Investigating circadian rhythmicity in pain sensitivity using a ne cord processi

Question

Investigating circadian rhythmicity in pain sensitivity using a ne cord processing of pain Conceptually, how does the gate theory of pain work? ral circuit model for spinal Jennifer A. Crodelle, Sofia H. Piltz, Victoria Booth and Megan Hastings Hagenauer Gate Theory Control of P ain mechanical stimulus the somatic sensory neuron uses the dorsal column pathway to the brain A fiber for touch s excited by A this inhibitory interneuron i touch fibers which closes the gate; it is also inhibited by Cpain fibers, which opens the gate C pain fiber ABI fast pain ABW IW he gate is here at pre-synaptic hibition of C pain fibers axon terminals of sensory neurons ASW brain 9IE ventrolateral or anterolateral pain pathway JEW gcw ICE l - Inhibitory interneurons slow pain Excitatory interneurons W- WVide-dvnamic range proiection neurons

Explanation / Answer

Ronald Melzack and Patrick Wall put forth gate theory of pain which describe that pain perception is impacted by thoughts and emotions.

Depending on gate theory of pain model input, and on the connections between the neuron populations in the dorsal horn, The model forecasts the activity of the projection neurons that then proceeds to the mid-brain and pain is realized.

In the dorsal horn circuit, the population of the wide-dynamic range (i.e., neurons

that respond to both nociceptive and non-nociceptive stimuli) projection neurons

(W) is connected to the population of inhibitory interneurons (I) and excitatory interneurons

(E)

These response functions determine the average firing rate of a neuron population based on the external inputs (i.e., stimulations of the afferent fibers pre-processed in the dorsal root ganglion) and the firing rates of the presynaptic neuron populations. In the absence of input from other neuron populations and afferent fibers, we assume the average firing rate of the neuron population decays exponentially.

gate theory of pain explains that gating mechanism occurs within the dorsal horn of the spinal cord. Small nerve fibers act as pain receptors and large nerve fibers act as normal receptors synapse on projection cells which go up the spinothalamic tract to the brain, and inhibitory interneurons (I) within the dorsal horn.

The interplay among these connections determines when painful stimuli go to the brain:

If there is no input, the inhibitory neuron avoids the projection neuron from sending signals to the brain so in this situation gate is closed.

Normal somatosensory input occurs if there is more large-fiber. Now inhibitory neuron and projection neuron are stimulated, nevertheless the inhibitory neuron avoids the projection neuron from sending signals to the brain so in this situation gate is closed.

Pain reception occurs if there is more small-fiber stimulation or only small-fiber stimulation. This inactivates the inhibitory neuron simultaneously the projection neuron sends signals to the brain informing it of pain so in this situation gate is closed.

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