1．About pain, itching, and abnormal secretion
The reason why we don’t usually feel pain is because the analgesic effect is working without us noticing. When pain relief does not work, you will feel pain even if there is nothing wrong with your body. For example, in fibromyalgia, the whole body aches even though no abnormalities are found in the body.
In order to have an analgesic effect, it is necessary to calm negative emotions (anxiety, sadness, anger, fear). And to make a habit of moving your body as much as you can.
Much of the pain is not physical damage to the body. It is difficult to predict pain based on physical problems (posture, physical load, aging, bone deformity, nerve compression, etc.).
However, by focusing on the brain and heart, there is a possibility that pain can be predicted. For example, studies have shown that people with strong neurological connections in the prefrontal cortex, amygdala, and nucleus accumbens are more likely to experience chronic pain.
When thinking about treating pain, it seems that we are no longer in an age where we can ignore the brain.
Next, let’s talk about the function of the brain to know pain.
- Amygdala and hippocampus
The amygdala is indispensable for understanding pain. The amygdala is filled with sensory information from the whole body.
When the information is compared with the memory of the hippocampus and judged to be harmful, negative emotions (anxiety, sadness, anger, fear) are generated.
Negative emotions are sent to the hypothalamus and other places, triggering a stress response, leading to chronic pain. - Cingulate gyrus
It acts as a bridge between the networks in the brain and is strongly involved in pain, itching, and secretion abnormalities. In particular, the anterior cingulate gyrus is closely related to pain. - Island
The insular cortex is involved in the formation of self-consciousness, but it is also involved in the stress response by receiving information related to body sensations and emotions and sending it to the autonomic nervous system. - Prefrontal cortex
It is not only related to thinking, judgment, and cognition, but also to emotion. Within the prefrontal cortex, the dorsolateral prefrontal cortex (DLPFC) regulates the activity of the amygdala. However, when it comes to long-term battles, it can be exhausting and uncontrollable. - Thalamus and somatosensory cortex
Sensory information from the outside world enters the thalamus and is sent to the somatosensory cortex. There are primary and secondary types of somatosensory cortex, and information about where the pain hurts is sent to the primary (S1), and the nature of the pain and the emotions related to the pain are sent to the secondary (S2).
The thalamus and primary somatosensory cortex are characterized by a decrease in activity when pain becomes chronic. - Suppresses pain, itching, and secretory abnormalities by the mechanism of analgesia and reset in the brain
The intensity of the pain we actually feel changes depending on the struggle with the analgesic effect of the brain.
Dopamine System
When pain information enters the brain, dopamine is released from the ventral tegmental area toward the nucleus accumbens and ventral globus pallidus. When the nucleus accumbens is excited, multiple nerve nuclei are activated at once to exert an analgesic effect. Endorphins are famous as analgesics released at this time β
Descending pain suppression
When nerve excitation is transmitted to the periaqueduct gray matter of the midbrain, the descending pain suppression system works, and the pain signal is blocked when it reaches the dorsal horn of the spinal cord from the peripheral nerves. The periaqueduct gray matter is also the point of action of morphine and exerts a strong analgesic effect.