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. We have learned, however, that communication between the heart and brain actually is 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 to the brain also can affect performance.
The heart communicates with the brain and body in four ways:
- Neurological communication (nervous system)
- Biochemical communication (hormones)
- Biophysical communication (pulse wave)
- Energetic communication (electromagnetic fields)
Some of the first researchers in the field of psychophysiology to examine the interactions between the heart and brain were John and Beatrice Lacey. During 20 years of research throughout the 1960s and ’70s, they observed that the heart communicates with the brain in ways that significantly affect how we perceive and react to the world.
While the Laceys were conducting their research in psychophysiology, a small group of cardiologists joined forces with a group of neurophysiologists and neuroanatomists to explore areas of mutual interest. This represented the beginning of the new discipline now called neurocardiology. One of their early findings is that the heart has a complex neural network that is sufficiently extensive to be characterized as a brain on the heart. The heart-brain, as it is commonly called, or intrinsic cardiac nervous system, is an intricate network of complex ganglia, neurotransmitters, proteins and support cells, the same as those of the brain in the head. The heart-brain’s neural circuitry enables it to act independently of the cranial brain to learn, remember, make decisions and even feel and sense. Descending activity from the brain in the head via the sympathetic and parasympathetic branches of the ANS is integrated into the heart’s intrinsic nervous system along with signals arising from sensory neurons in the heart that detect pressure, heart rate, heart rhythm and hormones.
The anatomy and functions of the intrinsic cardiac nervous system and its connections with the brain have been explored extensively by neurocardiologists. In terms of heart-brain communication, it is generally well-known that the efferent (descending) pathways in the autonomic nervous system are involved in the regulation of the heart. However, it is less appreciated that the majority of fibers in the vagus nerves are afferent (ascending) in nature. Furthermore, more of these ascending neural pathways are related to the heart (and cardiovascular system) than to any other organ. This means the heart sends more information to the brain than the brain sends to the heart. More recent research shows that the neural interactions between the heart and brain are more complex than previously thought. In addition, the intrinsic cardiac nervous system has both short-term and long-term memory functions and can operate independently of central neuronal command.