebrain and AIC asymmetry 265
Psychophysiological evidence of forebrain and AIC asymmetry 267
Two recent reviews uncover asymmetric activation of the amygdala and the AIC 270
The alignment of autonomic, behavioral, and affective control 272
Opponent inhibition 274
Specialization and balance 275
And something curious 277
9A FEW MORE THOUGHTS ABOUT FEELINGS
Graded sentience and tail-wagging in dogs 280
A quick review 280
Scaling up homeostatic sentience 285
Graded sentience 289
Feelings in dogs 293
How about Watson? 295
Acknowledgments 297
Abbreviations 299
Glossary 301
Reference List 309
Illustration Credits 337
Index 339