Somatosensory system
They include mechanoreceptors such as tactile corpuscles that relay information about pressure and vibration; nociceptors, and thermoreceptors for temperature perception.
In this way, neighboring neurons in the somatosensory cortex represent nearby locations on the skin or in the body, creating a map or sensory homunculus.
[7] Merkel cell nerve endings are found in the basal epidermis and hair follicles; they react to low vibrations (5–15 Hz) and deep static touch such as shapes and edges.
Due to having a small receptive field (extremely detailed information), they are used in areas like fingertips the most; they are not covered (shelled) and thus respond to pressures over long periods.
They are responsible for the feeling of object slippage and play a major role in the kinesthetic sense and control of finger position and movement.
Area S2 is involved with specific touch perception and is thus integrally linked with the amygdala and hippocampus to encode and reinforce memories.
Insula also plays a role in conveying info about sensual touch, pain, temperature, itch, and local oxygen status.
[3] All afferent touch/vibration information ascends the spinal cord via the dorsal column-medial lemniscus pathway via gracilis (T7 and below) or cuneatus (T6 and above).
Cuneatus sends signals to the cochlear nucleus indirectly via spinal grey matter, this info is used in determining if a perceived sound is just villi noise/irritation.
[21] The receptor for the sense of balance resides in the vestibular system in the ear (for the three-dimensional orientation of the head, and by inference, the rest of the body).
Balance is also mediated by the kinesthetic reflex fed by proprioception (which senses the relative location of the rest of the body to the head).
[24][clarification needed] More precisely, the consistency of oxytocin neuron activation in rats stroked by humans has been observed, especially in the caudal paraventricular nucleus.
[27] Furthermore, the time course of grooming is related to vulnerability due to predation to which animals are exposed to whilst performing such social interaction.
Studies show a correlation between touching a soft or hard object and how a person thinks or even makes decisions.
A variety of methods have been used to measure passive tactile spatial acuity, perhaps the most rigorous being the grating orientation task.
Perhaps also due to cortical plasticity, individuals who have been blind since birth reportedly consolidate tactile information more rapidly than sighted people.
Researchers investigated the expression patterns and characteristics of 8 different affectionate touch actions - embracing, holding, kissing, leaning, petting, squeezing, stroking, and tickling - in a self-report study.
Besides the rather obvious sensory consequences of touch, it can also affect higher-level aspects of cognition such as social judgements and decision-making.
This effect might arise due to a physical-to-mental scaffolding process in early development, whereby sensorimotor experiences are linked to the emergence of conceptual knowledge.
[46] Such links might be maintained throughout life, and so touching an object may cue the physical sensation to its related conceptual processing.
Indeed, it was found that different physical properties - weight, texture, and hardness - of a touched object can influence social judgement and decision-making.
[47] For example, participants described a passage of a social interaction to be harsher when they touched a hard wooden block instead of a soft blanket prior to the task.
Building on these findings, the ability of touch to have an unconscious influence on such higher-order thoughts may provide a novel tool for marketing and communication strategies.
