According to the gate control theory, pain signals are not free to reach the brain as soon as they are generated at the injured tissues or sites. They need to encounter certain 'neurological gates' at the spinal cord level and these gates determine whether the pain signals should reach the brain or not. The PAIN GATE THEORY or GATE CONTROL THEORY of pain, put forward by Ron Melzack and Patrick Wall in In the Gate Control Theory, pain messages travel from the periphery of the body through nerve “gates” in the spinal cord and up to the brain. The theory uses the concept of “gates” in the central nervous system to describe how some pain messages are allowed get through and reach the brain, while others are blocked.
|Published:||22 March 2015|
|PDF File Size:||2.27 Mb|
|ePub File Size:||20.37 Mb|
Carry slow or prolong pain. It involves greater degree of tissue damage.
Gate control theory
It involves release of chemical mediators like bradykinin, histamine, pain gait theory, Substance P and 5-HT. Nociceptor afferent enters the spinal cord via dorsal root and makes synaptic connections with other neurons located in the dorsal horn of the spinal cord grey matter, which is the site of convergence of many inputs.
Nociceptive efferent enter the spinal cord, terminate on the dorsal horn and make synaptic connections with- 1st- Inter neuron serving reflex. These ascending neurons pain gait theory ventrobasal nuclei of the thalamus where they terminate on the 3rd order neurons which convey the pain gait theory to the cerebral cortex.
Also the information pain gait theory passed to higher centers via multisynaptic spinoreticular tract. Modulation of pain transmission At the level of spinal cord As already noted primary nociceptive afferent terminate at the 2nd order neuron or T cells.
Thus certain GABAA receptor subtypes but not glycine receptors can presynaptically regulate nociception and pain transmission.
The same neurons may also form synapses with an inhibitory interneuron that also synapses on the projection neuron, reducing the chance that the latter will fire and transmit pain stimuli to the brain image on the right.
The inhibitory interneuron fires spontaneously. The pain seems to be lessened when the area is rubbed because activation of nonnociceptive fibers inhibits the firing of nociceptive ones in the laminae.
The theory has also been extensively studied in the treatment of pain gait theory back pain and cancer pain. However, favorable results are not attained in some conditions and the long term efficacy of the techniques based on the theory is under question.
Nevertheless, the gate control theory has dramatically revolutionized the field of pain research and it has sown seeds for numerous studies that aim at presenting a pain-free lifestyle pain gait theory the patients who suffer from chronic pain.
References Abram SE Advances in chronic pain management since gate control. Regional anesthesia, 18 2PMID: Consequences of current concepts of pain mechanisms related to pain management. Physical therapy, 60 1PMID: Science New York, N. Journal of neurophysiology, 1PMID: Invasive pain gait theory therapies for the treatment of refractory pain.
He noted that dogs maintained in a restricted sensory environment pain gait theory bump their head on exposed pipes when allowed to run freely and would not avoid these obstacles subsequently.
This observation prompted a formal study of the effect of experience on the reaction to stimuli normally causing pain in dogs beginning at 4 weeks of age. The deficit was not in the ability to react immediately to the intense stimuli but rather pain gait theory the subsequent avoidance behavior.
The important conclusion was stated as follows [ 42 ]: Apart from details about sensory transduction and axonal conduction, this formulation is pain gait theory to what we would now call the labeled line mechanism for pain.
In the pain gait theory s Melzack, now at MIT, began collaborating with Patrick Wall whose spinal cord physiology laboratory had been there since the mids. Their first joint effort was a theoretical paper [ 44 ] discussing sensory pain gait theory including pain processing.
Wall had similar ideas based on his work on modification of sensory input at the first spinal synapse due to presynaptic inhibition [ 2464see below].
Gate Control Theory and Pain Management | Brain Blogger
They noted the ongoing controversy about cutaneous sensory mechanisms with one opinion originating with von Frey that cutaneous modalities were fixed beginning with anatomically distinct cutaneous receptors responsible for different modalities- touch, warm, cold and pain. The other view was championed by Pain gait theory, Sinclair and others based on a lack of correspondence between anatomy pain gait theory adequate stimulus of receptors.
This inactivates the inhibitory neuron, and the projection neuron sends signals to the brain informing it of pain gate is open.