Thalamus

Question 1

Describe the functional categories of thalamic nuclei and note the basic differences between each category

Answer 1

A. Specific

 a. reciprocally connected to SPECIFIC cortical areas
 b. Maintenance of spatial organization

 i. sensory specific
 ii. motor specific
iii. association
 iv. limbic specific

B. Non-specific

 a. Diffuse and multimodal sensory inputs
 b. Largely non-reciprocal innervation of cortex
 c. Strong inputs from reticular formation

Question 2

Describe the anatomy and organization of the thalamic fasciculus

Question 3

Explain how the thalamus works to globally link cortical activity, including the response modes of thalamocortical relay neurons and the nature of corticothalamic connections

Question 4

Discuss the clinical result of VPL/VPM Damage

Answer 4

Contralateral hemianesthesia

Question 5

Discuss the clinical result of Lateral Geniculate Nucleus damage

Answer 5

Contralateral hemianopsia (vision)

Question 6

Discuss the clinical result of VA/VL damage

Answer 6

Contralateral Hemichorea

Question 7

Discuss the clinical result of VL damage

Answer 7

Contralateral hemitremor and hemiataxia

Question 8

Discuss the clinical result of damage to the anterior, MD, and midline nuclei

Answer 8

Retrograde/anterograde amnesia

Question 9

Discuss the clinical result of damage to the intralaminar nuclei

Answer 9

Unilateral motor neglect

Question 10

Thalamic Nuclei and their Functions

Answer 10

Anterior Group (AN) - memory
Centromedian (CM) - Modulation of basal ganglia
Medial Dorsal (MD) - attention, planning, active memory
Lateral Dorsal (LD) - spatial learning and memory
Ventral Anterior (VA) - motor relay; Basal Ganglia
Ventral Lateral (VL) - motor relay; Cerebellum
(VPM) - somatosensory and taste relay from face (trigemino)
(VPL) - somatosensory relay from the body
Pulvinar (P) - sensory integration
Lateral Posterior (LP) acts in concert with pulvinar
(MGN) - auditory relay
(LGN) - visual relay
Intralaminar Group/centromedian (CM)- attention to motor tasks

Question 11

Thalamic Nuclei and their inputs and outputs

Answer 11

Anterior Group (AN)
Medial Dorsal (MD)
Lateral Dorsal (LD)
Ventral Anterior (VA)
Ventral Lateral (VL)
(VPM)
(VPL)
Pulvinar (P)
(MGN)
(LGN)
Midline Nuclear Group
Intralaminar Group

Question 12

Name the 5 vascular territories of the Thalamus and clinical signs if damaged

Answer 12

Thalamus is supplied by PCA

PARAMEDIAN (basilar and P1) irrigate MD

• apathy
• motor neglect
• memory
• learning problems

POSTERIOR CHOROIDALS (irrigate LGN, MGN, pulvinar)
 - hemianopsia

INFEROLATERALS (irrigate VA, VL, VPM, VPL)

• ataxia
• hemianesthesia
• hemiparesis
• hemihyperesthesia

ANTERIOR (tuberothalamic of Pcomm) irrigates AN

• amnesia
• language difficulties
• mood/euphoria

5. AOP variant irrigates MD
   - bilateral MD damage that leads to abulia, apathy, low affect, very low motivated drive

Question 13

Describe Dejerine-Roussy Syndrome

Answer 13

VPL and VPM damage usually involving the inferolateral perforators

• loss of pain/temp and fine touch
• spontaneous pain as well
• exaggerated pain and temperature
• can feel suddenly really hot/cold