In addition, many people find it difficult toconsciously maintain breathing rates at a 10-second rhythm for more than about a minute. On theother hand, by focusing attention on self-generating a positive emotion while pretending tobreathe this feeling through the area of the heart in a relaxed manner, smooth, coherent heartrhythm patterns occur naturally and are easier to sustain for longer periods of time. This has theadded benefit of not only establishing coherence as the familiar pattern, but also strengtheningthe connection between the constituent physiological patterns of coherenceof which heartrhythm is keyand the positive feeling state.Afferent input from the heart, and, in particular, the pattern of the hearts rhythm, also plays akey role in emotional experience. As described previously, our research suggested a fundamentallink between emotions and changes in the patterns of both efferent and afferent autonomicactivity, as well as changes in ANS activation, which are clearly reflected in changes in the heartrhythm patterns. The experience of negative emotions is reflected in more erratic or disorderedheart rhythms, indicating less synchronization in both the activity of brain structures that regulateparasympathetic outflow and in the reciprocal action between the parasympathetic andsympathetic branches of the ANS. In contrast, sustained positive emotions are associated with ahighly ordered or coherent pattern in the heart rhythms, reflecting greater overallsynchronization in these same systems.It is important to emphasize, however, that the hearts rhythmic beating patterns not onlyreflect the individuals emotional state, but they also play a direct role in determining emotionalexperience. At the physiological level, as shown in Figure 5, afferent input from the heart isconveyed to a number of subcortical regions of the brain that are involved in emotionalprocessing, including the thalamus, hypothalamus, and amygdala. Moreover, cardiac afferentinput has a significant influence on the activity of these brain centers (Adair & Manning, 1975;Cameron, 2002; Foreman, 1997; Frysinger & Harper, 1990; Oppenheimer & Hopkins, 1994;Zhang, Harper, & Frysinger, 1986). For example, activity in the amygdala has been found to besynchronized to the cardiac cycle (Frysinger & Harper, 1990; Zhang et al.). Theseunderstandings support the proposition that afferent information from the heart is directlyinvolved in emotional processing and emotional experience.INTEGRAL REVIEWDecember 2009Vol. 5, No. 2Afferent PathwaysCerebral Cortex Body perception Pain perception Arousal (sleep/waking) Hunger perceptionHypothalamusThalamusPeriaqueductalGray(PAG)ParabrachialComplexVisual andAuditory Input Fear/Anxiety Analgesia Autonomic modulation Fight-or-flight Affective defenseDorsal Vagal ComplexNucleus of TractusSolitarius (NTS) Receives afferent input from heart,lungs, baroreceptor nerves,chemoreceptors, upper respiratory andalimentary tracts, and faceVagusNerveFacialInputTasteInputAreaPostrema Monitors blood Food poisoning Motion sickness Emesis (vomiting)Figure 5. Diagram of the currently known afferent pathways by which information fromthe heart and cardiovascular system modulates brain activity. Note the direct connectionsfrom the NTS to the amygdala, hypothalamus, and thalamus. Although not shown, there is alsoevidence emerging of a pathway from the dorsal vagal complex that travels directly to the frontalcortex.These findings and those from our own research led us to ponder the fundamentalphysiological significance of the covariance between the hearts rhythms and changes inemotion. This question was especially intriguing in light of current views in neuroscience thatthe contents of feelings are essentially the configurations of body states represented insomatosensory maps (Cameron, 2002; Damasio, 2003). This was of course the