Difference between hypothalamus and thalamus

“Thalamus” and “hypothalamus” have a lot in common, or so it seems, since the names are very similar. Is this true?

In this post we will explain the differences between the hypothalamus and the thalamus and what is the function between each one.

Difference between hypothalamus and thalamus

While the thalamus is located almost directly in the center of the brain, the hypothalamus is located below it, so their locations are different, although not much. … The thalamus connects the cerebral cortex with the midbrain, the hypothalamus connects the nervous system in general with the endocrine system.

The diencephalon is a structure that contains several parts of the brain, each with the term “thalamus.” Most of these structures are derived from the developmental vesicle called the diencephalon. The contents of the diencephalon include the thalamus, subthalamus, epithalamus, and hypothalamus. The pineal gland is also part of the diencephalon.

It only represents 2% of the total weight of the central nervous system. However, it has very scattered and important connections.

The diencephalon, as we have already discussed, is made up of four components that border the third ventricle, which divides the diencephalon into two symmetrical halves. We are going to describe them below.

Hypothalamus

The hypothalamus is an area in the center of the brain that, although small, has many functions. It stands out that it plays an important role in the production of hormones. In addition, it helps stimulate many important processes in the body.

What’s more, when the hypothalamus doesn’t work properly, it can cause organ problems that cause many disorders. On the other hand, although diseases of the hypothalamus are rare, it is important to keep it healthy to reduce risk.

The word hypothalamus comes from two Greek words that translate as “under the thalamus.” This is where the hypothalamus is located, below the thalamus and above the pituitary gland. We are talking about a small area of ​​the brain, which does not mean that it plays an important role in the body by influencing both the endocrine and nervous systems.

Functions

A vital process: homeostasis

The hypothalamus is constantly receiving information from all parts of the body and sending orders accordingly because its task is to make sure that nothing that happens inside the body breaks the balance of how the whole body should function.

That is why it works as a mediator for different parts of the body, whether or not they are in contact with the brain; To influence the farthest parts, it allows hormones to be released into the blood that within minutes reach their destination to trigger the necessary process.

For example, if we see something that can be potentially dangerous, the hypothalamus will make sure that everything that happens in the body works consistently with the preparation to react quickly.

It will not let the heart start beating rapidly without many other organs acting accordingly: the muscles will tense, the amount of energy available in the blood will increase, etc.

In the same way, if we have not eaten for a long time, the hypothalamus will cause the neurons of the limbic system to generate dynamics that make the sensation of hunger appear, at the same time that it will intervene in the way in which available fats and sugars are burned in the body.

All this at the same time, so that there is always a balance and the property of homeostasis is maintained, that is, the ability to maintain stability in the functioning of things.

It also interferes with the regulation of emotions, sleep cycles, childbirth, blood pressure and heart rate, as well as the production of digestive juices and the balance of body fluids. In addition, it is considered that chemical substances are formed in the hypothalamus that generate anger, sadness, the feeling of being in love, and sexual satisfaction, among others.

Thalamus

The thalamus is an oval-shaped structure that constitutes the dorsal portion of the diencephalon. It transmits sensory input to the primary sensory zones of the cortex, but is more than just a repeater station.

The main function of the thalamus is the integration of sensory information directed to the cortex. It transmits most of the information that reaches the cerebral cortex and, in addition, it integrates various sensory modalities and facilitates or inhibits projections towards one lobes or another.

It is essential for the maintenance of cortical activity. It is also responsible for transmitting information from the cerebellum and the striatum to the cerebral cortex.

The cerebellum and striatum are centers that modulate the descending motor pathways of the cerebral cortex. Almost all sensorimotor information passes through the thalamus before reaching its destination (cortex).

The thalamus is organized into different nuclei with different functions. The only sensory information that does not take over from the thalamus is olfactory information, which passes directly from the olfactory bulb to the cerebral cortex.

The rest of the senses: taste, vision, touch and hearing are released in the nuclei of the thalamus and then project it to its corresponding area in the cortex.

But in addition to the ascending information, it also deals with the descending information, the information that the crust sends to other areas. Although its main function is to regulate sensorimotor projections, it is also involved in the functioning of some higher functions, such as memory or language.

The functions of the thalamus

We have seen that the thalamus is very well communicated, but its role is not that of being a simple communication bridge between relevant parts of the brain. The thalamus itself is a structure that plays an active role in processing information that comes to it from other areas. But … what are the functions that this brain structure performs?

1. Integration of sensory data

The most well-known and studied function of the thalamus is to be one of the first stops in the brain for information that comes to us through the senses, with the exception of smell.

The thalamus processes this sensory information, discards the parts that are not too important and sends the final result to the cortex of the brain, where this information will continue to be processed.

Thus, it facilitates the integration of sensory information to move from raw data to relatively complex information units capable of holding a meaning for us. In any case, it must be clear that this process not only takes place in the thalamus, but also involves several networks of neurons distributed throughout practically the entire brain.

2. The sleep-wake cycle

The thalamus, like its younger brother the hypothalamus, is involved in regulating the rate at which the sensation of sleep comes and goes. This function, in addition to being essential to regulate all nervous activity in general, is also related to the following.

3. Attention and awareness

Recent research indicates that the thalamus could play a very important role in the appearance of consciousness and everything related to it; from the ability to think about one’s own thoughts, to the use of language, through the ability to focus attention on specific information according to the objectives that are had at all times.

However, it is important to note that these processes related to conscious states are not consciousness itself, although they appear in parallel. We cannot focus our attention on anything when we do not realize that we exist, and we cannot speak or reflect; but when we are conscious, there are aspects of attention and language that are beyond consciousness.

 In addition, all these complex mental processes related to abstract thinking require the participation of many areas of the brain, not only the thalamus; 

This part of the diencephalon is a necessary but insufficient component in making thought, attention and language take place (something that can be said for practically all parts of the brain, because they all work in an interconnected way).

Because the thalamus is so well connected to many areas of the cortex at the same time, it might be able to intervene in the synchronization of neural activity necessary for the level of consciousness to be maintained. Without it, the other parts of the brain become non-functional, at least in the vast majority of cases. 

Exceptions can always appear of people born without thalamus or with a very underdeveloped one and who despite this can live for many years; in such cases, the rest of the brain would have learned to reconfigure itself to carry out the tasks of this absent structure using other networks of neurons.

4. The regulation of emotions

The thalamus is not only connected with circuits that carry sensory information, but also interacts with neural pathways that are directly involved in the appearance of emotional states. Not for nothing is the thalamus surrounded by the limbic system.

Thus, the thalamus integrates these two pathways and works by bringing these two types of information together, causing emotions to affect what is perceived and vice versa. In addition, it receives information from the hypothalamus, which in turn is directly involved in the regulation of emotions and the secretion of different types of hormones in the bloodstream.

What’s the difference between them?

While the thalamus is located almost directly in the center of the brain, the hypothalamus is located below it, so their locations are different, although not much. … The thalamus connects the cerebral cortex with the midbrain, the hypothalamus connects the nervous system in general with the endocrine system.

The thalamus could be said to be found deep within the brain, just above the brainstem and near the basal ganglia. It acts as a “relay station” and a synaptic integration center for the initial processing of sensory signals on their way to the cerebral cortex.

It screens for insignificant signals and directs important sensory impulses to areas of the somatosensory cortex and other regions of the brain.

And in the same way that it conducts sensory information to the cortex, it also receives signals from it, signals capable of modifying its own activity, varying the intensity and nature of the information that it sends to other centers.

While the hypothalamus, its position is, as its name suggests, lower than that of the thalamus, and somewhat more advanced. It is a collection of specific nuclei with their associated nerve fibers.

It is a center of integration of several and very important functions of homeostatic regulation of the organism. Functionally links the autonomic nervous system with the endocrine system; hence the integrating character to which we have just alluded.

In fact, the hypothalamus makes up the neuroendocrine integration system par excellence: the so-called hypothalamic-pituitary system which, as its name suggests, is made up of the pituitary gland (master gland of the hormonal system) and the hypothalamus. In future annotations we will refer in detail to this system.

FAQS: Difference between hypothalamus and thalamus

Is there a difference between hypothalamus and thalamus?

The thalamus is a structure that is located in the center of the brain, above the hypothalamus. It is part of the diencephalon, of which it constitutes about 80%.

What is hypothalamus and thalamus?

One of the hypothalamus’s most significant functions is to connect the nervous system through the pituitary gland to the endocrine system. Below the thalamus, the hypothalamus is located and is part of the limbic system.

What is the function of thalamus?

The main function of the thalamus is to relay motor and sensory signals to the cerebral cortex.

What are the functions of the thalamus and hypothalamus quizlet?

Controls emotional response, regulation of body temp, regulation of hunger and thirst sensations, controls behavior, regulation of sleep-wake cycle, control of endocrine system, formation of memory.

Does the hypothalamus regulate the thalamus?

No, the hypothalamus doesn’t regulate the thalamus.

In this post we explained the differences between the hypothalamus and the thalamus and what is the function between each one.

If you have any questions or comments please let usk now!

References

Boutros, N. J. (2008). The thalamus. Clinical EEG and Neuroscience, Vol.39(1), p.IV

Percheron, G. (1982). The arterial supply of the thalamus. En Schaltenbrand; Walker, A. E. (eds.). Stereotaxy of the human brain. Stuttgart: Thieme. pp. 218 – 232.