effects of sound on biological systems

Posted comment on ´Healing Rhythms` by E. Young and published in New Scientist 3038, 12th September 2015

SUMMARY

Young asks in her article how sound can affect our minds and how music can be used for the treatment of medical disorders. She quotes many examples of music therapy and its alleged benefits. For example its psychological effects shown by a Belfast University study where musical improvisation boosted self-esteem and reduced depression in children and adolescents with behavioural and emotional problems, supported by Brandes by his work on its positive effects on depression. Others found that listening to music activates the reward centres and hence, stimulates a feel-good feeling, an effect linked to the release of dopamine. Brandes found that patients suffering from burn-out syndrome demonstrated reduced symptoms when they listened to a special playlist and singing could help patients with left hemisphere damage, as too dementia sufferers. Music was also found to reduce the effect of stress (Gaynor) and therefore, help the body fight diseases and can act as an analgesic helping relieve pain after surgery (Levitin). Music is reported to decrease heart rate, blood pressure (with high blood pressure music was found to increase the variability in heart rate which indicated a healthy vagal tone) and body temperature, and other responses controlled by the brainstem. It is also said to aid in the regulation of movement, for example with Parkinson`s disease sufferers which Young supports with the link between dopamine and rhythm.
Rhythm appears to be important for the benefits of music combatting stress and anxiety and neurons in the brainstem fire synchronously with the tempo of the sounds heard. Slow tempo music can reduce heart rate, blood pressure, body temperature, and other responses controlled by the brainstem with a reported link to dopamine. Sleight found that slow music with 10 second repetitive cycle calms its listeners. This cycle matches the length of the cycle of signals sent from the brain to the heart to regulate blood pressure. Such 10 second cycles can be found in abundance in the music of Verdi, Beethoven`s 9th symphony, and arias in Puccini´s Turandot.
Young also gives in her article examples of how infra- and ultrasound can affect a person`s health. Ultrasound can cause nausea and discomfort and Tyler found that by focusing ultrasound waves on the cerebral cortex area where processing of sensory information from the hand takes place, then the sense of touch was more sensitive. Infrasound on the other hand produced feelings of uneasiness, nervousness or fear. The particular frequency of 111HZ was found by Chalk and Cook to be relaxing, inducing a mild trance like state with activity in the left frontal region being reduced thus affecting the language centre functioning. Cook linked this effect to reducing worry. Debertolis found that using the EEG that there appeared to be no left/right differences with sound of 90-120HZ, but each volunteer responded most strongly to a particular tone. The effect caused either manifested as activity in the frontal lobes and hence, ideas and thoughts were stimulated that were similar to those associated with meditation or there was a shift in activity in the posterior occipital lobe and more images were reported as being seen. The effects according to Parson were not due to neuron signals since this occurs at a frequency of 1000HZ, but could represent the firing of groups of neurons. However, Young also writes that even with the evidence for the medical benefits there are those that question the link. Thaut, a director of medical research, states that there needs to be more evidence for a link between clinical depression and severe stress and music and Levitin says that most of the support comes from anecdotes and so there needs to be more clinical research. In her article Young says that the problems with music therapy research is funding which is given a low priority compared to other areas, and there are not enough proper controls in the experiments, e.g. experiments on stress where a control of pleasant distractors of reading a book is required. Young also introduces the topic of the placebo effect with Thaut stating that with music that we like, the placebo effect is very strong.
Young concludes that much is not known, but evidence shows that music has health giving effects that are both mental and physical and has the advantage of being non-invasive, safe and cheap.

COMMENT

This article is interesting because it provides evidence that sound may have more effects on biological functioning than light. Light is perceived by the eye and provides us with information about our environment, forms visual memories, influences our movements, but it also affects biological system functioning via the pineal gland (i.e. circadian rhythms responding to day and night). Hence, changes in light can lead to alterations in biological system and cognitive functioning. Sound is similar to light, but the mechanisms are different. The auditory mechanism is well studied and hair cells and mechanoreceptors of the ears respond to sounds (whether music, noise, single sounds etc) leading to appropriate neuronal transmission in the brain including auditory cortex activation. Owing to the structure of the ear, the environmental sounds are actually converted to fluid pressure changes and hence the mechanoreceptor system that responds to pressure comes into play. Hence, it is possible that sound can affect any cells that have this type of system. Therefore, responses to sound include not only those from the mental appreciation of the sounds heard (e.g. emotive memories recalled on hearing specific music), but also indirect behavioural responses to activation of this mechanical system. These can include bodily movements and changes in respiration, heart rate, glandular activity and skin-colour for example. Successful music therapy reports similar behavioral responses, e.g. regulation of movement (entrainment), immune system changes, adrenal gland and anterior pituitary effects as well as circulatory system effects such as decreased heart rate and blood pressure. Music therapy also reports positive influence on mental and emotional state with increases in feel-good feeling, self-esteem, mood and decreased depression and stress. These effects can possibly be explained by the release of dopamine and opioid receptor involvement that has been associated with the beneficial effects of music (i.e. improvement of mood, removal of ´fight and flight` responses) and improved neuronal transmission and connectivity associated with rhythm (i.e. the regulation of brain and heart signals has been associated with music with a 10 second repetitive cycle). Therefore, the question is what effects can sound have at the biochemical and cellular level? Light of certain intensity can exhibit heating effects on non-visual cells for example, but research has shown that sound can cause various effects including whirling of protoplasm, displacement of small particles, cytolysis, disintegration of small bodies, acceleration of chemical reactions (sounds of high frequency, high intensity); increased growth (261HZ sound on human gingival cells); protein structure changes in tobacco cells with increased alpha strands and decreased beta turns; increased number of E. coli cells with 5HZ sound and increased cell growth with 1HZ; increased concentration of mitotic dividing cells in the S phase, decreased cell viability, cell volume and cell granularity with music with numerous periods of 10HZ music; decrease in proliferating cells in the hippocampus with extended noise and increased corticosterone levels. Therefore, sound can cause numerous effects not only at the mental, cognitive level, or biological system level, but also at the cellular level. Music therapy appears to exploit some of these effects, but it and the effect of sound in general needs to be researched more extensively and thoroughly before any conclusions can be made as to what happens.

Since we`re talking about the topic………….

….can we assume that we can investigate the effect of sounds and music on brain functioning during specific tasks by investigating the brain wave patterns produced at that time or by real-time imaging of specific brain areas?

…..if certain frequencies of sounds keep mitotic dividing cells in the S phase can we investigate whether the sound is affecting microtubule construction by using fluorescent imaging and introducing the sounds at later stages of the mitotic process instead?

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