Friday, May 13, 2022

How Is Pain Interpreted By The Brain

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What The Nervous System Does

What Are Symptoms? (Pain Perception & The Brain)

Your nervous system is made up of two main parts: the brain and the spinal cord, which combine to form the central nervous system and the sensory and motor nerves, which form the peripheral nervous system. The names make it easy to picture: the brain and spinal cord are the hubs, while the sensory and motor nerves stretch out to provide access to all areas of the body.

Put simply, sensory nerves send impulses about what is happening in our environment to the brain via the spinal cord. The brain sends information back to the motor nerves, which help us perform actions. Its like having a very complicated inbox and outbox for everything.

Transcutaneous Electrical Nerve Stimulation

A TENS machine is a simple way of blocking pain signals using self-adhesive pads to pass an electric current through the skin. Its a bit like rubbing the sore bit better or using a hot water bottle to provide comfort.

You can buy TENS machines from pharmacists, supermarkets or online. Prices start from £8.99 for a simple machine. You shouldnt need to spend more than £30 to get a machine with 2 sets of pads and a fully adjustable pulse rate and width.

More about TENS for pain relief from Pain Concern

What Role Does The Spinal Cord Play In Response To Pain

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 5000 for motor and sensory impulses would fit well. Look at your spinal cord like the office manager, not only does it send and receive messages it also makes basic decisions, known as reflexes.

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? Thats because your dorsal horn had already sent the message. 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. Ask your specialist at Southeast Pain & Spine Care if Dorsal root ganglion stimulation could be an option for your chronic pain.

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Central Amplification Of Chronic Back Pain

The brain and spinal cord receive signals from your nerves and also send out massive patterns of signals to our muscles that control our arm, leg, and spine movements. These signal patterns develop over years and explain how we learned to walk, run, ride a bicycle, dribble a basketball, and even play a musical instrument. The signal patterns constantly update the spinal cord to include the status of sensors that detect our muscle flexibility, strength, and endurance.

We think chronic pain starts when these sensors in your muscles , misfire or malfunction, and your brain and spinal cord adapt improperly to those malfunctioning sensors and become short-circuited. In a way, what happens is the spinal cord amplifies a normally harmless pain signal, which creates a loud chronic pain signal.

When your pain signals become amplified, your central nervous system latches onto these signals or recognizes them as intensely painful. This makes it so that even harmless stimuli appear to be intense pain signals.

Based on that, the best medical understanding for chronic pain is the entire system of microscopic pain sensors and the central nervous system has become short-circuited, making normal achy muscle pain signals seem unbearable.

When Acute Pain Becomes Chronic

How The Brain Changes With Chronic Pain

In this scenario, after your foot healed, the pain sensations would stop. This is because the nociceptors no longer detect any tissue damage or potential injury. This is called acute pain. Acute pain does not persist after the initial injury has healed.

Sometimes, however, pain receptors continue to fire. This can be caused by a disease or condition that continuously causes damage. 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. There may no longer be a physical cause of pain, but the pain response is the same. This makes chronic pain difficult to pin down and even more difficult to treat.

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Pain Really Is All In Your Head And Emotion Controls Intensity

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    When you whack yourself with a hammer, it feels like the pain is in your thumb. But really it’s in your brain.

    That’s because our perception of pain is shaped by brain circuits that are constantly filtering the information coming from our sensory nerves, says David Linden, a professor of neuroscience at Johns Hopkins University and author of the new bookTouch: The Science of Hand, Heart, and Mind.

    “There is a completely separate system for the emotional aspect of pain the part that makes us go, ‘Ow! This is terrible.’ “

    David Linden, neuroscientist, Johns Hopkins University

    “The brain can say, ‘Hey that’s interesting. Turn up the volume on this pain information that’s coming in,’ ” Linden says. “Or it can say, ‘Oh no let’s turn down the volume on that and pay less attention to it.’ “

    This ability to modulate pain explains the experiences of people like Dwayne Turner, an Army combat medic in Iraq who received the Silver Star for valor.

    In 2003, Turner was unloading supplies when his unit came under attack. He was wounded by a grenade. “He took shrapnel in his leg, in his side and he didn’t even notice that he had been hit,” Linden says.

    Despite his injuries, Turner began giving first aid and pulled other soldiers to safety. As he worked, he was shot twice one bullet breaking a bone in his arm. Yet Turner would say later that he felt almost no pain.

    Sensing Pain: A Relay From Stubbed Toe To Brain

    In your body, there are special sensory neurons called nociceptors whose job it is to tell the body this feels bad! . There are many different kinds of nociceptors some detect harmful chemicals , others harmful temperatures , and still others detect bodily damage . 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.

    Lets follow the stubbed toe message along its way to the brain. 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 . The electrical communication between these regions gives rise to the feeling of pain.

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    Musings On The Treatment Of Chronic Pain

    When you eliminate 90% of a patient’s pain, the remaining 10% is 100% of what is left. This reminds us that any pain is still pain. Furthermore, when pain becomes chronic, the goal in most cases is management rather than elimination. One of the most distressing recent developments in medicine is the explicit focus on eliminating pain manifested as pain as the fifth vital sign and relief of pain being used to measure the quality of a health care facility. Of course, relief of acute pain is an important function of health care, but too often there is no thought to the distinctions between acute and chronic pain and the negative outcomes of analgesics used for chronic pain. The institutionalized focus on eliminating pain is concomitant with the increase in use of opioids for chronic non-cancer pain .

    Potential Conflicts of Interest: None disclosed.

    Descending Central Modulation Of Pain

    Does pain change your brain?

    The brain does not passively receive pain information from the body, but instead actively regulates sensory transmission by exerting influences on the spinal dorsal horn via descending projections from the medulla. In their seminal Gate Control theory of pain, Melzack and Wall proposed that the substantia gelatinosa of the dorsal horn gates the perception of noxious stimuli by integrating upstream afferent signals from the peripheral nervous system with downstream modulation from the brain. Interneurons in the dorsal horn can inhibit and potentiate impulses ascending to higher brain centers, and thus they provide a site where the central nervous system controls impulse transmission into consciousness.

    The descending pain modulatory system exerts influences on nociceptive input from the spinal cord. This network of cortical, subcortical, and brainstem structures includes prefrontal cortex, anterior cingulate cortex, insula, amygdala, hypothalamus, periaqueductal grey, rostral ventromedial medulla, and dorsolateral pons/tegmentum. The coordinated activity of these brain structures modulates nociceptive signals via descending projections to the spinal dorsal horn. By virtue of the somatotopic organization of these descending connections, the central nervous system can selectively control signal transmission from specific parts of the body.

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    What Is The Role Of The Nerves In Relation To Identify Pain Sensations

    Some nerves send signals related to light touch, while others react to intense pressure. For instance, if you accidentally step on a toy truck left lying around, how is your sensory nerve in the peripheral nervous system able to decipher the difference in pain sensations? Well, thats because different sensory nerve fibers produce different chemical responses that are able to interpret the different sensations as well as reacting to it.

    Whenever an injury happens, special pain receptors called nociceptors are activated. Remember the toy truck from earlier? Well, lets say that when you stepped on that truck luck was on your side, and you didnt break any skin. 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.

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      What happens when you’re cutting a bagel and slice your hand with the knife? Besides all the blood, you’ll probably feel an immediate sharp pain, followed by a longer-lasting dull ache. Eventually, both pains will go away. But what actually is pain? How do you sense it? What makes it go away? In this article, we’ll examine the neurobiology of pain, the various types of pain and how pain can be treated or managed.

      Pain is the most common reason that people seek medical attention. But pain is actually hard to define because it’s a subjective sensation. The International Association for the Study of Pain defines it as an “unpleasant sensory and emotional experience associated with actual or potential tissue damage, or described in terms of such damage” .

      Obviously, this definition is pretty vague. One physician even remarked that pain is whatever the patient says it is. So let’s just say that pain is a warning sensation to your brain that some type of stimulus is causing or may cause damage, and you should probably do something about it.

      Pain perception, or nociception , is the process by which a painful stimulus is relayed from the site of stimulation to the central nervous system. There are several steps in the nociception process:

      Nociception uses different neural pathways than normal perception . With nonpainful stimulation, the first group of neurons to fire are normal somatic receptors. When something causes pain, nociceptors go into action first.

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      Can The Brain Itself Feel Pain

      Does the brain itself have pain receptors?

      There are no pain receptors in the brain itself. But he meninges , periosteum , and the scalp all have pain receptors. Surgery can be done on the brain and technically the brain does not feel that pain.

      With that said, the brain is the tool we use to detect pain. Lets say youre on the beach and you step on a sharp shell. Special pain receptors in your skin activate whenever there has been an injury, or even a potential injury, such as breaking the skin or causing a large indentation. Now, an impulse is heading through the nerve into the spinal cord, and eventually all the way to your brain. This happens within fractions of a second.

      Signals are also sent from the thalamus to the limbic system, which is the emotional center of the brain. Feelings are associated with every sensation you encounter, and each feeling generates a response. For example, your heart rate may increase, and you may break out into a sweat.

      Other Factors That Influence Pain Response


      While it may seem simple, the process of detecting pain is complicated by the fact that it is not a one-way system. It isnt even a two-way system. Pain is more than just cause and effect. It is affected by everything else that is going on in the nervous system. Your mood, your past experiences, and your expectations can all change the way pain is interpreted at any given time. How is that for confusing?

      If you step on that rock after you have a fight with your wife, your response may be very different than it would if you had just won the lottery. Your feelings about the experience may be tainted if the last time you stepped on a rock, your foot became infected. If you stepped on a rock once before and nothing terrible happened to you, you may recover more quickly. You can see how different emotions and histories can determine your response to pain. In fact, there is a strong link between depression and chronic pain.

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      What Are The Parts Of The Nervous System

      The nervous system is made up of the central nervous system and the peripheral nervous system:

      • The brain and the spinal cord are the central nervous system.
      • The nerves that go through the whole body make up the peripheral nervous system.

      The human brain is incredibly compact, weighing just 3 pounds. It has many folds and grooves, though. These give it the added surface area needed for storing the body’s important information.

      The spinal cord is a long bundle of nerve tissue about 18 inches long and 1/2-inch thick. It extends from the lower part of the brain down through spine. Along the way, nerves branch out to the entire body.

      Both the brain and the spinal cord are protected by bone: the brain by the bones of the skull, and the spinal cord by a set of ring-shaped bones called vertebrae. They’re both cushioned by layers of membranes called meninges and a special fluid called cerebrospinal fluid. This fluid helps protect the nerve tissue, keep it healthy, and remove waste products.

      From Sensing To Feeling

      So whats happening when it feels like your brain is hurting? Youre absolutely right that the brain has no nociceptors. In fact, nociceptors never develop in the brain in embryos, the cells that are responsible for making nociceptors are different from the ones that make up the brain . 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. So if a brain is incapable of sending this feels bad! signals, why do headaches exist?

      Although nociceptors embedded in your sinuses are in the front of your face, the brain can still interpret sinus pain as coming from the middle of your head. Source:

      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. Fellow sinus infection sufferers will know what Im talking about – inflammation of the spaces in just behind your forehead can feel like a knot of pain in the middle of your head.

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      Cognitive Appraisal Of Pain

      Pain involves a process of cognitive appraisal, whereby the individual consciously or unconsciously evaluates the meaning of sensory signals emanating from the body to determine the extent to which they signify the presence of an actual or potential harm. This evaluation is decidedly subjective. For instance, experienced weightlifters or runners typically construe the burn they feels in their muscles as pleasurable and indicative of increasing strength and endurance in contrast, a novice might view the same sensation as signaling that damage had occurred. The inherent variability of cognitive appraisal of pain may stem from the neurobiological dissociation between the sensory and affective aspects of the pain experience change in pain intensity results in altered activation of somatosensory cortex, whereas change in pain unpleasantness results in altered activation of the anterior cingulate cortex., Thus, a sensory signal originating from the muscles of lower back might be perceived as a warmth and tightness, or viewed as a terrible agony, in spite of the stimulus intensity being held constant. The manner in which the bodily sensation is appraised may in turn influence whether it is experienced as unpleasant pain or not.

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