The temporal lobe is one of the most important structures of the cerebral cortex, and therefore also one of the most studied in neuroscience. It is not possible to understand the functioning of the Central Nervous System without knowing even a little about what the temporal lobes are.

Not only does it cover a large part of the brain’s surface: it also allows the global integration of a large part of the sensory information that reaches us through the environment , and plays a very important role in the processing of the contents of vision and hearing, as well as language in general.

In this article we will see what the characteristics of the temporal lobes are (as there are a couple of them in each brain), where they are located, and what functions they carry out.

Location of the temporal lobe

Although the brain as a whole functions in a continuous interaction between different brain areas, studies from neuroscience reflect that many of the skills, abilities, capacities and functions of the nervous system are especially linked to certain regions.

In this sense, the human cerebral cortex has traditionally been divided into five sections, called brain lobes. One of these is the temporal lobe, a fundamental brain region for such fundamental skills as speech or auditory perception, as well as being closely linked to affectivity, memory and recognition.

The temporal lobe is located on the lower side of the brain, approximately at ear level . This region is anatomically separated from the parietal lobe, which corresponds to the upper lateral area, by Silvio’s fissure, and is in close contact with the occipital lobe. It is also the lobe with the greatest connection to the limbic system (together with the orbital-frontal area), thus having a great influence on emotions and moods, as well as on memory.

It is necessary to keep in mind that there are actually two temporal lobes, one in each brain hemisphere. This consideration is relevant since some of the functions of this lobe are located in most people in a specific hemisphere. However, when a part of a temporal lobe stops functioning due to neurological disorders, these functions may be performed in whole or in part by its counterpart in the opposite hemisphere.

On the other hand, the boundaries of the temporal lobe, like those of any other part of the brain, are very porous and to some extent diffuse. They do not exactly correspond to physical boundaries of areas of the nervous system in charge of certain tasks , but it is a concept that helps to locate when mapping the brain.

Most relevant brain locations

Within the temporal lobe there are a large number of structures . This is because many interconnections from different parts of the brain coincide in this area of the cerebral cortex, some of which are not very similar in function. In fact, the concept of the temporal lobe is much more anatomical than functional, so it is natural that there are groups of nerve cells and small organs specialized in different tasks.

This causes the temporal lobe to incorporate groups of neurons in charge of performing many tasks, for example, integrating types of perceptual information coming from different senses. This is what makes it play an important role in language, mental function in which they have to see sounds, letters, etc.

Some of the most relevant parts of the temporal lobe are the following.

1. Auditory cortex

The temporal lobe contains the primary, secondary and associative auditory cortex . These areas of the brain are responsible for, in addition to perceiving sounds, carrying out the coding, decoding and interpretation of auditory information, being an indispensable element for survival and communication. In this last aspect, it is important to highlight its participation in the comprehension of speech, which occurs in the Wernicke area.

2. Wernicke area

Within the secondary hearing area of the dominant brain hemisphere, which is usually the left for most people, is the Wernicke area. This area is the main area in charge of language comprehension , allowing verbal communication between individuals. However, language production takes place in another area known as the Broca area, located in the frontal cortex.

3. Angular rotation

This area is particularly relevant, because it is the one that allows reading and writing . It associates visual and auditory information, allowing each grapheme to be assigned its corresponding phoneme and making it possible to produce a change in the type of data with which the brain works, from images to sounds with a symbolic component.

In people with injuries in this area, the reading is usually affected, being very slow or nonexistent.

4. Supramarginal turn

It is part of the tertiary sensitive area . This turn participates in tactile recognition, in addition to participating in language. Thanks to it we are able to recognize the relief of letters through the fingers and associate them with sounds.

5. Medial Temporal

This area, which encompasses the hippocampal region and several relevant barks, participates in memory and recognition , processing information and helping to move from short-term to long-term memory. The left hemisphere handles verbal information, while the right hemisphere stores visual patterns.

It is in this area of the temporal lobe where the first lesions in Alzheimer’s appear, producing its initial symptomatology.

6. Parieto-temporal-occipital association area

This is an area of association that integrates visual, auditory and somatic perception . Among many other highly relevant functions, it is important to highlight its participation in the perception and attention to space, which may be caused by suffering from heminegligence.

7. Limbic system association area

This part of the temporal lobe is responsible for providing emotional information to perceptions , integrating emotion and perception. It also participates in memory and learning. Likewise, other research has shown that it is also involved in the regulation of sexual behaviour and in the maintenance of emotional stability.

In short, this part of the temporal lobe integrates mental processes linked to emotions and allows our experiences to leave a mark on us that goes beyond what we can explain with words.

Disorders resulting from injuries in the storm

All the areas we have seen are of great importance for the correct functioning of the human organism in general and the temporal lobes in particular.

However, it is not uncommon for accidents, illnesses and alterations to occur that can cause some of them to malfunction . Let’s look at some typical disorders of thunderstorm injury.

1. Cortical deafness

This disorder involves the total loss of the ability to hear , despite the fact that the sensory organs are functioning properly. In other words, auditory information reaches the perceptive organs, but is not processed by the brain, so that the perception of sound is completely lost. This alteration is produced by the destruction of the primary and secondary auditory cortexes, or the nerve pathways that access them, in both hemispheres.

2. Hemiacusis

As with deafness, this condition is caused by the destruction of the primary and secondary auditory cortex, with the difference that this destruction has only occurred in one hemisphere .

Thus, the hearing of the ear opposite to the hemisphere in which the injury occurred is completely lost, but since the auditory cortex of the other hemisphere is still functional, hearing is possible in the other ear.

In addition, in some cases it is possible that over time a certain level of hearing is also gained by the ear that has become unusable, because neural plasticity allows parts of the brain to learn functions that were previously performed by others, and this may even occur by passing tasks from one hemisphere to the other.

3. Prosopagnosia

In cases of prosopagnosia, the affected person loses the ability to recognize faces, even of their loved ones. The recognition of people has to occur through other processing routes in the brain.

This alteration is caused by bilateral injury in the temporoccipital area .

4. Heminegligence

Caused by the impairment of the parieto-temporal-occipital association area, this disorder involves the difficulty to orient oneself, act or respond to stimuli that occur on the opposite side from the injured hemisphere . Attention to that perceptive hemisphere ceases, although the person himself can move so that the stimuli that are lost remain within reach of the functional perceptive field. It usually appears together with anosognosia, which is the lack of knowledge of the existence of an alteration.

5. Aphasias

Aphasias are understood as language disorders due to a brain injury . The effects vary according to the location of the lesion, and when it affects the temporal lobe there are certain characteristic symptoms.

Of the aphasias that are produced by a lesion in the temporal region, Wernicke’s aphasia (produced by a lesion in the area of the same name, in which there is a loss or difficulty in verbal comprehension and repetition, which causes serious problems for those who suffer it) stands out, the anomic (loss or difficulty in finding the name of things, produced by lesions in temporoparieto-occipital associative areas) or the transcortical sensory (in which there are difficulties in understanding but not in repetition, being the product of lesions in temporoparieto-occipital associative areas).

If the connection of the Wernicke area with the Broca area, the arched fascicle, is injured, the so-called conduction aphasia will occur, in which the difficulty in repetition and a somewhat altered understanding but a good fluency is maintained.

6. Antegrade amnesia

This disorder involves the inability to record new material in the memory . That is, it is impossible for the patient to recover (either permanent or temporary disability) the declarative information of the activity carried out after the injury.

This alteration is produced by injury in the medial temporal lobe, especially in the hippocampus. Injuries in the left hemisphere will affect verbal information, while in the right hemisphere the affectation will tend to be from other routes or non-verbal.

7. Klüver-Bucy syndrome

This is a very common disorder in dementias, such as Alzheimer’s . This condition is characterised by the presence of meekness, passivity, hyperorality, difficulties in sustained attention, disappearance of fear and hypersexuality. It occurs in the presence of lesions of the medial temporal region at a bilateral level.

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