The book review “The Third Brain” – still, we need “contact” –
The skin has its own thought and will
Dr. Mitsuhiro Denda, who is the author of this book “The Third Brain (2007, ISBN-13: 978-42255003013)”, is a researcher of Shiseido, which is one of the world-leading cosmetic company. Unfortunately, this book is written in Japanese; however, you can read his research paper in English, which supports his idea in this book [1]. His background is engineering, not biology or chemistry. Thus, I guess his idea implies multiple angles, which is not only skin itself but environmental temperature or humidity, mental stress, other sensory systems, or hormone, etc. When he started his career as a researcher, he was influenced by the research of UCSF, the moisture of the skin is monitored and adjusted by a barrier function of the skin itself [2]. This book is a result of more profound research and integration of this research paper.
Why is skin “the third brain”?
In current science, not only a brain but intestines are considered as the organ which has a unique individual system to work. Because there is no creature without guts, while there are some creatures without a brain, intestines can react stimulations and work properly without the brain’s order. It means the brain came after than intestines in the process of evolution. The skin is the same origin as the nerve and the brain at cell division. The nerve system is, in brief, turning the switch on and off by electric stimulation. There is a threshold that turns on the switch; however, under this threshold, the switch is still off. In the past, it was thought that stimulation on the skin sent a signal to the nerve system, and then the central nervous system (including the brain) sends back the signal for the reaction. However, in his research, keratinoid, the top layer of the skin, has its unique system activated by electric stimulations to maintain its environment. Even it creates hormones if it is necessary without brain order that was also considered the only brain could send the order to the lower systems. In other words, the skin itself thinks and responds with stimulations for its homeostasis. His proposal as “skin is the third brain” is no multicellular organisms without skin (=surface), even virus has its “shield”; therefore, the skin can be said as the most primitive brain.
How much profoundly skin “thinks”?
Skin is the interface of the external (=temperature and humidity) and the internal (=mental stress) environment. In the book, the author says when the skin is stressed by temperature or humidity, it releases an inflammatory substance such as cytokinin that increases histamine, which causes itchiness. Also, when a person gets mental stress, the brain orders to release a hormone such as cortisone, but also the skin itself releases as well without the brain’s help for protection. Meanwhile, the skin has the opposite system, such as a rewards system. In ape society, grooming is its unique communication system. When apes do groom each other, endorphin (=happy hormone) is released. In one research, an ape is separated from its group and put into the cage by itself. A researcher shows a switch to the ape and does a demonstration; when the ape pushes the switch, a researcher rubs the ape’s back. Once the ape has learned this process, the ape pushes the switch frequently to get the rewards = grooming. The skin can release endorphins by stimulation as well that doesn’t rely on the brain system. It has considered that the brain was the top commander, and no other part could have the same function; however, it is not like that now.
Acupuncture and “skin sensory”
The author is a long-standing acupuncture patient, so that he has some knowledge about acupuncture. Skin is the most surface, even in Traditional Eastern Medicine. However, a difference between Western and Eastern is Eastern thinks that energy is running under the skin as protection, and acupuncture points consider the emerging point of energy on the body surface. The author had frequent meetings with one acupuncturist, which had Western Medicine knowledge as well. This acupuncturist considers acupuncture points and meridians, a body map made by connected acupuncture points, could be an aggregate of the nerves, blood vessels, and lymph system. Also, peripheral and central nervous systems would be deeply involved with the meridian system. In Western Medicine, it has proven the acupuncture point has a lower threshold for electric conductivity than other body areas that react quickly by stimulation. If the skin has its system to turn the switch on and off by itself, it may be the answer to why just contacting the needle on the skin works well as the needle goes to the muscles layer.
My thoughts for “contact” during this pandemic
Since we had the shelter-in-place, we are forced to be distanced from each other. Many businesses started “telework”, even some acupuncturists; they started a “tele-acupuncture” or “tele-herb consultation”. I don’t deny telecommunications itself; it expands a variety of people’s choices for living that is not a bad thing. However, as for hands-on therapy, whether “tele-acupuncture treatment” works well or not is uncertain (it would work to a certain extend or under the particular condition though). This novel virus makes us the distance that also makes us less physically contact each other. This virus seems to rock the value of our foundation of life. It clears up not only individuals but countries’ issues. I remember what my acupuncture master said, “when you perform acupuncture, especially if you are a beginner, you should touch a patient with care. Do not touch rough; try your best to make them comfortable by your touch”. Even he has said, “don’t think you can treat the patient with only such a thin metal bar (caution: he is one of the best in Japan with more than 50-years carrier). Acupuncture is love. You should have love at the bottom of your practice”. This book proposes the skin itself has the almost equivalent system as the central nervous system. If skin contact is shuttered, what outcome will we have in the future? We don’t know yet. Although this time is a bit rough for hands-on therapy, I still would like to believe a potential for “touching the skin” that enhances the human body’s system; and yet, it will boost up your immune system against this novel virus.
[1] Denda. M (2016), Epidermis as the “Third Brain”, Dermatorogica, Sineca, 33(2), P70-73, https://doi.org/10.1016/j.dsi.2015.04.011
[2] Grubauer. R, 1989, Transepidermal Water Loss: The Signal for Recovery of Barrier Structure and Function, Journal of lipid research, 30(3):323-33.
https://pubmed.ncbi.nlm.nih.gov/2723540/
