The angular gyrus is a region of the human brain located within the parietal lobe. It plays a role in complex cognitive processes, integrating different types of information. This brain region is involved in functions fundamental to human thought and interaction.
Location in the Brain
The angular gyrus is situated in the posteroinferior part of the parietal lobe, within the inferior parietal lobule. It lies where the parietal, temporal, and occipital lobes meet, acting as a “crossroads” for information from different sensory areas. While present in both hemispheres, the angular gyrus in the dominant hemisphere, typically the left, is particularly involved in many of its functions.
Key Roles in Language and Numbers
The angular gyrus is involved in language and numerical processing. It plays a role in reading comprehension by integrating visual and auditory inputs to make sense of text, linking visual symbols to their meanings, essential for both reading and writing. Damage to this area can lead to difficulties such as alexia (inability to read) and agraphia (inability to write).
Beyond language, the angular gyrus contributes to numerical cognition and mathematical operations. It is activated during tasks requiring numerical processing, such as mental arithmetic and comparing numbers. The left angular gyrus, specifically, is associated with the retrieval of arithmetic facts. Injuries to this brain region have been linked to acalculia (difficulty with mathematical calculations).
Integrating Information and Higher Cognition
The angular gyrus serves as a center for integrating diverse information, combining inputs from different senses like vision, hearing, and touch to create a coherent understanding of the environment. This integration is crucial for complex cognitive tasks. It contributes to spatial awareness and navigation by processing spatial relationships and directing attention to specific locations. The right angular gyrus, for instance, has been associated with directing spatiovisual attention.
This region also plays a role in memory retrieval, particularly for episodic and semantic memories. It helps combine separate memory components and pieces of information into a single representation for recalling vivid memories. The angular gyrus is also involved in social cognition, including the ability to understand and attribute mental states to oneself and others (theory of mind).
What Happens When It’s Damaged
Damage to the angular gyrus, which can result from events like strokes or injuries, often leads to specific cognitive deficits. One well-known consequence is Gerstmann’s Syndrome, a condition characterized by four primary symptoms: agraphia (difficulty writing), acalculia (difficulty with calculations), finger agnosia (inability to identify individual fingers), and left-right disorientation. These combined deficits highlight the angular gyrus’s role in integrating symbolic information and spatial awareness.
The angular gyrus’s involvement in language processing means that its damage can also contribute to certain types of aphasia. For example, it can play a role in transcortical sensory aphasia, where comprehension is impaired even though a person can speak fluently. Damage to the angular gyrus, particularly in the non-dominant hemisphere, can be associated with neglect syndromes, where individuals may have difficulty attending to one side of space. These clinical presentations underscore the angular gyrus’s importance in integrating sensory input and processing symbolic information for a wide range of cognitive functions.