The cerebral cortex is the outermost layer of the brain, composed of folded gray matter. It plays a crucial role in various complex cognitive processes including thought, perception, language, memory, attention, consciousness, and advanced motor functions.
The cerebral cortex is constructed primarily of grey matter, containing between 14 and 16 billion neurons.
Did you know? Although the cerebral cortex is only a few millimeters thick, it consists of approximately half the weight of the total brain mass.
Its wrinkled appearance, consisting of bulges (gyri) and deep furrows (sulci), allows for a wider surface area and increased number of neurons, enabling large amounts of information to be processed.
The cortex is divided into two hemispheres, right and left, separated by the medial longitudinal fissure.
These hemispheres are connected via nerve fiber bundles called the corpus callosum, allowing communication and further connections.
The cerebral cortex controls a vast array of functions through the use of the lobes, which are divided based on the location of gyri and sulci.
These lobes are called the frontal lobes, temporal lobes, parietal lobes, and occipital lobes.
Lobes and their Functions
The cerebral cortex, which is the outer surface of the brain, is associated with higher level processes such as consciousness, thought, emotion, reasoning, language, and memory.
Each cerebral hemisphere can be subdivided into four lobes, each associated with different functions.
Together, the lobes serve many conscious and unconscious functions, such as being responsible for movement, processing sensory information from the senses, processing language, intelligence, and personality.
Frontal Lobes
Located at the front of the brain, the frontal lobes are central to executive function, voluntary movement, and personality. The prefrontal cortex plays a major role in decision-making and social behavior.
Key functions:
- Executive functions – Planning, decision-making, problem-solving
Example: Organizing a project step-by-step - Motor control – Controlled by the primary motor cortex, which sends signals to muscles
Example: Learning to play piano - Speech production – Managed by Broca’s area (usually in the left hemisphere)
Example: Speaking grammatically correct sentences - Emotional regulation and impulse control
Example: Resisting the urge to lash out - Working memory and attention
Example: Holding a phone number in mind while dialing
Frontal lobe injury can lead to personality changes, impaired judgment, reduced motor control, and speech difficulties.
Parietal Lobes
Situated at the top and rear of the brain, the parietal lobes process sensory information and support spatial orientation. The primary somatosensory cortex receives input related to touch, pressure, temperature, and pain.
Key functions:
- Sensory integration – Combining information from touch, body position, and movement
Example: Identifying an object by touch alone - Spatial awareness and navigation
Example: Judging the distance between two cars while driving - Mathematical and logical reasoning
Example: Solving geometry problems - Attention to environment – Especially spatial attention and object recognition
Example: Noticing items on a cluttered desk
The parietal lobes are functionally lateralized. The right parietal lobe supports spatial processing, such as navigating environments.
The left parietal lobe specializes in symbolic functions, including language and mathematical reasoning.
Injury to the right parietal lobe may cause neglect syndrome, where individuals ignore the left side of their body or environment.
Temporal Lobes
Located near the temples, the temporal lobes are involved in auditory processing, language comprehension, and memory storage. They house critical structures like the hippocampus and amygdala.
Key functions:
- Auditory processing – Handled by the auditory cortex
Example: Recognizing the sound of a violin - Language comprehension – Managed by Wernicke’s area
Example: Understanding spoken or written sentences - Memory formation and retrieval – Linked to the hippocampus
Example: Recalling a recent conversation - Emotional processing – Influenced by the amygdala
Example: Recognizing anger in someone’s voice - Visual perception and object recognition
Example: Identifying a familiar face
Temporal lobe damage may result in memory loss, language deficits (e.g., Wernicke’s aphasia, or emotional dysregulation.
The temporal lobes, found on the sides of the brain near the ears, are involved in a diverse array of functions.
They play a crucial role in auditory processing, language comprehension, memory, and emotional processing.
Occipital Lobes
At the back of the brain lies the occipital lobe, home to the primary visual cortex (V1). It receives and interprets signals from the eyes to help us understand and respond to visual information.
Key functions:
- Basic visual processing – Detecting shape, color, and motion
Example: Seeing the edge of a sidewalk - Color recognition
Example: Distinguishing between red and orange - Motion perception
Example: Tracking a moving soccer ball - Visual word recognition – Part of the visual word form area
Example: Instantly recognizing familiar printed words
Injury here can cause visual deficits, such as color blindness, difficulty recognizing objects (visual agnosia), or even cortical blindness.
Functional Areas
The cerebral cortex can be divided into three main types of functional areas: sensory, motor, and association areas.
These divisions serve different purposes but work together to process information, control behavior, and enable complex cognitive functions.
While these areas are distributed across the different lobes, their specific functions contribute to the overall capabilities of the cerebral cortex.
Sensory Areas
Sensory areas receive and process information from various senses.
Key regions:
- Visual cortex: Located in the occipital lobe, it processes basic visual stimuli and contributes to object recognition. The left hemisphere processes the right visual field and vice versa.
- Somatosensory cortex: Found in the parietal lobe, it creates a ‘map’ of the body from tactile information, including temperature, touch, and pain. This sensory input is first relayed through the thalamus, a central hub that directs incoming signals from the body to the appropriate cortical areas for processing.
- Auditory cortex: Situated in the temporal lobes, it processes hearing information, including language. Some people can use this area for language switching.
- Gustatory cortex: Located in the frontal lobe, it’s responsible for taste and flavor perception.
Motor Areas
Motor areas regulate and initiate voluntary movement, primarily found within in the frontal lobes.
Primary components:
- Primary motor cortex: Contains a motor homunculus, a representational map of the body. Each hemisphere controls the opposite side of the body.
- Premotor cortex: Prepares and executes movements, crucial for imitation learning. It also plays a role in social cognition and empathy.
- Supplementary motor area: Plans complex movement sequences and contributes to movement control.
Association Areas
Association areas are regions of the cerebral cortex not directly involved in primary sensory processing or motor control.
These are found within all four lobes, make up a large portion of the cerebral cortex and are interspersed among primary, sensory, and motor areas.
Key roles:
- Integrate information from multiple sensory and motor areas
- Enable higher-order cognitive functions like abstract thinking and problem-solving
- Support complex processes such as language, memory, and attention
Structure
The cerebral cortex has a layered and highly organized structure that supports its role in complex thinking, perception, and behavior. Although only a few millimeters thick, it contains billions of neurons and forms the outermost part of the brain.
Layered Organization
The cortex is made up of six horizontal layers of cells, each playing a different role in how the brain processes information. These layers work together to receive sensory input, coordinate responses, and send information to other brain regions. While the full structure is complex, what’s most important to know is that this layering helps the brain organize signals efficiently.
Neurons and Support Cells
The cortex contains two main types of cells:
- Neurons, like pyramidal cells and stellate cells, transmit electrical signals. They allow different parts of the brain to communicate and process information.
- Glial cells, including astrocytes and oligodendrocytes, support and protect neurons. They help with nutrient transport, waste removal, and signal insulation.
These cells work together to form neural networks that support everything from movement and memory to emotion and decision-making.
Cortical Regions
The cerebral cortex is also divided into three evolutionary types:
- Neocortex – The most recently evolved and largest part, involved in higher-level functions like reasoning, language, and sensory perception.
- Allocortex – A smaller, older region that includes parts of the olfactory system and some memory-related structures.
- Archicortex – The oldest part, mostly found in the hippocampus, which plays a central role in memory and spatial navigation.
Together, these regions form the structural basis for the cortex’s wide-ranging psychological functions.
Brodmann Areas
Brodmann Areas, named after German neurologist Korbinian Brodmann, are a system for mapping and categorizing regions of the human cerebral cortex based on their distinct cellular architecture and functions.
These numbered areas, which range from 1 to 52, provide a structural framework for understanding different brain functions, such as sensory processing, motor control, and higher cognitive processes, contributing to our knowledge of brain organization and function.
References
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Further Information
- Kniermin J. Neuroscience online: an electronic textbook for the neurosciences. Chapter 5: Cerebellum. University of Texas Health Science Center at Houston.
- Stoodley, C. J. (2016). The cerebellum and neurodevelopmental disorders. The Cerebellum, 15(1), 34-37.
- D”Angelo, E. (2019). The cerebellum gets social. Science, 363(6424), 229-229.
