JACOPIN / SCIENCE PHOTO LIBRARY JACOPIN / SCIENCE PHOTO LIBRARY
PAIN, DRAWING Pain activation and inhibition. Illustration of the circuit of pain activation (left) and inhibition (right). Activation: through the effects of a nociceptive stimulus (wound, burn, inflammation, etc.), a nerve impulse is slowly transmitted by the nerve fibers to the spinal wide dynamic range neurons, then to the brain stem, through the hypothalamus, thalamus and cortex, for cognitive factors, or directly to the brain stem, for sensory factors. Inhibition by sensory tactile stimulus by the skin, which transmits the nerve impulse to the spinal wide dynamic range neurons more quickly. In this way, the information shortcircuits the pain sensations and reaches the brain stem, spreading throughout the brain. Pain is inhibited.
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