Aug 12 2013

Brain Cells in the Heart?

There is a certain flavor of misconception that occurs when a cultural belief intersects a scientific factoid that superficially seems to support the belief. A powerful meme emerges to the effect of – science now proves what we have known/believed all along. Gurus latch onto this idea to provide apparent credibility to their mysticism. The media eats it up.

One such meme that has been around for a while is that the heart contains brain cells, and therefore has a mind of its own, or at least is part of the human mind. There is a related meme that the GI system (the gut) also has a mind of its own.

The notion of “brain cells” in the heart has been co-opted to support various beliefs. One artist writes:

But for me it was exciting further evidence that thinking and mind is a deep connection between brain and mind and that we need to trigger all of our senses for effective creativity and learning.

A Times of India article declares:

It seems both heart and gut have minds of their own. Besides communicating with the brain, they might also be helping it develop, reducing depression and increasing the level of the individual’s well-being.

Guru Joseph Pearce (who apparently likes to be called, Joe) is quoted as saying:

The idea that we can think with our hearts is no longer just a metaphor, but is, in fact, a very real phenomenon. We now know this because the combined research of two or three fields is proving that the heart is the major center of intelligence in human beings.

He goes on to cite research about the feedback mechanisms from the heart to the limbic system of the brain.

What are these people talking about? The primary misconception here is to confuse “neuron” with “brain cell,” followed by equating brain cells with mind.

Not all neurons are brain cells (and not all brain cells are neurons – there are glia also, but that’s another story). ┬áNeurons are specialized cells of the nervous system that use the electrical potential across the membrane of all cells, which in neurons have evolved a special function, to trigger depolarizations that send an electrical signal down their axons which then sends a signal to another cell.

Not all neurons are in the brain. There are neurons in the spinal cord and in the peripheral nervous system as well.

Further, not all neurons contribute directly to the mind – conscious processes – or even subconscious processes beyond some basic sensory feedback to the brain. There is, for example, the autonomic nervous system, which (as the name implies) is concerned not with thinking but with regulating basic bodily function. This includes the function of the GI system and the heart.

It is no surprise, therefore, that the heart and the guts will contain their own specialized neurons that participate in autonomic function.

The function of the heart is highly regulated, because the demands on the cardiovascular system can fluctuate quickly and greatly. Just standing up requires a delicate adjustment in cardiac output and vessel tone in order to maintain perfusion pressure to the brain. Without this rapid adjustment we would get light-headed and possibly faint every time we stood up (this is a disorder some people have when there is a problem with autonomic function).

The heart responds to three systems that work together to regulate its function – the autonomic nervous system, the hormonal system (chemicals that are secreted in the blood that affect heart function, like adrenaline), and an intrinsic nervous system. The heart contains its own electrical system that regulates itself in order to keep the heart pumping in a coordinated fashion. This function is then further adjusted by the autonomic and hormonal systems.

A recent review of the evidence indicates that the heart contains a complex intrinsic nervous system comprised of multiple ganglia (clusters of neurons) that network with each other.

None of this means that the heart has a mind. It takes more than neurons, or even a system of neurons, to form a mind. A complex network of neurons can function like a computer chip, and no more has a mind than your laptop does.

It is true that the heart, like the rest of the body, especially the autonomic nervous system, provides sensory feedback to our brains. This can affect our emotions – when something physical is happening to our body we can feel anxious or depressed. Pain itself is a physical sensation that carries with it a specific emotional response, because pain pathways specifically send signal to the limbic system to create the negative emotional response to pain.

In the same way, in addition to anxiety making our heart race, when our heart races that makes us feel anxious. There is an obvious adaptive function here – our brains respond emotionally to the condition of our bodies, which might be telling us about a threat or danger.

None of this adds up to the heart or gut having a mind. The mind is entirely the product of the brain, which of course is part of the body and is extensively connected to the body through various feedback mechanisms – hardly a surprise.

Conclusion

The heart does not contain brain cells. It contains neurons that comprise its own intrinsic system for regulating cardiac function. Further, neurons alone do not equal mind or consciousness. It takes the specialized organization of neurons in the brain to produce cognitive processes that we experience as the mind.

This is all a complex and fascinating system. It is a shame that some gurus exploit this for a cheap mystical metaphor, distorting the very cool science.

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