Thalamic Connections Mnemonic

Structure of Thalamus

A vertical “Y” shaped white mater – internal medullary lamina divides thalamus into:

1. Anterior nuclear groups
2. Medial nuclear groups
3. Lateral nuclear groups

In anatomical position:

• Dorsal surface of brain: faces towards sky
• Ventral surface of brain: faces towards floor

Pulvinar = Posterior end or posterior pole of thalamus

Thalamic Connections

Picture mnemonic

Remember the schematic diagram drawn below showing important parts of thalamus in an anticlockwise fashion:

1. Anterior nucleus
2. Ventral nuclear group:
   • Anterior
   • Lateral
   • Posterior
     • Medial
     • Lateral
3. Lateral and Medial geniculate body
4. Medial-Dorsal nucleus

Now, we assign alphabets “A, B, C, D, E, F” sequentially to these important structures in anticlockwise fashion starting from anterior nucleus.

“A” for Anterior nucleus

A for:

• Alertness
• Attention
• Affect
• Acute memory

These are the functions of limbic system – Papez circuit:

• Afferent: Mamillary body
• Efferent: Cingulate gyrus

“B” for Ventral-anterior nucleus

B for: Basal ganglia

• Afferent: Globus pallidus and Substantia nigra
• Efferent: Brodmann Area 6 (Prefrontal and premotor cortex)

“C” for Ventral-lateral nucleus

C for: Co-ordination and Cerebellum

• Afferent: Cerebellum (Dentate nucleus) and Basal ganglia
• Efferent: Brodmann Area 4 (Primary motor cortex)

“D” for Ventral-Posterior nucleus

D for: Dermatome (Sensory)

• Afferent:
  • Ventro-postero-medial (VPM) nucleus: Trigemino-thalamic tract, Solitario-thalamic tract
    • Medial = Mask (face)
    • Taste (Nucleus tractus solitarius)
  • Ventro-postero-lateral (VPL) nucleus:
    • Lateral = Limbs
    • Spinothalamic tract
    • Medial lemniscus
• Efferent:
  • Brodmann Area 3, 1, 2 (Sensory cortex)

Thalamic pain syndrome: Involvement of primary somatosensory thalamic nucleus (ventral posterior lateral [VPL]/ventral posterior medial thalamus [VPM]) and the anterior pulvinar, a major spinothalamic target gives rise to thalamic pain syndrome. Approximately 25% of patients with a sensory stroke due to a thalamic lesion will develop central post-stroke pain. Thalamic pain is a severe, treatment-resistant pain syndrome. The pain is often described as burning or constrictive and is frequently accompanied by evoked pain (allodynia/hyperalgesia), paresthesias, or summation hyperpathia. 1http://www.ahcmedia.com/articles/137528-thalamic-pain-who-is-likely-to-develop-this-disorder

“E” for Geniculate Bodies

E for: Eyes and Ears

• Lateral geniculate body = Light (Eyes)
  • Afferent: Optic tract
  • Efferent: Primary visual cortex (Area 17)
• Medial geniculate body = Music (Ears)
  • Afferent: Inferior colliculus
  • Efferent: Primary auditory cortex (Area 41, 42)

“F” for Medial-Dorsal Nucleus

F for: Feelings (Limbic system)

• Afferent:
  • Amygdala
  • Olfactory cortex
• Efferent:
  • Prefrontal cortex
  • Limbic system

Thiamine deficiency in alcoholics (Wernicke-Korsakoff syndrome) results in degeneration of the medial-dorsal nucleus of thalamus, mamillary bodies, hippocampus and vermis of cerebellum.

Other mnemonics:

1. Lateral geniculate nucleus (LGN) = Light (Visual pathway)
2. Medial geniculate nucleus (MGN) = Music (Auditory pathway)
3. Ventral postero-lateral nucleus (VPL) = Very Painful Limbs (Spinothalamic tract and Dorsal column)
4. Ventral postero-medial nucleus (VPM) = Very Painful Mouth (Trigeminal and Gustatory pathway)
5. Ventrolateral nucleus (VL) = Victory Lap (Motor)
6. Dorsomedial nucleus (DMN) = Dog’s Memory and Nose (Memory, smell and emotions)