Research
Gate Control Theory of Pain
When we physically get hurt, the first thing we might do is rub the affected area where the pain is felt. But why do we do that? We know to rub or touch the affected area won't cure the injury, but somehow we knew that it would make us feel better. What made us think that this action will make us feel better? This question can be answered by the Gate Control Theory of Pain.
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The Gate Control Theory is a mechanism explaining the concept of pain perception using "gates" in our brain. Ronal Melzack and Patrick Wall first introduced their theory in 1965. They proposed the Gate Control Theory of Pain as a mechanism for how pain is reduced through the activation of non-painful sensations. After the occurrence of painful stimulation, the use of a non-painful stimulation is used to counteract the transmission of pain nerves.
Components
Receptors, Sensation, Perception
Pain is simply a sensation. In order to know how pain works, we must study the anatomy of sensation and examine how nerve endings work. There are 3 different types of nerve endings for touch: thermoreceptors to detect temperature, mechanoreceptors that detect mechanical pressure/distortion, and nociceptors that detect pain. When a person gets physically hurt (like getting punched in the face), the nerve endings send signals to the body that indicate that something has happened but, the brain hasn't fully registered the information. Getting punched in the face, activating the nociceptors, and sending signals to the brain is the first part of feeling pain. This concept is called a sensation, the process of sensing our environment. When the brain finally picks up and interprets the sensation, then the brain finally understands what is happening and activates the feeling of pain. This concept is called a perception, the process of understanding what is happening around us.
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Pain Pathways
There are 2 pathways that nociceptors can travel to in order to get to the substantia gelitanosa, an area of the dorsal horn of the brainstem. The 2 pathways are to transmission cells and inhibitory interneurons. Transmission cells pick up and send signals to the brain while inhibitory interneurons that make activities feel less intense. When pain stimulation travels to the brain, the activities of inhibitory neurons aren't often low, thus increasing the ability of the pain signal to get to the transmission cells and into the brain. Although, when pain signals travel through with the inhibitory interneurons, it is harder to pass through transmission cells, decreasing the perception of pain. Thus, when you rub or touch an area of pain, mechanoreceptors attach to the pain signals, increasing inhibitory interneurons, and decreasing the perception of pain. An affected area still gives off pain signals, although, stimulating the affected area closes the gate that allows the pain signals to reach your brain. When pain signals does not get to the brain, pain is not felt.
Mechanism
Nerve Fibers
The Gate Control Theory suggests that there are neurological "gates" in the spinal cord that have the ability to block and allow pain signals to travel to the brain. These gates function by differentiating between 2 types of fibers carrying pain signals: small and large nerve fibers. Small nerve fibers carry pain receptors while large nerve fibers are normal fibers that carry signals for touch, pressure, and temperature. These two nerver fibers are also known as transmission cells that carry information up to the spinal cord and brain, or as inhibitory interneurons that stop the transmission of the information.
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Open vs. Closed Gates
When a person gets hurt, pain signals are sent to the brain. This signal can be a large or small fiber. When large fibers excite inhibitory neurons, the transmission of pain information is destroyed. Thus, when there is more large fiber activities compared to small fiber activities, less pain is felt. When less pain is felt, it means pain gates are closed. On the other hand, small fibers stop the function of inhibitory interneurons. Thus, if there are more small fiber activities, pain fibers inactivate the inhibitory neurons, opening the gate and allowing pain to be felt.
Factors Affecting the Gates
Many of the factors that can close and open the gate of the Gate Control Theory of pain are divided into sensory, cognitive, and emotional factors. Sensory factors include contact with other physical beings and activities, cognitive factors include your thoughts, and emotional factors are your feelings.
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What opens the gates of the Gate Control Theory of Pain?
An open gate causes a person to perceive the feeling of pain. Conditions that can open gates that are sensory factor-based include physical injuries, inactivity, long-term narcotic use, poor body mechanics, and poor pacing of activities. Cognitive factors include constantly focusing and picking on your thoughts of having chronic pain. In addition, not partaking in activities that can create distractions, can further someone's feelings of pain. Lastly, worrying about the pain and negative thoughts will worse someone's feelings. Besides sensory and cognitive factors, emotional factors such as depression, anger, anxiety, stress, frustration, hopelessness, and helplessness will have the same effect of increasing how much pain a person feels.
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What closes the gates of the Gate Control Theory of Pain?
A closed gate blocks a person's ability to perceive the feeling of pain. Most of the influences that closes the gate is based on positivity and a good form of distraction. Sensory factors that have the ability to close a gate include increasing participation in activities, use of medications, relaxation, and meditation. Cognitive factors revolve around someone's ability to think of positive thoughts and distracting oneself from feeling the pain. Finally, emotional factors include having a positive attitude, overcoming depression, feeling reassured that the pain is temporary, having the ability to take control of your own pain, and stress management.