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== Introduction ==
== Thalamus Structure ==
[[File:Thalamus.gif|right|frameless|400x400px]]
[[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 serves as the main relay station for the [[Brain Anatomy|brain]]. Motor pathways, limbic pathways, and sensory pathways besides olfaction all pass through this central structure.
* The thalamus can divide into approximately 60 regions called nuclei. Each nucleus has unique pathways as inputs and various projections as outputs, most of which send information to the cerebral cortex<ref name=":1" />.
* Nestled beneath the cortex, the pair of egg-shaped structures called the thalamus have grown bigger and more complex throughout evolution (like our the [[Cerebral Cortex|cerebral cortex]]), and its wiring became much more intricate as mammals diverged from reptiles.  
* The thalamus (from the Greek thalamos or inner chamber) transmits 98 percent of sensory information to the cortex, including vision, taste, touch and balance; the only sense that doesn’t pass through this brain region is smell. The thalamus also conducts motor signals and relays information from the [[Brainstem|brain stem]] to the cortex, coordinating shifts in consciousness such as waking up and falling asleep<ref>Knowable magazine [https://knowablemagazine.org/article/mind/2018/long-overlooked-brain-region-may-be-key-complex-thought A long-overlooked brain region may be key to complex though]t Available from:https://knowablemagazine.org/article/mind/2018/long-overlooked-brain-region-may-be-key-complex-thought (accessed 26.12.2020)</ref>.
Image: Animation of rotation, brainstem and thalamus.


== Functions ==
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>
[[File:Thalamus connections.jpg|right|frameless|400x400px]]
The thalamus is part of the limbic system, the region of the brain largely associated with the emotions and is essential to memory and learning.


The thalamus joins a series of other machinery whose purpose is to distill sensory information into a more interpretable and manageable form for higher brain sections. The thalamus is engaged in an intimate relationship with the cerebral cortex, with numerous mutual connections. These connections make up the thalamacortical loop. The thalamus also modulates arousal mechanisms, maintains alertness, and directs attention to sensory events<ref name=":0">WISE GEEK [https://www.wisegeek.com/what-is-the-thalamus.htm What is the Thalamus] Available from:https://www.wisegeek.com/what-is-the-thalamus.htm (accessed 26.12.2020)</ref>.
=== Hypothalamus ===


Functionally, the thalamus divides into five major functional components as:
* Located inferior to the thalamus
* 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. The intralaminar circuit compares these pattern guesses with similar patterns in memory. All these circuits cooperate to produce a coherent framework for the interpretation of incoming sensory data
* Two rounded eminences protrude from the back, called '''mammillary bodies'''
* Sensory nuclei regulating all sensory domains except olfaction
* Anteriorly, the hypothalamus is connected to the pituitary gland by a long stalk called the '''infundibulum''', also known as the '''pituitary stalk'''
* Effector nuclei governing motor  language function
 
* Associative nuclei connoting cognitive functions
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.
* Limbic nuclei encompassing mood and motivation<ref name=":1">Torrico TJ, Munakomi S. [https://www.ncbi.nlm.nih.gov/books/NBK542184/ Thalamus.2019] Available from:https://www.ncbi.nlm.nih.gov/books/NBK542184/ (accessed 26.12.2020)</ref>
 
The specific nucleii are responsible for scanning the cerebral cortex and determining active brain regions (those firing at around 40Hz) then relaying this information to the rest of the thalamus<ref name=":0" />.
=== Epithalamus ===
 
* 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 ===
 
* Located beneath the thalamus
* Includes the '''subthalamic nucleus''', which is functionally considered part of the [[Basal Ganglia|basal ganglia]]
 
== Function of the Thalamus ==
<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.]] 
 
* The thalamus has many connections with the cerebral cortex,<ref name=":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<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" />
 
 
The thalamus can be divided into five major functional components.<ref name=":1" />
# '''Reticular and intralaminar nuclei''': involved in arousal and pain regulation
# '''Sensory nuclei''': regulate sensory domains, apart from olfaction
# '''Effector nuclei''': govern motor and language functions
# '''Associative nuclei''': involved in cognitive functions
# '''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.<ref name=":0" />  


== Thalamus and Injury ==
== Thalamus and Injury ==
[[File:4-physical-activity-for-disabled-adults.jpeg|right|frameless]]
The thalamus is involved in many critical functions and injury to the thalamus can cause a range of issues, including:
The thalamus contributes to a broad range of critical functions. The side effects of thalamus damage can vary from person to person.
* 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
 


Some of the most common side effects of thalamic damage include:
'''The following presentations are unique to thalamic injury''':
* Sensory issues such as tingling, numbness, hypersensitivity, and pain
* Vision loss or light sensitivity
* Motor impairments
* Tremors
* Attention problems
* Memory loss
* Insomnia
Because the thalamus controls sleep and arousal, severe damage to it can also result in a coma<ref>Flint Rehab. [https://www.flintrehab.com/thalamus-injury/ Thalamus Injury: Symptoms, Treatment, and Recovery after Thalamic TBI] Available from:https://www.flintrehab.com/thalamus-injury/ (accessed 26.12.2020)</ref>.


== 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. See the pages on [[Overview of Traumatic Brain Injury|Traumatic Brain Injury]], [[Traumatic Brain Injury Clinical Guidelines]], [[Physiotherapy Management of Traumatic Brain Injury]], [[Physical Activity Guidelines for Traumatic Brain Injury]].
* [[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.


== What is the Mind? ==
== Additional Resources ==
[[File:Traumatic Brain Injury Course Picture.JPG|right|frameless]]
For more information on treatment options, please read the following articles:
Think about how the physical structure of the brain creates the metaphysical structure known as the mind.


Our thoughts are more than compilations of sensory inputs from the visual world, auditory world, olfactory world, tactile world and the world of taste. There is a long list of memories charged with emotional content that flavour our thoughts.
* [[Overview of Traumatic Brain Injury|Traumatic Brain Injury]]
* Similar to “pop-ups” on a computer screen the thalamus “pops” information up to the cortex all the time. The cortex may serve as the screen on which the pop-ups appear, but who or what is watching the screen? Where that entity resides is a big question. Is the brain and the inputs it receives, both external and internal, part of a physical organ that is less than a greater organ, the mind. Or is our mind and in turn our behavior is controlled by the impulses our brain receives or by the controlling entity, the self.<ref>Think First [https://www.thinkfirst.org/youth-lesson9 The Thalamus] Available from: https://www.thinkfirst.org/youth-lesson9 (accessed 26.12.2020)</ref>
* [[Traumatic Brain Injury Clinical Guidelines]]
* [[Physiotherapy Management of Traumatic Brain Injury]]
* [[Physical Activity Guidelines for Traumatic Brain Injury]]
* [[Stroke: The Role of Physical Activity]]
* [[Stroke: Clinical Guidelines]]
* [[Post-Stroke Pain]]
* [[Mirror Therapy]]
* [[Pusher Syndrome#Management / Interventions|Management of pushing tendencies]]
* [[Desensitization|Desensitisation]] for thalamic pain


== References  ==
== References  ==
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[[Category:Neurology]]
[[Category:Neurology]]
[[Category:Anatomy]]
[[Category: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, Mason Trauger, Uchechukwu Chukwuemeka, Vidya Acharya and Rucha Gadgil  

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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