What is the Cerebral Cortex?

Alan Rankin

The cerebral cortex is the outermost layer of the brain in complex animals such as mammals, including humans. Despite a thickness of less than 0.2 inch (5 mm), it is responsible for most higher brain functions, including language, memory, and consciousness. The cerebral cortex is folded in on itself in complex grooves to aid and quicken brain activity. In brains preserved for study, the cortex is gray, inspiring the phrase “gray matter,” often used casually to refer to any part of the brain.

The cerebral cortex is responsible for higher brain functions like language and memory.
The cerebral cortex is responsible for higher brain functions like language and memory.

If the cerebral cortex were to be removed and unfolded, it would cover several yards or meters. The grooves that condense the cortex are called sulci, and the ridges formed by this process are called gyri. This structure allows more mental processing power in a smaller space and also allows neurons involved in similar brain functions to communicate information more quickly. A brain with more grooves and ridges is smarter; that is, it can retain more information and process it faster.

The cerebral cortex is a layer of the brain responsible for complex functions.
The cerebral cortex is a layer of the brain responsible for complex functions.

The cerebral cortex in humans has six layers, each dealing with different mental or physical functions. The parts of the brain dealing with sensory input have thinner cortical layers, while those dealing with motor functions are thicker. Each cortical area has a different brain function. Functions of the cortex include problem solving, emotional response, complex motor control, language, memory, speech, and processing of complex sensory data such as vision and sound.

These functions are not evenly distributed. The human brain is divided into two hemispheres, right and left, and each hemisphere has its own specialized functions. The right hemisphere, for example, processes complex visual data and focused attention. The left hemisphere processes language, and each hemisphere deals with different emotions. Left- or right-handedness indicates that the opposite brain hemisphere is “dominant” in that individual.

So-called gray matter is actually grayish-brown in living tissue, because of blood flow to the brain. The gray areas are nerve cells, or neurons, which occur throughout the brain and nervous system. It is their concentration in the cerebral cortex that gives the brain its familiar color.

Beneath the cortex is “white matter,” which, again, looks different depending on whether the brain is living or preserved. White matter is made of cellular structures, called axons, which relay information from the neurons to other parts of the brain and the body. Deeper regions of the brain control basic, involuntary functions such as heartbeat, respiration and digestion.

The  cerebral cortex is the outermost layer of brain.
The cerebral cortex is the outermost layer of brain.

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Discussion Comments



Interesting to note: this pattern also explains human interaction and collective intelligence quite well. There are various disciplines and realms of knowledge in the human race, and as these disciplines see patterns and learn from each other, new advancements are made. The human race is something like a giant brain.



I'm not sure if you meant to do this, but that last sentence described the very pattern of the human brain. It is much like a branching out organ with various neurons and synapses for various different sections, interacting to innovate and make new discoveries. As we grow and learn, our brain expands in a fractal manner, branching out again and again.



It is interesting to realize that we know so much about the stars, atoms, and large-scale phenomena, and yet know relatively little about the human mind. The more we discover, the more we realize that there are questions which we have not answered and every answer creates twenty thousand new questions. Knowledge is a like a tree, branching out into a thousand different sections, with the pattern of an ever-increasing fractal.


The cerebral cortex is the easiest to study and map because it is the outermost two-dimensional layer of the brain. In studying the brain, this is a good place to start. The reality is, however, the full function of the brain is three-dimensional and intricate. Certain functions require more than one and more than two parts of the brain to be active at once, making for an intricate combination process which is hard to map. Even once you've learned all that we know about the brain, there is still so much more left to learn, because we know barely anything in comparison to what there is to know. Discoveries are being made every day.

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