Wednesday, May 18, 2022

Where Is The Thalamus In The Brain

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Final Titles And Dissolution

The Thalamus

Thalamus entered the 1990s with a few more C64 titles, including Creatures and Creatures II: Torture Trouble from the Rowlands brothers, which have been lauded by several computer magazines for the strength of their gameplay and graphics on the aging machine. Cartoon-style platformers Summer Camp and Winter Camp were also released. In 1991, Newsfield ran into serious financial trouble. Newsfield were forced to halt publication of their popular gaming magazines. Europress stepped in to save the magazines, but they slowly died out over the next year or two as their respective markets dwindled.

Thalamus managed to survive the liquidation of Newsfield, but funds were running low. With 8-bit gaming being superseded by 16-bit gaming, production costs were rising, forcing hundreds of independent publishers, such as Thalamus, to either close down or allow themselves to be consumed by a publishing giant. Thalamus released their final C64 game, Nobby the Aardvark in 1993. With their various Amiga projects spiraling out of budget and no further income, Thalamus had no choice but to close down their operations.

Experimental Mediodorsal Thalamus Lesions

Earlier work in animals focused on determining the one critical structure within the medial thalamus that was causing the memory deficits associated with thalamic amnesia. As mentioned, there are many candidates within the medial thalamus to fulfill this critical role. Neuropathological evidence reported in clinical cases of Wernicke-Korsakoff’s syndrome supported a role for the MD in memory . However, Wernicke-Korsakoff’s patients invariably suffer extensive neural damage due to the widespread effects of alcohol in the brain , thus less equivocal evidence can only be obtained from experimental lesion studies involving circumscribed damage conducted in animal models. Table 1 details what we believe to be the extent of the experiments that have investigated cognitive and memory impairments after MD lesions over the past 40 years in rodents and monkeys collected using searches on pubmed involving mediodorsal, medial dorsal, dorsomedial, dorsalis medialis, and thalam*. Some of these studies and their conclusions are discussed below.

Table 1. Summary of studies involving MD thalamic lesions assessing performance in an array of memory tasks over the past 40 years.

Non-human primates

Rodents

Integration Of Sensations With Emotions

The dorsomedial nucleus of thalamus integrates the somatic, visceral and olfactory sensations of a person. This integrated information is fed to the mammillothalamic tract resulting in the emotional response to the sensation.

The medial and lateral geniculate bodies are part of auditory and visual pathways, respectively. Thus, it is essential for normal hearing and visual process of a person. Its disease will affect hearing as well as vision.

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Anatomical Structure Of The Thalamus

The invention of the microscope in the early 19th century saw an explosion of anatomical research on parts of the brain, including the thalamus. The introduction of sophisticated cell staining techniques showed physicians that the thalamus shared cortical connections with every region of the brain, thus furthering the case that the thalamus is involved in multi-sensory integration. It was also discovered that the thalamus itself was further divided into smaller specialized anatomical regions, regions that are each associated with a particular sensory system.

Humor is by far the most significant activity of the human brain. Edward de Bono

Side Effects Of Thalamus Damage After Brain Injury

Male Thalamus Brain Anatomy

As you can see, the thalamus contributes to a broad range of critical functions. Therefore, the side effects of thalamus damage can vary from person to person.

Some of the most common side effects of thalamic damage include:

  • Sensory issues such as tingling, numbness, hypersensitivity,
  • Chronic pain

Because the thalamus controls sleep and arousal, severe damage to it can also result in a coma.

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What Are The Parts And Functions Of The Limbic System

limbic systemrole

What are the main functions of the limbic system?

The limbic system is a set of structures in the brain that controls emotion, memories and arousal. It contains regions that detect fear, control bodily functions and perceive sensory information .

what are the functions of the different parts of the brain?brainpartsbrainfunctions

What Is Thalamus Responsible For

  • Why do you call the thalamus the gateway to the cerebral cortex?
  • What is the structural importance of the thalamus in the brain?
  • Is the role of the thalamus as a relation active or passive?
  • How do you make perception out of a sensation?

S. Murray Sherman and Ray W. Guillery in their book Exploring the Thalamushighlighted the role of the thalamus as the gateway to the cortex. According to them, it is the major relay station to your cerebral cortex.

Everything you know about yourself or the world around is owed to the messages passing through the thalamus.

Sandwiched between the outer layer of the cerebrum the cerebral cortex and the midbrain, the thalamus makes one of the three parts of the diencephalon, with the other two being the hypothalamus, and the third ventricle.

Did you know the diencephalon is also called the interbrain or the between brain?

In the book The Thalamus, Edward G. Jones gave the tripartite division of the thalamus. That is, it consists of three parts, viz. the dorsal, ventral, and epithalamus. Among these three divisions, it is only the dorsal thalamus which both sends to receives fibres from the cerebral cortex and striatum.

The ventral division only receives fibres from both the sides, i.e. the cerebral cortex and the striatum. The third division, the epithalamus, neither sends nor receives axons from either side.

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Mediodorsal Nucleus Of The Thalamus

Plailly et al. were the first to test the hypothesis that the MDT could be involved in odor attention processing. In humans, they designed a specific olfactory attention task and looked for the connectivity among the piriform cortexMDTOFC trans-thalamic pathway using functional magnetic resonance imaging . They showed that attending to odors specifically increased the functional connectivity between the piriform cortex and MDT and between the MDT and OFC. These results were corroborated by a recent fMRI study by Veldhuizen and Small who showed significant activation of the MDT when attending to odors. These results in healthy humans are further supported by the observation that humans with thalamic damages have deficits in olfactory attention-related tasks . These studies point out the possible contribution of the MDT in olfactory attention but have to be put in perspective of the recent report by Keller . Due to the modest amount of fibers from the piriform cortex to the MDT, Keller proposed that the MDT by itself could not support the attention to odors rather, Keller suggests that the MDT may be involved in the coordination of attentional shift between olfactory and other sensory modalities.

Finally, MDT has been proposed to be involved in neurological disorders including schizophrenia , bipolar disorder and depression . This is particularly interesting given that olfactory deficits are common among these neurological disorders .

Chihiro Ohye, in, 2002

Thalamus Anatomy Function & Disorders

The Functional Anatomy of the Thalamus

By Olivia Guy-Evans, published June 09, 2021

The thalamus is situated at the core of the diencephalon, which is a part of the forebrain also containing the hypothalamus, epithalamus, and subthalamus.

The thalamus is often described as the relay station of the brain as a great deal of information that reaches the cerebral cortex, first stops in the thalamus before being sent to its destination.

All of our senses, with the exception of smell, are outed through the thalamus before being directed to other areas of the brain for processing

There are two thalami, one in each hemisphere of the brain. They lie above the brain stem and the midbrain , which allows for connections of nerve fibers to reach the cerebral cortex in all directions.

This structure of the brain is able to relay and integrate a variety of motor and sensory signals between the higher centers of the brain and the peripheries.

The thalamus is mostly comprised of grey matter but is also surrounded by two layers of white matter. They are oval shaped in appearance, almost looking like eggs, with two protuberances on the surface.

One of these is known as the medial geniculate bodies, which are important for the processing of auditory information. The other is the lateral geniculate bodies, which are responsible for the processing of visual sensory inputs.

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Summary And Future Directions

Given that the neural networks themselves are somehow disrupted in neurodevelopmental disorders, that pathological changes in the dorsal thalamus may be part of altered processes that are taking place throughout the entire network, that neuroimaging has indicated co-occurring changes are seen throughout the reciprocal loop connecting the thalamic relay nuclei with the major cortical multimodal association areas, and critically, that behavioral and cognitive performance is altered as a consequence of subtle manipulations to the MD in animals, it is now, more than ever, relevant to re-evaluate the roles of different subdivisions of the dorsal thalamus in cognitive functions, cognitive control, and neuropsychiatric diseases.

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Physical Therapy And Rehabilitation

Your doctor will likely recommend rehabilitation, usually within a day or two of having a stroke. The goal is to relearn skills that you might have lost during the stroke. Roughly two-thirds of people who have a stroke require some level of rehabilitation or physical therapy.

The type of rehabilitation youll need depends on the exact location and severity of your stroke. Common types include:

  • physical therapy to compensate for any physical disabilities, such as not being able to use one of your hands, or to rebuild strength in stroke-damaged limbs
  • occupational therapy to help you perform everyday tasks more easily
  • speech therapy to help you regain lost speech abilities
  • cognitive therapy to help with memory loss
  • counseling or joining a support group to help you adapt to any new changes and connect with others in a similar situation

Categorized under Health,Science | Difference Between Thalamus and Hypothalamus

Thalamus and hypothalamus are both parts of the brain. Along with the epithalamus and perithalamus, they are both located in the region of the brain called the diencephalon.

Even though they have very similar names, which might make some people think they are similar, its actually the opposite they vary significantly in both size and function, as will be discussed in more detail below. The only reason they have such similar names is their location. Hypo means under in Greek, and the hypothalamus is in fact located right beneath the thalamus, hence the name.

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Damage To The Thalamus: Understanding The Side Effects And Recovery Process

Kayla Covert, PT, DPT Flint Rehab

When a brain injury affects the thalamus, it can lead to sensory and/or cognitive side effects. This article will share symptoms and treatment to help you understand the ways in which thalamus damage can affect your everyday life.

As with all types of TBI, its important to work closely with your medical team during recovery.

Relay Of Sensory Information

Thalamus

Thalamus occupies the central position between the cortex and spinal cord as well as other areas of the lower brain. Thus, it acts as an important relay center for the signals passing from the lower centers to the higher centers of the brain. Almost all sensory information pass through the thalamus before going to the higher centers of the brain.

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Essential Oils And The Limbic System

The limbic system gathers information from the environment through sensory information. As youve experienced firsthand many times, your senses can alter your emotional state rapidly. For example, a pleasurable meal can make you feel comforted, and very loud noises can make you feel anxious.

Ever wonder why certain smells conjure up memories and even physical feelings so vividly? Our sense of smell is unique compared to our other senses because it bypasses parts of the brain that other types of sensory information often cannot. Because of this, smells can often cause immediate and strong emotional reactions based on memories. Smells can bring us back to past events within milliseconds, making us feel a certain way based on past events, whether we realize why were suddenly feeling that way or not.

Essential oils, for example, can have dramatic effects on limbic function and how you feel. This is true because the strong fragrances they hold, which are found inside volatile molecules that can make their way into your bloodstream, travel directly through the blood/brain barrier very quickly.

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Is There A Role For The Thalamus In Modulating Pain

The classic pain pathway as was previously understood consists of a three-neuron chain that transmits pain information from the periphery to the cerebral cortex . The first order neuron has its cell body in the dorsal root ganglion and two axons, one extending distally to the tissue it innervates while the other extending proximally to the dorsal horn of the spinal cord . In the dorsal horn, this axon synapses with the second order neuron which in turn will cross the spinal cord through the anterior white commissure and ascends through the lateral spinothalamic tract to the thalamus. In the thalamus, the second order neuron synapses with the third order neuron, which ascends through the internal capsule and corona radiata to the postcentral gyrus of the cerebral cortex . This pathway is organized such that within tracts and nuclei up to the cortex, topological relations are maintained and different parts of the body are represented in an ordered arrangement in the postcentral gyrus. This arrangement is called somatotopy .

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Miscellaneous Functions Of The Thalamus

The thalamus, due to its many neuronal connections to parts of the limbic, endocrine, and nervous system, is also involved in many more bodily functions than emotions and sensory information. It is also a part of what gives us consciousness. Specifically, the thalamo-cortico-thalamic circuit is integral to arousal, the physiology of being awake, alertness, and activity.

In fact, attention and focus disorders such as obsessive-compulsive disorder are specifically attributed to damage or physiological malfunctions of this circuit due to its role in regulating task-dependent activities during a state of rest. Additionally, it is central to the process of impulse inhibition. So damage to this pathway manifests in attention deficit disorder as well.

It is also hypothesized that the thalamus is not only limited to information gathered during consciousness but that it has access to the regulation and storage of information gathered during unconsciousness as well. Interpretation of this information, however, is limited to a conscious state. You can almost think of this as your awareness of your dreams during deep sleep.

Your thalamus has stored information outside of your consciousness, and, despite your thalamus remembering this information, youre not quite able to recall it on your own or when youre awake.

This is why youre able to sleep through the sounds of rain and maybe even a particular TV show but wake to the sound of your alarm .

Embryonic Patterning Of The Innate Limbic System And Potential Link To Behavior

The Thalamus

Since innate behaviors are established without prior experience, the regulatory circuitry must be established during embryonic or early post-natal stages of neurodevelopment, likely through a series of hierarchical stages of genetic programming. Below we review our current knowledge of innate limbic system development, and present a novel model in which innate behaviors are generated by a coordination of genetic expression events and environmental cues.

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Speech And Cognitive Therapy

While thalamus damage primarily causes sensory problems, it can also lead to behavioral and cognitive changes.

For example, many patients with a thalamus injury have incorrect speech patterns and can struggle to find the right words. Others display apathy and memory problems.

To treat these issues, its crucial to begin speech therapy as soon as possible. Most speech therapists are familiar with the cognitive effects of brain injury as well. Therefore, they can teach you strategies to improve your memory, language, word-finding skills, and behaviors.

Function Of The Thalamus

The thalamus is often described as a relay station because it is an important transfer hub of information. It is mostly considered part of the central nervous system, where is processes sensory and movement information and passes this on to the relevant areas of the brain.

However, it is also an essential part of the limbic system, which is involved in processing emotion, pain response, and higher cognitive functions. The thalamus is also thought to contribute to our consciousness and alertness, as well as controlling the sleep-wake cycle.

Different nuclei within the thalamus are important for passing on different types of information to the appropriate targets in the brain. The thalamic relay neurons that make up each nucleus are excitatory neurons that receive signals from a variety of areas of the brain. They then pass this information on to the appropriate location of the cortex.

Some notable examples of these nuclei and their functions are discussed below.

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Nuclei Within The Thalamus

The thalamus is made up of a series of nuclei, all of which are responsible for the relay of different sensory signals.

The nuclei are both excitatory and inhibitory in nature and receive sensory or motor information from the body, presenting selected information via the nerve fibers to the cerebral cortex.

Described below are a list of some of the main groups of nuclei within the thalamus and what they are responsible for:

Anterior nucleus

The anterior nucleus is thought to be involved with memory due to its extensive connectivity to the hippocampus.

It is also connected to the mammillothalamic tract and the cingulate gyrus .

As these areas are linked with the limbic system, they are involved in organizing memory and emotion. The anterior nucleus essentially receives input from the limbic system and projects to the cingulate gyrus.

Dorsomedial nucleus

The dorsomedial nucleus is thought to be involved in emotional behavior and memory.

This nucleus relays information from the amygdala and olfactory cortex, which then projects to the prefrontal cortex and the limbic system, in turn relaying them to the prefrontal association cortex.

Because of this, the dorsomedial nucleus has an important role in attention, organization, planning, and higher cognitive thinking.

Ventral posterolateral and ventral posteromedial nucleus

Further, the ventral posteromedial nucleus receives sensory information from the trigeminal nerve regarding the face.

Lateral posterior nucleus

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