Physiology of thalamus

PHYSIOLOGY OF THALAMUS
Dr. REVAND R.
IMS-BHU
Varanasi

At the end of the class students will be able to
• Point out the location of thalamus in the brain
• Classify the various nuclei present in the thalamus
• Describe the afference and efference to various thalamic nuclei along
with their functions
• Clinically comprehend lesions involving thalamus

Clinical case 1:
A 60 years of age gentleman with hypertension was seen in the
emergency department, having apparently suffered a stroke. A
neurologist was called and made a complete examination of the
patient. The patient was conscious and was unable to feel any
sensation down the right side of his body. There was no evidence of
paralysis on either side of the body, and the reflexes were normal. The
patient was admitted to the hospital for observation.
On examination gaze was restricted and the eyes were pointing
towards the tip of the nose. CT brain was taken and it is provided below

Clinical case 1: (continued)
Three days later, the patient appeared to be improving, and there was
evidence of return of sensation to the right side of his body. The patient,
however, seemed to be excessively sensitive to testing for sensory loss. On
light pinprick on the lateral side of the right leg, the patient suddenly
shouted out because of excruciating burning pain, and he asked that the
examination be stopped. Although the patient experienced very severe pain
with the mildest stimulation, the threshold for pain sensitivity was raised,
and the interval between applying the pinprick and the start of the pain was
longer than normal; also, the pain persisted after the stimulus had been
removed. What is wrong with the patient?

BRAIN
PROSENCEPHALON
(FOREBRAIN)
RHOMBENCEPHALON
(HINDBRAIN)
MESENCEPHALON
(MIDBRAIN)
DIENCEPHALON
TELENCEPHALON
(CEREBRUM)
HYPOTHALAMUS
THALAMUS
MEDULLA
PONS

• Oval shaped
• Gray matter located deep
inside the cerebral cortex
• Collection of nuclei (neuron cell
bodies in CNS)
• Main relay centre for tracts to
and fro the cerebral cortex
• Thalamus receives sensory
communications from opposite
side of the body

• Two thalami one in each
cerebral hemisphere
• Located above the brainstem
• Located on either side of the
third ventricle
• Anteriorly – Massa
intermedia
• Posteriorly – widely
separated

CLASSIFICATION OF THALAMIC NUCLEI
ANATOMICAL
CLASSIFICATION
PHYSIOLOGICAL
CLASSIFICATION
Gray matter of thalamus is divided by a Y-shaped
white matter band Internal medullary lamina

ANATOMICAL CLASSIFICATION OF THALAMIC NUCLEI
ANTERIOR GROUP MEDIAL GROUPLATERAL GROUP
INTRALAMINAR
MIDLINE
DORSOMEDIAL

ANATOMICAL CLASSIFICATIONOFTHALAMIC NUCLEI
ANTERIORGROUP MEDIALGROUPLATERALGROUP
INTRALAMINAR
MIDLINE
DORSOMEDIAL

LATERAL GROUP OF NUCLEI
VENTRAL GROUP DORSAL GROUPGENICULATE BODIES
PULVINAR
LATERAL POSTERIOR
LATERAL DORSAL
MEDIAL
GENICULATE BODY
LATERAL
GENICULATE BODY
VENTRAL POSTERIOR
VENTRAL LATERAL
VENTRAL ANTERIOR
MEDIAL (VPM)
LATERAL (VPL)

THALAMIC NUCLEI
PULVINAR
LATERAL POSTERIOR
LATERAL DORSAL
MGB
LGB
VP
VL
VA
VPM
VPL
INTRALAMINAR
MIDLINE
DORSOMEDIALVENTRAL DORSALGENICULATE BODY

CLASSIFICATION OF THALAMIC NUCLEI
ANATOMICAL
CLASSIFICATION
PHYSIOLOGICAL
CLASSIFICATION
SPECIFIC
PROJECTION NUCLEI
NON SPECIFIC
PROJECTION NUCLEI
SENSORY RELAY
NUCLEI
INTEGRATIVE
FUNCTIONS NUCLEI
MOTOR
FUNCTIONS NUCLEI

How to remember?
• All medial group of nuclei are non specific projection nuclei
• In lateral group of nuclei
All dorsal group of nuclei are integrative functions nuclei
All ventral group of nuclei are sensory relay nuclei except
ventral lateral and ventral anterior
Both geniculate bodies are sensory in functions
• Ventral lateral, ventral anterior and anterior group of nuclei are
concerned with motor functions

THALAMIC NUCLEI
PULVINAR
LATERAL POSTERIOR
LATERAL DORSAL
MGB
LGB
VP
VL
VA
VPM
VPL
INTRALAMINAR
MIDLINE
DORSOMEDIALVENTRAL DORSALGENICULATE BODY
Motor
Sensory
Integrative
Non-specific

Sensory connections of thalamus
MGB
LGB
VPM
VPL
Somatosensory
cortex
Area 3, 1, 2
Visual cortex
Area 17
Auditory cortex
Area 41
Touch, pressure, vibration, pain, temperature
etc., from contralateral half of the body (medial
lemniscus)
etc., from contralateral half of the face
(trigeminal lemniscus)
Visual impulses via optic tract
Auditory impulses via fibres from inferior
collicului

Motor connections of thalamus
VL
VA
ANT
Cingulate gyrus
Area 24
Pre-motor cortex
Area 4, 6
Mammillary body of hypothalamus
via PAPEZ CIRCUIT
Basal ganglia
Basal ganglia + Cerebellum

Integrative connections of thalamus
PULV
LP
LD
Integrate language
functions
Integrate visual, auditory
and somatic information
Parietal cortex and other thalamic
nuclei
Parietal, occipital and temporal
cortex and other thalamic nuclei

Non-specific connections of thalamus
IL
MID
DM
Cerebral cortex
and other
thalamic nuclei
(diffuse)
Cerebral cortex and other thalamic
nuclei (diffuse)
Reticular formation
(alertness and consciousness)

MGB
LGB
VPM
VPL
Somatosensory
cortex
Area 3, 1, 2
Visual cortex
Area 17
Auditory cortex
Area 41
lemniscus)
collicului
VL
VA
ANT
Cingulate gyrus
Area 24
Pre-motor cortex
Area 4, 6
via PAPEZ CIRCUIT
Basal ganglia
PULV
LP
LD
Integrate language
functions
nuclei
IL
MID
DM
Cerebral cortex
and other
thalamic nuclei
(diffuse)
nuclei (diffuse)
Reticular formation

MGB
LGB
VPM
VPL
Somatosensory
cortex
Area 3, 1, 2
Visual cortex
Area 17
Auditory cortex
Area 41
lemniscus)
collicului
VL
VA
ANT
Cingulate gyrus
Area 24
Pre-motor cortex
Area 4, 6
via PAPEZ CIRCUIT
Basal ganglia
PULV
LP
LD
Integrate language
functions
nuclei
IL
MID
DM
Cerebral cortex
and other
thalamic nuclei
(diffuse)
nuclei (diffuse)
Reticular formation
Touch, pressure, vibration, pain, temperature, two
point discrimination, tactile localisation,
stereognosis, proprioception from the contralateral
side of the body
Vision
Audition
Recent memory and emotions
Tremors, involuntary movements,
tone, voluntary motor coordination
Vision
Audition
Language and
speech
Sleep, alertness,
consciousness, EEG
pattern

Thalamic phantom limb – due to loss of
kinaesthesia (proprioception)

Clinical case 1: Discussion
A 60 years of age gentleman with hypertension was seen in the emergency
department, having apparently suffered a stroke. A neurologist was called and made a
complete examination of the patient. The patient was conscious and was unable to feel any
sensation down the right side of his body. There was no evidence of paralysis on either side
of the body, and the reflexes were normal. The patient was admitted to the hospital for
observation.
Three days later, the patient appeared to be improving, and there was evidence of
return of sensation to the right side of his body. The patient, however, seemed to be
excessively sensitive to testing for sensory loss. On light pinprick on the lateral side of the
right leg, the patient suddenly shouted out because of excruciating burning pain, and he
asked that the examination be stopped. Although the patient experienced very severe pain
with the mildest stimulation, the threshold for pain sensitivity was raised, and the interval
between applying the pinprick and the start of the pain was longer than normal; also, the
pain persisted after the stimulus had been removed.

Hyper intensities in the left thalamus region
suggestive of left thalamic haemorrhage

“Eyes peering at the tip of the nose”
sign of thalamic haemorrhage

Left thalamic haemorrhagic stroke involving
thalamo-striate branch of posterior cerebral
artery (most common)
followed by
Dejerine – Roussy syndrome (or)
Analgesia dolorosa (or)
Central post-stroke pain syndrome (or)
Thalamic syndrome
Rewiring of the touch fibres in the
thalamus that were damaged due to
stroke into pain fibres due to cortical
plasticity leading to allodynia or
hyperalgesia
Clinical case 1: Diagnosis

Physiology of thalamus

Recommended

Recommended

More Related Content

What's hot

What's hot (20)

Similar to Physiology of thalamus

Similar to Physiology of thalamus (20)

Recently uploaded

Recently uploaded (20)

Physiology of thalamus