Under Pressure

The skin has four main senses: pressure, warmth, cold, and pain. Only pressure has identifiable receptors in the skin. The others’ relationship to skin receptors is unknown. Some sensations are caused by stimulating multiple types of nerve receptors. For example, a wet feeling can be created by stimulating nearby cold and pressure receptors (27).

Pain, Pain, Go Away

Pain is not caused by any specific type of stimulus nor is there special receptor cells located within the body dedicated to it. Though pain largely exists in the brain, it is your body’s way of communicated that something is wrong. This allows us to recognize when we are sick or injured so we can attend to our ailments. Many circumstances can influence how we perceive pain, such as distractions, society (such as in cases of epidemic-related mass hysteria), memory, and mental state (26, 27).

The gate control theory states that within the spinal cord is a neural gate-type structure that either impedes or allows pain signals to continue to the brain. The gate is opened by the pain impulse’s activity in surrounding fibers, and closed either by more influential fibers or a signal from the brain . This theory supports that chronic pain can be treated by stimulation of these large nerve fibers, such as through massage, which will then close the gate (27).

The Sixth Sense (And Seventh, Eighth, and Ninth)

Everyone knows about the five “main” senses. But what about those other types sensations that don’t neatly fit into those categories?

Vestibular sense: 

This is the sense involving body position and equilibrium. Movement of the fluid in the inner ear, due to head movement or gravitational pull, stimulates this sense. It can also be referred to as equilibrioception (22). 

Kinesthetic sense: 

This is the sense involving detection of the movement of individual body parts. It allows us to judge our position within a given space. The sense can also be referred to as proprioception (23). 

Sense of temperature: 

This is the ability of the human body to detect changes in external and internal temperatures by using, respectively, cutaneous (skin) thermoreceptors and homeostatic (related to maintaining equilibrium) thermoreceptors within the body. This sense is also known as thermoception (24).

Time perception: 

The sense that allows humans to estimate how much time has passed since a given moment. What allows us to sense time remains unknown. Some theorize that we have an internal stopwatch, so to speak, which allows us to measure time through a series of neural “pulses” (25).