“To reach the simplest truth requires years of contemplation”

Isaac Newton
(Woolsthorpe Manor 1643 – Kensington 1727)

What does science say?

(Literal translation of a fragment of the neuroscientist article “This Is Your Brain on Silence” originally published in the Finnish magazine “Nothingness” in August 2014 by freelance journalist Daniel A. Gross, specializing in history and science) (1 ) Very interesting. I have to do research to add some links. Studies of human physiology help explain how an invisible phenomenon can have such a pronounced physical effect. The sound waves vibrate the bones of the ear, which transmit movement to the cochlea in the form of a screw. The cochlea converts the physical vibrations into electrical signals that the brain receives. The body reacts immediately and powerfully to these signals, even in the midst of deep sleep.

Neurophysiological research suggests that the noises first activate the tonsil, groups of neurons located in the temporal lobes of the brain, associated with the formation of memory and emotion. Activation causes stress hormones to be released immediately, such as cortisol. People who live in strong environments often experience chronic stress hormone levels. In the same way that the noise of a hundred of cars accumulates in an annoying wall of background noise, the physical effects of the noise accumulate. In 2011, the World Health Organization attempted to quantify its burden of health in Europe. (2) He concluded that the 340 million residents of Western Europe, approximately the same population as the United States, lost annually a million years of healthy life due to noise. He even argued that 3,000 deaths of heart disease were, at the root of it, the result of excessive noise.

Therefore, we like silence for what it does not do; It does not wake up, it does not annoy or kill us, but what does it do? When Florence Nightingale attacked the noise as “cruel absence of attention,” he also stressed the opposite: tranquility is a part of attention, which is so essential for patients as medication or sanitation. It’s a strange idea, but the researchers have begun to appreciate it as true. Silence began to appear in scientific research as a control or reference, against which scientists compare the effects of noise or music. The researchers have studied it mainly accidentally, since the doctor Luciano Bernardi did a 2006 study on the physiological effects of music. “We have not thought about the effect of silence,” he says.

“This did not have to be studied specifically” (3) He had a calm surprise. Bernardi observed physiological metrics for two dozens of test subjects while listening to six musical themes. He discovered that the impacts of music could be read directly in the bloodstream, through changes in blood pressure, carbon dioxide and circulation in the brain. (Bernardi and his son are amateur musicians and want to explore a shared interest.) “During almost every type of music, there was a physiological change compatible with a condition of excitement,” he explains. This effect made sense, since the active listening requires attention.

But the most remarkable find appeared between the musical tracks. Bernardi and his colleagues discovered that silent sections inserted randomly also had a drastic effect, but in the opposite direction. In fact, silent pauses of two minutes were much more relaxing than “relaxing” music or a longer silence reproduced before starting the experiment. The blank pauses Bernardi considered irrelevant, that is, became the most interesting object of study. Silence seemed to increase by the contrasts, perhaps because it gave special attention to the subjects of the test. “Perhaps excitement is something that concentrates the mind in one direction, so that when there is nothing more awake, then you have more relaxation,” he says.

In 2006, Bernardi’s paper on the physiological effects of silence was the most downloaded research in Heart magazine. One of its main conclusions, that silence increases with contrasts, is reinforced by neurological research. In 2010, Michael Wehr, who studied sensory processing in the brain at the University of Oregon, observed the brain of mice during brief sound bursts. (4) The start of a sound causes a specialized network of neurons to be illuminated in the auditory cortex. But when the sounds continue relatively consistently, the neurons stop reacting to a great extent. “What the neurons really do is signal whenever there is a change,” says Wehr. The sudden appearance of silence is also a type of change, and this fact led to Wehr in surprise. Prior to their 2010 study, scientists knew that the brain reacted at the beginning of the silences. (This ability helps us react to dangers, for example, or distinguish words in one sentence.)

But Wehr’s research extended these results by showing that, notably, the auditory cortex has a separate network of neurons that trigger when the silence “When a sound is suddenly over, this is an event as sure as when a sound starts”. Although we usually think of silences as lack of sounds, our brains are structured to recognize them, as long as they represent an acute break of sounds. So, the question is what happens after this moment, when the silence continues and the auditory cortex is introduced in a state of relative inactivity. One of the researchers who has examined this issue is Duke University biologist Imke Kirste. (5)

Like Bernardi, Kirste did not try to study silence. In 2013, he was examining the effects of the sounds in the brain of adult mice. His experiment exposed four groups of mice to various auditory stimuli: music, mouse screams, white noise and silence. It was hoped that the screaming of mouse breeding, as a form of communication, could promote the development of new brain cells. Like Bernardi, he thought that silence was a control that would not produce any effect. As it turned out, although all the sounds had neurological effects in the short term, none of them did not have a lasting impact. However, for his great surprise, Kirste discovered that two hours of silence a day caused the development of cells in the hippocampus, a region of the brain related to the formation of memory, which implied the senses.

This was deeply disconcerting: the total absence of sound stimulation had a more pronounced effect than any type of input that was tested. That’s how Kirste made sense of the results. Did you know that “enrichment environmental “, such as the introduction of toys or companions of mice, encouraged the development of neurons, as they challenged the brains of mice. Perhaps the total absence of sound might have been so artificial, reasoned – so alarming, until everything – that caused a higher level of sensitivity or alert the mice. Neurogenesis could be an adaptive response to mysterious tranquility. The growth of new cells in the brain does not always have health benefits. But in this case, Kirste says that cells seem to be neurons in operation. “We saw that silence really helps the new cells generated to differentiate into neurons and integrate into the system.” While Kirste emphasizes that his conclusions are preliminary, he asks himself if this effect could have unexpected applications.

Conditions such as dementia and depression have been associated with the decrease in rates of neurogenesis in the hippocampus. If a link could be established between silence and neurogenesis in humans, he says, maybe neurologists could find a therapeutic use of silence. Although it is clear that external silence can have tangible benefits, scientists discover that under our skulls “there really is nothing like silence,” says Robert Zatorre, an expert in sound neurology. “In the absence of sound, the brain often tends to produce internal representations of sound.”

Imagine, for example, that you are listening to “The sound of silence” by Simon and Garfunkel, when the radio is pulled out abruptly. Neurologists have found that, if you know the song well, the auditory cortex of your brain remains active, as if the music is still playing. “What he feels” is not generating the outside world, “says David Kraemer, who has conducted such experiments in his Dartmouth College lab.” A memory is being recovered. “The sounds are not always responsible for the sensations, sometimes our subjective sensations are responsible for the enthusiasm of the sound. This is a reminder of the imaginative power of the brain: on the white sensory whiteness of silence, the mind can direct its own symphonies. But it is also a reminder that even in the absence of a sensory input such as sound, the brain is still active and dynamic.

In 1997, a team of neuroscientists at the University of Washington was collecting brain test data from test subjects during various mental tasks, such as arithmetic and word games. (6) One of the scientists, Gordon Shulman, realized that, although intense cognition caused spikes in some parts of the brain, as expected, it also caused a decrease in activity in other parts of the brain. It seemed that there was a type of brain activity in the background that was more visible, paradoxically, when the subject of the test was in a quiet room, doing absolutely nothing.

The chief scientist of the team was Marcus Raichle, and I knew there were good reasons to look at the data more closely. For decades, scientists had known that the “bottom” activity of the brain consumed most of its energy. Hard tasks, such as pattern recognition or arithmetic, in fact, only increased the energy consumption of the brain in a few percentages. This suggested that, ignoring the background activity, neurologists could overlook something crucial. “When I do it,” explains Raichle, “most of the brain’s activities end up in the courtroom.” In 2001, Raichle and his colleagues published a seminal document that defined a “defect mode” of brain function – located in the prefrontal cortex, active in cognitive actions – which implies that a “rest” brain is permanently active, compiling and evaluating information. Focused attention, in fact, reduces this scanning activity. The default mode, argued by Raichle and his company, has “an evolutionary rather than obvious importance.” Detection of predators, for example, should happen automatically and would not require additional intent and energy. The follow-up investigation has shown that the default mode is also claimed in self-reflection. In 2013, in Frontiers in Human Neuroscience, Joseph Moran and his colleagues wrote the network of the brain’s default mode “is observed more closely during the psychological task of reflecting on their personalities and characteristics (self-reflection ), instead of thinking of himself, thinking about the concept of himself or thinking of self-esteem, for example. “During this time, when the brain rests calmly, he wrote to Moran and his Colleagues, our brains integrate internal and external information into a space of conscious work.”

We extracted from the article by Daniel A. Gross that science has met with silence when looking into other directions, but has had to stop by considering the revelations of silence itself. Neurogenesis is something to continue to investigate. We have been able to synthesise through the various scientific voices that have extracted from their studies some principles related to the properties of silence in the body: Mental relaxation Reduction of stress and anxiety, decreased levels of cortisol in the blood Decreased blood pressure Sensation of psychological well-being Neurogenesis in the hippocampus Improvement of the immune system It promotes creativity and cognition Improves deep sleep, helps to fight insomnia Embrace altered emotional states

So we can affirm that silence is a mental state resulting from the absence of auditory contaminations among others, that relaxing body and mind predisposes the individual to organic regeneration and inner peace. Bibliographical references: 1. This chapter is mostly literal translation of the article “This Is Your Brain on Silence” originally published in the Finnish magazine “Nothingness” in August 2014 by freelance journalist Daniel A. Gross, specializing in history and science) http://nautil.us/issue/38/noise/this-is-your-brain-on-silence-rp Simply added some links and comments to the end.

2. Informe complert de l’estudi de l’OMS: http://www.euro.who.int/__data/assets/pdf_file/0008/136466/e94 88.pdf

3. Estudi de Bernardi complert: https://europepmc.org/abstract/med/16199412

4. Estudi de Wehr publicat a la revista Neuron ARTICLE| VOLUME 65, ISSUE 3 , P412-421, FEBRUARY 11, 2010: https://www.cell.com/neuron/fulltext/S0896-6273(10)00046-2

5. Estudi de kirste complert: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4087081/

6. Article sobre l’estudi de Raichle: https://www.pnas.org/content/98/2/676