How the Nervous System Detects and Interprets Pain
Pain is a complicated warning system to protect you from harm. When you stub your toe, your peripheral nervous system sends signals to your brain, which then decides how much danger there is. If it decides the signals are worth paying attention to, the pain volume is cranked up until the problem is resolved; if not, pain is put on mute. Pain messages travel along the peripheral nervous system until they reach the spinal cord. The gate control theory proposes that there are "gates" on the bundle of nerve fibers in the spinal cord between the peripheral nerves and the brain. These spinal nerve gates control the flow of pain messages from the peripheral nerves to the brain.
Tweets by StanfordBrain. I guess stranger things have happened within abnormal psychology, though. Are headaches and migraines how does pain travel to the brain secondary headaches essentially psychosomatic in nature? Fortunately, this is a great time to explain how the brain processes pain, which will help answer your question.
There how to get rid of warts on elbow many different kinds of nociceptors; some detect harmful chemicals like capsaicin, the ow-inducing ingredient in chili peppersothers harmful temperatures like the surface of a hot stoveand still others detect bodily damage like the strain that occurs in the tendons of your finger when you strike a piano key too forcefully.
Nociceptors can also differ in the way they relay messages to the brain. Some, called A-fibers, have a fatty myelin sheath surrounding their long, arm-like axons that acts like insulation on a wire to help messages get to the brain quickly. These neurons were responsible for that first burst of pain in my big toe right when I stubbed it.
Another type of nociceptor, called a C-fiber nociceptor, conducts signals much more slowly, but has many branches so that it reports to the brain from many different areas of the body.
This type of nociceptor is associated with diffuse pain, and is likely to blame for that achey, burning feeling I have in the front of my foot right now. First, the message passes from my foot, up my leg, and into my spinal cord, where it is relayed to neurons whose fibers climb all the way to the brain.
Up through the brainstem these fibers go, traveling in bundles to the brain itself where the message ping-pongs between the thalamus, hypothalamus, and a number of other regions scientists are just beginning to parse [Almeida ].
The electrical communication between these regions gives rise to the feeling of pain. In fact, nociceptors never develop in the brain; in embryos, the cells that are responsible how does pain travel to the brain making nociceptors are different from the ones that make up the brain [Woolf ].
The brain is so insensitive to painful stimuli that neurosurgeons do not apply anaesthesia to the brain tissue they operate upon, allowing patients to be awake and completely responsive for the whole procedure. You can see this phenomenon for yourself in the video linked here. Although nociceptors embedded in your sinuses are in the front of your what county is lincoln illinois in, the brain can still interpret sinus pain as coming from the middle of your head.
One answer is that the brain mistakenly identifies pain as coming from the middle of your head. Your brain can be bad at localizing certain types of head pain because there are so many different types of tissues in the head, and many of them are pretty bad at communicating where the hurt is happening.
As another example, consider brain freeze, the painful headache you get for a few seconds after eating ice cream too quickly. Why does it happen? Think back to a cold day spent outside: when the cold air first hits the blood vessels on your face, they eventually widen, giving you ruddy cheeks. The same thing happens when the top of your mouth is suddenly cooled - those blood vessels widen very suddenly, activating nociceptors in the roof of your mouth. You may have also heard of referred pain in the context of a heart attack - even though your heart is the damaged tissue, sufferers will often feel referred pain in their arm instead [Kosek ].
Finally, remember that your head is full of lots of tiny muscles. When these muscles are strained - say, because you were staring at your computer all day - the nociceptors embedded in these tissue types send pain signals.
Many of these nociceptors are the type with a lot of branches, so that it can be hard for the brain to pinpoint exactly where the pain is coming from, and as a result the pain is difficult what is the starboard side of a ship localize. Your brain also has the unfortunate ability to fabricate a sensation of pain when no nociceptors are active.
Consider, for example, when you scrape your knee during a soccer game. This can go the other way, too - if you suffered from psychosomatic pain, you would feel pain even though your nociceptors are quiet. Your brain can even create feelings of pain in places that have no nociceptors - like a hand that has been missing for years [Flor ]. Some scientists believe that migraines may be related to this kind of psychosomatic pain, but new evidence suggests that there is more to the story.
Another theory is that migraines occur when an aberrant electrical activity in brain accidentally stimulates nociceptors in surrounding blood vessels. Since this seems to affect areas of the cortex related to vision, the theory goes, this could explain why some migraine sufferers experience visual auras and dancing lights before the migraine starts. According to the CSD theory, this could kick off a chain of events whereby neurons induce neighboring cells called glia to release inflammatory factors that force blood vessels to narrow, stimulating a relay of painful headache signals.
So, to summarize, there could be a double whammy in the heads of people suffering debilitating headaches: neurons that are overly sensitive to normal sensations, and a brain that massively over-interprets where and how painful those sensations are. Scientists will need to investigate many more questions before they can truly explain why migraines happen. I hope that helps! Almeida, Tatiana F. Scientific American Mind, —,Vol. Dubin, Adrienne E. Flor, H. Phantom-limb pain as a perceptual correlate of cortical reorganization following arm amputation.
Nature No. Kosek, E. Moskowitz, M. Strassman, A. NaturePages - Vania Apkarian, A. Human brain mechanisms of pain perception and regulation in health and disease, European Journal of Pain, Volume 9, Issue 4, Pages Woolf, C.
Neuron, Volume 55, Issue 3, Pages Learn more about giving opportunities for the neurosciences at Stanford. Skip to content Skip to navigation. How to upgrade to ios 6 Tsai Neurosciences Institute. Search form Search. Pain in the Brain. Nov 10 NeuWrite West. Read the original post and comments Sources Almeida, Tatiana F. Massachusetts: Sinauer Associates, Inc. NaturePages - Vania Apkarian, A.
Nov 09, · Somatosensory neurons (and pain receptors all over the face and head) travel into the central nervous system through the trigeminal nerve. They synapse in the trigeminal nucleus (group of neurons) in the mid-medulla and also on neurons in the lower medulla. With arthritis, for example, the joint is in a constant state of disrepair, causing pain signals to travel to the brain with little downtime. Sometimes, even in the absence of tissue damage, nociceptors continue to fire. 1 ? There may no longer be a physical cause of pain, but the pain response is the same. describes how that pain signal is carried to the brain and sets in motion the pain response. A glossary of terms is provided in Box 1. Transmission of the pain signal Axons travel throughout the body back to the spinal cord. Their pathways look like a tree, where the spinal cord is the main trunk with branches extending out into.
By: Craig Freudenrich, Ph. The signals from your cut hand travel into the spinal cord through the dorsal roots. There, they make synapses on neurons within the dorsal horn the top half of the butterfly-shaped gray matter. They synapse on neurons within the spinal cord segment that they entered and also on neurons one to two segments above and below their segment of entry.
These multiple connections relate to a broad area of the body -- this explains why it's sometimes difficult to determine the exact location of pain, especially internal pain. The secondary neurons send their signals upward through an area of the spinal cord's white matter called the spinothalamic tract.
This area is like a superhighway where traffic from all of the lower segments rides up the spinal cord. The signals of the spinothalamic tract travel up the spinal cord through the medulla brain stem and synapse on neurons in the thalamus, the brain 's relay center. Some neurons also synapse in the medulla's reticular formation, which controls physical behaviors. Nerves from the thalamus then relay the signal to various areas of the brain's somatosensory cortex -- there is no single pain center in the brain.
Your face has its own mini spinal-cord system called the trigeminal nerve. Somatosensory neurons and pain receptors all over the face and head travel into the central nervous system through the trigeminal nerve. They synapse in the trigeminal nucleus group of neurons in the mid-medulla and also on neurons in the lower medulla. Then these neurons send signals through the tregeminal-thalamic tract within the midbrain to the thalamus.
Neurons in the thalamus relay signals to the somatosensory cortex and limbic system. Prev NEXT. Life Science. Inside the Mind. The Human Brain. Pain Information from the Face. Cite This! Print Citation. More Awesome Stuff.