The Neuroscience of Touch - A Primer
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Touch activates the orbitalfrontal cortex, which assigns value and determines if a stimulus is pleasurable or disgusting. Preferred surfaces for touch are smooth, soft, and non-sticky. Touch related to trust and relationships is processed slightly slower than touch to identify objects. A hug before public speaking reduces stress levels during the speech. Disruption of maternal touch in early life results in anxious behaviors later in life. Certain emotions like anger, fear, disgust, gratitude and sympathy can be detected through touch alone. Mirror neurons allow observing another's touch to simulate the feeling on one's own body.
The Neuroscience of Touch - A Primer
- 1. The Science of Touch - A Neuroscientific View for Beginners Touch activates a structure called the orbitalfrontal cortex (behind the forehead and above the eyes). Inside the orbitalfrontal cortex is the area responsible for assigning value to taste (usually from foods, but evolution allowed every pleasure to be processed in this area). Is it pleasurable to experience it? Is it disgusting? The orbitalfrontal cortex answers these questions, and is activated by touch. Touch bypasses conscious control over "trust" by creating a direct experience of reward and relaxation. Preferred surfaces are smooth, soft and not sticky. This has been tested in laboratories among many different kinds of textures and surfaces for what is universally preferred among humans in terms of how much pleasure they experience in touch. Touch related to trust and interpersonal relationships in processed by nerve channels that are slightly slower than touch for the purpose of understanding what an object is. This slowness is only about a second and a half. A human being is slightly slower to recognize emotional touch than he or she is to recognize a physical object's texture, shape or form. Touch can protect against immediate future stress. For example, in the laboratory, a hug before public speaking has been proven to improve levels of stress during a speech. One theory of how this works is that touch receptors close the gates to receive pain signals. Disruption of maternal touch in mammals (rats, monkeys, humans) results in anxious and hyperactive behaviors in adult offspring. Many studies show that "simple touch" (making a short contact with one part of the body) increases tips, sales, ratings of how much a person is trusted after a first meeting, ratings of attractiveness, and even the simple likelihood that a person will respond "yes" to a request. Some emotions hae been shown to be detected by simple touch alone. This means that a person is able to observe the emotion of his or her interaction partner without seeing the other person's facial expression or body language. The particular emotions able to be identified in this study were anger, fear, disgust, gratitude and sympathy. Our slow muscle fibers called "C-tactile" fibers are specifically evolved to encode the emotion of touch. They are found in the face and arms and in some areas of the legs. Usually C-tactile fibers are found only in body areas with hair. The ideal speed for touch that is lasting longer than a "simple" touch or a touch that is movement (such as petting, stroking, or touch associated with intimacy) is between 1 and 10cm per second. This rate of speed is perceived as the most pleasant in lab studies. Touch tells the body it is safe to relax. This is because pleasure in the OFC activates the parasympathetic nervous system, the body's mechanism for calming and repose.
- 2. A system of cells called "mirror neurons" allow a person to experience the touch of another person's body through observation alone by simulating how this touch would feel on his or her own body. There is about 20% of activated brain cells as if the person him or herself were being touched. Compassion felt toward another person will effect how much the mirror neuron system will activate. Previous interactions, the expressiveness of the person's face, and whether or not they are considered a part of the group (for example compassion can be limited by racial distinctions, religious tolerance, or a wider belief of one human family if the observer sees him or herself as belonging to a certain category or group).