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Location and Functions of the Angular Gyrus

Anuj Mudaliar
The angular gyrus is a very important part of the brain, which is responsible for processing language, numbers, and various other logic-oriented processes that we require in our day-to-day life. In this story, we will study the details of its location and functions more closely.
» Fun Fact
Recent research suggests that the angular gyrus is responsible for out-of-body experiences, where the subjects perceived the existence of phantom people, and could not accurately account for the actual positions of their own bodies.

What is an Angular Gyrus?

The cerebral cortex is the largest part of the human brain, which is divided into many sections. One part of the pareital lobe in the cerebral cortex is the angular gyrus.
This part is known as the Brodmann's area 39, and is considered as a part of the Wernicke's area. Its location is at the ridge in the brain at the inferior pareital lobe region, at the point where the temporal, occipital, and parietal lobes meet, i.e., the intersection between the middle and superior temporal gyri at the back of the head.
It is known for its psychology definition of mental phenomena and processes, such as understanding visual and audio inputs, interpreting languages, and retrieval of memories. This area is one of the last areas to mature functionally and anatomically.
Therefore, the capabilities associated with these regions, such as reading words and making numerical calculations develop late, at an age of around 4 - 8 years.

Functions of the Angular Gyrus

Language: The angular gyrus works to change audio stimuli into visual stimuli, and visual stimuli into audio. This ability is critical for a person to be able to read and write. The supramarginal gyrus and the angular gyrus work together on the language ability of a person by linking words with meanings. 
These two parts of the brain also work together to receive somatosensory - visual and audio inputs from other parts of the brain.

Memory Retrieval: Another purpose is to retrieve content and episodic memories, and also to check if the memory that is retrieved has any contradictions with what was expected.
Mathematics: Research has shown that the parietal lobe is largely made up of regions which are used in making approximate calculations; the angular gyrus is the most responsible for exact calculations. Therefore, a person with a more active angular gyrus will have better mathematical capabilities.
Awareness: The angular gyrus is extremely important in a person's consciousness of being aware of their own bodies, and what consequences are to take place due to any action/movement that they make.
Control of Motor Skills: It helps a person perform actions that he/she has observed or done before, by retrieving memories, and it helps to interpret 3D spaces and objects.

Effects of Damage

Alexia and Agraphia: The angular gyrus is essentially responsible for understanding written languages. Therefore, any damage to this area can result in a condition called alexia, where although a person can see the words, he will be unable to understand what he is reading, or not even write down words which he hears.
Dyslexia: If the processing of audio-visual inputs is poor in this region, it can lead to dyslexia.

Anomia: Damage to this region can also lead to anomia, where one cannot name people or objects.

Finger Agnosia: One cannot identify which finger is which through touch. It can also lead to difficulties in differentiating between the left and right directions.

Acalcula: One usually experiences difficulties while attempting to solve even simple problems of arithmetic.
Research also suggests that damage to the right side of the gyrus results in poor artistic skills, while damage to the left side leads to poor calculation skills. In case a tumor exists near the angular gyrus, it is possible that the subject's logical reasoning can be impaired.
However, with a successful surgery, one can regain his/her mental abilities to a great extent.