Neuroscience of Pain: Nociceptors, Fibers, and Tracts

Nociceptors

Pain receptors which detect noxious stimuli to send electrical signals to the somatosensory cortex to determine pain severity

Noxious stimuli

Heat, chemical, mechanical stimuli that require a high threshold to activate nociceptors

A delta fibers

Myelinated nerves, fast transmission, associated with sharp pain

C delta fibers

Unmyelinated nerves, slow transmission, associated with dull or burning pain

Spinothalamic tract

Localizes pain and sends signals to the somatosensory cortex

Spinoreticular tract

Processes the emotional aspects of pain, causes arousal and alertness; signals usually go to brain stem

Endorphins

Body's natural neuropeptides that reduce pain by binding to opioid receptors and blocking pain signals

Endogenous opioids

Released during stress to modulate pain