The Polyvagal Theory by Stephen W. Porges

Author:Stephen W. Porges
Language: eng
Format: epub
Publisher: W. W. Norton & Company

CHAPTER 11

Love: An Emergent Property of the Mammalian Autonomic Nervous System

There is no fear in love; but perfect love casteth out fear. —1 John 4:18

Love has had a variety of expressions. Foremost in our culture is the love between individuals of different genders. The products of this love are observed in terms of children, of cooperative and shared responsibilities to survive, of the transmitting of culture, and of pleasure and ecstasy. Although we assume that love is a unique human emotion, several neurobiological processes involved in the experience and expression of love are shared with other mammals. The phylogenetic origins of these processes reflect their antecedent adaptive function. In mammals, these processes have evolved into an integrated neurobehavioral system, which promotes proximity, reproduction, and physical safety. Central to the neural mediation of these processes is the autonomic nervous system. The focus of this chapter is to describe how the autonomic nervous system is involved in the processes associated with feelings of love and behaviors linked to reproduction. The chapter proposes a hypothetical model, which speculates that the phylogenetic changes in the autonomic nervous system are related to the emergence of two components of love: an appetitive phase associated with courting and seductive behaviors and a consummatory phase associate with passionate sexual behaviors and the establishment of enduring pair-bonds. According to this model, courting and seduction are dependent on phylogenetically newer structures. For example, the cortex, via corticobulbar pathways, regulates facial expressions and vocalizations to express availability to a prospective mate. In contrast, passionate visceral feelings are dependent on phylogenetically older structures, such as the hypothalamus and medulla, which involve phylogenetically more recent neuropeptides (oxytocin and vasopressin).

EVOLUTION AND DISSOLUTION: A HIERARCHICAL RESPONSE STRATEGY DURING MATE SELECTION

The evolution of the autonomic nervous system provides substrates for the emergence of the three emotion subsystems described above. Although reminiscent of the triune brain proposed by MacLean (1990), the polyvagal theory emphasizes that even the phylogenetically more primitive structures have changed in structure and function. This phylogenetic adjustment of the autonomic nervous system represents an exaptation (i.e. a shift in the function) of structures to express emotions. The ancient gill arches that characterize primitive vertebrates evolved into structures that convey emotional state via facial expressions, gestures and vocal communication.

The polyvagal theory emphasizes the phylogenetic changes in the autonomic nervous system. Specifically, as mammals evolved, the vagal regulation of the viscera was maintained by two vagal pathways. The second vagal circuit has myelinated efferent pathways and originates in the nucleus ambiguus, a nucleus ventral to the dorsal motor nucleus of the vagus. The ventral vagal circuit is described as the ventral vagal complex (VVC). The dorsal vagal circuit is shared with most other vertebrates and is described as the dorsal vagal complex (DVC). These two vagal circuits in concert with the sympathetic nervous system (SNS) form a hierarchical system regulating visceral organs. The polyvagal theory proposes a hierarchical response strategy to environmental challenges, with the most recent modifications employed first (i.e., VVC) and the most primitive (i.

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