DESCENDING PATHWAYS – MODULATION OF THE PAIN SIGNAL
Neuronal centres of the cortex and subcortical areas of the brain respond to incoming (ascended) pain signals, which they can modulate by activating the inhibitory descending (efferent) pathways. The impulses (again, action potentials) descend to the dorsal horn of the spinal cord (where corresponding painful stimuli are transmitted to the second order neuron). Activated inhibitory interneurons release inhibitory neurotransmitters such as noradrenaline and serotonine, which modulate the ascending pain transmission. Endorphins are also involved in the inhibitory modulation of pain signals.