Touch The body or somatic senses includes skin senses, which detect touch, temperature, and pain. Pacinian corpuscles, located beneath the skin, detect touch and pressure.   There are also receptors that detect temperature variations.

Pain Pain tells the body that something has gone wrong. Pain: an unpleasant feelings and discomfort experienced when a person is exposed to an aversive stimulus. Gate-Control Theory: suggests that pain is determined by the opening and closing of neurological gates in the spinal cord. When the gates are closed the individual doesn’t experience pain; when they are open, sensory neurons detect and send pain messages to the brain. When free nerve endings are stimulated they release substance P, a neurotransmitter that activates other neurons to open the “gate”, resulting in the perception of pain. This information is sent to the thalamus, which relays the information to the somatosensory cortex, the frontal lobes, and the limbic system. The limbic system provides the emotional elements associated with pain. Psychological factors can also affect the sensation of pain. These factors can inhibit the release of endorphins, a neurotransmitter that reduces pain by blocking substance P in the spinal cord. Phantom Limb Sensations: the brain misinterprets the spontaneous central nervous system activity that occurs in the absence of normal sensory input. People with hearing loss often experience the sound of silence: phantom sounds – a ringing in the ears sensation know as tinnitus. 

Chemical Senses - Taste Taste is a chemical sense and is referred to as gustation. Taste buds are sensory receptors that are activated when substances enter the mouth. There are five types of taste buds: 1) sweet 2) salty 3) sour 4) bitter 5) umami – “meaty” foods Each taste bud has about 50 to 100 receptor cells, which are sensitive to and activated by particular substances. Taste buds are located in groups on the tongue called papillae, and are also scattered throughout the mouth. Taste buds regenerate about every two weeks, but as a person ages, his/her taste buds don’t regenerate as quickly. “Supertasters” vs. “Nontasters” – depends on the number of taste buds a person has.

Chemical Senses - Smell The sense of smell is referred to as olfaction and is identified as a chemical sense. The sensation of smell comes from molecules that enter the nose. The nasal passage is lined with millions of olfactory receptor cells, which are responsible for the detection of air molecules. Once a receptor cell is stimulated, a neural message passes through its axon, which combines with other olfactory axons to form olfactory nerves. Olfactory nerves then carry information to the olfactory bulb. The olfactory bulb, located at the end of the olfactory cortex, is responsible for processing the sensation of smell.

Body Position and Movement The kinesthetic sense monitors and coordinates movement among body parts through information sent from sensory neurons called proprioceptors, which are located in joints, muscles, and the inner ear. The vestibular sense monitors balance in response to movement detected by the proprioceptors. The vestibular sense receives information from the semicircular canals and the vestibular sacs, located in the ear.

Sensory Interaction Sensory interaction occurs when one sense influences another. McGurk Effect: The McGurk effect is a perceptual phenomenon that demonstrates an interaction between hearing and vision in speech perception. The illusion occurs when the auditory component of one sound is paired with the visual component of another sound, leading to the perception of a third sound.