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

thin

C delta fibers

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

thin, thinner than A delta fibers

Spinothalamic tract

sends signals to the somatosensory cortex about temperature,pain, and crude/broad touch

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

allodynia

non noxious stimulus becomes painful, caused by nerve hypersensitivity which is due to overactivation of prostaglandins

hyperalgesia

which condition causes a increased perception of noxious stimuli

prostaglandins

increases sensitivity of nociceptors caused by damaged tissue