Gate Control Theory: Can you control pain perception?

What is pain? Is there a single perception of pain common to all people? We all know what it feels to be burnt, and the first impulse is to remove our hand from the fire to relieve the pain. But why do we act this way? Does it really work to relieve pain? In this article, we will review everything involving pain, the factors influencing its increase or decrease, and the basis and application of the gate control theory.

What is pain?

Pain is defined as a subjective perception of discomfort experienced by individuals in negative situations. In spite of the aversive connotation that characterizes it, pain fulfills fundamental functions for survival. For example, it is the motivational factor that pushes a subject to remove the hand from the fire when it burns. In addition, pain functions as an alarm signal sent by the organism to the brain when it detects that something is not working properly.

It is a completely subjective perception since it is conditioned by physiological, psychological and experiential factors that make pain a unique experience to each person. This gives way to a concept called pain threshold.

Pain threshold can be defined as the ability of each person to withstand the sensation of pain. For example, when someone is said to have a high pain threshold, it means that they have a greater ability to tolerate the pain sensation than another person with a lower threshold. However, pain threshold may vary within a person depending on the context, circumstances, and the physical and psychological state of the person in question.

The following is a list of existing types of pain according to their source of origin, duration, intensity, course and pathogenesis.

Types of pain

Depending on the source of the pain:

Physical pain

It is the subjective, localized, more or less intense, unpleasant or annoying sensory perception that is felt in one or several parts of the body. It is the result of the stimulation of specialized sensitive nerve endings. An example would be a toothache, a burn or muscle pain.

Emotional pain

It is a subjective and intense feeling of sadness, pity or sorrow that is experienced for emotional or psychic reasons. Regardless of the cause that, the origin usually refers to the impossibility to face or manage a life-changing situation. An example would be the death of a loved one, a break-up love or being fired.

Psychological pain

It is what is known as somatization of pain. This occurs when emotional pain is reflected as physical pain. The most common is through sexual problems, stomach problems, headaches or continued pains in the joints.

Depending on the duration:

Acute pain

It is a short-term pain that acts as a warning sign of real or imminent pain. It has a mainly a physiological function since it warns the nervous system that an area of the body is exposed to a situation that can cause a more serious injury. An example would be a burn.

Chronic pain

When pain becomes chronic when it lasts more than six months. Chronic pain is initiated and usually maintained by, a physical cause. However, the environmental and psychological factors that accompany it can make it worse. An example of this are patients with Multiple Sclerosis (MS).

Depending on the intensity:

Mild

It’s the least intense. The individual with this type of pain can perform daily activities. The pain can become so mild that under certain circumstances it is not perceived and may “disappear” completely.

Moderate

It is a pain with a certain intensity that interferes with daily activities, although it does not totally incapacitate the person.

Severe

It’s the most intense. It interferes with daily activities and with the person’s sleep.

Depending on the course:

Continuous

Pain persists at all times and does not go away

Irruptive

It is when there is a sudden and transient intensification of pain that appears on the basis of persistent and stable pain.

Depending on the pathogenesis:

Nocioceptive

It’s the most common. It is a type of pain beneficial to the body as it is a protective action to prevent further damage. It is defined as a normal response produced by the person in the face of a dangerous stimulus.

Neuropathic

It is a stabbing pain that is usually characterized by an increasing sensation just after the injury. This is due to the fact that the central nervous system is being stimulated. Unlike the previous one, it is not considered an adaptive response of the organism since it can develop without the need for a harmful stimulus.

Psychogenic

It is a pain that, unlike the previous ones, has a psychological cause. Some psychic variables that influence this pain are certain beliefs, fears, memories or emotions. It is a real pain and, therefore, requires psychological treatment.

Gate Control Theory: How does pain work? How do we perceive it?

A very common mistake established in popular culture is to think that pain is generated in the tissues where the threat or aggression has taken place. The reality is that pain arises from the brain, thanks to aversive mechanisms that detect the variations that happen in the body and send signals through the spinal cord to the brain that produces the pain.

Therefore, the nervous system sends a signal in the form of an unpleasant sensation, prick, tingling, stinging, burning or discomfort, through the spinal cord to the brain and this signal encourages the individual to focus their attention to the affected area.

The Gate Control Theory

The Gate Control Theory, formulated by Melzack and Wall in 1965 states that non-painful stimuli close the doors to painful stimuli by preventing the sensation of pain from traveling through the central nervous system. Therefore, this theory is based on the assertion that non-harmful stimulation is capable of suppressing pain. It is an explanation of how the brain plays a fundamental role in the perception of pain.

In order to understand in more detail what is happening, it is important to understand how four different neurons interact in the spinal cord. Nociceptive neurons (or C fibers) are responsible for detecting dangerous stimuli such as burn damage. Non-nociceptive neurons (or Aβ fibers) are the ones that send the touch signal. Through the spinal cord, these neurons transmit the information to the projection neurons. These neurons will be in charge of sending the signal to the central nervous system. Apart from these 3, there are a fourth set called interneurons (so called because they function as an intermediary). They have an inhibiting effect on the projection neuron, meaning it deactivates it and prevents it from sending a signal to the central nervous system.

The key to the gate control theory is that inhibitory interneurons can be controlled through C and Aβ fibers: C (nociceptive) fibers deactivate it, causing the projection neuron to transmit the stimulus; and Aβ (not nociceptive) fibers activate it, causing it to be transmitted weaker. This means that, when a harmful stimulus is received, the C fibre is put into operation and its signal is sent by the projection neuron to the central nervous system where it is processed and makes us feel pain. However, if a touch stimulus is simultaneously received, as would occur when rubbing the area after the blow, the fiber Aβ activates the inhibitory interneuron although the C fiber is deactivating it, so the signal that is transmitted is lower and less pain is perceived.

Thus, the nociceptive fibers open the door to pain and the non-nociceptive ones close it. That is why if we rub an area after a blow or if we shake it we can partly relieve the pain.

Factors influencing the Gate Control Theory

There are factors that influence the perception of the individual, which serve to facilitate the ability of the individual to open or close the door to pain.

Gate Control Theory: Physical factors

• Door open (increase pain): muscular tension, lack of physical activity, inadequate postures, hypersensitization of the painful area.
• Door close (reduce pain): medication, exercise, relaxation techniques.
  

Gate Control Theory: Emotional factors

• Door open (increase pain): anxiety, depression, anger and all kinds of negative emotions.
• Door close (decrease pain): relaxation, joy, illusion and positive emotions.
  

Gate Control Theory: Psychological factors

• Door open (increase pain): thoughts of helplessness, attention or thoughts focused on pain, catastrophic thoughts, cognitive dissonances.
• Door close (decrease pain): focus attention on pleasant things, mindfulness, positive or distracting thoughts, relaxation exercises.
  

Gate Control Theory: Social factors

• Door open (increase pain): isolation, lack of support, lack of trust in the social environment (caregivers, doctors, family, friends)
• Door close (decrease pain): feeling understood, carrying out social activities, maintaining quality interpersonal relationships and social support.

Sara Nevado Arroyo

Soy graduada en psicología por la Universidad Autónoma de Madrid, especializada en el itinerario clínico. Tengo experiencia en el trabajo y la investigación con colectivos en riesgo de exclusión social, especialmente menores. Además, trabajo como educadora social de menores con dificultades. Me siento particularmente interesada en la psicología social, el diseño de intervenciones y la neuropsicología.