It is clear that if an organ is no longer used or used less, it degrades.
Brain metabolism is the set of cerebral biochemical reactions that use mainly oxygen and glucose and that allow the brain to develop its functions.
Although the human brain makes up 2% of body weight, the processes that consume energy to ensure its functioning account for 25% of the total glucose used in the body and almost 20% of the O 2 consumption. all the organism, that is, about 160Umol / 100g of brain tissue weight. With an overall flow of 57 ml / 100 g / min, the brain extracts approximately 50% of the oxygen and 10% of glucose from the arterial blood. Therefore, the use of glucose by the brain, estimated by measurements of the difference between arterial and venous blood, is 31 mmol / 100 g / min. As the oxygen consumption is practically equal to the production of CO 2 , the respiratory quotient (RQ) is close to 1, indicating that carbohydrates are the substrates used for oxidative metabolism.
Brain tissue is highly dynamic in terms of electrical activity and energy demand. In this way, the brain is the organ that consumes more energy and uses large amounts of metabolic energy for the process of information, based solely on the participation of two substrates: glucose and oxygen. The maintenance of cerebral metabolic activity is highly expensive and there are not enough reserves to maintain this high metabolic activity. An increase in interneuronal synaptic activity consumes large amounts of energy, a finding that has been exploited in functional magnetic resonance imaging (iRMf) and positron emission tomography (PET) imaging experiments. Oxygen and glucose are the main components involved in the production of adenosine triphosphate (ATP), which is used in cellular energy and its speed or rate of use provides a useful measure of brain metabolism. Neurons and glia differ metabolically as much as they differ in their functionality, but little is known about the subtypes of neurons and astrocytes in their interaction with oligodendrocytes.Regional variations in metabolism in different brain regions or cell types in the brain may help explain susceptibility to neurodegeneration. The average utilization of glucose in human gray matter is ten times more than the total body average. With this value and the known stoichiometry of the oxidation of glucose (C6H12O6 + 6O2 6CO2 + 6H2O), and their coupled reactions it is possible to obtain an estimated flow at different points of the metabolic chain. As glucose passes to glycolysis and the Krebs cycle, its released energy is divided into small packets and its molar flow increases, reaching a maximum of 31 molecules of ATP per molecule of glucose consumed. The metabolic dynamics are determined, in addition , by the concentration, in such a way that the lower the concentration, the greater the impact of a determined flow on the metabolic pool.
The main cause of brain degeneration is the neurotransmitter deficit.
The cells within the black substance called basal ganglia are responsible for the production of dopamine. If these cells cease this function when they are damaged, messages can not be sent to the muscles to move naturally.Parkinson’s is a progressive disease, and although the symptoms may begin and be barely noticeable, when Dopamine levels begin to fall, eventually the levels of dopamine in the body will continue to drop until they become the worst of Parkinson’s symptoms. Parkinson’s Disease by itself is not serious, but when dopamine levels are low enough a person will be totally unable to move or take care of themselves.
Regarding Alzheimer’s disease (AD), it has been shown that the modulation of Glutamate uptake in neurons or astrocytes in culture is a survival mechanism.
The modulation of glial activation as a therapeutic target for neurodegenerative diseases. Endocannabinoids decrease microglial activation both in vitro and in vivo, and the relevance of this mechanism in the context of AD. In fact, endocannabinoids such as Anandamide are neuroprotective and anti-inflammatory agents.
The reduction of synaptic connections between brain cells may explain why people with chronic stress and depression lose brain volume. The cause lies in a genetic switch known as a transcription factor. This factor triggers the loss of connections in the brain of people and causes depression in animals. Depression is the effect of decreased serotonin levels in the brain.
Since neurotransmitters can not be replaced externally since they do not cross the blood-brain barrier, only the internal activation of them can ensure that the cells that produce them are active and their performance is optimal.
That is, low level of Dopamine induces Parkinson’s, Glutamate’s Alzheimer’s, Anandamida neurodegenerative diseases and depression and loss of brain mass due to Serotonin deficiency.
The epigenetic effect is also known. The descendants of a generation that has suffered a strong deficit of some vital substance express it genetically.In this way the limit of the individual is transferred to reach that of the species.
Having established this point, the lack of sufficient production of neurotransmitters evolutionarily degrades the brain, we will consider that it has happened on an evolutionary scale.
Well, it turns out that the human brain has reduced its size in the last 30,000 years – hence age has to do at an unconventional level – so the average brain volume of Homo Sapiens, in this time span, has decreased by 10%, that is, from 1,500 to 1,359 cubic centimeters. Exactly the same decline that is attributed to the effects of old age and the consumption of certain types of substances. In other words, the modern human is an old and sick Cro-Magnon.
In addition, the man of Cromagnon, 17,000 years ago, that is, a Homo Sapiens, was endowed with a brain larger than that of his descendants, but smaller than that of the Neanderthal man, since, although he was physically stronger than Homo Sapiens Sapiens, was weaker than its predecessor.
The explanation of the division of labor due to culture gives a partial answer. The size of the brain decreases when the density of the population increases. Put another way: «With the emergence of more complex societies, the human brain has shrunk because individuals no longer need to be as smart as they used to be to survive; the others help them. «
Another possible key would be the replacement of animal fats by carbohydrates and as a logical consequence that the brain shows a gradual decrease in a time interval as pronounced as 30,000 years.
Although neurologists, meanwhile, say in synthesis that the decline in the size of the brain is something evident, does not necessarily mean that modern men, we have less intellectual abilities than our ancestors, but we have developed new forms of intelligence that they are characterized by being more abbreviated, that is, of less consumption and more adapted to a much easier life.
Without going back so far, we can see from the suttas that 2,500 years ago in India there were a lot of people who practiced jhānas, in one way or another. And we know that this practice requires the prior learning and practice of the generation of neurotransmitters at will. Today, only a tiny minority of people are able to do so, so it is shown that neurodegeneration is the key to our time.
In summary, not knowing how to generate the neurotransmitters themselves endogenously, that is, generating them directly and not only through external stimuli is key in human degradation. Not only as an individual, but as a species.
Finally, from a strictly functional point of view, a modern individual with brain deficits and deficits can not be considered as human as a Cromagnon or even a Neanderthal.
The human species goes less, and possibly no longer has the capacity to recover. The generation of neurotransmitters is not a luxury, it is a need that can put the modern human at the height that their ancestors had to think to survive.
Today, thinking is a luxury that hurts.