Somatosensation

Overview

• Somatosensation refers to the body's ability to sense different types of sensations from the environment.
• These sensations include information on:
  • Type of sensation
  • Intensity
  • Timing
  • Location

Types of Sensations

1. Thermoception

   • Sensation of temperature (e.g., hot or cold).

2. Mechanoception

   • Sensation of pressure (e.g., foot on the ground, force from an object).

3. Nociception

   • Sensation of pain (e.g., from a peck or injury).

4. Proprioception

   • Awareness of the body’s position in space.

Intensity of Stimuli

• Intensity is encoded by the rate of neuron firing.
• High-intensity stimuli result in rapid neuron firing.
• Example:
  • It’s very hot → Neurons fire more frequently than when it’s mildly hot.

Timing of Stimuli

• Timing helps determine when a sensation starts and stops.
• Types of Neuronal Responses:
  • Non-adapting Neurons
    • Consistent firing rate throughout the duration of the stimulus.
  • Slow Adapting Neurons
    • Fire rapidly at the onset, then slow down over time.
  • Fast Adapting Neurons
    • Fire at the start and end of a stimulus.

Location of Stimulus

• Location of sensation is determined by dermatomes.
• Each body part is innervated by specific nerves that send signals to the brain.
• Example:
  • A bird pecking an arm → Nerves from the arm send information to the brain.

Example Scenarios

• Scenario 1: Superhero Collision
  • Senses Activated:
    • Pressure: Due to the impact.
    • Pain: From the collision.
    • Proprioception: Due to change in body position.
  • Intensity:
    • High intensity – Neurons fire rapidly.
  • Timing:
    • Non-adapting neurons: Fire throughout contact.
    • Fast-adapting neurons: Fire at the start and end of contact.
    • Slow-adapting neurons: Fire throughout contact but slow over time.
  • Location:
    • Torso and possibly arms involved.
    • Nerves send signals of pressure, pain, and positional changes to the brain.