from the heartand other visceral organs are relayed to the brain. Psychophysiologist Paul Lehrer has shown thatby using heart rhythm feedback to facilitate a state of physiological coherence (which he callsresonance), a lasting increase in baroreflex gain10 is accomplished independent of respiratoryand cardiovascular changes, thus demonstrating neuroplasticity of the baroreflex system (Lehreret al., 2003). This shift in baroreflex gain indicates that with repeated episodes of coherence, theactivation threshold of some of the mechanosensory neurons in the baroreflex system is resetand, as a result, these neurons increase their output accordingly.In addition, a basic property of mechanosensory neurons is that they generally increase theiroutput in response to an increase in the rate of change in the function they are tuned to (heartrate, blood pressure, etc.). During heart rhythm coherence, there is an increase in beat-to-beatvariability in both heart rate and blood pressure, which is equivalent to an increase in the rate ofchange. This results in an increase in the vagal afferent traffic sent from the heart andcardiovascular system to the brain. With regular practice in maintaining the coherence mode, it islikely that increased vagal afferent traffic would also be observed even when one is not in thismode. This is due to the fact that the mechanosensory neurons threshold is reset as a result ofthe coherence-building practice, thus establishing a new baseline level of afferent traffic.Generating an increase in vagal afferent traffic through noninvasive approaches such as heart-based emotion refocusing techniques and heart rhythm coherence feedback has a number ofpotential benefits. In recent years, a number of clinical applications for increasing vagal afferenttraffic have been found; however, the increase in afferent activity is usually generated byimplanted or external devices that stimulate the vagal afferent pathways, typically in the leftvagus nerve. Vagal stimulation is an FDA-approved treatment for epilepsy and is currently underinvestigation as a therapy for obesity, depression, anxiety, and Alzheimers disease (Groves &Brown, 2005; Kosel & Schlaepfer, 2003). It has been established that an increase in the normalintrinsic levels of vagal afferent traffic inhibits the pain pathways traveling from the body to thethalamus at the level of the spinal cord (discussed below) and a recent study has found thatstimulation of the afferent vagal pathways significantly reduces cluster and migraine headaches(Mauskop, 2005). Vagal nerve stimulation has also been shown to improve cognitive processingand memory (Hassert, Miyashita, & Williams, 2004)findings that are consistent with those ofseveral recent studies of individuals using heart rhythm coherence-building techniques(discussed later in this article).Baroreflexes are homeostatic reflexes that regulate blood pressure. Through them, increases in bloodpressure produce decreases in heart rate and vasodilation, while decreases in blood pressure produce theopposite. Baroreflex gain is commonly calculated as the beat-to-beat change in heart rate per unit ofchange in blood pressure. Decreased baroreflex gain is related to impaired regulatory capacity and aging.INTEGRAL REVIEWDecember 2009Vol. 5, No. 2Afferent signals from the heart modulate the neural pathways involved in the perception ofpain. Numerous reports from individuals using the HeartMath coherence-building techniquesindicate that they are able to greatly reduce their experience of bodily pain, often to a pointwhere they can reduce or eliminate pain medications. This is