Sensory Neuroscience

  1. Somatosensory System – The sensory system responsible for the perception of touch, pressure, pain, temperature, position, movement, and vibration, originating from muscles, joints, skin, and fascia.

  2. Cutaneous Senses – The perception of touch and pain from stimulation of the skin.

  3. Proprioception – The ability to sense the position of the body and limbs.

  4. Kinesthesis – The ability to sense movement of the body and limbs.

  5. Epidermis – The outer layer of the skin, composed of dead skin cells.

  6. Dermis – The inner layer of the skin, containing mechanoreceptors that respond to stimuli such as pressure, stretching, and vibration.

  7. Mechanoreceptors – Sensory receptors in the skin that respond to mechanical stimuli such as touch, pressure, and vibration. Four main types:

    • Merkel Receptor – Disk-shaped receptor near the epidermis/dermis border, responsible for fine touch and pressure.

    • Meissner Corpuscle – Stack of flattened disks in the dermis, detecting light touch and vibration.

    • Ruffini Cylinder – Branched fibers inside a cylindrical capsule, responding to skin stretch.

    • Pacinian Corpuscle – Onion-like capsule deep in the skin, detecting high-frequency vibrations.

  8. Temporal Response Properties – How quickly mechanoreceptors adapt to pressure:

    • Rapidly Adapting (RA) Fibers – Found in Meissner and Pacinian corpuscles, firing at stimulus onset and offset.

    • Slowly Adapting (SA) Fibers – Found in Merkel and Ruffini receptors, firing continuously while pressure is applied.

  9. Pathways from Skin to Cortex – The neural routes through which sensory information travels:

    • Medial Lemniscal Pathway – Large fibers carrying proprioceptive and touch information.

    • Spinothalamic Pathway – Smaller fibers carrying temperature and pain information.

  10. Somatosensory Cortex (S1 & S2) – Brain areas in the parietal lobe responsible for processing sensory information.

  11. Homunculus – A cortical map showing the proportion of sensory representation for different body parts.

  12. Cortical Plasticity – The brain’s ability to reorganize and adapt based on sensory experience, such as after amputation.

  13. Phantom Limb Syndrome – The perception of a missing limb’s presence, often accompanied by pain due to cortical reorganization.

  14. Gate Control Theory of Pain – A model suggesting that pain perception is regulated by a “gate” in the spinal cord that modulates nociceptive signals.

  15. Pain Matrix – A network of brain regions involved in processing pain, including the somatosensory cortex, insula, and anterior cingulate cortex.

  16. Endorphins – Neurotransmitters that act as natural painkillers by binding to opiate receptors.

  17. Placebo Effect – The phenomenon where a person experiences pain relief due to the belief that they received treatment.

  18. Haptic Perception – Active touch used to explore objects, combining sensory, motor, and cognitive systems.

  19. Taste Receptors & Pathways – The sensory system for taste, involving:

  • Five Basic Tastes – Salty, sour, sweet, bitter, and umami.

  • Chorda Tympani Nerve – Transmits taste information from the front and sides of the tongue.

  • Glossopharyngeal Nerve – Transmits taste information from the back of the tongue.

  • Vagus Nerve – Transmits taste signals from the mouth and throat.

  1. Olfactory System – The sensory system for smell, involving:

  • Olfactory Mucosa – The area in the nasal cavity containing sensory neurons.

  • Olfactory Bulb – Processes smell signals before relaying them to the brain.

  • Piriform Cortex – The primary olfactory processing area in the temporal lobe.