Pain

Nociceptors

Pain receptors in the skin

Spinothalamic tract (STT)

Pain and temperature pathway

Nociceptors —> 1st synapse in the spinal cord —> VPL thalamus —> S1

Info crosses in spinal cord

Multimodal nature of pain

Multiple components to pain

Sensory component - “rate pain intensity”

Affective or emotional component - “rate unpleasantness”

Brain areas for pain perception

Sensory component - S1

Affective component - anterior insula and dorsal anterior cingulate cortex (dACC)

Gate control model or theory of pain

Descending pain pathway to control pain from the brain

Periaqueductal gray area (PAG)

Primary control area for descending pain control

Top-down processing or cognitive processes that influence pain perception

Expectation - placebo effect

Attention

Emotion - like images or music

Phantom limb pain and sensation

Experiencing pain perception in an amputated limb

Mirror box therapy can rely on multisensory integration - visual input from the mirror can “override” the pain perception in the amputated hand

Reorganization of S1 may be a mechanism for why phantom pain/sensation may occur

Rubber hand experiment

illusion!

Rubber hand has to look like your own, can’t see your own hand, and there has to be training

About vision overriding touch/pain

Aδ Fibers

Acute sharp pain and cold signals from skin to spinal cord and brain

C-Fibers

slow lingering pain, warm and itch sensations