The thalamus is a midline paired structure in the brain that relays sensory and motor signals to the cerebral cortex. It contains several nuclei that subserve different functions. The ventral posterior nuclei relay sensory information from the body and face. The ventral anterior and ventral lateral nuclei are major motor relay nuclei. The medial geniculate and lateral geniculate bodies relay auditory and visual information respectively. Damage to specific nuclei causes localized neurological deficits, while more widespread damage can impact functions like arousal, memory and behavior.

2.  Thalamus
 Ventral thalamus/subthalamic nucleus
 Epithalamus/pineal body
 Hypothalamus

6.  Midline paired structure within brain –gray
matter
 Between cerebral cortex and brain stem
 Sends fibres out to cerebral cortex in all
directions
 Main largest product of embryonic diencephalon
 Great sensory gateway to cerebral cortex

7.  Last major relay station for all ascending impulses
(except olfactory) before they continue via
thalamocortical fibers to the cortex
 Cutaneous sensory receptors
 Visceral sensory receptors
 Visual impulses
 Auditory impulses
 Impulses from the hypothalamus
 Impulses from the cerebellum
 Impulses from the brainstem reticular formation
 Nuclei and projections maintain somatotopic
organization

11.  External medullary lamina separates the thalamus from the internal
capsule
 Reticular nucleus is a thin layer of cells closely applied to the external
medullary lamina
 Internal medullary laminae divides the thalamus into 3 major regions
 Anterior nuclei sit in the angle of the Y
 Ventrolateral nuclei laterally
 Ventral nuclei: ventral anterior (VA), ventral lateral (VL), ventral posterolateral (VPL)
and ventral posteromedial (VPM)
 Lateral nuclei: lateral dorsal and lateral posterior
 Medial nuclei medially
 Pulvinar lies caudally with medial and lateral geniculate bodies attaching to
underside
 The three major groups have been divided into 120 smaller nuclei
 Interlaminar nuclei and centromedian nucleus lie within the internal
medullary laminae

15.  Relay thalamic nuclei
 Association thalamic nuclei
 Nonspecific thalamic nuclei

16.  VPL
 VPM
 VA
 VL
 LGB
 MGB

17.  Pulvinar
 LP
 LD
 DM/MD

18.  Intralaminar
 Reticular
 Midline

21. Ventral Posterolateral and
Ventral Posteromedial Nuclei
• Fibers ascending in the medial
lemniscus, spinothalamic tract and
trigeminothalamic tract terminate
in a relay station in the
ventroposterior nuclear complex
• Medial lemniscus/lateral
spinothalamic tract  VPL
• Trigeminal afferents  VPM
• Gustatory fibers from the nucleus
of the tractus solitarius  medial
tip of the VPM  postcentral
region overlying the insula
VPL/VPM then project fibers to the
somatosensory cortex

22. Damage to VPL & VPM
Hemianesthesia to all sensory modalities
(light touch, conscious proprioception, 2-
point discrimination, vibration, pain and
temperature).
After recovery, patients may have
hyperalgesia or causalgia.

24. Ventral Anterior and Ventral
Lateral
Major motor relay nuclei. Receive
inputs from the cerebellum and
basal ganglia.
Dentate nucleus and red nucleus 
dentatothalamic tract  VL
nucleus  motor cortex
Globus pallidus  VA nucleus 
premotor cortex

25. Medial and Lateral
Geniculate Bodies
Specific thalamic nuclei
Optic tract  LGB 
optic radiation  visual
cortex
Damage causes a
contralateral
homonymous
hemianopsia.
Auditory impulses via
lateral lemniscus  MGB
 auditory radiation 
auditory cortex

27. Anterior nucleus
• Mammillothalamic tract connects the
anterior nuclear group with the mamillary
body, which is linked to the hippocampus
and entorhinal cortex.
Along with the fornix, binds anterior thalamic
nuclei into the neural system that
subserves learning and memory
• Contains bidirectional, point-to-point
connections with the cingulate gyrus, thus
making it an integral part of the limbic
system
Relays visceral and emotional information to
the limbic system structures.

28. Medial nucleus
• Contains connections with the association areas of
the frontal lobe and the premotor region.
• The ventral amygdalofugal pathway links the
amygdala with the medial part of MD, and damage
may therefore contribute to amnesia as well as to
emotional dysregulation
• Receives input from other thalamic nuclei,
hypothalamus, midbrain nuclei and globus pallidus.
• Receives pain afferents from the LSTT and the TTT,
projects to the frontal lobe and is involved the the
pain response.
• Visceral impulses reach the medial nucleus by way of
the hypothalamus influencing the affective state of an
individual (sense of well-being, uneasiness, good/bad
mood)
• Also receives olfactory inputs from the primary
olfactory cortex after they have been to the cortex and
then relays them to the insular and orbitofrontal
cortex.
• Damage causes frontal brain syndrome with
personality change (loss of self-representation)

29. Pulvinar
• Reciprocal, point-to-point connections with the
association areas of the parietal, temporal and
occipital lobes.
• Connects to the secondary visual areas and
aids in stimulus location.

31. Intralaminar nuclei and
Centromedian Nucleus
Located within the internal medullary lamina
Non-specific nuclei
• Receive afferent input through ascending
fibers from the brainstem reticular formation
and the emboliform nucleus of the
cerebellum as well as from the internal
pallidal segment and other thalamic nuclei.
• Project to the caudate, putamen and globus
pallidus.
• Play a role in autonomic drive
Centromedian nucleus
• Thalamic portion of the ascending reticular
activating system
• Connections with the motor system and the
basal ganglia

32. Reticular nucleus
• Surrounds the thalamus and conveys afferents from the cortex into
the thalamus
• Regulate sleep wake cycles
• Critical for arousal and attention
• Diffuse projections to all other thalamic nuclei
• Does not project to the cortex

35.  Polar artery
 PCOM branch
 Supplies the rostral thalamus
 Posterior thalamoperforating artery
 PCA branch
 Supplies basal and medial thalamus and the pulvinar
 May share a common trunk called the artery of Percheron
 Thalamogeniculate artery
 PCA branch
 Supplies the lateral thalamus
 Medial and lateral posterior choroidal arteries
 PCA branch
 Supply the geniculate bodies, medial and posteromedial
thalamic nuclei and the pulvinar

36.  Typically accompanied by other deficits because
the thalamus is immediately bounded by the
internal capsule and is in close proximity to the
deep motor nuclei of the cerebral hemisphere
(putamen, caudate and globus pallidus).
 Small branches of the PCAs supply much of the
thalamus, therefore selective lesions do occur..

37.  Supplies
 Reticular nucleus
 VA nucleus
 Rostral VL nucleus
 Ventral pole of the MD nucleus
 Mamillothalamic tract
 Ventral amygdalofugal pathway
 Ventral part of the internal medullary lamina
 Anterior thalamic nuclei

38.  Severe and wide-ranging neuropsych deficits
 During early infarction, patients will exhibit fluctuating
levels of consciousness and appear withdrawn
 Persistent personality changes include disorientation in
time and place, euphoria, lack of insight, apathy, and lack of
spontaneity
 Patient often have impairment of recent memory,
impairment of new learning, and temporal
disorientation
 More prominent with left sided lesions
 Represents a disconnection between anterior thalamic
nuclei and hippocampal formation due to disruption of the
mamillothalamic tract between the amygdala and the
anterior nuclei by damage to the amygdalothalamic
projections passing through the internal medullary lamina

39.  Language disturbances (left hemisphere lesions)
 Anomia with decreased verbal output and impaired
fluency
 Impairment of comprehension
 Fluent paraphasic speech that may be hypophonic and
lacking content
 Reading may be preserved, but reading comprehension
may be poor
 Repetition is well preserved

40.  Acalculia (left thalamic lesion)
 Visual spatial processing, visual memory deficits
and hemispatial neglect (right thalamic lesion)
 Other:
 “Emotional central facial paralysis” – volitional facial
movements are intact, but asymmetry is noted during
laughing, crying, etc…
 Constructional apraxia
 Mild/moderate contralateral weakness or clumsiness

41.  Supplies
 Dorsomedial nucleus
 Internal medullary lamina
 Intralaminar nuclei including the centromedian
nucleus
 Paraventricular nuclei
 Posteromedial part of the VL
 Ventromedial part of the pulvinar

42.  Unilateral infarction produces neuropsych
disturbances in the areas of arousal and memory
 Confusion, agitation, aggression and apathy may persist
 Bilateral infarction may result in disorientation,
confusion, hypersomnolence, deep coma, “coma
vigil” or akinetic mutism and severe memory
impairment
 Agitation, dysphoria or acute confusion
 Loss of autobiographical memory, but sparing of
knowledge of famous people and public events has
been reported

43.  Supplies
 External MGN
 Ventral posterior nuclei (VPL, VMP, VPI)
 Ventral and lateral VL nucleus
 Rostral and lateral pulvinar
 LD nucleus

44.  Sensory loss with impaired extremity movement and
sometimes post-lesion pain due to variable involvement of
the VPM or VPL
 Sensory loss with ataxic hemiparesis is strongly
indicative a thalamic lesion in this area
 Ataxia due to VL regions conveying cerebellar fibers to
the motor cortex
 Thalamic pain syndrome
 Thalamic hand – flexed and pronated with the
thumb buried beneath the other fingers

45.  Subthalamic nucleus
 Midbrain
 MGN
 LGN
 Posterior intralaminar nuclei CM and CL
 Pulvinar

46.  Limited evidence, but lesions may include
 Visual deficits (quadrantanopsia)
 Hemisensory deficits
 Aphasia
 Memory deficits
 Ataxia
 Tremor
 Dystonia

47.  https://jneuro.wordpress.com/2016/03/06/the
-thalamus-of-secrets/
 Secrets of thalamus