The 5 auditory areas of the brain

People are used to living with sound. Hearing everything that we have around us is something that we have so internalized that neither we only stop to think how this information enters our ears and becomes experienced by U.S.

In this article we will talk about the auditory areas of the brain, which, together with the auditory system, is responsible for collecting these signals sent by the auditory nerves and sending the information already processed to the rest of the nervous system.

• Related article: "Parts of the human brain (and functions)"

What are the auditory areas of the brain?

Within the auditory areas of our brain include both the auditory pathways, which They consist of bundles of fibers that carry information from the ear to the brain and vice versa. What the areas of the brain dedicated to hearing.

These brain areas are the Brain stem together with the upper olive complex, the lemniscus and the colliculus; the thalamus and the primary auditory cortex.

In addition, it is necessary to point out the importance of the function of the auditory nerve. This nerve is essential for our hearing. Composed of more than 30,000 neurons, it is in charge, together with the auditory pathways, of transporting information to the brain through electrical impulses.

• You may be interested: "The 10 parts of the ear and the process of receiving sound"

Role of the auditory pathways

Like the rest of sensory modalities, the auditory system is made up of a series of primary pathways and centers in the brain whose function is to process and transport auditory information.

In the case of the auditory pathways we find the primary auditory pathway whose sole purpose is to transport auditory information, and the non-primary pathway which also integrates other modalities sensory.

Primary auditory pathway

The primary auditory pathway is a short neural circuit and with the ability to transport information very quickly, since it is made up of thick myelinated fibers.

Its sole purpose is to transport the information that is collected by the cochlea, performing decoding and interpretation tasks at each of the levels. This information is transferred from one level to another until it reaches the auditory cortex.

However, before the information reaches the auditory cortex, the thalamus integrates the information and prepares to issue a response or reaction to auditory stimulus.

Non-primary pathway

After the first level, which integrates both auditory pathways as one, a part of this pathway known as the non-primary pathway is diverted joining the ascending reticular pathway, which integrates sensory information of all kinds.

The main function of this route is to bring together several different sensory messages, but which are being given at the same time, to select those that must be processed more urgently.

Parts of the brain stem involved in hearing

The brainstem is the structure through which almost all sensory pathways pass and its function is to communicate the spinal cord, cerebellum, and brain. In it we can locate the nuclei corresponding to the auditory system in the brain. These are the following.

1. Cochlear nuclei

Cochlear nuclei are found on the surface of the brain stemIts main function is to examine the intensity of the sound, as well as the beginning, the duration and the end of this. In addition, they also provide information to the brain about the frequency of the sound, that is, whether it is bass or high-pitched sounds.

2. Superior olive complex

One of the most complex systems of the auditory brain is the upper olive complex. Its dense neural network is designed to analyze and filter all acoustic information that targets the cerebral cortex.

3. Lateral lemniscus and colliculus

The nucleus of the lateral lemniscus is involved in encoding the duration of the most complex sounds.

On the other hand, the colliculus divides into the dorsal and outer cortex and the central nucleus, which is composed of a large number of neurons.

The dorsal and external cortex is engaged in examining acoustic information and in recognizing complex sounds. While the central core analyzes the frequency of the sound and divides it into bass or treble.

The thalamus and auditory cortex

Other areas of the brain involved in hearing are the thalamus and the auditory cortex. Let's see how they work.

Auditory thalamus

The auditory thalamus, also known as the Medial Geniculate Body (CGM), receives fibers from both the dorsal and external cortex of the colliculus and its central nucleus. This part of the thalamus is divided into three specialized zones in one function. These areas are: the dorsal area, the middle area and the ventral area.

Dorsal area

Neurons in the dorsal area send projections to the secondary auditory cortex. These neurons tend to respond to a number of different sensory stimuli.

Ventral zone

Their neurons travel to the primary auditory cortex and are also involved in the analysis of the frequency of sound, maintaining latency between communications.

Primary auditory cortex

In people, the auditory cortex covers 8% of the entire surface of the cerebral cortex.

This primary auditory cortex consists of more than twelve different auditory fields that are located in the upper area of ​​the temporal lobe, where they extend by the angular turn towards the Silvio fissure; there they meet the transverse gyrus of Heschl.

This brain area can in turn be divided into two regions differentiated by the organization of their neurons and by their functions. These areas are as follows.

• Area AI is composed of neurons that determine the spatial representation of the stimulus.
• The AII area is dedicated to locate sound in external space, examine complex sounds and it is closely related to auditory memory.

Finally, the area surrounding these two areas is in charge of analyzing and integrating the auditory information with the other sensory information that the person perceives.