Gate Control Theory

Gate Control Theory

1. Idea proposed by Melzack and Wall (1965)

2. Pain is transmitted to the spinal cord by large A Delta and smaller C fibres

   • These fibres terminate on inhibitory interneurons in the substantia gelatinosa (laminae in the dorsal horn or the spinal cord)
     • Cells in the substantia gelatinosa act as a gate, regulating transmission impulses to the CNS
       • Stimulation of the non-nociceptive A fibres, such as touch, vibration or thermal stimuli, cuase the cells in the substantia gelatinosa to 'close the pain gate'.
         • This diminishes pain perception
       • Small fibre input inhibits cells in the substantia gelatinosa to 'open the pain gate'
         • This enhances pain perception
       • The CNS through efferent pathways, may also close, partially close or open the gates

3. GCT is inadequate to explain some chronic pain problems such as 'phantom limb pain' instead the Neuromatrix theory was proposed to explain this.

4. The perception of pain is called nociception and depends on specifically dedicated receptors and afferent pathways that detect and transmit noxious or damaging stimuli

   • The experience of pain by Gate Control Theory emphasises the activation of non-nociceptive afferent input coming into the dorsal horn of the spinal cord to inhibit pain signals as well as the dynamic role of the brain in modulating the pain process