were practicing the same meditative focus, this raises the possibility that heartrhythm coherence and increased gamma-band phase synchrony are linked in a deeper way. Thisis consistent with the hypothesis that heart rhythm coherence reflects a state of increased globalcoherence in the bodys function as a whole.In summary, the mechanisms that underlie the source of oscillatory rhythms in the thalamusare complex, and there are a number of different hypotheses concerning these. The mechanismsresponsible for the synchronization of remote cells in the brain are even more complex, as thereare both local and global levels of synchronization and also interactions between the local andglobal levels. Whatever the mechanisms turn out to be that facilitate synchronous activity inremote cell assemblies, it is clear that the input from the heart to the brain affects the activity ofthe thalamus and its ability to synchronize cortical activity. This is important in understandingthe relationship between global coherence, emotional stability, and optimal performance.Over the past several decades, several lines of scientific evidence have established that, farmore than a mechanical pump, the heart functions as a sensory organ and as a complexinformation encoding and processing center. Groundbreaking research in the relatively new fieldof neurocardiology has demonstrated that the heart has an extensive intrinsic nervous system thatis sufficiently sophisticated to qualify as a little brain in its own right. Pioneer neurocardiologyresearcher Dr. J. Andrew Armour first described the anatomical organization and function of theheart brain in 1991 (Armour, 1991). Containing over 40,000 neurons, its complex circuitryenables it to sense, regulate, and remember. Moreover, the heart brain can process informationand make decisions about cardiac control independent of the central nervous system (Armour,2003; Armour & Kember, 2004).The heart brain senses hormonal, heart rate, and blood pressure signals, translates them intoneurological impulses, and processes this information internally. It then sends the information tothe central brain via afferent pathways in the vagus nerves and spinal column. When differenthormones or neurotransmitters in the bloodstream are detected by the sensory neurites in theheart, the pattern in the afferent neural output sent to the brain is modified (Armour, 1994). Inother words, in addition to its better-known functions, the heart is also a sensory center thatdetects and transmits information about the biochemical content of the regional blood flow.Neurological signals originating in the heart have an important and widespread influence inregulating the function of organs and systems throughout the body. For example, it is nowknown that in addition to modulating the activity of the nervous and endocrine systems, inputfrom the heart influences the activity of the digestive tract, urinary bladder, spleen, respiratoryand lymph systems, and skeletal muscles (Chernigovskiy, 1967). In more specific terms,cardiovascular afferent signals regulate efferent ANS outflow, (Grossman, Janssen, & Vaitl,1986) modulate pain perception (Randich & Gebhart, 1992) and hormone production (DrinkhillINTEGRAL REVIEWDecember 2009Vol. 5, No. 2& Mary, 1989), and influence the activity of the locus coeruleus and that of the pyramidal tractcells in the motor cortex (Coleridge et al., 1976; Svensson & Thoren, 1979). Also, spinal cordexcitability varies directly with the cardiac pulse, as does physiological tremor of normal skeletalmuscles (Forster & Stone, 1976).Beyond the key role of cardiac