Let's say that it would take you ten minutes to solve this puzzle. How long would it take if you received constant electric shocks to your hands? Longer, right? Because the pain would distract you from the task. Well, maybe not; it depends on how you handle pain. Some people are distracted by pain. It takes them longer to complete a task, and they do it less well. Other people use tasks to distract themselves from pain, and those people actually do the task faster and better when they're in pain than when they're not. Some people can just send their mind wandering to distract themselves from pain. How can different people be subjected to the exact same painful stimulus and yet experience the pain so differently? And why does this matter? First of all, what is pain? Pain is an unpleasant sensory and emotional experience, associated with actual or potential tissue damage. Pain is something we experience, so it's best measured by what you say it is. Pain has an intensity; you can describe it on a scale from zero, no pain, to ten, the most pain imaginable. But pain also has a character, like sharp, dull, burning, or aching. What exactly creates these perceptions of pain? Well, when you get hurt, special tissue damage-sensing nerve cells, called nociceptors, fire and send signals to the spinal cord and then up to the brain. Processing work gets done by cells called neurons and glia. This is your Grey matter. And brain superhighways carry information as electrical impulses from one area to another. This is your white matter. The superhighway that carries pain information from the spinal cord to the brain is our sensing pathway that ends in the cortex, a part of the brain that decides what to do with the pain signal. Another system of interconnected brain cells called the salience network decides what to pay attention to. Since pain can have serious consequences, the pain signal immediately activates the salience network. Now, you're paying attention. The brain also responds to the pain and has to cope with these pain signals. So, motor pathways are activated to take your hand off a hot stove, for example. But modulation networks are also activated that deliver endorphins and enkephalins, chemicals released when you're in pain or during extreme exercise, creating the runner's high. These chemical systems help regulate and reduce pain. All these networks and pathways work together to create your pain experience, to prevent further tissue damage, and help you to cope with pain. This system is similar for everyone, but the sensitivity and efficacy of these brain circuits determines how much you feel and cope with pain. This is why some people have greater pain than others and why some develop chronic pain that does not respond to treatment, while others respond well. Variability in pain sensitivities is not so different than all kinds of variability in responses to other stimuli. Like how some people love roller coasters, but other people suffer from terrible motion sickness. Why does it matter that there is variability in our pain brain circuits? Well, there are many treatments for pain, targeting different systems. For mild pain, non-prescription medications can act on cells where the pain signals start. Other stronger pain medicines and anesthetics work by reducing the activity in pain-sensing circuits or boosting our coping system, or endorphins. Some people can cope with pain using methods that involve distraction, relaxation, meditation, yoga, or strategies that can be taught, like cognitive behavioral therapy. For some people who suffer from severe chronic pain, that is pain that doesn't go away months after their injury should have healed, none of the regular treatments work. Traditionally, medical science has been about testing treatments on large groups to determine what would help a majority of patients. But this has usually left out some who didn't benefit from the treatment or experienced side effects. Now, new treatments that directly stimulate or block certain pain-sensing attention or modulation networks are being developed, along with ways to tailor them to individual patients, using tools like magnetic resonance imaging to map brain pathways. Figuring out how your brain responds to pain is the key to finding the best treatment for you. That's true personalized medicine.
這麼說吧!如果你平常能以 十分鐘完成這幅拼圖 你要花多久才能完成 如果你的手不斷受到電擊? 更久的時間,對吧? 因為痛會分散你對任務的注意力 唔,不見得 要看你對痛的反應是什麼 有些人會因為痛而分心 他們要花更久的時間完成任務 而且他們做得也較差 另一些人則以任務 來分散他們對痛的注意力 所以其實這些人做任務時 在痛苦中的表現會比 不痛的時候更快更好 有些人就是可以讓他們的心智漫遊 以分散他們對痛的注意力 為什麼不同的人 在面對同樣的痛覺刺激時 會經歷全然不同的反應? 而為什麼這很重要? 首先,什麼是痛? 痛是一種不愉快的感覺及情緒經驗 與實際或潛在的組織損傷有關 痛是我們主觀的經歷 所以最好的測量法 是我們自己說有多痛 痛有強度 你以量表來描述 從 0 不痛,到 10 最痛 但是痛也有不同的種類 像是銳痛、鈍痛、灼痛或疼痛 到底是什麼讓我們產生對痛的知覺? 你受傷的時候 針對組織損傷感測的神經細胞 稱為痛覺受器會激發 且送出信號到脊髓 然後上傳到腦部 傳輸處理的過程 由稱為神經元及神經膠的細胞完成 這就是你的灰質 而大腦超級高速公路承載資訊 以電脈衝方式 從一處傳到另一處 這就是你的白質 一條超級高速公路承載痛的資訊 從脊髓傳到腦部 則是我們的感測路徑 其終點在皮質 它是大腦的一部分 在接受痛覺信號之後 由其決定要做出什麼反應 互連腦細胞的另一種系統 稱做突顯網路 則決定要注意什麼事 因為痛會帶來非常嚴重的後果 痛覺信號會立刻活化 突顯網路 現在,你會集中注意力了 腦部也對痛覺作出反應 也必須因應這些痛覺信號 所以,運動路徑因此活化 譬如說,讓你的手從火燙的爐上縮回 但是調節網路也會活化 以輸送腦內啡及腦素 這些化學物質,使在你受痛 或在玩極限運動的時候 產生所謂「跑者的愉悅感」 這些化學系統幫助調節及減低痛感 這些網路及路徑一同合作 產生你的痛覺體驗 以預防進一步的組織損傷 及幫助你因應疼痛 這個系統在每個人身上都很類似 但是這些腦迴路的敏感度及效力 將決定你到底覺得有多痛 以及對痛產生什麼反應 這就是為什麼有些人比較怕痛 及為什麼有些人會產生慢性疼痛 對治療毫無反應 但其他人卻治療效果良好 痛覺敏感度的變異性 與回應其它刺激的變異性 其實相差不大 就像為什麼有人愛雲霄飛車 但有些人一坐就暈的七葷八素 為什麼在我們腦迴路 有變異性是這麼重要? 嗯,我們有很多治療痛的方法 針對不同的系統下藥 對輕度疼痛,非處方藥 在痛覺信號一開始就對細胞作用 其它更強的止痛藥及麻醉藥 則減緩痛覺感測迴路 或增強我們的因應系統 即腦內啡 有些人應付疼痛 是用一些方法如 分心、放鬆、靜坐、瑜珈 或是用可以訓練的策略 像認知行為治療 對那些遭受嚴重慢性疼痛之苦的人 也就是痛覺依然存在 即使在他們所受的傷應該 已經痊癒的數月之後 常規的藥石也是罔然 醫學發展傳統上是在 大群人身上測試治療法 以找出對多數病人有幫助的方法 但是這通常會排除 對測試治療無效的人 或經歷副作用的人 現在,新的治療法以直接刺激或阻斷 某些痛感測的注意力或調節網路 已在開發階段 同時也在為個別患者 用核磁共振法 繪出大腦各式路徑以量身打造藥物 找出你的大腦如何對疼痛反應 是找出對你最佳的治療法的關鍵 那可真是有個性的藥啊!