Last edited: 8/19/2021
11.
THALAMUS
Medical Editor: Camilla E. Fiorucci
Neurology | Thalamus Anatomy & Function
(A) LIMBIC THALAMIC NUCLEI
OUTLINE
(1) Anterior nuclei
I) ANATOMY
II) FUNCTION
III) RECAP
IV) REFERENCES
I) ANATOMY
The thalamus acts as a
relay station between the
cerebral cortex and the
subcortical areas.
Part of Papez circuit: important for emotional episodic
memory
Damage to this area causes disruption of the Papez
circuit and therefor loss of emotional episodic memory
o Leads to several diseases:
 Alzheimer’s disease
 Parkinson’s disease
 Korsakoff syndrome: caused by Thiamine (B1)
deficiency
It carries sensory and
motor information, and is
also involved in the limbic
system.
It’s an egg-shaped structure, subdivided by a white matter
structure Internal medullary lamina into 3 groups:
The 3 groups are:
o Anterior
o Lateral
o Medial
It also has a fourth group contained within the Internal
medullar lamina, called Intralaminar group.
Each group further contains different nuclei.
Papez circuit:
o Starts from Hippocampus → fornix, passing by
corpus callosum → mammillary bodies →
mammillothalamic tract → anterior thalamic nucleus
→ cingulate gyrus 1 → entorhinal cortex 2 →
perforant pathway → hippocampus
(2) Medial dorsal nucleus (or dorsomedial nucleus)
Table 1: Thalamic groups and associated nuclei
Thalamic group
Nucleus
Anterior
Anterior nucleus (AN)
Medial
Medial dorsal nucleus
(MDN)
Ventral nuclei
o Ventral anterior
nucleus (VA)
o Ventral lateral
nucleus (VL)
o Ventroposterior
lateral nucleus
(VPL)
o Ventroposterior
medial nucleus
(VPM)
o Lateral geniculate
nucleus (LGN)
o Medial geniculate
nucleus (MGN)
Lateral
Part of the Medial group
Involved with:
o Emotions, in particular the emotional aspect of
memory
o Motivation
o Drive
Damage causes changes in personality, since the patient
loses their motivation and emotional memory
o Leads to Korsakoff syndrome
Afferents of the medial dorsal nucleus:
o Olfactory cortex: found in the temporal lobe,
processes emotions related to smell
 Example: the good memory we can associate to
the smell of bacon
o Amygdala: part of the limbic system, involved with
emotions such as fear, anxiety, aggression.
o Hypothalamus: also part of the limbic system
Dorsal nuclei:
o Pulvinar
Centromedian nucleus
Parafascicular nucleus
Intralaminar
II) FUNCTION
Efferent: all this information about e motional memory,
motivation, anger and fear is sent from the medial dorsal
nucleus to the prefrontal cortex
We will be analyzing the thalamic nuclei based on their
function.
1
Part of the limbic system
THALAMUS ANATOMY AND FUNCTION
2
Part of parahippocampal gyrus
NEURO PHYSIOLOGY: Note #11
1 of 4
(3) Pulvinar
(3) Centromedian nucleus
Part of Intralaminar nuclei
It applies emotional component to pain sensation:
o It receives inputs from the slow pain pathway
(spinothalamic pathway):
 The painful stimulus is transmitted by C fibers to
the posterior grey horn of the spinal cord →
decussation → spinal lemniscus → (reticular
formations) → Centromedian nucleus →
nonspecific cortical areas
• They are called “nonspecific” because they’re
not fully understood
• One of these areas is believed to be the
Cingulate gyrus: part of the limbic system,
involved with emotions
(B) SENSORY THALAMIC NUCLEI
(1) Lateral geniculate nucleus
Most posterior nucleus of the thalamus, on the dorsal
aspect of lateral group
Afferents:
o Medial geniculate nucleus: carries auditory
information
o Lateral geniculate nucleus: carries visual information
o Superior colliculus: involved in reflexes and
coordination of movement between eyes, head and
neck starting from visual information
o Inferior colliculus: involved in reflex and coordination
of head and neck movement based on auditory
stimuli.
Efferent: Visual association areas (BA18, 19)
o The Pulvinar is involved in visual processing:
interpretation of an image in order to give it meaning
+ recognition of objects, faces, expressions...
(4) Ventroposterior lateral nucleus (VPL)
Mnemonic: L of lateral for Light = Vision
Part of visual pathway
o Visual stimulus → retina → optic nerve, in particular
the median lateral fibers → optic tract → lateral
geniculate nucleus → sends to:
 Midbrain
 Primary Visual cortex (BA17), in the occipital
lobe
(2) Medial geniculate nucleus
Mnemonic: M of medial for Music = Hearing
Part of auditory pathway
o Auditory stimulus → vestibulocochlear nerve ( CN
VIII) → cochlear nuclei in pontomedullary junction →
decussation at trapezoid body → (superior olivary
nucleus) → lateral lemniscus → inferior colliculus →
inferior brachium → medial geniculate nucleus →
 Gives rise to acoustic radiation → Primary
auditory cortex (BA41, 42), in temporal lobe
2 of 4
NEURO PHYSIOLOGY: Note #11
Afferents:
o Dorsal column – medial lemniscus pathway:
carries proprioception, fine touch and vibration sense
from the body
 Fine touch/proprioception/vibration stimulus →
posterior grey horn → fasciculus gracilis and
fasciculus cuneatus → nucleus gracilis and
nucleus cuneatus (medulla) → decussation →
VPL
o Spinothalamic tract:
 Can be further divided in:
• Anterior: carries crude touch and pressure
sensations
• Lateral: carries pain and thermic sensations
 Pain/temperature/crude touch stimulus →
posterior grey horn → decussation →
• To anterior funiculus: makes the anterior
spinothalamic tract
• To lateral funiculus: makes lateral
spinothalamic tract
• → the 2 tracts ascend and fuse together again
→ VPL
Efferent: Primary somatosensory cortex (BA3, 1, 2), in
parietal lobe
THALAMUS ANATOMY AND FUNCTION
(5) Ventroposterior medial nucleus (VPM)
(C) MOTOR THALAMIC NUCLEI
(1) Ventral anterior nucleus
Receives 2 types of information:
o All information from the face (proprioception, pain,
temperature, vibration, touch)
 Carried through trigemino-thalamic tract:
• Stimulus from the face → sensory fibers of
Trigeminal nerve (CN V) → enter the
brainstem at different level to reach the
trigeminal nuclei:
o Mesencephalic trigeminal nucleus
o Principal pontine nucleus
o Spinal nucleus of the trigeminal nerve
• From these nuclei → VPM
o Gustation:
 From the taste buds, the information is carried by
3 cranial nerves:
• Facial nerve (CN VII): receives information
from the anterior 2/3 of the tongue
• Glossopharyngeal nerve (CN IX): receives
information from the posterior 1/3 of the
tongue
• Vagus nerve (CN X): receives information
from epiglottis and oropharynx
 These 3 nerves make the Tractus Solitarius, which
arrives at the Nucleus Tractus Solitarii
(medulla) → central tegmental tract → VPM
Most anterior nucleus of the lateral group
Afferent: basal ganglia
o The Ventral anterior nucleus is involved in initiation
and planning of movement
o Its involved in enhancing or inhibiting a planned
movement, through different pathways:
 Direct pathway: enhances movement
• Cortex (premotor and primary motor areas,
mainly) → putamen → Globus pallidus
internus → ventral anterior nucleus → sends
back to cortex to perform the movement
 Indirect pathway: inhibits movement
• Cortex → putamen → Globus pallidus
externus → subthalamus → Globus pallidus
internus → ventral anterior nucleus → cortex
 An additional station can be the substantia nigra,
found in the midbrain
• Contains many dopaminergic neurons and can
promote both the direct and indirect pathway,
depending on what’s needed in a give
situation.
Efferent: the ventral anterior nucleus sends information to
Premotor cortex (BA6)
(2) Ventral lateral nucleus
Efferent: Primary somatosensory cortex (BA3, 1, 2)
2 functions:
o Coordination of motor movement
o Modulation of motor movement
Afferent:
o Basal ganglia:
 Motor cortex → basal ganglia → direct or indirect
pathway → ventral lateral nucleus → motor cortex
o Cerebellum:
 Motor cortex → dentate nucleus of cerebellum:
• This nucleus receives different types of
information: proprioception, equilibrium from
the inner ear, and from the motor cortex
o It elaborates all of them to obtain the best
movement to perform in a given situation.
 From the dentate nucleus → (red nucleus) →
ventral lateral nucleus
Efferent: Primary motor cortex (BA4), which allows us
to perform the proper movement
THALAMUS ANATOMY AND FUNCTION
NEURO PHYSIOLOGY: Note #11
3 of 4
III) RECAP
Table 2: Recap
Group
Nucleus
Anterior
Anterior
Medial
Medial dorsal
Ventral
o Ventral
anterior
o Ventral
lateral
o VPM
o VPL
Lateral
o Medial
geniculate
nucleus
o Lateral
geniculate
nucleus
Dorsal
o Pulvinar
Intralaminar
Centromedian
Afferent(s)
Mammillary bodies (MTT)
Efferent(s)
Cingulate and parahippocampal
gyrus
Prefrontal cortex
System
Limbic system
Basal ganglia, dentate nucleus
Primary motor cortex
Motor system
Basal ganglia
Premotor cortex
Motor system
Trigeminothalamic tract
Dorsal column system,
spinothalamic tract
Inferior brachium (auditory
pathway)
Primary somatosensory cortex
Primary somatosensory cortex
Sensory system
Sensory system
Primary auditory cortex
Sensory system
Optic tract
Primary visual cortex
Sensory system
Medial geniculate nucleus
Lateral geniculate nucleus
Superior colliculus
Inferior colliculus
Spinothalamic pathway
Visual association area
Sensory system
Nonspecific areas (cingulate
gyrus)
Limbic system
Olfactory cortex
Amygdala
Hypothalamus
IV) QUESTIONS
1) Question 1: regarding the Papez circuit?
a) It’s important for emotional episodic memory
b) It passes through the caudate nucleus
c) It passes through the Pulvinar
2) Question 2: what is the function of the medial dorsal
nuclei?
a) Coordination and Modulation of motor movements
b) Contains the emotional aspect of memory and is
involved in a person’s drive and motivation
c) Applies an emotional component to pain sensations
Limbic system
a) Pulvinar
b) Ventral anterior nucleus
c) Lateral geniculate nucleus
V) REFERENCES
● Drake, Richard L, Wayne Vogl, Adam W. M. Mitchell, and
Henry Gray. Gray's Anatomy for Students. Philadelphia:
Elsevier/Churchill Livingstone, 2005. Print.
3) Question 3: which of the following is part on the
Central Visual pathway?
4 of 4
NEURO PHYSIOLOGY: Note #11
THALAMUS ANATOMY AND FUNCTION