Head-Heart Interactions

Traditionally, the study of communication pathways between the "head" and heart has been approached from a rather one-sided perspective, with scientists focusing primarily on the heart’s responses to the brain’s commands. However, we have now learned that communication between the heart and brain is actually a dynamic, ongoing, two-way dialogue, with each organ continuously influencing the other’s function. Research has shown that the heart communicates to the brain in four major ways: neurologically (through the transmission of nerve impulses), biochemically (via hormones and neurotransmitters), biophysically (through pressure waves) and energetically (through electromagnetic field interactions). Communication along all these conduits significantly affects the brain’s activity. Moreover, our research shows that messages the heart sends the brain can also affect performance.

The heart communicates with the brain and body in four ways:

• Neurological communication (nervous system)
• Biophysical communication (pulse wave)
• Biochemical communication (hormones)
• Energetic communication (electromagnetic fields)

The studies described in this section probe several of these communication pathways, looking specifically at how the brain responds to patterns generated by the heart during positive emotional states. The first two studies focus primarily on neurological interactions, demonstrating that the afferent signals the heart sends the brain during positive emotions can alter brain activity in several ways. In the first study, we find that cardiac coherence can drive entrainment between very low frequency brainwaves and heart rhythms, thus further expanding our understanding of the physiological entrainment mode described in the previous section. In the second study, we learn that coherent heart rhythms also lead to increased heart-brain synchronization. The implications of these findings are explored in the third study, which shows that in states of high heart rhythm coherence, individuals demonstrate significant improvements in cognitive performance. 
Taken together, the results of these studies demonstrate that intentionally altering one’s emotional state through heart focus modifies afferent neurological input from the heart to the brain. The data suggest that as people experience sincere positive feeling states, in which the heart’s rhythms become more coherent, the changed information flow from the heart to the brain may act to modify cortical function and influence performance. These findings may also help explain the significant shifts in perception, increased mental clarity and heightened intuitive awareness many individuals have reported when practicing the HeartMath techniques. 
The final two studies in this section are concerned with energetic communication by the heart, which we also refer to as cardioelectromagnetic communication. The heart is the most powerful generator of electromagnetic energy in the human body, producing the largest rhythmic electromagnetic field of any of the body’s organs. The heart’s electrical field is about 60 times greater in amplitude than the electrical activity generated by the brain. This field, measured in the form of an electrocardiogram (ECG), can be detected anywhere on the surface of the body. Furthermore, the magnetic field produced by the heart is more than 5,000 times greater in strength than the field generated by the brain, and can be detected a number of feet away from the body, in all directions, using SQUID-based magnetometers (Figure 12). Prompted by our findings that the cardiac field is modulated by different emotional states (described in the previous section), we performed several studies to investigate the possibility that the electromagnetic field generated by the heart may transmit information that can be received by others.

Thus, the last two studies summarized in this section explore interactions that take place between one person’s heart and another’s brain when two people touch or are in proximity. This research elucidates the intriguing finding that the electromagnetic signals generated by the heart have the capacity to affect others around us. Our data indicate that one person’s heart signal can affect another’s brainwaves, and that heart-brain synchronization can occur between two people when they interact. Finally, it appears that as individuals increase psychophysiological coherence, they become more sensitive to the subtle electromagnetic signals communicated by those around them. Taken together, these results suggest that cardioelectromagnetic communication may be a little-known source of information exchange between people, and that this exchange is influenced by our emotions.

Head-Heart Entrainment: A Preliminary Survey

Key findings: As people learn to sustain heart-focused positive feeling states, the brain can be brought into entrainment with the heart. 
Summary: This study examines in further detail the entrainment mode of cardiac function described previously in "Cardiac Coherence: A new noninvasive measure of autonomic nervous system order." In the previous investigation it was found that when the heart is functioning in the entrainment mode, there is a marked shift in the HRV power spectrum to the resonant frequency range of the baroreceptor feedback loop (around 0.1 Hz), and frequency locking between the HRV waveform, respiration and pulse transit time occurs. The present study shows that as individuals learn to maintain the entrainment mode through sustaining sincere, heart-focused states of appreciation or love, the brain’s electrical activity can also come into entrainment with the heart rhythms. Figure 13, below, shows an example of entrainment occurring between a subject’s HRV and the very low frequency band region of the electroencephalograph (EEG) recordings after the individual practices the Freeze-Frame intervention for 5 minutes. There is nearly a hundred-fold increase in power in the 0.1 Hz frequency range of the HRV power spectrum after the Freeze-Frame intervention and a correlated 4 to 5-fold increase in the EEG signal power in that same frequency range. Our present hypothesis is that a strong and sustained increase in baroreceptor system activity leads to greatly increased coupling between the heart (HRV) and the brain (EEG) via nerve conducted signals and increased coherence in the vascular system. The results of this experiment provide one example of how increasing coherence in the heart rhythms, by intentionally generating positive emotions, can alter brain activity.

Cardiac Coherence Increases Heart-Brain Synchronization

Key findings: The brain’s alpha wave activity is synchronized to the cardiac cycle. During states of high heart rhythm coherence, alpha wave synchronization to the heart’s activity significantly increases. 
Summary: This investigation explores further how the heart’s activity influences that of the brain. In this pilot study, heartbeat evoked potentials were analyzed in ten individuals. The analysis of heartbeat evoked potentials is a signal processing technique used to identify segments of the EEG (brainwaves) that are correlated to or affected by the heartbeat (Figure 14). In this way, it is possible to determine specific changes in the brain’s electrical activity that are associated with afferent signals from the heart. 
The subjects’ EEGs were recorded using electrodes placed along the medial line and the frontal sites. To determine which brainwave frequencies showed cardiac-related activity, the region of the EEG between 50 and 600 milliseconds post R-wave was then subjected to spectrum analysis. As a control, this procedure was repeated but instead of using the ECG as the signal source, an artificial, randomly generated signal with the same mean inter-beat interval and standard deviation as the original ECG was used for the time reference. It was found that the brain’s alpha wave activity (8-12 Hz frequency range) is synchronized to the cardiac cycle. There was significantly more alpha rhythm synchronization when the real ECG was used for the signal source as compared to the control signals. Additionally, analyses revealed that brainwave activity at a lower frequency than alpha is also synchronized to the ECG signal. 
In the next phase of the study, we sought to determine if there is a change in the degree of alpha rhythm synchronization to the ECG during periods of increased heart rhythm coherence. In this phase, subjects used the Cut-Thru technique, an emotional refocusing exercise, a means of quieting inner emotional dialogue, instilling a positive emotional state and increasing heart rhythm coherence. Subjects’ heart rhythm coherence and heartbeat evoked potentials were analyzed during a 10-minute baseline period, and again while they practiced the Cut-Thru technique for 10 minutes. There was a significant increase in heart rhythm coherence during the period that subjects used the Cut-Thru technique. Heartbeat evoked potential data showed that in this state of increased heart rhythm coherence, alpha wave synchronization to the cardiac cycle increases significantly (Figure 15).

In conclusion, this study shows that the brain’s activity is naturally synchronized to that of the heart, and also confirms that intentionally altering one’s emotional state through heart focus modifies afferent neurological input from the heart to the brain. Results indicate that the brain’s electrical activity becomes more synchronized during psychophysiologically coherent states. Implications are that this increased synchronization may alter information processing by the brain during the experience of positive emotions.

In conclusion, this study shows that the brain’s activity is naturally synchronized to that of the heart, and also confirms that intentionally altering one’s emotional state through heart focus modifies afferent neurological input from the heart to the brain. Results indicate that the brain’s electrical activity becomes more synchronized during psychophysiologically coherent states. Implications are that this increased synchronization may alter information processing by the brain during the experience of positive emotions.

Cardiac Coherence Improves Cognitive Performance

Key findings: States of increased heart rhythm coherence are associated with improvements in cognitive performance. 
Summary: Given our previous findings (above) indicating that states of increased heart rhythm coherence give rise to distinct changes in the brain’s activity, we subsequently performed an experiment to determine whether these changes might have a measurable impact on cognitive performance. Thus, this study assessed changes in cognitive performance associated with states of increased heart rhythm coherence. In this investigation, 30 subjects were randomly divided into matched control and experimental groups based on age and gender. Cognitive performance was assessed by determining subjects’ reaction times in an oddball auditory discrimination task before and after practicing the Cut-Thru emotional self-management technique to increase cardiac coherence. In this test, subjects listened to a series of two different tones through headphones. They were presented with 300 tones, each with a 50-millisecond duration. Eighty percent of the tones were 1000 Hertz sine waves (standard), and the other 20 percent were 1100 Hertz tones (odd) randomly mixed in between the standard tones, spaced around two seconds apart. Subjects were instructed to push a button as quickly as possible upon hearing an odd tone. The interval between the presentation of the tone and the pressing of the button is the reaction time. 
Following a 10-minute baseline period, subjects were given a practice session to gain familiarity with pressing the button and identifying the different tones. This was followed by the first 10-minute auditory discrimination task. Thereafter, the experimental group subjects were asked to employ the Cut-Thru self-management technique for 10 minutes, while control subjects engaged in a relaxation period during this interval. Following this, all subjects performed a second 10-minute auditory discrimination task, the results of which were compared to the first. Subjects’ ECGs, pulse transit time and respiration were continuously monitored throughout this entire experimental sequence. Heart rhythm coherence, derived from the ECG, was calculated for all subjects during each phase of the testing sequence. As shown in Figure 16, there was a significant increase in heart rhythm coherence in the subjects who used the Cut-Thru technique that was not evident in the relaxation group.

As compared to the control group, subjects using the Cut-Thru technique demonstrated a significant decrease in reaction times in the discrimination task following the application of the technique, indicating improved cognitive performance (Figure 17). In addition, a significant relationship was found between the degree of heart rhythm coherence and reaction times. Increased cardiac coherence was associated with a significant decrease in reaction times (improved performance).
The results of this study support the hypothesis that the changes in brain activity that occur during states of increased psychophysiological coherence lead to changes in the brain’s information processing capabilities. Results suggest that by using heart-based interventions to self-generate coherent states, individuals can significantly enhance cognitive performance.

The Electricity of Touch: Detection and Measurement of Cardiac Energy Exchange Between People

Key findings: When people touch or are in proximity, one person’s heartbeat signal is registered in the other person’s brainwaves. 
Summary: The concept of an energy exchange between individuals is central to many healing techniques. This concept has often been disputed by Western science due to the lack of a plausible mechanism to explain the nature of this energy or how it could affect or facilitate the healing process. The fact that the heart generates the strongest electromagnetic field produced by the body, coupled with our findings that this field becomes measurably more coherent as the individual shifts to a sincerely loving or caring state, prompted us to investigate the possibility that the field generated by the heart may significantly contribute to this energy exchange. This study presents a sampling of results which provide intriguing evidence that an exchange of electromagnetic energy produced by the heart occurs when people touch or are in proximity. Signal averaging techniques are used to show that one person’s electrocardiogram (ECG) signal is registered in another’s electroencephalogram (EEG) and elsewhere on the other person’s body (See Figure 18 for an example). While this signal is strongest when people are in contact, it is still detectable when subjects are in proximity without contact.

This study represents one of the first successful attempts to directly measure an energy exchange between people, and provides a solid, testable theory to explain the observed effects of many healing modalities that are based upon the assumption that an energy exchange takes place. Nonlinear stochastic resonance is a mechanism by which weak, coherent electromagnetic fields, such as those generated by the heart of an individual in a caring state, may be detected and amplified by biological tissue, and potentially produce measurable effects in living systems. Evidence that the cardiac field changes as different emotions are experienced, combined with this study’s finding that this field is registered physiologically by those around us, provides the foundation of one possible mechanism to describe the impact of our emotions on others at a basic physiological level. One implication is that the effects of therapeutic techniques involving contact or proximity between practitioner and patient could be amplified by practitioners consciously adopting a sincere, caring attitude, and thus increasing coherence in their cardiac field.

The Role of Physiological Coherence in the Detection and Measurement of Cardiac Energy Exchange Between People

Key findings: When two people are at a conversational distance, the electromagnetic signal generated by one person’s heart can influence the other person’s brain rhythms. When an individual is generating a coherent heart rhythm, synchronization between that individual’s brainwaves and another person’s heartbeat is more likely to occur. 
Summary: This investigation was designed to determine whether cardioelectromagnetic communication between individuals is affected by the degree of subjects’ cardiac coherence. In this experiment we looked at heart-brain interaction effects across larger distances in subject pairs who were not in physical contact. As in the previous study, subjects’ ECGs and EEGs were simultaneously monitored, and signal averaging techniques were employed to discern heart-brain interaction effects. In addition, heart rate variability patterns were analyzed to determine the degree of heart rhythm coherence for each subject. 
Data showed that in subjects separated by several feet, synchronization can occur between the alpha waves in one person’s EEG and the other’s ECG signal. However, in this experiment, whether the "receiving" subject’s brainwaves synchronized to the "source" subject’s heart signal was determined by the degree of coherence in the receiving subject’s heart rhythms. Subjects who demonstrated high heart rhythm coherence were more likely to show alpha wave synchronization to the other subject’s ECG. This effect was not apparent in subjects with low heart rhythm coherence. 
Figure 19 shows the results for one set of subjects who were seated four feet apart, facing each other. Note the change in Subject 2’s brainwave patterns (onset of alpha rhythms) that is synchronized to the R-wave of Subject 1’s ECG. The bottom-most trace displays Subject 2’s heart rhythm patterns, which were highly coherent during this experiment.

Figure 20 is an overlay plot of one of Subject 2’s EEG traces and Subject 1’s ECG. Note the similarity of the wave shapes, indicating a high degree of synchronization between the two waves. 
This study’s findings have intriguing implications, suggesting that individuals in a physiologically coherent state become more sensitive to the subtle electromagnetic information encoded in the heart signals of others around them. Interestingly, this also supports extensive behavioral data and experience with a HeartMath communication technique called Intuitive Listening. This technique involves focusing on the heart and maintaining a neutral or appreciative attitude while listening to another person. When individuals apply this tool, they often not only report hearing the speaker’s words with more clarity and focus because of a reduction in their own internal dialogue, but also acknowledge becoming more aware of deeper and more subtle aspects of the communication that are not contained in the words alone. This is often described as an increased sensitivity and intuitive awareness of the other person’s underlying feelings and the ’essence’ of their communication. The results shown above support the concept that this deeper, more sensitive form of communication, which establishes a heartfelt connection between people, may occur based on the increased heart rhythm coherence generated by the listener (receiver) when using the Intuitive Listening technique. 
In conclusion, this study represents a further step in uncovering the physiological underpinnings of subtle, ongoing energetic forms of communication between people. Results have countless implications, and invite continued scientific exploration of the relationship between emotions, physiology and human interactions.

http://www.heartmath.org/research/science-of-the-heart/head-heart-interactions.html