How is pain interpreted by the brain

Whenever an injury happens, special pain receptors called nociceptors are activated. Remember the toy truck from earlier? Your nociceptors will still shoot off a response from your nerve, through the spinal cord, en route to your brain due to the compression of the tissues in your foot from stepping on the toy truck. The complexity of the spinal cord, with all its bundles of nerves transmitting all sorts of signals back and forth from the brain at will.

Calling it the Indy for motor and sensory impulses would fit well. At the same time — directing impulses to the brain and back down the spinal cord to the injured area is the information hub. The information hub is an area of your spinal cord known as the dorsal horn. So, when you stepped on that truck, the first impulse was to quickly lift your foot, right?

So again, your spinal cord is like an office manager, but your brain is the CEO running the show. DRG neurons arise from the spinal nerves of the dorsal root, which carries sensory messages from several receptors, inclusive of the response from the nervous system towards pain and temperature. A pain message is transmitted to the brain by specialized nerve cells known as nociceptors, or pain receptors pictured in the circle to the right.

When pain receptors are stimulated by temperature, pressure or chemicals, they release neurotransmitters within the cells. As seen in the diagram, these messengers transmit a pain signal from the pain receptor to the spinal cord, and then to the thalamus, a region of the brain.

The thalamus then transmits the pain signal to other areas of the brain to be processed. Once the brain has received and interpreted the pain message, it coordinates an appropriate response.

The brain can send a signal back to the spinal cord and nerves to increase or decrease the severity of pain. For example, the brain can signal the release of natural painkillers known as endorphins.

Histamine receptors activate when skin irritation, bug bites, or allergies trigger the release of histamine in the body. Itch receptors have molecular channels in their cell membrane that open when they detect histamine.

Scientists have identified other itch-specific receptors that activate when they detect other molecules including, prostaglandins, neuropeptides, and proteases the body releases in response to pain and irritants. Injury triggers the release of various chemicals at the site of damage, causing inflammation.

Prostaglandins make receptors more sensitive to pain, so pain feels more intense. A long-lasting injury may lead to nervous system changes that enhance perceived pain, even without pain stimuli. This neuropathic pain is caused by an over-sensitive nervous system rather than an injury. In diabetic neuropathy, prolonged exposure to high blood sugar damages nerves in the hands and feet, sending signals of numbness, tingling, burning, or aching pain.

Pain and itch messages travel to the spinal cord via A-delta and C nerve fibers. Myelinated A-delta fibers insulate the nerve, so electrons are channeled effectively and travel faster letting you feel immediate, sharp, and easily identifiable pain. Unmyelinated C fibers transmit messages more slowly and their nerve endings spread over a large area.

They help you feel dull aches difficult to pinpoint. From the spinal cord, signals head to the thalamus , which relays signals to areas of the cerebral cortex transforming messages into conscious experience. Once aware, you can decide to be more careful the next time you approach the door.

Pain depends both on the strength of the stimulus and the emotional state and setting in which the injury occurs. When messages arrive in the cortex, the brain can process them differently depending on whether you had a good day or just broke up with your girlfriend.

The cortex sends pain messages to the periaqueductal gray matter, which activates pathways that modulate pain. Pathways send messages to networks that release endorphins — natural opioids that act like the pain reliever morphine. Adrenaline produced during emotionally stressful situations also serves as a pain reliever.

Releasing these chemicals helps regulate and reduce pain by intercepting signals traveling through the spinal cord and brainstem. Although everyone has these brain circuits, how well they work and how sensitive they are influence how much pain someone feels. Endorphins act at multiple types of opioid receptors in the brain and spinal cord. Doctors can deliver opioid drugs to the spinal cord before, during, and after surgery to reduce pain.