Agostoni, E., Chinnock, J.E., DeBurgh Daly, M., & Murray, J.G. (1957). Functional and histological studies of the vagus nerve and its branches to the heart, lungs and abdominal viscera in the cat. Journal of Physiology - London, 135, 182-205.

Barbas-Henry, H.A., & Lohman, A.H.M. (1984). The motor nuclei and primary projections of the IXth, Xth, XIth, and XIIth cranial nerves in the monitor lizard, varanus exanthematicus. The Journal of Comparative Neurology, 226, 565- 579.

Bazhenova, O.V. (1995). Vagal tone reactivity: A psychophysiological parallel of the dynamics of affect. Paper presented at the Biennial meeting of the Society for Research in Child Development. Indianapolis, IN, March 30, 1995.

Belkin, D.A. (1964). Variations in heart rate during voluntary diving in the turtle Pseudemys concinna. Copeia, 321-330.

Bennett, J.A., Ford, T.W., Kidd, C., & McWilliam, P.N. (1984). Characteristics of cat dorsal motor vagal motoneurones with axons in the cardiac and pulmonary branches. Journal of Physiology, 351, 27p.

Berntson, G.G., Cacioppo, J.T., & Quigley, K.S. (1991). Respiratory sinus arrhythmia: Autonomic origins, physiological mechanisms, and psychophysiological implications. Psychophysiology, 30, 183-196.

Berntson, G.G., Cacioppo, J.T.,& Quigley, K.S. (1991). Autonomic determinism: The modes of autonomic control, the doctrine of autonomic space, and the laws of autonomic constraint. Psychological Review, 98, 459-487.

Berntson, G.G., Cacioppo, J.T., & Quigley, K.S. (1993). Respiratory sinus arrhythmia: Autonomic origins, physiological mechanisms, and physiological implications. Psychophysiology, 30, 183-196.

Berntson, G.G., Cacioppo, J.T., & Quigley, K.S. (1993). Cardiac psychophysiology and autonomic space in humans: Empirical perspectives and conceptual implications. Psychological Bulletin, 114, 296-322.

Berntson, G.G., Cacioppo, J.T., & Quigley, K.S. (1994). Autonomic cardiac control. I. Estimation and validation from pharmacological blockades. Psychophysiology, 31, 572-585.

Bieger, D., & Hopkins, D.A. (1987). Viscerotropic representation of the upper alimentary tract in the medulla oblongata in the rat: the nucleus ambiguus. Journal of Comparative Neurology, 262, 546- 562.

Billman, G.E., & DuJardin, J-P. (1990). Dynamic changes in cardiac vagal tone as measured by time-series analysis. American Journal of Physiology, 258 (Heart Circulation Physiology 27): H896-H902.

Brown, J.W. (1974). Prenatal development of the human chief sensory trigeminal nucleus. Journal of Comparative Neurology, 156, 307-335.

Brown, J.W. (1990). Prenatal development of the human nucleus ambiguus during the embryonic and early fetal periods. American Journal of Anatomy, 189, 267-283.

Byrne, E.A., & Porges, S.W. (1993). Data-dependent filter characteristics of peak-valley respiratory sinus arrhythmia estimation: A cautionary note. Psychophysiology, 30, 397-404.

Cacioppo, J.T., Berntson, G.G., Binkley, P.F., Quigley, K.S., Uchino, B.N., Fieldstone, A. (1994). Autonomic Cardiac Control II. Noninvasive indices and basal response as revealed by autonomic blockades. Psychophysiology, 31, 586-598.

Cournand, A. (1979). Claude Bernard's Contributions to Cardiac Physiology. In: E.D.Robin (Ed), Claude Bernard and the Internal Environment. New York: Marcel Dekker, pp. 97-121..

Darrow, C.W. (1929). Differences in the physiological reactions to sensory and ideational stimuli. Psychological Bulletin, 26, 185-201.

Darrow, C.W., Jost, H., Solomon, A.P., & Mergener, J.C. (1942). Autonomic indicators of excitatory and homeostatic effects on the electroencephalogram. Journal of Psychology, 14, 115-130.

Darwin, C. (1872). The Expression of the Emotions in Man and Animals. New York: D. Appleton.

Dellinger, J.A., Taylor, H.L., & Porges, S.W. (1987). Atropine sulfate effects on aviator performance and on respiratory- heart period interactions. Aviation Space Environment Medicine, 58, 333-338.

De Meersman, R.E. (1993). Aging as a modulator of respiratory sinus arrhythmia. Journal of Gerontology: Biological Sciences, 48, B74-B78.

Dexter, F., Levy, M.N. & Rudy, Y. (1989). Mathematical model of the changes in heart rate elicited by vagal stimulation. Circulation Research, 65, 1330-1339.

Donald, D.E., Samueloff, S.L., & Ferguson, D. (1967). Mechanisms of tachycardia caused by atropine in conscious dogs. American Journal of Physiology, 212, 901-910.

Donchin, Y., Feld, J.M., & Porges, S.W. (1985). Respiratory sinus arrhythmia during recovery from isoflurane-nitrous oxide anesthesia. Anesthesia and Analgesia, 64, 811-815.

Donchin, Y., Constantini, S., Szold, A., Byrne, E. A., & Porges, S. W. (1992). Cardiac vagal tone predicts outcome in neurosurgical patients. Critical Care Medicine, 20, 941-949.

Duffy, E. (1957). The psychological significance of the concept of "arousal" or "activation." Psychological Review, 64, 265- 275.

Else, PL. & Hulbert, A.J. (1981). Comparison of the "mammal machine" and the "reptile machine": Energy production. American Journal of Physiology, 240, (Regulatory Integrative comparative Physiology 9): R-3-R9.

Finger, T.E., & Dunwiddie, T.V. (1992). Evoked responses from an in vitro slice preparation of a primary gustatory nucleus: the vagal lobe of goldfish. Brain Research, 580, 27-34.

Ford, T.W., Bennett, J.A., Kidd, C., & McWilliam, P.N. (1990). Neurons in the dorsal motor vagal nucleus of the cat with non-myelinated axons projecting to the heart and lungs. Experimental Physiology., 75, 459-473.

Fouad, F.M., Tarazi, R.C., Ferrario, C.M., Fighaly, S., & Alicandro, C. (1984). Assessment of para-sympathetic control of heart rate by a noninvasive method. American Journal of Physiology, 246, H838-H842.

Frysinger, R.C. & Harper, R.M. (1986). Cardiac and respiratory relationships with neural discharge in the anterior cingulate cortex during sleep-waking states. Experimental Neurology, 94, 247-263.

Frysinger, R.C. & Harper, R.M. (1989). Cardiac and respiratory correlations with unit discharge in human amygdala and hippocampus. Electroencephalography and Clinical Neurophysiology, 72, 463-470

Frysinger, R.C., Zhang, J.X., & Harper, R,M. (1988). Cardiovascular and respiratory relationships with neuronal discharge in the central nucleus of the amygdala during sleep-waking states. Sleep, 11, 317- 332.

Gellhorn, E. (1964). Motion and Emotion: The role of proprioception in the physiology and pathology of the emotions. Psychological Review, 71, 457-472.

George, D.T., Nutt, D.J., Walker, W.V., Porges, S.W., Adinoff, B., & Linnoila, M. (1989). Lactate and hyperventilation substantially attenuate vagal tone in normal volunteers: A possible mechanism of panic provocation? Archives of General Psychiatry, 46, 153-156.

Goldberger, J.J., Ahmed, M.W., Parker, M.A., & Kadish, A.H. (1994). Dissociation of heart rate variability from parasympathetic tone. American Journal of Physiology, 266 (Heart Circulation Physiology 35), H2152-H2157.

Gonzalez Gonzalez, J., and de Vera Porcell, L. (1988). Spectral analysis of heart rate variability of lizard, Gallotia galloti. American Journal of Physiology, 254 (Regulatory Integrative Comparative Physiology 23) R242-R248.

Graham, F.K., & Clifton, R.K. (1966). Heart-rate change as a component of the orienting response. Psychological Bulletin, 65, 305- 320.

Gribben, B., Pickering, T.G., Sleight, P., & Peto, R. (1971). Effect of age and high blood pressure on baroreflex sensitivity in man. Circulation Research, 29, 424-431.

Grossman, P., Karemaker, J., & Weiling, W. Prediction of tonic parasympathetic cardiac control using respiratory sinus arrhythmia: The need for respiratory control. Psychophysiology, 28, 201-216.

Grossman, P., & Kollai, M. (1993). Respiratory sinus arrhythmia, cardiac vagal tone, and respiration: Within- and between- individual relations. Psychophysiology, 30, 486-495.

Hager, J.C., & Ekman, P. (1985). The asymmetry of facial actions is inconsistent with models of hemispheric specialization. Psychophysiology, 22, 307-318.

Harper, R.M., Frysinger, R.C., Trelease, R.B., & Marks, J.D. (1984). State-dependent alteration of respiratory cycle timing by stimulation of the central nucleus of the amygdala. Brain Research, 306, 1-8.

Haselton, J.R., Solomon, I.C., Motekaitis, A.M., and Kaufman, M.P. (1992). Bronchomotor vagal preganglionic cell bodies in the dog: An anatomic and functional study. Journal of Applied Physiology, 73, 1122-1129.

Heilman, K.M., Bowers, D., & Valenstein, E. (1985). Emotional disorders associated with neurological diseases. In: K.M. Heilman and E. Valenstein (Eds.), Neuropsychology. New York: Oxford University Press.

Hopkins, D.A. (1987). The dorsal motor nucleus of the vagus nerve and the nucleus ambiguus: structure and connections. In R. Hainsworth, P.N. Williams, & D.A.G.G. Many (eds.) Cardiogenic reflexes: Report of an International Symposium . Oxford: Oxford University Press, pp. 185-203.

Humphrey, T. (1970). Function of the nervous system during prenatal life. In U. Stave (ed.) Physiology of the perinatal period. New York: Appleton-Century-Crofts, pp. 751-796.

Jacob, J.S., & McDonald, H.S. (1976). Diving bradycardia in four species of North American aquatic snakes. Comparative Biochemistry and Physiology. 53A, 69-72.

Jennings, J.R., & McKnight, J.D. (1994). Inferring vagal tone from heart rate variability. Psychosomatic Medicine, 56, 194- 194.

Jerrell, T.W., Gentile, C.G., McCabe, P.M., & Schneiderman, N. (1986). Sinoaortic denervation does not prevent differential Pavlovian conditioning of bradycardia in rabbits. Brain Research, 100, 3-10.

Jordan, D., Khalid, M.E.M., Schneiderman, N., & Spyer, K.M. (1982). The location and properties of preganglionic vagal cardiomotor neurones in the rabbit. Pflugers Archiv, 395, 244-250.

Kaklia, M., & Masulam, M.-M. (1980). Brain stem projections of sensory and motor components of the vagus complex in the cat. I. Laryngeal, tracheobronchial, pulmonary, cardiac, and gastrointestinal branches. Journal of Comparative Neurology, 193, 467-508.

Katona, P.G., & Jih, R. (1975). Respiratory sinus arrhythmia: A non-invasive measure of parasympathetic cardiac control. Journal of Applied Physiology, 39, 801-805.

Lacey, B.C., & Lacey, J.I. (1978). Two way communication between the heart and the brain. American Psychologist, 33, 99-113.

Lacey, J.I. (1967). Somatic response patterning and stress: Some revisions of activation theory. In M.H. Appley & R. Trumbull (Eds.), Psychological Stress: Issues in Research. New York: Appleton- Century-Crofts, pp. 14-37.

Leslie, R.A., Reynolds, D.J.M., & Lawes, I.N.C. (1992). Central connections of the nuclei of the vagus nerve. In S. Ritter, R. C. Ritter, & C. D. Barnes (Eds.). Neuroanatomy and physiology of abdominal vagal afferents. Boca Raton: CRC Press, pp.81-98.

Levy, M.N (1984). Cardiac sympathetic-parasympathetic interactions. Federation Proceedings, 43, 2598-2602.

Lindsley, D. (1951). Emotion. In S.S. Stevens (Ed.), Handbook of experimental psychology. New York: Wiley.

Machado, B.H., & Brody, M.J. (1988). Effect of nucleus ambiguus lesion on the development of neurogenic hypertension. Hypertension, 11, 135-138.

MacLean, P.D. (1990). The Triune Brain in Evolution. New York: Plenum Press.

Malik, M., & Camm, J.A. (1993). Components of heart rate variability - What they really mean and what we really measure. The American Journal of Cardiology, 72, 821- 822.

Malmo, R.B. (1959). Activation: A neurophysiological dimension. Psychological Review, 66, 367-386.

McAllen, R.M., & Spyer, K.M. (1976). The location of cardiac vagal preganglionic motoneurones in the medulla of the cat. Journal of Physiology, 258, 187-204.

McAllen, R.M., & Spyer, K.M. (1978). Two types of vagal preganglionic motoneurones projecting to the heart and lungs. Journal of Physiology, 282, 353-364.

McCabe, P.M., Yongue, B.G., Porges, S.W., & Ackles, P.K. (1984). Changes in heart period, heart period variability and a spectral analysis estimate of respiratory sinus arrhythmia during aortic nerve stimulation in rabbits. Psychophysiology, 21, 149-158.

McDonald, H.S. (1974). Bradycardia during death-feigning of Heterodon platyrhinos Latreille (Serpentes). Journal of Herpetolog, 8, 157-164.

Mera, F., Wityk, R., & Porges, S.W. (1995). Abnormal heart variability in brainstem injury. Presented at the American Academy of Neurology. Seattle, Washington, May 9-11, 1995.

Mitchell, G.A.G. & Warwick, R. (1955). The dorsal vagal nucleus. Acta Anatomica, 25, 371-395.

Nara, T., Goto, N., & Hamano, S. (1991). Development of the human dorsal nucleus of vagus nerve: a morphometric study. Journal of the Autonomic Nervous System, 33, 267-276.

Ni, H., Zhang, J.X., & Harper, R.M. (1990). Respiratory-related discharge of periaqueductal gray neurons during sleep- waking states. Brain Research, 511, 319-325.

Nelson, N.M. Respiration and circulation before birth. In Smith, CA, & Nelson, NM, (eds.), The physiology of the newborn infant, 4th edition. Thomas: Philadelphia; 1976, 15-116.

Neuheuber, W.L., & Sandoz, P.A. (1986). Vagal primary afferent terminals in the dorsal motor nucleus of the rat: Are they making monosynaptic contacts on preganglionic efferent neurons? Neuroscience Letters, 69, 126-130.

Obrist, P.A. (1976). The cardiovascular behavioral interaction - as it appears today. Psycho-physiology, 13, 95-107.

Obrist, P.A. (1981). Cardiovascular Psychophysiology. New York: Plenum.

Obrist, P.A., Webb, R.A., Sutterer, J.R., and Howard, J.L. (1970). The cardiac-somatic relationship: some reformulations. Psychophysiology 6, 569- 587.

Porges, S.W. (1972). Heart rate variability and deceleration as indexes of reaction time. Journal of Experimental Psychology, 92, 103-110.

Porges, S.W. (1986). Respiratory sinus arrhythmia: Physiological basis, quantitative methods, and clinical implications. In P. Grossman, K. Janssen, and D. Vaitl (eds.), Cardiorespiratory and Cardiosomatic Psychophysiology. New York: Plenum, 101-115.

Porges. S. W. (1992). Vagal Tone: A physiological marker of stress vulnerability. Pediatrics, 90, 498-504.

Porges, S.W., & Bohrer, R.E. (1990). Analyses of periodic processes in psychophysiological research. In J.T. Cacioppo and L.G. Tassinary (eds.), Principles of Psychophysiology: Physical, Social, and Inferential Elements. New York: Cambridge University Press, 708-753.

Porges, S.W., & Raskin, D.C. (1969). Respiratory and heart rate components of attention. Journal of Experimental Psychology, 81, 497-503.

Potter, E.K., & McCloskey, D.I. (1986). Effects of hypoxia on cardiac vagal efferent activity and on the action of the vagus nerve at the heart in the dog. Journal of the Autonomic Nervous System, 17, 325-329.

Regal, P.J. (1978) Behavioral differences between reptiles and mammal: An analysis of activity and mental capabilities. In N. Greenberg and P.D. MacLean , (eds.), Behavior and Neurology of Lizards, Rockville, MD: National Institute of Mental Health. p. 183-202.

Richards, J.E., & Casey, B.J. (1991). Heart rate variability during attention phases in young infants. Psychophysiology, 28, 43-53.

Richter, D.W., and Spyer, K.M. (1990). Cardiorespiratory Control. In A.D. Loewy & K.M. Spyer (eds), Central Regulation of Autonomic Function, .pp. 189-207.

Riniolo, T., Doussard-Roosevelt, J., & Porges, S.W. (1994). The relation between respiratory sinus arrhythmia and heart period during waking and sleep Psychophysiology, 31, S81 (abstract).

Rinn, W.E. (1984). The neurophysiology of facial expression: A review of the neurological and psychological mechanisms for producing facial expressions. Psychological Bulletin, 95, 52-77.

Ross, E.D., Homan, R.W. & Buck, R. (1994) Differential hemispheric lateralization of primary and social emotions. Neuropsychiatry, neuropsychology, and behavioral neurology, 7, 1-19.

Rowell, L.B. (1993). Central circulatory adjustments to dynamic exercise. In L.B. Rowell (Ed.). Human Cardiovascular Control. New York: Oxford Press, pp. 162-203.

Sargunaraj, D., Lehrer, P.M., Carr, R.E., Hochron, S.M., & Porges, S.W. (1994). The effects of paced resistance breathing. Psychophysiology, 31, S85 (abstract).

Saul, J.P., Berger, R.D., Chen, M.H., & Cohen, R.J. (1989). Transfer function analysis of autonomic regulation. II. Respiratory sinus arrhythmia. American Journal of Physiology, 256 (Heart Circulation Physiology 25): H153-H161.

Schneiderman, N. (1974). The relationship between learned and unlearned cardiovascular responses. In P.A. Obrist, A.H. Black, J. Brener, L.V. DiCara (eds.) Cardiovascular Psychophysiology: Current issues in response mechanisms, biofeedback, and methodology. Chicago: Aldine Publishing Company. pp. 190-210.

Schwaber, J.S. (1986). Neuroanatomical substrates of cardiovascular and emotional-autonomic regulation. In A. Magro, W. Osswald, D. Reis & P. Vanhoutte (eds) Central and peripheral mechanisms of cardiovascular regulation. New York: Plenum Press, pp. 353-384.

Sokolov, E.N. (1963). Perception and the Conditioned Reflex. Oxford: Pergamon Press.

Sostek, A.M., Glass, P., Molina, B.C., & Porges, S.W. (1984). Neonatal vagal tone and subsequent sleep apnea in preterm infants. Psychophysiology, 21, 599.

Spyer, K.M., & Jordan, D. (1987). Electrophysiology of the nucleus ambiguus. In R. Hainsworth, P.N. Williams, & D.A.G.G. Many (eds.) Cardiogenic reflexes: Report of an International Symposium . Oxford: Oxford University Press, pp. 237-249.

Uvnas-Moberg, K. (1987). Gastrointestinal hormones and pathophysiology of functional gastrointestinal disorders. Scandinavia Journal of Gastroenterology, 22 (Supplement 128), 138-146.

Uvnas-Moberg, K. (1989). Gastrointestinal hormones in mother and infant. Acta Pediatrica Scandinavia, 351(Supplement), 88-93.

Uvnas-Moberg, K. (1994). Role of efferent and afferent vagal nerve activity during reproduction: Integrating function of oxytocin on metabolism and behaviour. Psychoneuroendocrinology, 19, 687-695.

Vanhoutte, P.M., & Levy, M.N. (1979) Cholinergic inhibition of adrenergic neurotransmission in the cardiovascular system. In C. McC. Brooks, K. Koizumi, & A. Sato (eds.) Integrative functions of the autonomic nervous system. Tokyo: University of Tokyo Press, 159-176.

Warwick, R. & Williams, P.L. (ed). (1975) Gray's Anatomy. Philadelphia: W.B. Saunders.

Weiling, W., van Brederode, J.F.M., de Rijk, L.G., Borst, C., & Dunning, A.J. (1982). Reflex control of heart rate in normal subjects in relation to age: A data base for cardiac vagal neuropathy. Diabetologia, 22, 163-166.

Weise, F., & Heydenreich, F. (1991). Age-related changes of heart rate power spectra in a diabetic man during orthostasis. Diabetes Research and Research and Clinical Practice, 11, 23-32.

Wolley, D.C., McWilliam, P.N., Ford, T.W., & Clarke, R.W. (1987). The effect of selective electrical stimulation on non- myelinated vagal fibres on heart rate in the rabbit. Journal of the Autonomic Nervous System, 21, 215- 221.

Yokoyama, K, Jennings, R., Ackles, P., Hood, P., & Boller, F. 1987. Lack of heart rate changes during an attention- demanding task after right hemisphere lesions. Neurology, 37, 624-630.

Author Notes

This paper is based on the presidential address to the Society for Psychophysiological Research, Atlanta, Georgia, October 8, 1994. The presidential address and the published manuscript are dedicated to the memory of my close friend and collaborator, Robert E. Bohrer. The theory described in this paper evolved from over three decades of research and interactions with colleagues and students. I am indebted to four individuals who have served as scientific guides. David C. Raskin introduced me to psychophysiology. Robert E. Bohrer tutored me in time series statistics. Ajit Maiti mentored me in the neurophysiology and embryology of the brain stem. Evgeny Sokolov provided a model as a mentor and stimulated me to generate an integrative theory. Additionally, I have been fortunate to have outstanding associates, collaborators, and students including Olga Bazhenova, Evan Byrne, Michael Cheung, Aaron Chun, Georgia DeGangi, Janet DiPietro, Yoel Donchin, Jane Doussard-Roosevelt, Nathan Fox, Phil Goddard, Stanley Greenspan, Sandy Larson, Susan Linnemeyer, Phil McCabe, Oxana Plonskaia, Lourdes Portales, Shawn Reed, Todd Riniolo, Pat Suess, and Brandon Yongue who have contributed to the research and development of The Poly-Vagal theory. An additional thanks to Jane Doussard-Roosevelt who provided the intellectual and emotional ballast in my laboratory during my presidency and who contributed to the manuscript and talk by editing earlier versions and generating the graphics. A special thanks to Sue Carter who has patiently supported my scientific curiosity for 25 years and who has provided several helpful comments in the organization of the manuscript. The preparation of this manuscript was support, in part by grant HD 22628 from the National Institute of Child Health and Human Development and by grant MCJ 240622 from Maternal and Child Health Bureau. Address reprint requests to Stephen W. Porges, Department of Human Development, University of Maryland, College Park, Maryland 20742, or email at

Figure Captions

Figure 1. Primary brainstem nuclei of the vagus. Nuclei are bilateral and only one of each bilateral pair is illustrated. Figure 2. (a) Bradycardia during fetal distress. (b) Background heart period variability at time of bradycardia. Figure 3. Bradycardia elicited by electrical stimulation of the DMNX in an anesthetized rabbit. Figure 4. Bradycardia elicited by aortic depressor nerve stimulation in an anesthetized rabbit. Figure 5. Topographic organization of the nucleus ambiguus in the rat (Bieger & Hopkins, 1987).

Appendix A

Title of the paper.

The title was selected to emphasize the concept that evolutionary processes have sculpted the neural regulation of autonomic function. Not only has evolution provided obvious divergences in behavior and appearance, but evolution has impacted on the autonomic strategies related to the detection of novelty in the environment. The focus of the paper was not directed at a theory of orienting, nor has the paper attempted to distinguish between the autonomic components of orienting or defensive reflexes. Rather, the paper has focused on the neurogenic regulation of cardiac responses via two vagal responses systems. A primitive system that we have inherited from reptiles produces a rapid neurogenic bradycardia that reduces the activity of our cardiopulmonary system to conserve oxygen. This is the strategy of sit and wait feeders, common to reptiles. In contrast, the evolution of the energy-demanding mammal required two autonomic-behavioral shifts: 1) mammals needed to obtain great amounts of food; and 2) mammals needed to protect their nervous systems from oxygen loss. These two objectives are linked. In the evolution of mammals, success in obtaining food resources was dependent upon the ability to detect threat. Thus, mobilization and attention became two important behavioral dimensions. Unlike reptiles, which orient in response to novelty and attack or return to a quiescent state or lumber off, mammals orient and then attend. Following this phase of attention a mammal may rapidly depart or approach (attack) within the context of the classic fight or flight response. With the increasing complexity of behavior, there is a parallel increase in complexity in the organization and function of the autonomic nervous system. The title also intended to emphasize the concept that evolution has placed mammals in a defensive world. The survival systems of reptiles and other lower phyla can be organized into orienting and defensive dimensions. Mammals, to survive in this defensive and reactive world, had to circumvent these potentially lethal reactions of other species. The evolution of the mammalian nervous system enables mammals to rapidly escape danger and to use neural resources for the complex information processes required to detect subtleties in the environment. Moreover, evolution promoted additional motor systems related to communication. Motor systems developed to communicate conditions related to survival with facial expressions and vocalizations associated with primary emotions. The evolutionary modifications not only had to coexist with the oxygen hungry metabolic system, but by increasing the complexity of motor behaviors, there was an additional increase in oxygen needs. Thus, there is a link between the special visceral efferent actions regulating the communicative processes of emotion, and later language, with the general visceral efferent actions regulating cardiopulmonary function. The ability to detect subtleties in the environment coupled with the ability to communicate threat or comfort via facial expressions and vocalizations contributed to within- species social behavior, parenting, and pairbonding. These complex functions evolved while the demanding oxygen needs of mammals were programmed into the background of nervous system function via the autonomic nervous system.

Appendix B

Personal retrospective

In discussing any theoretical perspective, it is important to place the ideas and speculations in the context of earlier research conducted by the investigator. My early research focused on the use of heart rate measures as indicators of attention. While conducting research for my master's thesis (Porges & Raskin, 1969), I noted that attention demanding tasks produced heart rate response patterns with two prominent characteristics. First, heart rate exhibited a rapid transitory directional change in response to task onset and stimulus changes. Second, when subjects became involved in the task and focused their attention on the task demands, heart rate variability was reduced. I was intrigued with these observations and speculated on the possible physiological mechanisms. This evolved into a two-component theory of attention in which the components were labeled "phasic or orienting" and "tonic or attention" responses (Porges, 1972). These findings stimulated me to investigate neural mechanisms of heart rate regulation and to develop the Vagal Tone Index () of RSA, which I believed would help provide insight into the mechanisms mediating the more tonic sustained attention response. The preceding sections of this paper provide the basis for the Poly-Vagal Theory and enable an interpretation of the two heart rate components associated with attention. The first component, associated with orienting and the neurogenic bradycardia, is determined reflexively by the vegetative vagus, originating in the dorsal motor nucleus. The second component, associated with voluntary engagement with the environment and depression of RSA, is determined by the smart vagus, originating in the NA. Thus, after years of studying heart rate patterns, a speculative two-component psychophysiological model of attention is evolving into the neuroanatomically and neurophysiologically based Poly-Vagal Theory.

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