turn, is reflected in increased heart rhythmcoherence. Thus, the greater the degree of emotional stability and system-wide coherence, thegreater the facilitation of cognitive and task performance. We call this hypothesis the heartrhythm coherence hypothesis.A number of research projects have been carried out to test this hypothesis. Appendix Cdescribes three studies that show evidence supporting the hypothesis. The first showed thatmacro-scale patterns of cardiac activity can produce a larger effect on the inhibition/facilitationof cognitive performance than the much smaller inhibition/facilitation fluctuations inperformance observed by Wolk and Velden. It found an approximately six times greaterINTEGRAL REVIEWDecember 2009Vol. 5, No. 2improvement in performance than previous studies involving similar methods. The second wasan independent study conducted in the UK by Dr. Keith Wesnes, who concluded that learningand practicing the HeartMath positive emotion-focused coherence-building techniques appears toenhance an individuals memory capacity and also improves self-reported calmness. The thirdstudy was funded by the U.S. Department of Education and carried out with the cooperation ofthe Claremont Graduate Universitys School of Educational Studies involving tenth gradestudents in two large California high schools. It found significant reduction in test anxiety as wellas higher test scores for students who learned the positive emotion-focused coherence-buildingtechniques in the TestEdge program.Overall, the evidence provided by the three studies described in Appendix C indicates that aspecific macro-scale pattern of cardiac activityheart rhythm coherenceis associated withsignificant improvement in cognitive performance. Not only is this outcome observed in a simplereaction time experiment, but the data suggest that this facilitative effect also extends acrossmore complex domains of cognitive function, including memory and even academic testperformance. It also appears that the influence of the coherence mode on cognitive performanceis substantially larger in magnitude than that previously documented for changes in cardiacactivity patterns on a micro scale.Assuming these results are validated by other researchers, it is worth considering the likelypathways and mechanisms that could explain these findings. This entails developing anexplanation that complements the micro-pattern hypotheses of the Laceys and Wolk and Velden,by identifying other physiological mechanisms that may account for these results. The micro-pattern hypothesis presents a somewhat simplified view of heartbrain interactions, which is notadequate to describe the full range of information communication that takes place between theheart and brain: it only addresses the smaller fluctuations in performance that are associated withphysiological changes occurring within a single cardiac cycle or across several heartbeats. As wehave seen, however, there are macro-scale temporal patterns that have a significant carry-overeffect on cognitive performance. To build an adequate understanding of the physiologicalmechanisms involved requires developing a deeper understanding of the complexity of heartbrain interactions. This is reflected in the discussion below in three primary ways: first, that theinfluence of cardiovascular afferent input on the brain is more elaborate than that considered inthe micro-pattern hypothesis; second, that afferent input from the heart has effects on braincenters other than the thalamus; and third, that the alpha rhythm is not the only brain rhythmsynchronized to the heart.A More Complex PictureComplexity of Cardiac Afferent SignalsOne of the underlying assumptions of the micro-pattern hypothesis is that there is a one-to-one correspondence between each heartbeat and the burst of