I’ve learned through academic study and personal investigation into mental and physical health that understanding the intrinsic connection between the mind and body is absolutely imperative.
It was not until I began actively listening to doctors and neuroscientists about the brain and body that I realised the extent to which they depend on each other. The cellular structures forming our nervous system constantly communicate with each other, including communication to the brain via the spinal cord.
Everything we think, feel, touch, smell, see, and the behaviours resulting from these interactions are merely biological experiences. There is much to research, but I often find that when I remove emotion and narratives from my thoughts, feelings, and behaviours, treating them as biological experiences – for instance, my body undergoing a biological process triggered by environmental factors or consumption of food, drink, or media – my psychology becomes clearer and less hopeless.
Consider this: if you could identify and track the reasons for your feelings or behaviours through an understanding of cognition, neurobiology (e.g., your central nervous system), and the effects of hormones on your body, wouldn’t this knowledge significantly alleviate your burden? Understanding the mechanisms of your body and their impact on your mood, mental state, and physical condition can prepare you to manage your wellbeing. For me, grasping at least the basics of our bodies’ and brains’ biology is essential to understand our life experiences. Without this knowledge, how can we truly take control of our psychology?
About the Nervous System
The cells of the nervous system, known as neurons and glial cells, are primarily located in the central nervous system (CNS) and the peripheral nervous system (PNS), the latter contains nerves such as sensory nerves responsible for transmitting sensations, such as pain and touch.
The brain is the central processing unit of the nervous system and contains billions of neurons and glial cells. The spinal cord is an extension of the brain and consists of nervous system neurons and glial cells. It plays a crucial role in transmitting signals between the brain and the rest of the body.
Let’s illustrate this with an example related to anxiety, examining step-by-step the mechanisms involved when humans perceive a threat.
Trigger of Anxiety
- Identification of a Stressful Stimulus: It begins with an external or internal stimulus perceived as threatening or stressful. This could be a specific event, thought, or even a memory.
- Initial Sensory Processing: The sensory organs perceive the stimulus and send this information to the brain via sensory nerves.
Activation of the CNS
- Threat Assessment in the Brain: The information reaches the amygdala, a part of the brain involved in emotional processing. The amygdala assesses the emotional significance of the stimulus.
- Activation of the Hypothalamus: If the stimulus is perceived as a threat, the amygdala signals the hypothalamus. The hypothalamus acts as a command centre, communicating with the rest of the body through the autonomic nervous system.
Stress Response and Effects on the CNS
- Sympathetic Nervous System Activation: The hypothalamus activates the sympathetic nervous system, part of the autonomic nervous system. This leads to the “fight-or-flight” response.
- Release of Stress Hormones: The adrenal glands release stress hormones like cortisol and adrenaline. These hormones prepare the body to respond to the threat, causing physical symptoms of anxiety such as increased heart rate, rapid breathing, and heightened senses.
Feedback to the Brain
- Physical Sensations and Further Brain Activation: The physical changes are sensed by the brain, particularly the cortex, which is responsible for conscious thought and reasoning.
- Rationalisation and Interpretation: The prefrontal cortex, involved in decision-making and moderating social behaviour, tries to rationalise and interpret these physical sensations and the initial threat.
- Emotional Processing: The limbic system, including the hippocampus and amygdala, continues to process emotions. If the threat is perceived as ongoing or the emotional intensity is high, it can reinforce the response, leading to sustained anxiety.
Response and Coping Mechanisms
- Behavioural Response: Depending on the interpretation and the perceived severity of the threat, the person may respond with avoidance, confrontation, or other coping mechanisms.
- Modulation of Response: Over time, the parasympathetic nervous system, another part of the autonomic nervous system, acts to dampen the stress response and restore balance.
Long-Term Implications and Adaptation
- Neural Adaptation: With repeated exposure to similar stressors, the brain may adapt. This can lead to heightened sensitivity or, conversely, desensitisation to certain types of anxiety triggers.
- Potential for Anxiety Disorders: Prolonged or intense stress responses can contribute to the development of anxiety disorders, especially if the body’s stress response becomes maladaptive.
The central nervous system (CNS) is crucial in shaping our experience of anxiety, from the initial recognition of a potential threat, through its processing and the brain’s response, to coping mechanisms and possible adaptation. This process is unique to each individual, influenced by their perceptions of what constitutes a threat, their interpretation of it, and their chosen coping strategies. However, the underlying biological response remains consistent.
Consider the empowering potential of understanding and identifying specific stressors and the reasons behind the brain’s interpretation of these as threats. For example, imagine a childhood experience where a pet cat frequently scratched you, posing a real threat at the time. This could lead to a lingering fear of all cats in adulthood. Initially, the brain’s perception of cats as a threat was justified due to the repeated injuries. However, as time passes and the specific cat is no longer present, maintaining this fear of all cats becomes irrational. If you experience anxiety when a cat passes by without recognising this connection, it could lead to unwarranted stress and confusion about the sudden anxiety.
The key is in making these connections. By understanding that your anxiety around cats stems from a childhood experience, you recognise the irrationality of fearing all cats based on that singular experience. Realising that the threat is no longer present, you can reassure yourself that fearing all cats is unnecessary. Through repeated, non-threatening interactions with cats, such as stroking a cat without adverse consequences, you retrain your nervous system, diminishing the fear.
This is where the concept of brain plasticity comes into play. Brain plasticity refers to the brain’s ability to change and adapt as a result of experience. By consciously exposing yourself to non-threatening situations with cats and altering your perception of them, you leverage brain plasticity to reshape your nervous system’s response. This demonstrates not only the adaptability of the CNS but also the power we have to influence our psychological responses through understanding and intentional action.
Understanding this process is key to developing effective strategies for managing anxiety.
A dysfunctional nervous system can have a significant impact on mental health because the nervous system plays a crucial role in regulating emotions, cognition, and behaviour.
Mood Disorders: Dysfunctional communication between neurons and neurotransmitter imbalances can lead to mood disorders.1
There is evidence that low levels of the serotonin neurotransmitter have been associated with depression2. However, from what I’ve read in 2023 journals, this is under scrutiny as some researchers argue that studies that support the serotonin hypothesis have not produced convincing evidence of a biochemical basis for depression. Even so, this still seems to be the prevelant stance within the scientific community.
Anxiety Disorders: An overactive sympathetic nervous system, which is responsible for the “fight or flight” response, can lead to chronic anxiety disorders. This can result in constant feelings of fear, restlessness, and apprehension3.
Cognitive Impairments: Nervous system dysfunction can impair cognitive function, leading to difficulties in memory, attention, concentration, and problem-solving4.
Substance Abuse and Addiction: Dysfunctional brain circuits and reward pathways can contribute to substance abuse and addiction. Drug use can alter the normal functioning of the nervous system, leading to further mental health problems5.
Stress and PTSD: Chronic stress can disrupt the balance of hormones and neurotransmitters in the brain, contributing to anxiety and depression6. Additionally, traumatic experiences can lead to post-traumatic stress disorder (PTSD), which involves long-lasting changes in nervous system function and emotional regulation7.
So, our nervous system truly does play a crucial role in our everyday psychological and physical experiences. We should not underestimate it’s significance and it’s power over our wellbeing. However, we do have the power to change the blueprint that our nervous system is using. For instance, like in my example of the cat, we can change what our CNS perceives as a threat. We can also retain hormonal, neuron and neurotransmitter balance by adapting negative environments, by the way we perceive the world, by improving our diet, by improving what we tell ourselves, who we surround ourselves with, increasing our time outdoors and making time for reflection and mindful practices, giving more time to the positive things we enjoy, and becoming more aware of maladaptive behaviours. It’s all possible because our brain is plastic.
References
- Ashok AH, Marques TR, Jauhar S, Nour MM, Goodwin GM, Young AH, Howes OD. (2017) The dopamine hypothesis of bipolar affective disorder: the state of the art and implications for treatment. Mol Psychiatry. 22(5):666-679. ↩︎
- Parsey R, V., Hastings R, S., Oquendo M, A., Huang Y., Simpson N., Arcement J., Huang Y., Ogden R, T., Heertum R, L, V., Arango V., Mann J, J. (2006) Lower serotonin transporter binding potential in the human brain during major depressive episodes. Am J Psychiatry. 163(1):52-8. ↩︎
- Martinez, Jose M. MA; Garakani, Amir MD; Kaufmann, Horacio MD; Aaronson, Cindy J. MSW, PhD; Gorman, Jack M. MD. (2010) Heart Rate and Blood Pressure Changes During Autonomic Nervous System Challenge in Panic Disorder Patients. Psychosomatic Medicine 72(5):442-449. ↩︎
- Rajasekaran A, Venkatasubramanian G, Berk M, Debnath M. (2015) Mitochondrial dysfunction in schizophrenia: Pathways, mechanisms and implications. Neuroscience & Biobehavioural Reviews. 24:10-21. ↩︎
- Koob GF, Volkow ND. (2016) Neurobiology of addiction: a neurocircuitry analysis. Lancet Psychiatry. 3(8):760-773. ↩︎
- Vyas S, Rodrigues AJ, Silva JM, Tronche F, Almeida OF, Sousa N, Sotiropoulos I. (2016). Chronic Stress and Glucocorticoids: From Neuronal Plasticity to Neurodegeneration. Neural Plast. 2016:6391686. ↩︎
- Vermetten, E and Bremner, J, D. (2002). Circuits and systems in stress. II. Applications to neurobiology and treatment in posttraumatic stress disorder. Wiley. 16(1):14-38. ↩︎