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== Introduction to the Thalamus ==
== Thalamus Structure ==
[[File:Thalamus.gif|400x400px|alt=|thumb|Rotation: brainstem and thalamu]]The thalamus is located medial to the cerebrum.  It is a pair of egg-shaped structures which functions as a relay station for motor and sensory information moving out and into the CNS. Motor pathways, [[Limbic System|limbic]] pathways, and sensory pathways (with the exception of olfaction) pass through this central structure.
[[File:Brain stem and thalamus.jpeg|thumb|The thalamus is located centrally in the brain, just above the brainstem.]]The thalamus is located medial to the cerebral hemispheres and consists of two oval-shaped masses connected by the intermediate mass. Each mass consists of several groups of nuclei that serve different functions. Motor and sensory pathways (except olfaction) pass through this central structure.


* The thalamus transmits 98 percent of sensory information to the cortex, including vision, taste, touch and [[balance]].
The thalamus can be divided into approximately 60 regions known as '''thalamic nuclei'''. Each nucleus has unique pathways as inputs and various projections as outputs, most of which send information to the '''[[Cerebral Cortex|cerebral cortex]]'''.<ref name=":1">Torrico TJ, Munakomi S. [https://www.ncbi.nlm.nih.gov/books/NBK542184/ Neuroanatomy, Thalamus]. [Updated 2023 Jul 24]. In: StatPearls [Internet].</ref>
* The thalamus also conducts motor signals from the cerebral cortex to the spinal cord and ultimately to the peripheral nervous system.
* The thalamus also functions to relay information from the [[Brainstem|brain stem]] to the cortex, coordinating shifts in consciousness such as waking up and falling asleep.<ref name=":0">Halassa, M.M., Kastner, S. Thalamic functions in distributed cognitive control. ''Nat Neurosci, 2017;'' 20, 1669–1679. </ref>


The thalamus can be divided into approximately 60 regions known as '''thalamic nuclei'''. Each nucleus has unique pathways as inputs and various projections as outputs, most of which send information to the '''[[Cerebral Cortex|cerebral cortex]]'''.<ref name=":1" />
=== Hypothalamus ===


== Thalamic Function ==
* Located inferior to the thalamus
[[File:Thalamus connections.jpg|right|frameless|400x400px]]
* Two rounded eminences protrude from the back, called '''mammillary bodies'''
The thalamus is part of the [[Limbic System|limbic system]], the region of the brain largely associated with the emotions and is essential to memory and learning.
* Anteriorly, the hypothalamus is connected to the pituitary gland by a long stalk called the '''infundibulum''', also known as the '''pituitary stalk'''


The thalamus joins a series of other machinery whose purpose is to distill sensory information into a more interpretable and manageable form before transmitting it to higher brain areas.  
The hypothalamus plays a major role in maintaining homeostasis via the [[Autonomic Nervous System|autonomic nervous system]], the [[Endocrine System|neuroendocrine system]], and the [[Limbic System|limbic system]]. It regulates emotions, hormone production from the pituitary gland, and bodily functions such as appetite, body temperature, reproduction, and circadian rhythms.


* The thalamus is engaged in an intimate relationship with the cerebral cortex, with numerous mutual connections. These connections make up the '''thalamacortical loop'''.
=== Epithalamus ===
* The thalamus also modulates arousal mechanisms, maintains alertness, and directs attention to sensory events.<ref name=":0" />


* Located behind the thalamus
* Includes the '''pineal gland''', which secretes the hormone melatonin in response to darkness, regulating our circadian rhythms and sleep-wake cycles


Functionally, the thalamus divides into five major functional components:
=== Subthalamus ===
# '''Reticular and intralaminar nuclei''' dealing with arousal and pain regulation.
 
#* The reticular formation is constantly making intelligent guesses as to what sensory object is generating these activation patterns.  
* Located beneath the thalamus
#* The intralaminar circuit compares these pattern guesses with similar patterns in memory.  
* Includes the '''subthalamic nucleus''', which is functionally considered part of the [[Basal Ganglia|basal ganglia]]
#* All these circuits cooperate to produce a coherent framework for the interpretation of incoming sensory data.
 
# '''Sensory nuclei''' regulating all sensory domains, except olfaction
== Function of the Thalamus ==
# '''Effector nuclei''' governing motor language function
<blockquote>The '''thalamus''' functions as a relay station between the brain and the body, filtering through various types of sensory and motor information.</blockquote>[[File:Brain cross section with subcortical structures.jpeg|thumb|500x500px|Note the central location of the thalamus in relation to other subcortical structures and the cerebral cortex.]] 
# '''Associative nuclei''' connoting cognitive functions
 
# '''Limbic nuclei''' managing mood and motivation<ref name=":1">Torrico TJ, Munakomi S. Neuroanatomy, Thalamus. [Updated 2023 Jul 24]. In: StatPearls [Internet].</ref>
* The thalamus has many connections with the cerebral cortex,<ref name=":1" /> which are known as '''thalamacortical loops'''
These specific nuclei are responsible for scanning the cerebral cortex and determining active brain regions then relaying this information to the rest of the thalamus.<ref name=":0" />  
* It transmits nearly all sensory information to the cortex, including vision, taste, touch and balance, but excludes olfactory information
* It conducts motor signals from the cerebral cortex to the spinal cord and ultimately to the peripheral nervous system
* The thalamus also modulates arousal mechanisms, maintains alertness, and directs attention to sensory events<ref name=":0">Halassa, M.M., Kastner, S. Thalamic functions in distributed cognitive control. ''Nat Neurosci, 2017;'' 20, 1669–1679. </ref>
* The thalamus has connections with a number of structures of the [[Limbic System|limbic system]], including the hippocampus, mammillary bodies, and fornix, so it has a role in learning and episodic memory<ref name=":1" />


== Thalamus and Injury ==
[[File:4-physical-activity-for-disabled-adults.jpeg|right|frameless]]
The thalamus contributes to a broad range of critical functions therefore injury to the thalamus can present clinical signs and symptoms unique to each individual.


'''Some of the most common symptoms of thalamic damage or dysfunction include:'''
The thalamus can be divided into five major functional components.<ref name=":1" />
* Sensory issues such as tingling, numbness, hypersensitivity, and [[Pain Behaviours|pain]]
# '''Reticular and intralaminar nuclei''': involved in arousal and pain regulation
* Vision loss or light sensitivity
# '''Sensory nuclei''': regulate sensory domains, apart from olfaction
* Motor impairments
# '''Effector nuclei''': govern motor and language functions
* Tremors
# '''Associative nuclei''': involved in cognitive functions
* Attention problems
# '''Limbic nuclei:''' manage mood and motivation
* Memory loss
These specific nuclei help to scan the cerebral cortex and determine active brain regions, relaying this information to the rest of the thalamus.<ref name=":0" />
* Insomnia
* Impairments to proprioception


== Thalamus and Injury ==
The thalamus is involved in many critical functions and injury to the thalamus can cause a range of issues, including:
* sensory issues (e.g. pain, paraesthesia, numbness, hypersensitivity)
* vision impairment and light sensitivity
* motor impairment
* tremor
* issues with attention
* memory impairment
* sleep difficulties
* proprioception impairment


'''Additional presentations unique to thalamic injury involve''':


* '''Thalamic pain syndrome''': an excruciating sensation of pain unresponsive to narcotics. Once called Dejerine-Roussy Syndrome, this condition is commonly associated with infarct affecting the ventroposterolateral thalamus <ref>Jahngir MU, Qureshi AI. [https://www.ncbi.nlm.nih.gov/books/NBK519047/ Dejerine roussy syndrome]. 2023.In: StatPearls [Internet]. </ref> <ref>Dydyk AM, Munakomi S. [https://www.ncbi.nlm.nih.gov/books/NBK554490/ Thalamic Pain Syndrome].[Updated 2023 Aug 13]. StatPearls [Internet]. Treasure Island (FL): StatPearls Publishing. 2023.</ref>.
'''The following presentations are unique to thalamic injury''':
* [[Pusher Syndrome|'''Pusher Syndrome''']] (also referred to as "persons who push"): a lesion to the posterior thalamus interrupts a connection to the vestibular nuclei, leading to lateropulsion in the direction of the impaired side. <ref>Rosenzopf H, Klingbeil J, Wawrzyniak M, Röhrig L, Sperber C, Saur D, Karnath HO. [https://academic.oup.com/brain/article-abstract/146/9/3648/7082493?redirectedFrom=fulltext&login=false Thalamocortical disconnection involved in pusher syndrome.] Brain. 2023;146(9):3648-3661.</ref>
* '''Vegetative state and coma''': a lesion to the non-specific (intralaminar and reticular) nuclei. <ref>Adams JH, Graham DI, Jennett B. [https://academic.oup.com/brain/article/123/7/1327/380151?login=false The neuropathology of the vegetative state after an acute brain insult.] Brain. 2000 Jul;123 (Pt 7):1327-38.</ref> Coma may occur due to the thalamus's impacts on sleep and arousal.


== Physiotherapy Treatment ==
* '''thalamic pain syndrome''': an excruciating sensation of pain that does not respond to narcotics. Once called Dejerine-Roussy Syndrome, this condition is commonly associated with infarction of the ventroposterolateral thalamus.<ref>Jahngir MU, Qureshi AI. [https://www.ncbi.nlm.nih.gov/books/NBK519047/ Dejerine roussy syndrome]. 2023.In: StatPearls [Internet]. </ref> <ref>Dydyk AM, Munakomi S. [https://www.ncbi.nlm.nih.gov/books/NBK554490/ Thalamic Pain Syndrome].[Updated 2023 Aug 13]. StatPearls [Internet]. Treasure Island (FL): StatPearls Publishing. 2023.</ref>
Treatment for thalamic damage will revolve around restoring the abilities lost after brain injury. Treatment is symptom specific, therefore thorough and ongoing therapy assessment is required for proper management and treatment.  
* [[Pusher Syndrome|'''Pusher syndrome''']] (also referred to as "persons who push"): a lesion to the posterior thalamus interrupts the connection to the vestibular nuclei, leading to lateropulsion in the direction of the affected side.<ref>Rosenzopf H, Klingbeil J, Wawrzyniak M, Röhrig L, Sperber C, Saur D, Karnath HO. [https://academic.oup.com/brain/article-abstract/146/9/3648/7082493?redirectedFrom=fulltext&login=false Thalamocortical disconnection involved in pusher syndrome.] Brain. 2023;146(9):3648-3661.</ref>
* '''vegetative state and coma''': a lesion to the non-specific (intralaminar and reticular) nuclei.<ref>Adams JH, Graham DI, Jennett B. [https://academic.oup.com/brain/article/123/7/1327/380151?login=false The neuropathology of the vegetative state after an acute brain insult.] Brain. 2000 Jul;123 (Pt 7):1327-38.</ref> Coma may occur due to the role of the thalamus in sleep and arousal.


For more information, please read the following articles:
== Additional Resources ==
For more information on treatment options, please read the following articles:


* [[Overview of Traumatic Brain Injury|Traumatic Brain Injury]]
* [[Overview of Traumatic Brain Injury|Traumatic Brain Injury]]
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* [[Mirror Therapy]]
* [[Mirror Therapy]]
* [[Pusher Syndrome#Management / Interventions|Management of pushing tendencies]]  
* [[Pusher Syndrome#Management / Interventions|Management of pushing tendencies]]  
* [[Desensitization]] treatment for thalamic pain
* [[Desensitization|Desensitisation]] for thalamic pain


== References  ==
== References  ==
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[[Category:Anatomy]]
[[Category:Anatomy]]
[[Category:Brain - Anatomy]]
[[Category:Brain - Anatomy]]
[[Category:Plus Content]]
[[Category:Course Pages]]

Latest revision as of 19:41, 1 July 2024

Original Editor - Lucinda hampton

Top Contributors - Lucinda hampton, Jess Bell, Stacy Schiurring, Kirenga Bamurange Liliane, Uchechukwu Chukwuemeka, Vidya Acharya, Rucha Gadgil and Mason Trauger  

Thalamus Structure[edit | edit source]

The thalamus is located centrally in the brain, just above the brainstem.

The thalamus is located medial to the cerebral hemispheres and consists of two oval-shaped masses connected by the intermediate mass. Each mass consists of several groups of nuclei that serve different functions. Motor and sensory pathways (except olfaction) pass through this central structure.

The thalamus can be divided into approximately 60 regions known as thalamic nuclei. Each nucleus has unique pathways as inputs and various projections as outputs, most of which send information to the cerebral cortex.[1]

Hypothalamus[edit | edit source]

  • Located inferior to the thalamus
  • Two rounded eminences protrude from the back, called mammillary bodies
  • Anteriorly, the hypothalamus is connected to the pituitary gland by a long stalk called the infundibulum, also known as the pituitary stalk

The hypothalamus plays a major role in maintaining homeostasis via the autonomic nervous system, the neuroendocrine system, and the limbic system. It regulates emotions, hormone production from the pituitary gland, and bodily functions such as appetite, body temperature, reproduction, and circadian rhythms.

Epithalamus[edit | edit source]

  • Located behind the thalamus
  • Includes the pineal gland, which secretes the hormone melatonin in response to darkness, regulating our circadian rhythms and sleep-wake cycles

Subthalamus[edit | edit source]

  • Located beneath the thalamus
  • Includes the subthalamic nucleus, which is functionally considered part of the basal ganglia

Function of the Thalamus[edit | edit source]

The thalamus functions as a relay station between the brain and the body, filtering through various types of sensory and motor information.

Note the central location of the thalamus in relation to other subcortical structures and the cerebral cortex.
  • The thalamus has many connections with the cerebral cortex,[1] which are known as thalamacortical loops
  • It transmits nearly all sensory information to the cortex, including vision, taste, touch and balance, but excludes olfactory information
  • It conducts motor signals from the cerebral cortex to the spinal cord and ultimately to the peripheral nervous system
  • The thalamus also modulates arousal mechanisms, maintains alertness, and directs attention to sensory events[2]
  • The thalamus has connections with a number of structures of the limbic system, including the hippocampus, mammillary bodies, and fornix, so it has a role in learning and episodic memory[1]


The thalamus can be divided into five major functional components.[1]

  1. Reticular and intralaminar nuclei: involved in arousal and pain regulation
  2. Sensory nuclei: regulate sensory domains, apart from olfaction
  3. Effector nuclei: govern motor and language functions
  4. Associative nuclei: involved in cognitive functions
  5. Limbic nuclei: manage mood and motivation

These specific nuclei help to scan the cerebral cortex and determine active brain regions, relaying this information to the rest of the thalamus.[2]

Thalamus and Injury[edit | edit source]

The thalamus is involved in many critical functions and injury to the thalamus can cause a range of issues, including:

  • sensory issues (e.g. pain, paraesthesia, numbness, hypersensitivity)
  • vision impairment and light sensitivity
  • motor impairment
  • tremor
  • issues with attention
  • memory impairment
  • sleep difficulties
  • proprioception impairment


The following presentations are unique to thalamic injury:

  • thalamic pain syndrome: an excruciating sensation of pain that does not respond to narcotics. Once called Dejerine-Roussy Syndrome, this condition is commonly associated with infarction of the ventroposterolateral thalamus.[3] [4]
  • Pusher syndrome (also referred to as "persons who push"): a lesion to the posterior thalamus interrupts the connection to the vestibular nuclei, leading to lateropulsion in the direction of the affected side.[5]
  • vegetative state and coma: a lesion to the non-specific (intralaminar and reticular) nuclei.[6] Coma may occur due to the role of the thalamus in sleep and arousal.

Additional Resources[edit | edit source]

For more information on treatment options, please read the following articles:

References[edit | edit source]

  1. ↑ 1.0 1.1 1.2 1.3 Torrico TJ, Munakomi S. Neuroanatomy, Thalamus. [Updated 2023 Jul 24]. In: StatPearls [Internet].
  2. ↑ 2.0 2.1 Halassa, M.M., Kastner, S. Thalamic functions in distributed cognitive control. Nat Neurosci, 2017; 20, 1669–1679.
  3. ↑ Jahngir MU, Qureshi AI. Dejerine roussy syndrome. 2023.In: StatPearls [Internet].
  4. ↑ Dydyk AM, Munakomi S. Thalamic Pain Syndrome.[Updated 2023 Aug 13]. StatPearls [Internet]. Treasure Island (FL): StatPearls Publishing. 2023.
  5. ↑ Rosenzopf H, Klingbeil J, Wawrzyniak M, Röhrig L, Sperber C, Saur D, Karnath HO. Thalamocortical disconnection involved in pusher syndrome. Brain. 2023;146(9):3648-3661.
  6. ↑ Adams JH, Graham DI, Jennett B. The neuropathology of the vegetative state after an acute brain insult. Brain. 2000 Jul;123 (Pt 7):1327-38.
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