The loving mother’s right brain to right brain connection up-regulates positive and down-regulates negative emotions to shape the child’s right subcortical-cortical circuits during the brain’s growth spurt in the first two years of life (Schore, 2019). This right brain to right brain interpersonal neurobiological mechanism continues to activate emotional circuits in later right brain growth spurts in childhood, adolescence and adulthood in which the emotional brain becomes more complex. Schore references Porges and Carter who claim that although the brain remains plastic throughout life, early experience may set the parameters of that plasticity. Attachment sets up social and emotional homeostasis. Emotional homeostasis is located in subcortical brain structures and their links to cortical structures all of which are shaped by early experience. Throughout the lifespan positive and negative emotional experiences with an intimate other are internalised into deeper levels of the right brain expanding self-integration which happens beneath conscious awareness. At all points in the lifespan any affective moment of mutual love between two unconscious systems are synchronising, resonating and regulating each other. In all the later Eriksonian stages interpersonal signals of love are processed unconsciously triggering changes in emotional arousal and these experiences are incorporated into right brain autobiographical memory.

The window of tolerance refers to the range of arousal within which a system can maintain the harmonious and adaptive flow of integration (Siegel, 2012). At one end of the window the system moves into rigidity and at the other end chaos. The window can be widened which means broadening the range of arousal within which a person, relationship or group of people can function adaptively. The window can be narrowed in states that are less tolerated. The window is specific in width to the state of mind we are in at the time. Our ability to tolerate a state will depend on our current internal and external context. Moving within the window brings us toward the edges of rigidity or chaos. This shifting flow is like a river of integration with a harmonious flow bounded on both sides by the banks of chaos and rigidity. A window of tolerance is like a river at one particular moment.

Homeostasis conjures images of equilibrium and balance (Damascio, 2019). Damascio argues that homeostasis is not the neutral state of status quo such a term may imply but a state in which the operations of life feel that they are up-regulated to well-being. The forceful projection into the future is signified by the underlying well-being. Homeostasis can be thought of as a driver of evolution.  The organism can only survive if homeostatic limits are observed. Deviations from this result in disease and unless a correction occurs it can lead to death. All organisms are endowed with regulatory mechanisms that are automated.

Living organisms are a collection of dynamic, adaptive, interdependent and interactive systems (Porges, 2021). The heart is not ‘floating in a visceral sea’ but is anchored to central structures and always signalling regulatory structures through afferent pathways. The treatment of cardiac function and manifestations of autonomic dysfunction in the neural regulation of the heart should be based on bidirectional connections between autonomic and central brain structure. This knowledge informs us about vulnerability to cardiac disease and dysfunction that is linked with triggering the autonomic system into states of defense that are chronic as well as the resilience that comes from management by the social engagement system.


Damasio, A. (2019). The strange order of things: Life, feeling, and the making of cultures. Vintage.

Porges, S. W. (2021). Polyvagal safety: Attachment, communication, self-regulation (IPNB). W. W. Norton & Company.

Schore, A. N. (2019). The development of the unconscious mind (Norton series on interpersonal neurobiology). W. W. Norton & Company.

Siegel, D. J. (2012). Pocket guide to interpersonal neurobiology: An integrative handbook of the mind (Norton series on interpersonal neurobiology). W. W. Norton & Company.