Associative cortex (brain): types, parts and functions

We see, hear, smell, touch... The human being receives a large number of different stimuli that we experience through the senses. However what our sensory receptors pick up is just raw data, which by themselves would not help us to survive.

For example, if we weren't able to link visual perception with a sense of threat, a predator could easily devour us. Nor would we be able to compose a melody, or to enjoy a kiss. Even if we speak only of a perception and focus it only on one sense, we would not be able to give it a meaning.

We need to be able to collect the perceived data and integrate it so that it makes sense. This is done by different nuclei such as the thalamus, as well as brain areas such as the associative cortex. This article will deal with the latter, focused on exploring the types, functions and lesions associated with the associative cortex and its parts.

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

The associative cortex and its functions

We call the associative cortex the part of the cerebral cortex (the most external and visible part of the brain) that is mainly responsible for associating and

link together the different information from brain regions in charge of the various senses or of having the necessary programs for the movement

In other words, these are the areas of the cerebral cortex that allow the integration of information from a same sense and / or several so that we can have a joint perception of the stimuli and the environment. Thus, they are the ones that broadly allow us to be aware of what surrounds us and even of ourselves, since thanks to them we can interpret reality and react adaptively to her. The processed information can be sensory or motor.

Types of associative cortex

There are different types of associative cortex, depending on the type of information they process.

1. Unimodal associative cortex

The unimodal association cortex is the one that is in charge of processing information from a single sense or in order to perform a single function (such as movement). These cortices are generally located in the vicinity of the regions that process the information of the senses or that necessary to move.

These are those areas that are linked to the processing and integration of sensory or motor information. They allow, among other things, the recognition and interpretation of stimuli.

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2. Multimodal associative cortex

This type of cortex is responsible for integrating information from different sensory modalities, allowing the interpretation of the environment and the planning and execution of mental operations or behaviors.

3. Supramodal associative cortex

This type of associative cortex differs from the previous ones by the fact that it does not work directly with information from any sensory modality, but rather that is linked to cognitive aspects. It is often considered multimodal.

• Related article: "Cognition: definition, main processes and operation"

Main unimodal associative areas

The number of associative areas and structures is very high, due to the need to integrate the information coming from the brain and act accordingly. In fact, it is considered that more than 80% of the cerebral cortex performs some type of association function.

If we talk about unimodal association areas, we can find the following among them.

1. Secondary visual area

Visual information is integrated into this brain region, linking aspects such as color, shape or depth.

2. Secondary hearing area

Thanks to it we are able to integrate auditory information, such as tone and volume.

3. Secondary somatic area

In this area are integrated the perceptions from somesthesia, the set of sensations that we capture from our own body.

4. Premotor area and supplementary motor cortex

Associative motor-type areas dedicated to the integration of the signals necessary to prepare an action or behavior. Has the necessary programs to carry out a movement.

Three major areas of multimodal and supramodal association

With regard to the multimodal and supramodal association areas, in a general way we can indicate the existence of three large brain areas.

1. Associative prefrontal cortex

Located in front of the motor cortex, the prefrontal cortex is one of the areas of the brain that relationship has with respect to the control and management of behavior, being largely responsible for how are. It is mainly in charge of cognitive and behavioral management tasks, including aspects such as reasoning, predicting and planning, making decisions or inhibiting behavior.

The set of executive functions, as well as the formation of the personality of each one of us, start from this area. Thanks to it we are able to adapt to situations and develop strategies and goals. It is also relevant in the expression of language, due to the important role of the Broca's area.

2. Parieto-temporo-occipital association area

This association area is located between the lobes temporary, parietal Y occipital, integrating different information from senses such as vision, touch and hearing. This associative area is fundamental for the human being, since it is largely thanks to it that we link the data from the different perceptual pathways.

It allows the symbolism, interpretation and understanding of reality as a whole. Also allows awareness and orientation. Thanks to it (specifically the one located in the left hemisphere) we are also able to interpret both oral and written language.

3. Limbic cortex

The limbic cortex is the third of the great multimodal association areas. In this associative cortex the information coming from the limbic system. It allows us to understand our emotions and associate them with specific aspects of reality, as well as their connection with memories. It also influences the capture of emotions in others.

Effects of damage in these areas

The effect of an injury or alteration of any of these areas can have various effects of varying intensity and severity, altering our behavior and perception.

Lesions in areas of unimodal association will cause difficulties in the recognition of stimuli, generating agnosias. Namely, we see something but we don't know what it is, or we touch something but cannot determine what it is. With regard to injuries in areas of motor association, specifically in the supplementary motor, it tends to generate incoordination and apraxia so that the follow-up of actions that require sequenced movements will be deeply affected, being minimal or non-existent.

When it comes to injuries in multimodal association areas, the damage can affect a large number of complex mental processes and functions. If language areas are damaged, aphasia (especially those in which there are comprehension problems). In the case of the prefrontal, damage in this area can alter personality and self-management of the person, causing from disinhibition and aggressiveness to inability to maintain concentration, set goals or follow plans.

Regarding the associative cortex, emotional expression may be made difficult or impossible or the capture of it in others, as well as disconnecting the emotion from the stimulation that is being received.

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