It is a busy place in the human brain, and a spill there can have a wide range of effects.
The Thalamus, which means “internal chamber” in Greek, is in the upper part of the brainstem near the brain’s center. It has two halves, each the size of a walnut.
It is divided into different areas, which are very explicitly connected to other parts of the brain. A blow to a thalamus part will not have the same effect as a blow elsewhere.
The Thalamus is a group of neuron bodies, a gray matter structure, just like the cerebral cortex. However, within this set, there is a series of nuclei of the Thalamus:
- Specific connection nuclei: They send sensory information to specific areas of the cerebral cortex specialized in working with that type of data coming from a particular sense.
- Nuclei of non-specific connection: They send information to vast areas of the cerebral cortex without discriminating by specializations.
- Association nuclei are part of an information circuit that communicates the cerebral cortex with subcortical structures.
The neurons of the Thalamus
The Thalamus only has reason to be if it is connected to other areas of the nervous system, which is reflected in the type of neurons that compose it.
- Local interneurons: Its primary function is to send nerve impulses to other interneurons of the Thalamus. They account for approximately 25% of the thalamus neurons.
- Projection neurons: These nerve cells are responsible for sending information out of the Thalamus into the cerebral cortex. They make up 75% of thalamic neurons.
Functions of the Thalamus
The Thalamus has many functions, including:
- Manage our sensitivity to temperature, light, and physical touch and control the flow of visual, auditory, and motor information.
- The Thalamus is involved in motivation, attention, and wakefulness. He is in charge of our sense of balance and awareness of our arms and legs.
- It controls how we experience pain.
- He is also involved in learning, memory, speech, comprehension, language and even emotional experiences, expression, and our personalities involve the Thalamus.
It can be thought that the Thalamus is a “relay station” that receives signals from the outer regions of the brain (cerebral cortex), interprets them, and then sends them to other areas of the brain to complete their work.
Although relatively small, the Thalamus controls a large part of how our body functions and responds to the world around us.
The Thalamus has strong connections with all brain parts and receives information from its features.
Only a tiny part of the Thalamus receives information from the outside world or sends information to the outside world. Especially the Thalamus helps the cortex and other cells inside the brain to communicate with each other.
Central pain syndrome
A stroke in a particular area of the Thalamus can cause “thalamic pain,” also known as central pain syndrome.
The pain may be intense, usually in the affected arm and hand, and may cause an annoying feeling of burning or frostbite. Some survivors report an intense prickly sensation, such as being repeatedly pinned with needles.
A similar problem, called pseudo thalamic pain syndrome, occurs when a stroke in the white matter of the brain breaks the connections between the Thalamus and the cerebral cortex but does not damage the Thalamus itself.
Central pain usually does not respond to regular painkillers and often does not occur until weeks after the stroke. This can be an obstacle to the recovery of a survivor who is performing well in rehabilitation.
What makes the Thalamus very special is its relatively small and highly concentrated area inside the brain. A small change in the location of the stroke can produce a substantial change in the way the attack affects the survivor.
For example, a stroke in the Thalamus can cause drowsiness, contribute to the development of epilepsy, affect a survivor’s attention span, or cause a feeling of apathy. A spill in the front of the Thalamus can affect memory, including memories of one’s life.
As a result, a patient with CVA may have what appears to be the instantaneous onset of Alzheimer’s disease.
Injury to another part of the Thalamus can impede movement, balance, or force. Massive blows in the Thalamus can cause many problems. If both sides get hurt, destroying the connections with the rest of the brain can cause a coma.
Fortunately, the brain’s wiring has a degree of plasticity, and if the stroke is only in the Thalamus, some people can recover and do it quite well because the rest of the brain has ways of compensating for it.
However, they may not return ultimately to normal. Because the Thalamus shares its blood supply with the brainstem, the occipital lobe, and the brain’s temporal lobe, strokes in those areas can also affect the Thalamus.
Depending on which lobe is affected, the survivor may experience loss of visual field ( hemianopsia ), loss of memory, or problems swallowing and breathing.
Recovery is more challenging for these strokes because many more brain areas are involved.
A thalamic stroke affects the survivor depending on which part of the Thalamus is injured and whether the injury is on the left or right side of the Thalamus.
Effects may include loss of sensation, strength, and movement control on the opposite side of the body, loss of memory, language deficits ( aphasia ), and loss of ability to remember faces. However, the prognosis for the survivors of the thalamic stroke is generally better than that of those who suffer a stroke in the cerebral cortex.