Pain perception, illustration. The sensation of pain occurs when afferent nerve fibres transmit nerve signals from the site of an injury (hand at lower left) to the brain, via the spinal cord. The brain processes the signals to produce the sensation of pain. Afferent nerve fibres are the axons of sensory neurons that carry sensory information from the body to the central nervous system (spinal cord and brain). The response shown here to harmful stimuli is known as nociception, and so is known as nociceptive pain.