Somatosensation

Introduction[edit | edit source]

The body functions and interacts with its surrounding environment through the simultaneous inputs of our five senses; gustation (taste), ocular (vision), olfaction (smell), vestibular (balance) and auditory (hearing), respectively. However, it is often forgotten that we also have a "sixth sense", understood to be our sense of somatosensation. Somatosensation is an overarching sense which includes the sub-modalities of:

  • Thermoception (temperature);
  • Nociception (pain);
  • Equilibrioception (balance);
  • Mechanoreception (vibration, discriminatory touch and pressure);
  • Proprioception (positioning and movement).

Collectively, these senses allow us to participate in our activities of daily living (ADLs) by guiding our movements, all the while minimizing the possibility of sustaining an injury.

Somatosensation. Retrieved from: Ager, A.L., Borms, D., Deschepper, L., Dhooghe, R., Dijkhuis, J., Roy, J.S., &  Cools, A.Proprioception and shoulder pain: A Systematic Review. J Hand Ther. 2019 Aug 31. pii: S0894-1130(19)30094-8. doi: 10.1016/j.jht.2019.06.002. 

What is Somatosensation?[edit | edit source]

Somatosensation is a mixed sensory category, and is mediated, in part, by the somatosensory and posterior parietal cortices. They underlie the ability to identify tactile characteristics of our surroundings, create meaning about sensations, and formulate body actions related to the sensations[1]. These various sensations contribute to the somatic aspects of the body scheme as a basis for interacting with our environments[2].

Body representations are reliant on multi-sensory cortical and sub‐cortical areas, including particularly premotor cortex, posterior parietal cortex and the putamen[3].

It is also important to note that the experience of sensing often involves a more complex integration of somatosensory inputs, and may be influenced by emotional and social contexts as well[2].

Word origin: somato– from soma (body) + sensation.

Receptors[edit | edit source]

Sensory receptors are classified into five categories:

1.     Mechanoreceptors: Detects mechanical changes or deformations in tissues.

2.     Thermoreceptors: Detects changes in temperature.

3.     Proprioceptors: Detects changes to limb position (joint position sense), movement detection (kinesthesia).

4.     Pain receptors (nociceptors): Neural processing of injurious stimuli in response to tissue damage.

5.     Chemoreceptors: Detects changes and is responsive to chemical stimuli.

A single stimulus usually activates many receptors, and each receptor is capable of encoding stimulus features such as intensity, duration and direction. It is the central nervous system (CNS) which interprets the activity of the different receptors involved in the sensation and uses these interpretations to generate coherent perceptions[4].

Resources[edit | edit source]

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References[edit | edit source]

  1. Romo R, Hernández A, Salinas E, et al. From sensation to action. Behav Brain Res 2002;135:105–118.
  2. 2.0 2.1 Dunn W. Implementing neuroscience principles to support habilitation and recovery. In: Christiansen C, Baum CM, editors. Occupational Therapy: Enabling Function and Well-being. Thorofare, NJ: SLACK; 1997:182–223.
  3. Holmes NP, Spence C. The body schema and multisensory representation(s) of peripersonal space. Cogn Process 2004; 5: 94–105.
  4. Martín-Alguacil N., de Gaspar I., Schober J.M., Pfaff D.W. (2013) Somatosensation: End Organs for Tactile Sensation. In: Pfaff D.W. (eds) Neuroscience in the 21st Century. Springer, New York, NY. https://doi.org/10.1007/978-1-4614-1997-6_27.