The Thalamus
What is the thalamus?
The thalamus is mostly compromised of grey matter but is also surrounded by two layers of white
matter (Guy-Evans, 2021). Additionally, it is largest structure stemming from the embryonic
diencephalon- the posterior segment of the forebrain located between the midbrain and the
cerebrum (Torrico & Sunil Munakomi, 2019). Also, the term diencephalon includes the epithalamus,
metathalamus, hypothalamus and the subthalamus. In addition, the thalamus is made up of various
nuclei (dorsomedial nucleus, the lateroventral nucleus and the ventroposterior nucleus). Each of
which serves a specific purpose, such as relaying sensory and motor signals or controlling
consciousness and alertness (Motomura & Kosaka, 2021). Moreover, the thalamus is the centre of
pain and protopathic sensations (Torrico & Sunil Munakomi, 2019).
Where is the thalamus located in the brain?
The thalamus lies in the middle of the cerebrum and bounded medially by the third ventricle,
laterally by internal capsule and basal ganglia, and ventrally continuous with the subthalamus
(Torrico & Sunil Munakomi, 2019). The human brain is divided into two hemispheres (sides). The
thalamus is a symmetrical structure so for this reason, you have one thalamus in each hemisphere of
your brain situated on top of the brain stem, at the core of the diencephalon, on each side of the
third ventricle (see Figure 1 for position in the human brain). This allows for nerve fibre connections
to reach all areas of your cerebral cortex – the outer layer of your brain (Sherman & Guillery, 2002).
So, what is actually the purpose of the thalamus?
As we go about our daily lives, we consciously and unconsciously pick up information from our
environment. The thalamus plays a vital role in relaying this sensory information to other areas of
the brain and body. The sensory data travels to the thalamus where it is then transmitted to a
specific nucleus. These nuclei are formed mainly by neurons of excitatory and inhibitory nature.
After the information is sent to the tailored nucleus, it is then sent to the appropriate area in the
cerebral cortex where it is further processed. For example, visual information from your retina
Word count- 711
, travels to the lateroventral nucleus of the thalamus. The information is then directed to the main
area for visual processing known as the primary visual cortex which is situated in the occipital lobe.
With the exception of our smell, all sensory input can be relayed through the thalamus (Tibbetts,
1999). In actuality, the thalamus receives almost all signals (not just sensory signals) that travel to
the cortex. As a result, it is not a surprise that the thalamus also operates in the regulation of sleep
and wakefulness (Steriade & Llinás, 1988). Moreover, as thalamic nuclei are tightly connected to the
cerebral cortex, these pathways, specifically through the interlaminar nuclei of the thalamus, are
thought to be linked consciousness (Sheridan & Tadi, 2021). What’s more, the connection of limbic
structures (a compilation of structures involved in processing emotion and memory including the
hippocampus, the amygdala, and the hypothalamus) to the anterior nuclei of the thalamus allows
the thalamus to be associated in learning and episodic memory (Guy-Evans, 2021). All in all, the
thalamus serves as a relay station, collecting all types of sensory information, but not olfactory
(smell), and relaying it to the cerebral cortex (Sherman, 2006). It benefits you to become more
successful at making decisions and living in your natural environment.
What happens if I damage my thalamus?
Damage to your thalamus has been shown to cause many side effects but these can vary from
person to person. Research has shown that damage to the thalamus can cause sensory issues such
as tingling, numbness, hypersensitivity, and pain. An example of this can be seen when a person
suffers with ‘Thalamic Hand”. This involves involuntary hand movements and is caused by damage to
the thalamus. Furthermore, injury may cause vision loss, light sensitivity, motor impairments,
tremors, attention problems, memory loss and insomnia. Such research conducted by Abdel-Dyan et
al (1998) who performed a single photo emission CT (Computed Tomography) study of 228 patients,
found that 77% of patients with mild or moderate brain trauma displayed the most common clinical
complaints associated with great numbers of focal areas in the thalamus, These included headaches,
dizziness, and memory problems. Additionally, the thalamus is the first relay station to prevent the
cerebral cortex from receiving peripheral stimuli at sleep onset. Therefore, this shows that it has a
crucial role in the sleep-wake cycle and damage to the thalamus may cause people to suffer with
insomnia (Grossman & Inglese, 2016). This has been supported by Wu et al (2016) who summarised
those patients with minor thalamic lesions are at increased risk for sleep disturbance, insomnia,
sleep-relating breathing disorders, and memory deficits. Another study, conducted by Van Der Werf
Word count- 711
What is the thalamus?
The thalamus is mostly compromised of grey matter but is also surrounded by two layers of white
matter (Guy-Evans, 2021). Additionally, it is largest structure stemming from the embryonic
diencephalon- the posterior segment of the forebrain located between the midbrain and the
cerebrum (Torrico & Sunil Munakomi, 2019). Also, the term diencephalon includes the epithalamus,
metathalamus, hypothalamus and the subthalamus. In addition, the thalamus is made up of various
nuclei (dorsomedial nucleus, the lateroventral nucleus and the ventroposterior nucleus). Each of
which serves a specific purpose, such as relaying sensory and motor signals or controlling
consciousness and alertness (Motomura & Kosaka, 2021). Moreover, the thalamus is the centre of
pain and protopathic sensations (Torrico & Sunil Munakomi, 2019).
Where is the thalamus located in the brain?
The thalamus lies in the middle of the cerebrum and bounded medially by the third ventricle,
laterally by internal capsule and basal ganglia, and ventrally continuous with the subthalamus
(Torrico & Sunil Munakomi, 2019). The human brain is divided into two hemispheres (sides). The
thalamus is a symmetrical structure so for this reason, you have one thalamus in each hemisphere of
your brain situated on top of the brain stem, at the core of the diencephalon, on each side of the
third ventricle (see Figure 1 for position in the human brain). This allows for nerve fibre connections
to reach all areas of your cerebral cortex – the outer layer of your brain (Sherman & Guillery, 2002).
So, what is actually the purpose of the thalamus?
As we go about our daily lives, we consciously and unconsciously pick up information from our
environment. The thalamus plays a vital role in relaying this sensory information to other areas of
the brain and body. The sensory data travels to the thalamus where it is then transmitted to a
specific nucleus. These nuclei are formed mainly by neurons of excitatory and inhibitory nature.
After the information is sent to the tailored nucleus, it is then sent to the appropriate area in the
cerebral cortex where it is further processed. For example, visual information from your retina
Word count- 711
, travels to the lateroventral nucleus of the thalamus. The information is then directed to the main
area for visual processing known as the primary visual cortex which is situated in the occipital lobe.
With the exception of our smell, all sensory input can be relayed through the thalamus (Tibbetts,
1999). In actuality, the thalamus receives almost all signals (not just sensory signals) that travel to
the cortex. As a result, it is not a surprise that the thalamus also operates in the regulation of sleep
and wakefulness (Steriade & Llinás, 1988). Moreover, as thalamic nuclei are tightly connected to the
cerebral cortex, these pathways, specifically through the interlaminar nuclei of the thalamus, are
thought to be linked consciousness (Sheridan & Tadi, 2021). What’s more, the connection of limbic
structures (a compilation of structures involved in processing emotion and memory including the
hippocampus, the amygdala, and the hypothalamus) to the anterior nuclei of the thalamus allows
the thalamus to be associated in learning and episodic memory (Guy-Evans, 2021). All in all, the
thalamus serves as a relay station, collecting all types of sensory information, but not olfactory
(smell), and relaying it to the cerebral cortex (Sherman, 2006). It benefits you to become more
successful at making decisions and living in your natural environment.
What happens if I damage my thalamus?
Damage to your thalamus has been shown to cause many side effects but these can vary from
person to person. Research has shown that damage to the thalamus can cause sensory issues such
as tingling, numbness, hypersensitivity, and pain. An example of this can be seen when a person
suffers with ‘Thalamic Hand”. This involves involuntary hand movements and is caused by damage to
the thalamus. Furthermore, injury may cause vision loss, light sensitivity, motor impairments,
tremors, attention problems, memory loss and insomnia. Such research conducted by Abdel-Dyan et
al (1998) who performed a single photo emission CT (Computed Tomography) study of 228 patients,
found that 77% of patients with mild or moderate brain trauma displayed the most common clinical
complaints associated with great numbers of focal areas in the thalamus, These included headaches,
dizziness, and memory problems. Additionally, the thalamus is the first relay station to prevent the
cerebral cortex from receiving peripheral stimuli at sleep onset. Therefore, this shows that it has a
crucial role in the sleep-wake cycle and damage to the thalamus may cause people to suffer with
insomnia (Grossman & Inglese, 2016). This has been supported by Wu et al (2016) who summarised
those patients with minor thalamic lesions are at increased risk for sleep disturbance, insomnia,
sleep-relating breathing disorders, and memory deficits. Another study, conducted by Van Der Werf
Word count- 711
