Our brain is tied to our heart by the vagus nerve. Recent research has discovered that minute variations in our heart rate reveal the strength of this brain-heart connection and, as such, provides an index of our vagal tone. The vagal tone can be either “dorsal” or “ventral”. The dorsal reflects passivity and a shutting down that occurs when there has been cumulative neglect and a lack of relational contact. The ventral reflects pleasurable social engagement that comes from such activities as nursing, eye-to-eye contact, soothing touch, kissing, and pleasant voice tones. The higher our ventral vagal tone, the better we are able to regulate the internal systems that keep us healthy, such as our cardiovascular and immune responses. Neuroscientists used to think that the vagal tone was largely stable, like our height in adulthood. Fredrickson’s data show that this part of our brain-to-heart connection, the vagal tone, is plastic and amenable to change. Our ventral vagal tone can be increased by our engaging and caring social habits.
From : Integrative Psychotherapy Articles: Contact, Attunement, and Our Vagal Tone: Richard G. Erskine