National Geographic - USA (2020-01)

Somatosensory

cortex

Dorsal horn

Thalamus

Anterior

cingulate

cortex

Prefrontal

cortex

Nucleus

accumbens/

ventral striatum

Rostral/

ventromedial

medulla

Anterior

insular cortex

Periaqueductal

gray

JASON TREAT, NGM STAFF; MEG ROOSEVELT. ART: SINELAB

SOURCE: LUANA COLLOCA, UNIVERSITY OF MARYLAND

THE OPIOID PROBLEM

Opioids reduce pain by numbing indiscrimi-

nately, dampening signals from the ascending

pathway of pain as well as the body’s beneficial

descending response. The drugs do provide

relief from pain—but can also elicit a sense of

euphoria that can lead to addiction.

THE BRAIN RESPONDS

After the signals are received by the brain,

the descending pathway is engaged.

It cues the entire central nervous

system to modulate and respond

to the painful stimulus.

ACUTE VS. CHRONIC

While acute pain signals follow

ascending pathways to the brain,

chronic pain, such as persistent

back pain, is due to damaged

neurons or axons. Its pathways

aren’t well understood.

Perceiving pain

The signals travel to the

somatosensory cortex and

other areas that identify the

location and intensity of pain.

Reacting to pain

These areas send

neuro chemical signals

down to start blunt-

ing the pain.

Pain reduction

The neurochemicals intercept

and act as a brake on the

ascending signal in the dorsal

horn and periaqueductal gray.

Emotional reaction

The pain signals are registered

in the anterior cortex, which

can trigger anxiety, fear,

and depression.

Ascending pain

The spinal cord

receives the signals

and relays them up

3 to the brain.

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