WhiskersDorsal Parietal Cortex
The dorsal parietal cortex, a critical component of the parietal lobe, plays a crucial role in integrating sensory information, spatial awareness, and motor control. This highly interconnected region of the brain receives input from various sensory modalities, including visual, somatosensory, and auditory, and integrates this information to generate a comprehensive representation of the external world. The dorsal parietal cortex is involved in a wide range of cognitive functions, including attention, working memory, spatial reasoning, and motor planning, making it a fundamental element in our ability to interact with and navigate our environment.
Location and Structure
The dorsal parietal cortex occupies the posterior portion of the parietal lobe, located above the temporal lobe and behind the frontal lobe. It is divided into several distinct areas, each with specialized functions. The most prominent subdivisions include the posterior parietal cortex and the superior parietal lobule . The PPC, also known as the parieto-occipital cortex, is the most posterior part of the dorsal parietal cortex, bordering the occipital lobe. It receives visual information directly from the occipital cortex and plays a critical role in visuomotor control and spatial awareness. The SPL, situated anterior to the PPC, integrates information from various sensory modalities, including visual, somatosensory, and auditory input, and contributes to complex cognitive tasks such as attention, working memory, and spatial reasoning.
Dorsal Parietal Cortex Function
The dorsal parietal cortex is involved in a wide array of cognitive functions, highlighting its multifaceted role in brain function. Its key roles include:
Spatial Processing
The dorsal parietal cortex is central to our ability to perceive and interact with the spatial environment. It processes information about object location, size, shape, and distance, allowing us to navigate our surroundings effectively. The dorsal parietal cortex is crucial for tasks such as reaching for objects, grasping, and planning movements. It integrates visual information with motor commands, enabling us to accurately direct our movements towards specific targets. This spatial processing ability is also crucial for mental imagery, allowing us to visualize and manipulate objects in our minds.
Attention
The dorsal parietal cortex plays a critical role in directing our attention to specific locations in space or to specific features of objects. It filters out irrelevant information and enhances the processing of relevant stimuli, allowing us to focus on the most important aspects of our environment. This selective attention mechanism is essential for tasks requiring sustained attention, such as reading, listening, and problem-solving.
Motor Planning and Control
The dorsal parietal cortex is involved in planning and executing complex movements, working closely with the motor cortex to coordinate movement sequences and generate the appropriate motor commands. It integrates sensory information with internal representations of the body and the environment, allowing us to adapt our movements based on changing conditions. The dorsal parietal cortex also contributes to the control of fine motor skills, such as writing, drawing, and using tools.
Working Memory
The dorsal parietal cortex is crucial for maintaining and manipulating information in working memory, a temporary storage system that allows us to hold information in mind while performing cognitive tasks. It plays a role in both spatial working memory, holding information about locations and spatial relationships, and object working memory, holding information about features of objects. The dorsal parietal cortex is essential for tasks such as planning, reasoning, and problem-solving, which rely on the ability to hold and manipulate information in working memory.
Dorsal Parietal Cortex Autism
There is growing evidence suggesting that the dorsal parietal cortex may be involved in the development of autism spectrum disorder . Research indicates that individuals with ASD often exhibit altered brain activity in the dorsal parietal cortex, particularly in regions associated with spatial processing and attention. These findings suggest that dysfunction in the dorsal parietal cortex may contribute to some of the core symptoms of autism, such as social communication difficulties, repetitive behaviors, and sensory sensitivities.
One of the most common challenges faced by individuals with ASD is social communication impairment. This may be linked to difficulties in processing social cues, such as facial expressions and body language. The dorsal parietal cortex plays a crucial role in integrating these visual and social cues, and dysfunction in this area may contribute to the difficulties with social understanding observed in ASD.
Repetitive behaviors are another hallmark of ASD, and research suggests that the dorsal parietal cortex may be involved in their development. Studies have shown that individuals with ASD often exhibit altered brain activity in areas associated with motor planning and control, including the dorsal parietal cortex. This suggests that dysfunction in this area may contribute to the repetitive movements and behaviors often seen in ASD.
Finally, individuals with ASD often experience sensory sensitivities, which can range from heightened sensitivity to sensory stimuli to an unusual preference for certain sensory experiences. The dorsal parietal cortex plays a key role in processing sensory information, and dysfunction in this area may contribute to the sensory sensitivities observed in ASD. However, more research is needed to fully understand the role of the dorsal parietal cortex in the development of autism spectrum disorder.
Posterior Parietal Cortex
The posterior parietal cortex is a specific area within the dorsal parietal cortex that plays a crucial role in integrating sensory information, particularly visual input, with motor commands. It is located in the most posterior portion of the dorsal parietal cortex, bordering the occipital lobe. The PPC receives direct input from the visual cortex and plays a key role in visuomotor control and spatial awareness.
Posterior Parietal Cortex Function
The PPC is involved in a wide range of functions, including:
Visuomotor Control
The PPC is essential for coordinating visual information with motor commands, enabling us to reach for objects, grasp them, and manipulate them effectively. It integrates visual input about object location, size, shape, and distance with information about the position and movement of our limbs, allowing us to accurately guide our movements towards specific targets.
Spatial Awareness
The PPC plays a crucial role in our ability to perceive and navigate the spatial environment. It processes information about object location, distance, and orientation, allowing us to understand the layout of our surroundings. This spatial awareness is essential for tasks such as navigation, map reading, and object recognition.
Attention and Working Memory
The PPC is also involved in attentional processes, particularly in directing our attention to specific locations in space or to specific features of objects. It filters out irrelevant information and enhances the processing of relevant stimuli. Additionally, the PPC contributes to working memory, holding and manipulating spatial information in mind while performing cognitive tasks.
Posterior Parietal Cortex Damage
Damage to the posterior parietal cortex can result in a variety of impairments, depending on the specific area affected. Some common deficits include:
Spatial Neglect
Spatial neglect is a condition in which individuals fail to attend to or perceive stimuli on one side of their body or in their visual field. This may manifest as difficulty recognizing objects on the neglected side, ignoring information from that side, or neglecting one side of their body during activities such as dressing or grooming.
Apraxia
Apraxia is a disorder that affects the ability to plan and execute motor movements, even when there is no physical impairment. Individuals with apraxia may have difficulty performing purposeful actions, such as waving goodbye or using tools. This condition can be caused by damage to various areas of the brain, including the PPC.
Visual Agnosia
Visual agnosia is a condition in which individuals are unable to recognize familiar objects despite intact visual perception. This impairment can result from damage to various areas of the brain, including the PPC. Visual agnosia may be related to difficulties in integrating visual information with knowledge about objects stored in memory.
Posterior Parietal Cortex Brodmann
In 1909, Korbinian Brodmann, a German neuroanatomist, developed a map of the cerebral cortex based on the cytoarchitectonic organization, or the arrangement of neurons and cell layers. Brodmann areas are numbered regions of the cerebral cortex that are distinct in their cellular structure and function. The posterior parietal cortex encompasses several Brodmann areas, including:
Brodmann Area 5
Brodmann area 5 is located in the posterior parietal cortex and is associated with the integration of somatosensory information, including touch, pressure, temperature, and pain. It also plays a role in spatial awareness and motor planning. It is involved in the processing of tactile information and its integration with visual information. It also contributes to the planning of movements, particularly those requiring coordination of multiple body parts.
Brodmann Area 7
Brodmann area 7 is another area within the posterior parietal cortex, located more posteriorly than Brodmann area 5. It is involved in spatial awareness, attention, and working memory. It receives input from both the visual cortex and the somatosensory cortex and integrates this information to create a representation of the environment and our location within it. Brodmann area 7 is also crucial for directing our attention to specific locations in space and for holding and manipulating spatial information in working memory.
Brodmann Area 39
Brodmann area 39, also known as the angular gyrus, is located at the junction of the parietal, temporal, and occipital lobes. It is involved in a wide range of cognitive functions, including language processing, spatial reasoning, and number processing. It receives input from both the visual cortex and the auditory cortex and integrates this information to process language, understand the meaning of words, and perform tasks involving spatial reasoning and numerical operations.
Brodmann Area 40
Brodmann area 40, also known as the supramarginal gyrus, is located on the lateral surface of the parietal lobe, adjacent to the angular gyrus. It plays a role in language processing, spatial reasoning, and working memory. It receives input from both the auditory cortex and the somatosensory cortex and is involved in integrating these modalities to process language, perform tasks involving spatial reasoning, and hold and manipulate information in working memory.
Understanding the functions and connections of these Brodmann areas within the posterior parietal cortex sheds light on the complex cognitive processes that occur in this brain region. It highlights the crucial role that the posterior parietal cortex plays in integrating sensory information, generating spatial awareness, and executing complex motor commands.