The bark cerebral It is the newest (evolutionarily) and largest part of the . This is where perception, imagination, thinking, judgment and decision occur. It is the largest region of the mammalian brain and plays a key role in memory, attention, perception, cognition, consciousness, thinking, language and consciousness.
In the following Psychology-Online article, we are going to explain in detail What is the cerebral cortex, what are its layers, parts and functions.
What is the cortex or cerebral cortex – definition and function
The cerebral cortex is primarily a thin gray matter layer – typically 6 neurons thick, in fact – above a vast collection of white matter pathways. The thin layer is strongly convoluted, so if you spread it out, it would occupy about 2500 cm2. This layer includes about 10 billion neurons, with about 50 trillion synapses. Gyri have “crests,” which are called gyri, and “valleys,” which are called sulci.
Parts and functions of the cerebral cortex
Some grooves are quite pronounced and long and are used as agreed boundaries between the four areas of the brain called lobes. The far front part is called the frontal lobe. This one seems to be especially important: this lobe is responsible for voluntary movements and planning and is thought to be the most important lobe for personality and intelligence.
At the back of the frontal lobe, along the sulcus that separates it from the parietal lobe, there is an area called motor cortex. In studies with patients undergoing brain surgery, stimulating areas of the motor cortex with small electrical shocks caused movements. It has been possible for researchers to make a fairly precise map of our motor cortex. The lower parts of the motor cortex, near the temples, control the muscles of the mouth and face. The parts of the motor cortex near the top of the head control the legs and feet.
Under the frontal lobes is the parietal lobe (which is Latin for “wall”). This includes an area called somatosensory cortex, just below the sulcus that separates this lobe from the frontal lobe. Again, the doctors stimulated points in this area and found that their patients described sensations as if they were being touched in various parts of their body. As with the motor cortex, the somatosensory cortex can be mapped, with the mouth and face near the temples and the legs and feet on the top of the head.
Next to the head is the temporal lobe (this is the Latin term for “temples”). The special area of the temporal lobe is the auditory cortex. As its name suggests, this area is closely connected to the ears and specialized in hearing. It is located near the connections of the temporal lobe with the parietal and frontal lobes. At the back of the head is the occipital lobe. At the back of the occipital lobe is the visual cortex, which receives information from the eyes and specializes, of course, in vision. The areas of the lobes that are not specialized are called association cortex. In addition to connecting the sensory and motor cortices, it is thought that this is also the place where our thought processes occur and many of our memories are ultimately stored.
Below we offer you an image so that you know the main parts of the cerebral cortex
Layers of the cerebral cortex
There are 6 layers of the cerebral cortexNext, we are going to explain each one of them, ordered from the surface to the inside of it:
- Molecular layer: Also called the plexiform layer, it is the most superficial layer of the cerebral cortex. It is a synaptic layer composed of a dense network of nerve fibers, which derive from dendrites of pyramidal and fusiform cells, the axons of Martinotti and stellate cells. Being the outermost layer, many synapses are established between neurons.
- External granular layer: It is located below the molecular layer and, in it, there are many small stellate and pyramidal cells. The dendrites of the cells and the axons infiltrate into deeper layers, so this layer is interconnected with the different parts of the cortex.
- External pyramidal layer: It is made up of pyramidal cells and has an irregular shape with a size that increases from the surface to the deepest part. Pyramidal cells direct their axons to other parts of the cortex in the form of projection, association or commissural fibers.
- Inner granular layer: It is made up of stellate cells, which are arranged compactly. It has the external Baillarger band, which are fibers arranged horizontally.
- Inner pyramidal layer: Also called the ganglion layer, it has medium and large pyramidal cells. It has a large number of fibers arranged horizontally, which make up the so-called internal Baillarger band.
- Multiform or polymorphic layer: It is made up of spindle cells and also has modified pyramidal cells, which have a triangular or ovoid body. The nerve fibers from this layer of the cerebral cortex enter the underlying white matter, connecting with the intermediate regions. Spindle cells send information to the cortex, thalamus, and striatum.
The cerebral hemispheres
If you look at the brain from above, it becomes immediately obvious that there is a division in two from front to back. There are, in fact, two hemispheres, as if we had two brains in our heads instead of just one. Of course, these two halves are intimately joined by an arc of white matter called hard body. In several ways, researchers have found that the two sides have some specialization.
Functions and differences of the cerebral hemispheres
The left hemisphere It is related to the right side of the body (usually), and the right hemisphere It is related to the left side of the body. Furthermore, it is the left hemisphere that normally has language, and appears to be primarily responsible for similar systems such as mathematics and logic. The right hemisphere has more to do with things like spatial orientation, face recognition, and body image. It also seems to govern our ability to appreciate art and music. Some of the most interesting work that has been done related to the two hemispheres was carried out by Roger Sperry . He worked with people who had had quite serious surgery to control his epilepsy.
The right part of each retina (which sees things to the left of the fixation point) goes to the left hemisphere. What this means is that if you have someone staring at a fixation point and you briefly show them something to the left, it is the right hemisphere that receives the information. If you show them something on the right, it is the left hemisphere that receives the information. Sperry projected things on a screen and asked patients to either say what they had seen or to pick up what they had seen with one hand or the other from a box full of things. Thus, if he showed a ball on the left side of the screen and a pencil on the right, the person could say “pencil” (using the language centers of the left hemisphere) but pick up a ball from the box with his left hand ( using the right hemisphere).
Image: areaciencias.com
Left and right hemisphere: experiments on epilepsy
It appears that, in some cases, severe epilepsy can be almost eliminated sectioning the corpus callosum. In a sense, these people really had two brains (or cortices, to be more exact).
For example, Sperry found that if he put something in the right hand of one of these people after their operation, they could tell what it was. But if he put it in her left hand, they couldn’t do it. This is easy to understand: The sensation of an object in the right hand goes to the left hemisphere and, since this is the language area, the person could tell what it was. The sensation of something in the left hand, however, went to the right hemisphere, which cannot speak much. The eyes are connected to the hemispheres in a somewhat complicated way.
Today, it is often questioned whether the functions are really so separated by hemispheres or rather they are located distributed throughout the cerebral cortex.
Language and the cerebral cortex
Therefore, language is predominantly a function of the left hemisphere. Actually, the right hemisphere has a bit of language too: it has a good understanding of insults and swear words. Additionally, if you have left hemisphere brain damage early enough in childhood, the right hemisphere takes over language function. And it seems that there are some people who have language on the right side or even both sides. It is interesting to consider that monkeys and gorillas appear to be sensitive to calls of their own species in the left hemisphere: they turn their right ears toward the sound. Even some songbirds, such as canaries, have hemispheric specialization. One of the earliest things discovered about the brain was language centers.
One of them is called the Broca’s area, in the name of the doctor who first discovered it. It is located in the lower part of the left frontal lobe. A patient who has had damage to that area loses the ability to speak, which is called expression aphasia. Another area is the area of Wernicke , which is close to Broca’s area but in the temporal lobe, right next to the auditory cortex. This is where we understand the meaning of language, and damage to this area would lead to a reception aphasia, meaning that you would not be able to understand what is being said to you.
Occasionally, someone has damage to the connections between them. This leads to a conduction aphasia. Some people with this problem can understand language quite well, and can produce it equally well. But they cannot repeat something they just heard. Another important area is the turn angular, just above and below Wernicke’s area. It serves as a connection between the language centers and the visual cortex. If this area is damaged, the person will suffer from alexia (inability to read) and agraphia (inability to write).
Photos about the cerebral cortex
If you want to know more about the functions of the cerebral cortex and anatomy of the nervous system We offer you the following article: .
Below, we also show you a battery of photographs and images about the cerebral cortex so that you can observe and study it.
Image source: snowbrains and pinterest
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