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• 1 2018-05-16T15:46:59-07:00 "Ballads on the Brain: A Neurobiological Hypothesis" Copy 17 plain 2018-05-17T18:46:03-07:00
   -- Pamela Reinagel
   
  At
  one time, popular ballads were known and sung by ordinary people for entertainment as well as edification. This is evidenced by the flourishing of the broadside ballad trade in England from the 1600s through 1800s, as well as the oral transmission of traditional ballads within the British Isles and among emigrants to America and elsewhere during this same time period.¹ In this article, I will analyze the function such ballad singing not from the perspective of a literary or cultural critic but from that of a scientist. Specifically, I will summarize current theories in the neuroscience of emotion which suggest that the singing of ballads may have conferred neurophysiological benefits to the singers, listeners, and communities that sang together. Recent research in clinical psychology has demonstrated the effectiveness of somatic therapies for treatment of mental illnesses. Controlled deep breathing is common to many of these therapies, and a neural pathway has been identified whereby controlled breathing could bring about physiological calming responses. Singing ballads involves sustained, controlled deep breathing and therefore may have (and historically have had) similar therapeutic benefits. Moreover, recent studies have identified a specialized neural pathway in mammals that links somatic calming signals to social communication mechanisms. By combining a somatic calming stimulus (controlled deep breathing) with soothing social communication signals (specific vocal tones and speech patterns), singing may efficiently stimulate calm states within singers, generate calming effects in listeners, and promote emotional connections among participants. This hypothesis is now directly testable with neurophysiological measurements and emerging computational methods. The possible significance of tunes and narrative content is a matter of pure speculation, but such speculations are also empirically testable.
  
        In the sections below I will first present a simplified review of an integrated brain-body system that is fundamental to emotional regulation. I will then discuss how ballad singing might impact this system. I will start with the most general feature of singing—deep breathing—for which there is the most supportive evidence. I will proceed to discuss increasingly narrow features of ballad singing: voicing tones, arranging tones into tunes, the particular types of tunes used in traditional folk ballads; and finally singing words to these tunes and arranging these words into narrative stories. The unifying observation is that the same brain system that promotes emotional resilience and physical wellness is intimately involved in how we use our voices for emotional communication.
  
  A Brief Primer on the Neuroscience of Threat and Safety Responses
  
  To review the neuroscience background as briefly and clearly as possible for the non-technical reader, I shall present a simplified version and avoid the use of jargon and acronyms. If the reader wishes to resolve the resulting imprecision, hovering over a highlighted word or phrase will show the technical meaning I intend, and clicking will take you to the glossary for a definition or more information. Of course the system is much more complicated than this.²
  
       All vertebrate animals have a complex neural system that automatically and unconsciously monitors the environment for immediate danger or safety, and coordinates adaptive responses throughout the body. The Fight-or-Flight Response is activated by perceived danger, and regulates almost every organ of the body to prepare for vigorous physical effort to survive an immediate threat.³ In order to achieve peak performance in moments of crisis, other non-urgent functions are temporarily shut down, such as feeding, digestion, immune response, and reproduction. These somatic effects underlie visceral sensations associated with the emotion of fear, such as a racing or pounding heart, sweaty palms, shallow and rapid breathing, dry mouth, or a sinking feeling in the stomach. The "Fight-or-Flight Response" is energetically costly, and not sustainable.
  
        The exact opposite occurs during the opposing “Rest-and-Digest Response,” which is most active when conditions of safety are detected. This neural pathway slows the breath and heart rate, and promotes regenerative and self-sustaining functions throughout the body. In a healthy person, these opposing systems dynamically engage and disengage in response to the demands of each situation. By way of illustration and summary, Figure 1 presents a sketch of what might be happening in these pathways in different situations.
  
       It is extremely important to recognize that this mind-body interface is a two-way street. The brain centers that regulate Fight-or-Flight and Rest-and-Digest responses are themselves receiving sensory information from within the body, such as sensations of breathing, heart rate, hunger or nausea. Thus not only do these neural pathways cause changes throughout the entire body, but the reverse is also true: the internal states of the body can influence the activity of these neural pathways.
  
       The signals underlying Rest-and-Digest functions travel through the vagus nerve, and therefore the level of activity in this system is sometimes referred to as “vagal tone.” This is an oversimplification, in that different parts of the vagus nerve are involved in different and sometimes even opposing functions.⁴ The Rest-and-Digest system can be roughly divided into two subdivisions. Both subdivisions can slow down the heart rate, but one of them uniquely synchronizes the heart with breathing, resulting in a distinct heart rhythm. In research, vagal tone is often measured by heart rate variability which is an indirect measure of this distinct heart rhythm.⁵High vagal tone by this measure is generally associated with states of calmness. For now, I will refer to activity in this subdivision of the Rest-and-Digest system as the Calming Response; but other distinctive features of this subdivision will be considered further below.
  
  Deep Breathing as Somatic Therapy
  
  The ability to appropriately coordinate responses to danger and safety is crucial for mental health and emotional regulation. For example, excessive or inappropriate activity in the Fight-or-Flight system could result in excessive or inappropriate fear, anger, panic, anxiety or chronic stress. After survival of extraordinary stresses, Post-Traumatic Stress Disorder (PTSD) can occur, in which Fight-or-Flight responses may be triggered without warning.
  
       Several somatic interventions have been found to be beneficial in clinical practice for treating emotional regulation symptoms, especially in trauma-spectrum disorders. These therapies are distinct from and complementary to cognitive, behavioral, situational or pharmacological interventions, in that they focus on actions or sensations within the body. There is evidence that many of these somatic therapies engage the Calming Response. To give just a few examples, Somatic Experiencing,⁶ yoga,⁷Mindfulness-Based Stress Reduction,⁸ and Eye Movement Desensitization Reprogramming (EMDR)⁹) are all somatic therapies thought to increase vagal activity. Although more data are needed, evidence is accumulating that somatic practices and therapies work by producing physical signals in the body that stimulate the Calming Response pathway from within, by means of internal sensory feedback pathways.
  
       A leading hypothesis for how yoga and meditation increase vagal tone is the use of controlled deep breathing exercises. There is considerable evidence that deep breathing stimulates vagal activity.¹⁰ Singing requires highly controlled deep breathing. For this reason alone it could have protective and therapeutic benefits comparable to those found for yoga and meditation. Consistent with this prediction, singing has been shown to increase heart rate variability, a physiological indicator of the Calming Response.¹¹
  
       Traditional ballads tend to have slow tempos and long phrases, requiring very long slow exhalations. This breathing pattern is repeated without interruption for the long (4-8 min.) duration of the ballad. These properties of ballads may be particularly efficient for stimulating the Calming Response, which slows the heart rate specifically during exhalation. For a demonstration of this type of singing, listen to the ballad "Barbara Allen": ¹²
  
  
  To illustrate how this hypothesis about breathing can be tested experimentally, the breathing and heart rate of a singer was recorded for one hour of ballad singing (ten ballads). As seen in Figure 2¹³, ballad singing slowed down the breathing rate and changed the breathing pattern (compare 2A to 2D). During and after singing ballads, the singer’s pulse slowed down very slightly during each exhalation. This is a hallmark of the Calming Response.
  
  
  Neural Mechanisms Governing Social Communication
  
  The part of the Rest-and-Digest system that controls the Calming Response is evolutionarily recent, found only in mammals. In addition to its effects synchronizing breathing and the heart, this sub-circuit also regulates facial muscles involved in social communication of emotion. Activity in this pathway is thought to increase facial expressions, vocal expressiveness, and even the ability to hear human voices and make eye contact during times of perceived safety. Porges therefore calls this subdivision of the Rest-and-Digest pathway the “Social Engagement System,” which he theorizes evolved to support the extensive social engagement mammals require for partnering and parenting.¹⁴
  
       According to this theory, when people feel unsafe or attacked, defensive Fight-or-Flight responses are engaged, resulting in voice and speech patterns that others automatically receive as harsh or threatening. During times of safety, the same neural pathway that slows the heart also alters the voice. Specifically the Calming Response makes vocal tone softer and more resonant and speech cadence slower, resulting in more melodious (“prosodic”) vocalizations that others innately receive as non-threatening and even soothing. In conditions like depression and autism spectrum disorders, the ability to produce and/or detect prosodic speech is impaired, which could contribute to deficits in social engagement.¹⁵
  
       Some of the evidence that the Calming Response changes vocal tone comes from Stewart and colleagues, who showed that activity of the Calming Response, as measured from heart rhythms, is correlated with acoustic features in the cries of babies¹⁶ as well as in the vocalizations of social rodents.¹⁷
  
       Like the mind-body interaction discussed above, the social communication functions of this circuit are thought to be bidirectional. Perception of safety increases calm states which in turn promote social connection; but social connection can also promote perception of safety and lead to increased calmness. The relationship of the Calming Response to the Social Engagement System is illustrated in Figure 3.
  
  
       Because of this connection to vocal communication, simply vocalizing a tone might have calming effects beyond the effects of controlled breathing noted above. Controlled breathing activates the Calming Response, which then alters vocal tone. When vocal tone changes, there is a possibility of sensory feedback from the vocal muscles and auditory feedback from hearing one’s own voice or other voices. Interestingly, clinicians who treat PTSD have reported that an overwhelmed patient can be quickly calmed by having him or her take a deep breath and intone “Voooooo.”¹⁸ Based on these observations, it is possible that when previous studies demonstrated beneficial effects of yoga and meditation, vocalization during chanting might have contributed to the effects.
  
       There is more to singing than deep breathing and vocalization of tones. Songs also have tunes. Prosodic speech is characterized by greater modulation of pitch. The melodic patterns in songs could potentially mimic the prosodic patterns of speech that are normally produced by the Calming Response pathway, thereby producing signals innately associated with safety. Even passively listening to songs can improve both communication and emotional symptoms of autistic children, especially if frequency bands associated with prosodic vocal tone are enhanced.¹⁹
  
       Traditional ballads in particular often employ gapped scales²⁰ and unusually fluid timing, compared with other types of songs. To clarify what I mean by gapped scales, listen to the tunes of “Cherry Tree Carol” and “Lord Bateman”:
  
  
  
  Notice that in each tune, only five notes are used and none of the notes are close together in pitch; both of these tunes could be played on a piano using only black keys. Pitch variation is a hallmark of prosody in speech. Melodies with large intervals between notes might resemble or exaggerate that property.
  
       To clarify what I mean by fluid timing, listen to this field recording of “Game of All Fours” sung by Phoebe Smith, a traditional singer from England:
  
  
  Notice how completely free the timing is; it would be nearly impossible to tap your foot to this tune. Fluidity of timing is a hallmark of prosody in speech. A regular beat or rhythm is necessary to coordinate singing in groups, to sing with instrumental accompaniment, or for use in dance. But traditional unaccompanied ballad singing does not have any such constraints, and therefore rhythms were often freely modified in response to the text.²¹
  
       In summary, ballad singing, specifically of the traditional kind I discuss in this essay, could stimulate the Calming Response through engagement of specialized circuits for social communication of emotion. In mammals the brain pathway that makes deep breathing calming is closely integrated with the brain systems that allow us to communicate emotions, including vocal expression. This social engagement system receives and responds to the internal feelings as well the sounds of the voice. The melodies of ballads may further enhance this effect by mimicking the pitch variation and fluid timing that is naturally found in emotionally expressive speech. We can feel our breathing and vocal muscles and hear our own voices, and these sensations send feedback to the Calming Response circuit. Therefore, activation of the Calming Response by singing could tend to be self-reinforcing. Because other people can hear and respond to the emotional signals in our voices, these beneficial effects could also be socially contagious. For all these reasons, singing could be more powerful than just deep breathing for helping people regulate their own emotions, recover from stress and maintain resiliency. Singing together with other people could open up a neural window for making positive emotional connections.
   
  Language and Stories
  
  Until now I have only considered breathing, voicing, and tunes. But unlike humming, songs also have words. Surely ballads engage higher brain areas specialized for processing of language. The implications of this for the brain circuits I have been discussing are unknown. I note with interest, however, that patients with speech deficits such as stuttering or Aphasia often are able to sing fluently.²² This suggests that production of speech in the context of song involves partly distinct neural mechanisms.
  
       Traditional ballads, furthermore, are not only verbal; they are narrative. Some ballad stories have been sung for centuries and spread across continents, both as broadsides and in oral tradition. While some of these songs are relatively simple and humorous ditties, many relate extensive narratives that have violent, tragic or morbid themes.²³ One might speculate in broad terms that engaging emotionally difficult content within an emotionally supportive and socially connecting activity could have a cathartic function. A more mechanistic version of this hypothesis is that the strong modulation of the affective content in ballad stories serves to robustly exercise both the Fight-or-Flight and Calming Response pathways, thereby strengthening responsiveness and increasing adaptive regulation capacity.
  
  Conclusion
  
  From the seventeenth through the early twentieth centuries, singing was not only a performance art reserved for professional singers. Throughout the English-speaking world, recreational singing of ballads by amateurs was also a widespread participatory activity. What impact would that have had on human life and culture? The brain science of emotions now suggests the intriguing hypothesis that ballad singing could serve (and historically may have served) to stimulate or strengthen a neural pathway that is known to be important for emotional regulation, recovery from stress, promotion of calm states, and strengthening of social bonds. Although the scientific evidence for this inference is far from complete, the hypothesis could be directly tested, and that is a test well-worth undertaking.
  
  Glossary

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  Adrenaline—a hormone that circulates in the blood and acts on numerous tissues as part of the response to challenge or threat. Works in conjunction with noradrenaline. The sympathetic branch of the autonomic nervous system is responsible for its release.
  
  Autonomic Nervous System—part of the nervous system that coordinates control of organs throughout the body according to the safety or danger an animal is experiencing. Consists of the sympathetic and parasympathetic branches. Sometimes abbreviated ANS.
  
  Calming Response—behavioral and physiological responses associated with an evolutionarily newer branch of the parasympathetic nervous system in mammals, termed the “Social Engagement System” by Porges (see Porges, The Polyvagal Theory). Coordinates heart, breath, and social communication circuits with the perception of safety. It arises in the Nucleus Ambiguus, and sends and receives signals through the ventral, myelinated branch of the Vagus nerve.
  
  Fight-or-Flight Response—a term commonly used to refer to the behavioral and physiological responses of the sympathetic branch of the autonomic nervous system. Termed the “Mobilization Response” by Porges (see Porges, The Polyvagal Theory).
  
  Heart Rate Variability—fluctuations in heart rate associated with activity of the parasympathetic system; Often abbreviated HRV. Some but not all heart rate variability is caused by respiratory sinus arrhythmia (Lewis et al., “Statistical Strategies”).
  
  Noradrenaline—the chemical signal (neurotransmitter) used by nerves that transmit signals directly to organs and tissues as part of the response to challenge or threat. Works in conjunction with adrenaline. The nerves that communicate with noradrenaline are part of the sympathetic branch of the autonomic nervous system.
  
  Nucleus Ambiguus (NA)—an evolutionarily recent brainstem nucleus found in mammals that is central to the Calming Response component of the parasympathetic nervous system. Named thus because its anatomical borders are not easy to see. Sends and receives signals through the mammalian (ventral, myelinated) branch of the vagus nerve.
  
  Parasympathetic nervous system—branch of the autonomic nervous system classically associated with baseline health functions such as nutrition and reproduction; often called the “Rest-and-Digest” or “Feed-and-Breed” system. Sends and receives signals through the vagus nerve.
  
  Polyvagal theory—the theory that the parasympathetic system in mammals is divided into two fundamentally different branches: an evolutionarily older branch (dorsal, unmyelinated) involved in freeze/immobilization behavior (not discussed in this article), and a distinctly mammalian branch (ventral, myelinated) involved in social communication and calm behavioral states (see Calming Response). This theory is supported by evidence in anatomy, phylogeny, embryology, physiology, and behavior (Porges, The Polyvagal Theory).
  
  Prosody—a quality of speech intonation exhibited by healthy people in safe environments. Characterized by varying pitch, varying loudness, flowing timing, and resonant vocal tone; important for communicating emotional information. Highly prosodic speech described as lilting or song-like. Un-prosodic speech sounds flat, monotone, and emotionless.
   
  Respiratory Sinus Arrhythmia—the regulation of the heart rate by the breath; heart rate increases during inhalation and decreases during exhalation, due to the respiratory rhythm of the neurons in the Nucleus Ambiguus, the brainstem center that controls the Calming Response.
  
  Rest-and-Digest Response—a term commonly used to refer to the behavioral and physiological responses of the Parasympathetic nervous system. Also called “Feed-and-Breed” response.
  
  Sympathetic nervous system—the branch of the autonomic nervous system associated with Fight-or-Flight responses. Uses the hormone Adrenaline and the neurotransmitter Noradrenaline.
  
  Vagal—pertaining to the Vagus nerve.
  
  Vagal Tone—overall activity of the Vagus nerve. Typically estimated from observed Heart Rate Variability.
  
  Vagus nerve—the nerve responsible for carrying the majority of parasympathetic signals to and from tissues and organs. According to Polyvagal Theory there are two branches with distinct functions (See Polyvagal Theory).

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  Bibliography