17.6: Association Areas of the Cortex
Association areas are regions of the cerebral cortex that do not have a specific sensory or motor function. Instead, they integrate and interpret information from various sources to enable higher cognitive processes such as memory, learning, and decision-making. Some key association areas include the following:
Prefrontal Association Area: This area is located in the frontal lobe and is involved in planning, decision-making, and moderating social behavior. It connects with primary motor areas, sensory areas, and the limbic system, which processes emotions.
Parietotemporal Association Area: Found at the junction of the parietal and temporal lobes, this area is crucial for understanding language and spatial awareness. It receives input from the primary auditory cortex, somatosensory cortex, and other sensory areas.
Limbic Association Area: This area is essential for memory formation and emotional processing. Located in the medial part of the temporal lobe, it connects with the hippocampus, amygdala, and other parts of the limbic system.
Broca's Area: Broca's area, located in the posterior part of the left inferior frontal gyrus, plays a crucial role in speech production. It connects with the primary motor cortex, responsible for controlling speech muscles, and Wernicke's area through a bundle of nerve fibers called the arcuate fasciculus.
Damage to Broca's area can result in Broca's aphasia, a condition characterized by non-fluent speech, difficulty forming complete sentences, and trouble finding the right words. However, comprehension usually remains relatively intact.
Wernicke's Area: Wernicke's area, situated in the superior temporal gyrus of the left temporal lobe, is responsible for language comprehension. It receives input from primary auditory and visual cortices, allowing it to process spoken and written language. Wernicke's area connects with Broca's through the arcuate fasciculus, enabling communication between speech production and comprehension.
Damage to Wernicke's area can lead to Wernicke's aphasia, a condition where individuals have fluent but nonsensical speech with poor comprehension. They may also need help understanding written language.
Association Areas of Special Senses: The association areas of special senses are responsible for processing and interpreting information from our primary sensory cortices. These include:
Visual Association Area: The visual association area, or the visual association cortex, is located in the brain's occipital lobe. This region plays a crucial role in processing and interpreting visual information, allowing us to make sense of what we see. It receives input from the primary visual cortex (V1), which detects basic features such as edges, colors, and motion. The visual association area then integrates this information to create a more comprehensive understanding of the visual scene, enabling us to recognize objects, faces, and other complex elements. Damage to the visual association area can result in visual agnosia, where individuals can see objects but cannot recognize or identify them.
Auditory Association Area: Found in the temporal lobe, this area interprets sounds and speech from the primary auditory cortex. Damage to the auditory association area can lead to auditory agnosia, where individuals can hear sounds but cannot understand or interpret them.
Somatosensory Association Area: This area is situated in the parietal lobe. It integrates and interprets tactile information from the primary somatosensory cortex. Damage to the somatosensory association area can result in difficulties recognizing objects by touch, astereognosis, or identifying body parts' position in space, and agnosia for body schema.
Orbitofrontal Cortex
The orbitofrontal cortex (OFC) is a region in the brain's frontal lobes, situated just above the orbits of the eyes. It involves various cognitive functions, including decision-making, emotional regulation, and reward processing. While not directly responsible for visual processing, the OFC is interconnected with other brain regions that handle visual information, such as the visual association cortex and the fusiform face area.
The OFC contributes to our ability to make decisions based on visual stimuli, such as choosing between different food items or evaluating the attractiveness of a potential mate. Additionally, it helps process the emotional content of visual information, allowing us to respond appropriately to facial expressions and other emotionally charged visual cues.
Facial Recognition Area
The facial recognition area, commonly known as the fusiform face area (FFA), is located in the fusiform gyrus of the temporal lobe. This region is dedicated explicitly to recognizing faces and distinguishing them from other objects. The FFA allows us to identify familiar faces quickly and accurately interpret facial expressions and emotions. The FFA works with other brain regions, such as the occipital face area (OFA) and the superior temporal sulcus (STS), to create a robust facial recognition system. While the FFA focuses on processing the invariant aspects of faces (e.g., identity), the OFA and STS deal with more changeable aspects, such as gaze direction and expression.
Frontal Eye Field Area
The frontal eye field (FEF) is a region within the frontal cortex that explicitly controls eye movements and visual attention. The FEF guides our eyes toward relevant visual stimuli and away from irrelevant or distracting information. It coordinates saccadic eye movements, which are rapid, voluntary shifts in gaze that allow us to explore our visual environment efficiently. Additionally, the FEF contributes to higher-order cognitive processes, such as working memory and attention. The FEF enables us to prioritize and process relevant information more effectively by directing our visual attention to specific locations or objects.
