The Gate Theory of Pain

Understanding how pain impacts on our body and mind

The way the nerves activate the pain response
How the sense of touch soothes pain
Why anxiety and other feelings increase the pain response

The topic of pain is complex and yet this gate theory on which the explanation of pain is based is from 1965! To my knowledge there are no new ways of thinking about pain from the scientific perspective!
However read on and I have simplified the story so hope you find this useful and informative.

The Gate control theory.

(Melzack and Wall ’65) The complex, subjective experience of pain results from a pattern of neural activity within the brain. The activity is initiated when the nerve impulse conveying painful information arrive from the periphery via the rising pathways of the spinal cord. 

A neural mechanism in the dorsal horn of the spinal cord acts as a gating mechanism through which peripheral information passes = 2 types of neurones; cells in the substantia gelatinosa (SG cell) and transmission cell (TCell). 

Small unmyelinated fibres initiate pain whilst the larger myelinated fibres inhibit pain. The T cell is influenced by the brain via descending nerve fibres. Relaxation stimulates the SG cell and anxiety causes activity from the limbic area which activates the T cells increasing the perception of pain. 

The amount of stimulation passing through the gate giving rise to pain is dependant on the proportion of activity in the large diameter and small diameter nerves; and also from influencing factors from the brain. When the amount of information passing through the gate reaches a critical level it activates the neural areas responsible for pain experience and response. 

A brain stem area exerts a powerful inhibitory control over information projected by the gate; also influenced by body input as well as input from visual and auditory systems.

More information on Comfortable Body page    

   

Cortical projections

Nerves from the ‘thinking’ cortex, especially those which respond to conditioning influences, influence the gate control system. Thinking processes act via large fast-conducting nerves and directly modulate pain experience. Anxiety or excitement may close or open the gate from all inputs via a central control trigger which is susceptible to memory and past experience via conditioning. These psychological processes have an extremely important role in pain perception. 

Psychological components

Time and space awareness. In addition to the transmission of pain stimuli this component requires the large fibre component of touch to establish the source, site and severity of the pain. This is via the thalamus in the limbic system. The limbic system also activated when we touch something hot to withdraw the hand quickly. 

Other factors which influence pain

Response to pain is controlled by cultural values, anxiety, attention and many other factors and they can affect the above systems. Thus excitement in war appears to block the above dimensions of pain, while placebo may modulate the motivational-affective component. It is thought that TENS affects the inhibitory part of the pain gate and stimulate the production of endorphins. 

All neurones transmitting pain eventually synapse in the thalamus of the brain. From here some run to the sensory cortex where the above influences mediate the pain perception. Axons in the spinothalamic tracts also synapse with the medulla, hypothalamus and the limbic system before reaching the thalamus. This determines the individual’s response to pain.

     

The endorphins modify pain transmission rather than alter pain perception and inhibit prostaglandin synthesis during the inflammatory response by the production of substance P. They are present in the anterior pituitary gland

This theory doesn't tell us everything about pain perception, but it does explain some things. If you rub or shake your hand after you bang your finger, you stimulate normal somatosensory input to the projector neurons. This closes the gate and reduces the perception of pain.

   

 

 

Over 30 years as a Massage therapists and Coach I have helped people understand why their pain is affecting them and helped them to address and cope with their pain.

Work with me to understand and address your particular challenge with pain

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