What is the function of the brain?

Based on her ethnographic study of psychiatric residency programs, anthropologist T.M. Luhrmann concluded psychiatry is “of two minds,” much like the Axis I and Axis II diagnoses organizing the Diagnostic and Statistical Manual of Mental Disorders. While some prefer to emphasize the role of genetics for the formation of mental disorders, others stress the environmental contributors to suffering, such as early life relationships and past traumas.

However, behavioral scientists in a wide range of fields have been dismantling such “nature versus nurture” explanations for decades, preferring instead an interactionist model. They conclude there are no behaviors or traits that purely result from nature or nurture. This has been shown to be true of mental disorders as well. 

Unfortunately, in a world of limited resources, including limited time, the implicit guiding question — What should be the focus? — continues to divide attention and determine how mental disorders are treated. Is it best to address the effects of genes in efforts to reach best outcomes? Is it more efficacious to respond to social and psychological consequences of mental disorders? Historically, the needs of service users have taken a backseat to such questions, which often serve allegiances and professional agendas more than persons in the throes of mental suffering. This consequence has not gone unnoticed by those carrying out biomedical research on mental disorders. Quoting Tom Insel, former director of the National Institute of Mental Health (NIMH):

I spent 13 years at NIMH really pushing on the neuroscience and genetics of mental disorders, and when I look back on that I realize that while I succeeded at getting lots of really cool papers published by cool scientists at fairly large costs — I think $20 billion — I don’t think we moved the needle in reducing suicide, reducing hospitalizations, improving recovery for the tens of millions of people who have mental illness. I hold myself accountable for that. (Quoted in Casper, 2019).

This suggests to me the challenge is not so much choosing between competing theories as it is about the financial stakes that have an outsized impact on how disorders are conceptualized and treated. I wonder what it would be like for all of us who either work in the field or have received treatment for a mental disorder (a Venn diagram of these two groups would show quite an overlap) to restart the quest for truly comprehensive mental health services with the very simple question:

What is the function of the brain?

With this question, we might begin treating the brain like any other organ of the body. Appropriate treatments would be measured by their capacity to return the brain to optimal functioning. I believe this question could also encapsulate the complex relationship between biology, self, and community that complicates understanding the origins of mental disorders as well as identifying best treatments.

When the focus is an organ’s function, it follows healing that organ involves returning it to its homeostatic state. What counts as disease or trauma are those things that interfere with normal functioning. For example, we know the function of the heart is to pump blood repeatedly and continually through the blood vessels; anything that interferes with this process is identified as disease or trauma. Similarly, functions of the stomach include storing food during a meal and breaking down food particles into molecules small enough to be absorbed by other parts of the body. Whatever interferes with these functions is treated as disease or trauma.

We can identify the functions of every major organ of the body — the lungs, the skin, the intestines, the skeleton, the immune system — and with this knowledge, provide both diagnoses and treatments. Whereas there may be many paths to the cure, and many causes of pathology, there is nevertheless a shared understanding of how the organ is meant to function. This simple approach has evaded the mental health sciences. 

We know the brain is part of the central nervous system and functions like a command center for the rest of the body, gathering and acting upon sensory information from both internal and external environments. The biomedical model of mental disorders relies heavily on this understanding of brain functioning, such as its focus on neurotransmitters. Having a well-functioning central nervous system certainly seems crucial to mental well-being. However, it is also only one contributor to mental disorders and cannot adequately account for the psychological and social suffering also experienced. Although the biomedical model is not necessarily wrong, it nevertheless is too limited in scope to account for the myriad phenomena associated with mental disorders.

Alternative models of the brain have emerged with research of the neurobiological effects of trauma and the modularity of the mammalian brain. With these models, the brain is understood in terms of the functions of its components and adaptations to environmental conditions, especially environments created through relationships with significant people in our lives. This is an important change in scope from a focus on the central nervous system that seems to rely on the “command, control, communicate” metaphor that has dominated information systems thinking since World War II.

In contrast, the neurobiology of trauma model examines how specific areas of the brain — often depicted as three primary regions: the cortex, limbic system, and brain stem — take part in the process of gathering information from body and environment, synthesizing this information, and then acting in accordance with often implicit needs or desires. This research also identifies two dominant action tendencies organizing how the brain functions, which also correlate with two dominant environmental scenarios:

  1. Conditions of attachment and normal daily activities; and
  2. Conditions of activated defenses (e.g., fight, flight, freeze, submit, cling, please/appease).

From the perspective of the neurobiology of trauma, sociality — defined here as the capacity to engage with others in meaningful ways that contribute to internal integration of the different brain regions — is inversely related to the amount of traumatic stress a person experiences. Too little of the conditions that contribute to sociality, along with too many of the conditions that activate defense responses (including low levels of chronic stress), lead to poor mental functioning. Yet both the action tendency of attachment and daily living and the action tendency of defense are necessary functions of a healthy brain, person, and community. Sometimes defense is necessary. What is most important is how sociality is regained following states of defense and maintained during activities of daily living. (An added benefit of the neurobiology of trauma model is that it replaces notions of pathology with notions of adaptation.)

The neurobiology of trauma model of the brain can also incorporate functions of the central nervous system, especially when the primary function associated with the brain is this concept of sociality. When the brain is seen as primarily a “social” organ, it has two main functions:

  1. Communication between the different regions of the brain and the rest of the body in the creation of coordinated responses to stimuli (creating “internal” sociality); and
  2. Communication with others that contributes to shared sociality.

When the primary function of the brain is seen as sociality, mental disorders can be generalized to a failure of function in two predominant categories:

  1. Interference with the capacity for internal integration that is necessary for self-awareness and self-regulation; and
  2. Interference with the capacity to maintain meaningful and supportive relationships.

Just as there are many ways for the heart, stomach, or any organ to be diseased or traumatized, there are many ways for the brain to lose functionality. Impairment does sometimes involve genetic predispositions, although typically in combination with environmental stressors such as exposure to toxins or viruses, poor diet, high levels of stress, or injuries that alter the physiology of the brain or its normal development. Environmental stressors also include adverse childhood experiences, assault, combat, and other situations where people hurt people, not only activating defense responses, but also interfering with the capacity to function as social beings.

The idea of sociality as the function of the brain is also supported by current thinking of the role of integration for mental health. According to psychiatrist Daniel Siegel: 

“Integration is the organizing principle that links the ways energy and information flow is shared (relationships), is shaped (the mechanisms of the embodied nervous system or, termed simply, the brain), and is regulated (the mind)” (Siegel, 2012, 8).

He also wrote:

“Integration can be seen as a deep mechanism that enables us to gain insight into both synaptic and societal connections and how they impede or promote the development of a healthy mind” (Siegel, 2012, 29-30).

The opposite of internal integration — inner fragmentation — demands a lot of energy and attention and often leads to isolation and limited integration with the larger community, thus also limiting the capacity for sociality. Furthermore, inner fragmentation is a common response to attachment failures and interpersonal traumas, and hence, social fragmentation. 

Lacking the capacity for sociality seems central to the suffering associated with mental disorders, irrespective of cause. And isn’t the reason we have a mental healthcare system is to help people overcome suffering? When overloaded with competing theories, professional agendas, and the potential for large profits, we lose sight of this otherwise straightforward goal. Yet if we can agree on the primary function of the brain, I believe we can also be more astute in our choices about how to best support people when they need help the most.


References

Casper, Stephen T. “The History and Future of Neurological Care.” Science 364, no. 6437 (19 April 2019): 243-44.

Luhrmann, T. M. 2000/2001. Of Two Minds: An Anthropologist Looks at American Psychiatry. 2nd ed. New York: Vintage Books.

Siegel, Daniel J. 2012. The Developing Mind: How Relationships and the Brain Interact to Shape Who We Are. Second ed. New York: The Guilford Press.

Originally published 2014/01/28

Revised 2022/04/06

© Laura K Kerr, PhD. All rights reserved (applies to writing and photography).

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