Thalamus Lecture Notes

Introduction

• Purpose: Discuss various nuclei of the thalamus and their functions as a relay station.
• Types of Information:
  • Limbic system information
  • Sensory information
  • Motor information
• Main Function: Relay station sending information to the cerebral cortex.

Limbic Nuclei

Anterior Thalamic Nucleus

• Function: Involved in emotional episodic memory via Papez circuit.
• Associated Disorders:
  • Alzheimer’s disease
  • Parkinson’s disease
  • Korsakoff syndrome

Papez Circuit Pathway:

1. Hippocampus → Fornix → Mammillary Bodies
2. Mammillary Bodies → Anterior Thalamic Nuclei
3. Anterior Thalamic Nuclei → Cingulate Gyrus
4. Cingulate Gyrus → Entorhinal Cortex → Hippocampus

Medial Dorsal Nucleus

• Function: Emotional memory, motivation, and drive.
• Affected by: Korsakoff syndrome (Thiamine deficiency)
• Connections:
  • Inputs: Amygdala, Hypothalamus
  • Output: Prefrontal Cortex

Centromedian Nucleus

• Function: Involved in emotional aspect of pain.
• Receives: Slow pain pathways (C fibers via spinothalamic tract)
• Sends to: Non-specific cortical areas, including the cingulate gyrus.

Sensory Thalamic Nuclei

Lateral Geniculate Nucleus

• Function: Visual pathway
• Process: Retina → Optic nerve → Lateral Geniculate Nucleus → Primary Visual Cortex (Broadman Area 17)

Medial Geniculate Nucleus

• Function: Auditory pathway
• Process: Cochlear Nuclei → Lateral Leminiscus → Inferior Colliculus → Medial Geniculate Nucleus → Primary Auditory Cortex (Broadman Areas 41, 42)

Pulvinar Nucleus

• Receives from: Medial and Lateral Geniculate Nuclei, Superior and Inferior Colliculi
• Function: Visual processing and recognition in the visual association area (Broadman Areas 18, 19)

Ventral Posterior Lateral Nucleus

• Function: Sensory information from body
• Pathways:
  • Dorsal Column Medial Leminiscus (Proprioception, fine touch)
  • Spinothalamic Tract (Pain, temperature)
• Sends to: Primary Somatosensory Cortex (Broadman Areas 3, 1, 2)

Ventral Posterior Medial Nucleus

• Function: Sensory information from face and taste sensations
• Tracts:
  • Trigeminothalamic tract
  • Central Tegmental Tract
• Sends to: Primary Somatosensory Cortex (Broadman Areas 3, 1, 2)

Motor Thalamic Nuclei

Ventral Anterior Nucleus

• Function: Initiation and planning of motor movement
• Pathway: Basal Ganglia → Thalamus → Pre-motor Cortex (Broadman Area 6)

Ventral Lateral Nucleus

• Function: Coordination and modulation of motor movement
• Inputs: Basal Ganglia, Cerebellum (via Dentate Nucleus)
• Sends to: Primary Motor Cortex (Broadman Area 4)

Conclusion

• Summary: Covered thalamic nuclei, their functions, and connections.
• Engagement: Encouragement to engage with content on different platforms and membership options.

This lecture covered the essential functions and pathways involving the thalamic nuclei, providing crucial insights into the relay roles in sensory, limbic, and motor pathways.