The 5 auditory areas of the brain

These parts of the brain, located in and below the cerebral cortex, are essential.

People are used to living with sound. Hearing everything around us is something we have so internalized that we don't even stop to think about how this information enters our ears and comes to be experienced by us.

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

What are the auditory areas of the brain?

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

These brain areas are the brainstem together with the superior olivary 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 responsible, together with the auditory pathways, for transporting information to the brain by means of electrical impulses.

Function of the auditory pathways

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

Primary auditory pathway

The primary auditory pathway is a neuronal circuit of short length and with the capacity to transport auditory information. and with the capacity to transport information very quickly, since it is made up of thick myelin fibers.

Its only task is to transport the information that is collected by the cochlea, performing decoding and interpretation tasks at each level. 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 the auditory stimulus. or reaction to the 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 diverges to join the ascending reticular pathway, which integrates sensory information of all types. integrates sensory information of all types.

The main function of this pathway is to bring together several different sensory messages, but which are occurring at the same time, to select those that need to be processed most urgently.

Parts of the brainstem involved in hearing

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

1. Cochlear nuclei

The cochlear nuclei are located on the surface of the brainstem.Their main function is to examine the intensity of the sound, as well as the beginning, duration and end of the sound. In addition, they also provide information to the brain about the frequency of the sound, i.e. whether it is a low or high-pitched sound.

2. Superior olivary complex

One of the most complex systems in the auditory brain is the superior olivary complex. Its dense neural network is designed to analyze and filter all acoustic information that is directed to the cerebral cortex. information that is directed to the cerebral cortex.

3. Lateral lemniscus and colliculus

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

On the other hand, the colliculus is divided into the dorsal and external cortex and into the central nucleuswhich is composed of a large number of neurons.

The dorsal and external cortex is dedicated to the examination of acoustic information and the recognition of complex sounds. While the central nucleus analyzes the frequency of the sound and divides it into bass or treble.

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 (MGB), receives fibers from both the auditory cortex and the auditory thalamus.receives fibers from both the dorsal and outer cortex of the colliculus and the central nucleus of the colliculus. This part of the thalamus is divided into three functionally specialized zones. These zones are: the dorsal zone, the medial zone and the ventral zone.

Dorsal zone

Neurons in the dorsal zone send projections to the secondary auditory cortex. These neurons have to respond to various different sensory stimuli.

Ventral zone

Its neurons travel to the primary auditory cortex and are also involved in sound frequency analysis. also intervene in the analysis of the frequency of the soundmaintaining the latency between communications.

Primary auditory cortex

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

This primary auditory cortex consists of more than twelve different auditory fields that are located in the are located in the superior area of the temporal lobe, where they extend through the gyrusThey extend through the angular gyrus towards the Sylvian fissure, where they meet the transverse gyri of Heschl.

This cerebral area can be further divided into two regions differentiated by the organization of its neurons and by their functions. These areas are as follows.

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

Finally, the area surrounding these two areas is responsible for analyzing and integrating auditory information with the other sensory information perceived by the person.