Lecture Notes: Somatosensory Homunculus

Introduction

• Maps as Representations
  • Digital maps on cell phones represent real world areas.
  • The brain has a similar map of the body called the somatosensory homunculus.

Brain's Representation of the Body

• The brain contains a map of the body known as the somatosensory homunculus.
• Focus on the cortex, specifically the sensory strip.

Sensory Strip

• Located in the cortex.
• Receives sensory inputs from the entire body (e.g., pain, heat).
• Information from the body travels through the spinal cord to the sensory strip.

Somatosensory Homunculus

• Definition: A map of the body in the brain.
• Specific areas in the sensory strip correspond to specific body parts:
  • Fingers: Specific areas in the sensory strip for each finger.
  • Hand & Wrist: Different areas map to palm, wrist, etc.
  • Foot & Toes: Located in another area.
  • Face: Region for lips, eyes, etc.

Application in Neurosurgery

• Brain Tumor Example:
  • Surgeons use electrodes to stimulate parts of the cortex.
  • Stimulation gives the patient sensation in corresponding body parts.
  • Helps ensure sensory areas are not removed during surgery.

Importance of Mapping

• Ensures preservation of sensation by identifying critical areas.
• Potential Loss of Sensation:
  • Removing a mapped area can result in loss of sensation for that body part.

Summary

• The sensory homunculus is a topological map of the body within the cortex.
• This mapping allows distinct body parts to be represented in specific areas of the sensory strip.
• Understanding this map is crucial for procedures like neurosurgery to avoid sensory deficits.