Today we are going to take it light. I am going to review a number of sayings, proverbs or old knowledge that recent science has confirmed. So technically we have not learnt anything we did not know, it is just we (modern scientifically driven human beings of the XXI century) were not aware that we knew these things for the last few thousand years.
Executive summary: I will review the science behind ”muscle memory”, someone else’s “broken heart” and your “gut feeling”.
For those with time and those who frequently enjoy these free pearls of knowledge 😉
I will start with “muscle memory”. Whenever we say that we have acquired “muscle memory” we describe the ease with which we do some physical gesture after training. Mastering any physical skill takes practice, a lot of it. Through practice we repeat a specific action time and again.
So, what does practice do in our muscles to make us better at things?
Well, it turns out it is not our muscle the one acquiring memory of an activity, the muscle is a brute and brainless collection of muscle cells. It is the nerve the one that improves its conduction of the specific signal.
Our brains have two kinds of neural tissue: grey matter and white matter. The grey matter processes information in the brain, directing signals and sensory stimuli to nerve cells, while white matter is mostly made up of fatty tissue and nerve fibers. When we produce any movement in our body information travels from the brain’s grey matter, down the spinal cord, through a chain of nerve fibers called axons to our muscles.
The axons are wrapped with a fatty substance called myelin. And it’s this myelin covering, or sheath, that seems to change with practice. Myelin is like insulation on electrical cables. It prevents loss of electrical signals moving them more efficiently along neural pathways. Recent studies in mice suggest that the repetition of a physical motion increases the layers of myelin sheath that insulates the axons. And the more layers, the greater the insulation around the axon chains; forming a sort of superhighway for information connecting your brain to your muscles. So while many athletes and performers attribute their successes to muscle memory, muscles themselves don’t really have memory. Rather, it may be the myelination of neural pathways that gives these athletes and performers their edge with faster and more efficient neural pathways.
My favorite is the broken heart which science has baptized as “Takotsubo myocardiopathy”. This “broken heart” concept so prevalent in literature and old proverbs has a footing in real life. When we suffer an emotional loss the term “I have a broken heart” is an easy currency in common language. Takotsubo cardiomyopathy was first described in 1990 in Japan ( Kazuo et al, 2014). More than 90% of reported cases are in women ages over 50. In this cardiomyopathy the left ventricle is weakened as a result of severe emotional or physical stress (loss of a loved one, an accident, or a natural disaster). This condition is also called stress-induced cardiomyopathy or broken-heart syndrome. As in any cardiomyopathy with some level of heart failure the main symptoms are chest pain and shortness of breath. The current hypothesis says that a surge in stress hormones (such as adrenaline) “stun” the heart, producing changes in heart muscle cells or coronary blood vessels that prevent the left ventricle from having an effective contraction.
The abnormality that gives the disorder its name — is ballooning of the lower part of the left ventricle (apex). During contraction (systole), this ventricle resembles a tako-tsubo, a pot used by Japanese fishermen to trap octopuses. There you have it, there is an explanation for that chest pain you feel when your loved one leaves …
And the last one I will review is very interesting and something science is currently digging deeper and deeper: the intimate relationship between guts and brains. We commonly use the expression “I have a gut feeling that …” and we mean that we sense something that is not right or that is very right, in any case we attach an emotional intuition to the gut. What is the basis for that?
It turns out that the ‘microbiome’, a name for all the bacteria in our intestines who live in symbiotic relationship with us, do a lot of work for us. Research shows that gut microbiome may play an role in our brain, behavior, and mood.
These bacteria have the capacity to generate many neurotransmitters and neuromodulators commonly found in the brain (GABA, norepinephrine, 5HT, dopamine, and acetylcholine). Furthermore, there is evidence of the existence of a gut-brain axis. These pathways of communication include the enteric nervous system (ENS), the endocrine system, the metabolic system, and even the immune system.
There are numerous animal studies showing behavioral changes with different food schemes that produce different microbiomes. It is always difficult to translate such animal studies results into a clinically meaningful result in humans. That is why I will mention human studies.
A recently published systematic review of clinical studies retrieved 10 studies that met criteria and were analyzed for effects on mood, anxiety, and cognition. Five studies assessed mood symptoms, seven studies assessed anxiety symptoms, and three studies assessed cognition. The majority of the studies found positive results on all measures of depressive symptoms; however, the strain of probiotic, the dosing, and duration of treatment varied widely and no studies assessed sleep. The study concluded that there is compelling evidence that probiotics may alleviate depressive symptoms is compelling but additional double-blind randomized control trials in clinical populations are warranted to further assess efficacy ( Wallace et al, 2017).
In summary, though we still lack randomized placebo controlled evidence (the highest level of scientific evidence) there is a clear body of evidence and science pointing towards that direction. Food is health and has an impact on your emotional welfare.
Yes, you have a gut feeling!
References
Kazuo Komamura, Miho Fukui, Toshihiro Iwasaku, Shinichi Hirotani, and Tohru Masuyama. Takotsubo cardiomyopathy: Pathophysiology, diagnosis and treatment. World J Cardiol. 2014; 6: 602–609.
Wallace CJK, Milev R. The effects of probiotics on depressive symptoms in humans: a systematic review. Ann Gen Psychiatry 2017;16:14.
Effects of physical exercise on myelin sheath regeneration: A systematic review and meta-analysis. https://www.researchgate.net/publication/319309032_Effects_of_physical_exercise_on_myelin_sheath_regeneration_A_systematic_review_and_meta-analysis