THE GATE CONTROL THEORY OF PAIN
Melzack and Wall (1965, 1982; Melzack 1979), developed the gate control theory of pain (GCT), which represented an attempt to introduce psychology into the understanding of pain. This model is illustrated in Figure 12.1. It suggested that although pain could still be understood in terms of a stimulus-response pathway, this pathway was complex and mediated by a network of interacting processes. Therefore, the GCT integrated psychology into the traditional biomedical model of pain and described not only a role for physiological causes and interventions but also allowed for psychological causes and interventions.
Input to the gate
Melzack and Wall suggested that a gate existed at the spinal cord level, which received input from the following sources:
- Peripheral nerve fibers. The site of injury (e.g. the hand) sends information about pain, pressure or heat to the gate.
- Descending central influences from the brain. The brain sends information related to the psychological state of the individual to the gate. This may reflect the individual’s behavioral state (e.g. attention, focus on the source of the pain); emotional state (e.g. anxiety, fear, depression); and previous experiences or self-efficacy (e.g. I have experienced this pain before and know that it will go away) in terms of dealing with the pain.
- Large and small fibers. These fibers constitute part of the physiological input to pain perception
The output from the gate
The gate integrates all of the information from these different sources and produces an output. This output from the gate sends information to an active system, which results in the perception of pain. (PAIN THEORIES)
How does the GCT differ from earlier models of pain?
The GCT differs from earlier models in a number of fundamental ways.
- Pain is a perception. According to the GCT, pain is a perception and an experience rather than a sensation. This change in terminology reflects the role of the individual in the degree of pain experienced. In the same way that psychologists regard vision as a perception, rather than a direct mirror image, pain is described as involving an active interpretation of the painful stimuli.
- The individual is active, not passive. According to the GCT, pain is determined by central and peripheral fibers. Pain is seen as an active process as opposed to a passive one. The individual no longer just responds passively to painful stimuli, but actively interprets and appraises these painful stimuli.
- The role of individual variability. Individual variability is no longer a problem in understanding pain but central to the GCT. Variation in pain perception is understood in terms of the degree of opening or closing of the gate.
- The role of multiple causes. The GCT suggests that many factors are involved in pain perception, not just a singular physical cause.
- Is pain ever organic? The GCT describes most pain as a combination of physical and psychological. It could, therefore, be argued that within this model, pain is never totally either organic or psychogenic.
- Pain and dualism. The GCT attempts to depart from traditional dualistic models of the body and suggests an interaction between the mind and body.
What opens the gate?
The more the gate is opened the greater the perception of pain. Melzack and Wall (1965, 1982) suggest that several factors can open the gate:
- Physical factors, such as injury or activation of the large fibers;
- Emotional factors, such as anxiety, worry, tension, and depression;
- Behavioral factors, such as focusing on the pain or boredom.
What closes the gate?
Closing the gate reduces pain perception. The gate control theory also suggests that certain factors close the gate.
- Physical factors, such as medication, stimulation of the small fibers;
- Emotional factors, such as happiness, optimism or relaxation;
- Behavioral factors, such as concentration, distraction or involvement in other activities
Problems with the GCT
The gate control theory represented an important advancement in previous simple stimulus-response theories of pain. It introduced a role for psychology and described a multidimensional process rather than a simple linear one. However, there are several problems with the theory. (PAIN THEORIES)
First, although there is plenty of evidence illustrating the mechanisms to increase and decrease pain perception, no one has yet actually located the gate itself. Second, although the input from the site of physical injury is mediated and moderated by experience and other psychological factors, the model still assumes an organic basis for pain. This integration of physiological and psychological factors can explain individual variability and phantom limb pain to an extent, but, because the model still assumes some organic basis it is still based around a simple stimulus-response
Third, the GCT attempted to depart from traditional dualistic models of health by its integration of the mind and the body. However, although the GCT suggests some integration or interaction between mind and body, it still sees them as separate processes. The model suggests that physical processes are influenced by the psychological processes, but that these two sets of processes are distinct.
This post contains the content of book Health Psychology – a Textbook below is a link of a complete book Health Psychology – a Textbook