Touch and Pain By: Anne George and Lydia Zhang http://www.thedailybeast.com/articles/2016/04/11/the-pain-gap-why-doctors-offer-less-relief-to-black-patients.html

Why is our sense of touch important? Humans are social animals. Therefore, touch is essential to our development. A lack of physical engagement can lead to a higher risk for physical, emotional, behavioral and social problems as they grow up, whereas consistent engagement speed up their recognition of self. The sense of touch is the first sensory pathway that develops in animals. It allows animals to derive information about their surroundings when the other sense are not important.

How do we sense touch? Touch is a sense that is all over your body The receptor cells in the skin can be broken down into three functional categories: mechanoreceptors (pressure) thermoreceptors (warm and cold) nociceptors (pain)

How do we sense touch? Sense neurons are located on the bottom layer of the skin called the dermis. Here there are nerve endings that are called sensory neurons. These neurons carry signals to the brain, where they are quickly processed into useful information that the body reacts to. Reaction involves signals from the brain traveling to the appropriate muscle neuron where action will be taken.

Pain Warns us of potential dangers Pain experiences vary widely Women more pain sensitive than men Individual sensitivity varies depending on genes, physiology, experience, attention, and surrounding culture Reflects both top-down and bottom-up processes

Biological Influences More than one type of stimulus triggers pain Nociceptors— sensory receptors that detect hurtful temperatures, pressure, or chemicals Gate-Control Theory: (psychologist Ronald Melzack and biologist Patrick Wall) theory that the spinal cord contains a neurological “gate” that blocks pain signals or allows them to pass on to the brain. “Gate” is opened by the activity of pain signals traveling up small nerve fibers. It is closed by activity in larger fibers or by information coming from the brain. Treatment of chronic pain= stimulation of “gate-closing” activity in large neural fibers

Is pain simply a physical phenomenon? Brain-to-spinal-cord messages can also close the gate Explanation of the influences that act on our pain Distracted from our pain (psychological influence) and soothed by a release of naturally painkilling endorphins (biological influence)=decrease in pain experienced

Is pain simply a physical phenomenon? Brain can create pain Phantom Limb Sensation: when it misinterprets the spontaneous central nervous system activity that occurs in the absence of normally sensory input.

Psychological Influences Memories of pain differ from the we actually experienced Memories record pain’s peak moments and how much pain felt at the end Overlook a pain’s duration Kahneman, Fredrickson, Schreiber, Redelmeier (1993) Participants were asked to immerse one hand in painfully cold water for 60 seconds and the other hand in the same water for 60 seconds followed by a slightly less painful water for 30 more seconds. Prefered the longer trial with more net pain, but less pain at the end Physicians apply this principle to patients undergoing colon exams.

Social-Cultural Influences When feeling empathy for another’s pain, a person’s own brain activity may partly mirror that of the other’s brain in pain.

Personal experience of pain Biological Influence: Activity in spinal cord’s large and small fibers Genetic differences in endorphin production The brain’s interpretation of CNS activity Psychological Influences: Attention to pain Learning based on experience Expectations Personal experience of pain Social-cultural Influences: Presence of others Empathy for other’s pain Cultural expectations

Controlling Pain Depending on the type of symptoms, pain control clinics select one or more therapies from a list that includes drugs, surgery, acupuncture, electric stimulation, massages, exercise, hypnosis, relaxation training, and thought distraction. Inert placebos can help by dampening the central nervous system’s attention and responses to painful experiences. Distraction people with pleasant images or drawing their attention away from the painful stimulation is an especially effective way of activate pain-inhibiting circuits and to increase pain tolerance.

Let’s review some concepts https://www.youtube.com/watch?v=mQoS62jEvNA