Let’s consider whether only human brains create minds. Few people who have pets or live on farms or go camping would say that the animals they encounter don’t have minds. (This view accords with abundant evidence that the genes, receptors, and neurotransmitters involved in human brain function are present in animals.) Again, if we are asked, “Where is your cat’s mind?” we’d point at its head (unlike an ancient Egyptian, Greek or Roman, who would point to the heart, as he would for himself). Saying that different kinds of animal brains create minds is not so troublesome. We aren’t able to describe what those minds are like (some may lack anything like human self-awareness), but we shouldn’t have a problem conceiving that these creatures at least have one.
Evolutionarily, nervous systems are not always central. Some creatures, like jellyfish, have neuronal nets distributed throughout the body. While humans do possess a central nervous system, we also have other, more distributed nervous systems as well. We have a peripheral nervous system, which includes nerves that gather information for the brain (e.g. the nerves in our sense organs) and nerves that send signals from the brain (e.g. telling our muscles what to do).
After it was observed that the gastrointestinal tract could function quite well when severed from the peripheral nervous system, it was concluded that this constitutes a weblike enteric nervous system.
What makes this a separate nervous system is that there are specialized ganglion cells that are located between muscle layers in the intestinal wall which act like a local brain. If one severs any nerves which contact them (from the brain, by way of the peripheral nervous system), these ganglion cells continue to instruct the intestine to move and absorb and secrete, working quite well and quite autonomously as a self-contained functional unit.
It turns out that the intestinal tract only takes advice from the rest of the body. It harbors its own reactions. When bad news gives you a sinking feeling in the pit of your stomach, you are experiencing an emotion as surely as you experience it in your head. In fact, your gut reaction precedes the thought, “Oh no!” Did the enteric nervous system create such a sensation on its own? That’s unclear, but it’s tempting to think so. Certainly many people trust their gut reactions over the confused and compromised responses that the brain is often saddled with when over-thinking sets in.
The muscles of your face are directly linked to your brain. While we assume that the brain is telling the mouth and lips to smile when we’re feeling happy, the reverse is also true. Seeing a smile on someone else’s face can make you happy, and children are taught to smile as a way to break out of a sad mood. Whether this works or not varies from person to person, but it could be argued that the face is controlling the brain in those instances.
Findings about brain-like processes outside the skull have become common. The conduction system of the heart, which organizes your heartbeat, can be thought of as the heart’s brain in the same way the ganglion cells in the gut are the brain of the intestines. The independence of the conduction system is shown when a transplanted heart keeps beating even though the nerves that connected it to the donor’s central and peripheral nervous systems have been severed. The interaction between the heart’s independent processing and the brain’s is complex and not fully understood. Still more mysterious are the bacteria that outnumber the body’s cells by ten to one, living mostly inside the digestive tract but also in the brain and other organs. We think of these as invaders, but over eons bacteria have been incorporated into vast stretches along the double helix of human DNA. The implications for what we call “being human” are enormous and largely uncharted.
We think we’ve established that cultural assumptions about mind and brain are full of gaps. The location of mind is in doubt, and any attempt to isolate it physically in the skull run into valid objections. In the next post we’ll pursue more of the fascinating possibilities that arise when thinking literally gets out of the box.
(To be cont.)
Deepak Chopra, MD is the author of more than 70 books with twenty-one New York Times bestsellers, including co-author with Sanjiv Chopra, MD of Brotherhood: Dharma, Destiny, and The American Dream, and co-author with Rudolph Tanzi of Super Brain: Unleashing the Explosive Power of Your Mind to Maximize Health, Happiness, and Spiritual Well-being (Harmony). Chopra serves as Founder of The Chopra Foundation and host of Sages and Scientists Symposium – August 16-18, 2013 at La Costa Resort and Spa.
Menas Kafatos, Ph.D., Fletcher Jones Endowed Professor in Computational Physics, Director of the Center of Excellence at Chapman University, co-author with Deepak Chopra of the forthcoming book, Who Made God and Other Cosmic Riddles. (Harmony)
P. Murali Doraiswamy, MBBS, FRCP, Professor of Psychiatry, Duke University Medical Center, Durham, North Carolina and a leading physician scientist in the area of mental health, cognitive neuroscience and mind-body medicine.
Rudolph E. Tanzi, Ph.D., Joseph P. and Rose F. Kennedy Professor of Neurology at Harvard University, and Director of the Genetics and Aging Research Unit at Massachusetts General Hospital (MGH), co-author with Deepak Chopra ofSuper Brain: Unleashing the Explosive Power of Your Mind to Maximize Health, Happiness, and Spiritual Well-being. (Harmony)
Neil Theise, MD, Professor, Pathology and Medicine, (Division of Digestive Diseases) and Director of the Liver and Stem Cell Research Laboratory, Beth Israel Medical Center — Albert Einstein College of Medicine, New York.www.neiltheise.com