Corpus Callosum

The Corpus Callosum connects the hemispheres of the brain together. It runs across and consists of a multitude of fibers. It will also bar called.

What is the corpus callosum?

The corpus callosum is medically called Commissura magna designated. In addition, it is also titled Beam. It consists of over 200 million nerve fibers. In the cerebrum, a distinction is made between efferent and afferent nerve fibers.

The cerebrum is called the telencephalon. It makes up most of the human brain. The cerebrum is part of the central nervous system and has two hemispheres. This differentiates between the right and left hemispheres. The cerebrum is responsible for processing many thought and action processes. There are various web systems made of fibers in it. These are divided into three categories. These include the commissure fibers, the projection fibers and the association fibers. The projection fibers connect the basal ganglia to the brain stem.

The association fibers connect individual areas of the same hemisphere with one another. The corpus callosum forms the commissure fibers. These connect the areas of almost all parts of both hemispheres with one another. The area of ​​the primary auditory and visual cortex is excluded. The corpus callosum is responsible for ensuring that communication and information transfer between the two hemispheres of the brain can function.

Anatomy & structure

The corpus callosum has a curved structure and is located at the level of the temporal lobes. Seen from above, it is in the middle of the head and runs along the longitudinal fissure of the brain. It forms the roof of the two lateral ventricles. The commissure fibers contained in it are double-barreled.

The corpus callosum is divided into three areas. The frontal section is the bar knee or genu. The middle section is called the log trunk or trunk. The rear area represents the bar bulge or the splenium. The corpus callosum runs out as a thin rostrum below the genu. The fibers that connect both frontal lobes are called forceps frontalis or forceps minor.

The fibers that connect both occipital lobes are the forceps occipitalis or forceps major. The corpus callosum connects the cortex areas with the identical tasks of the respective hemispheres. The posterior and anterior fibers of the corpus callosum are U-shaped. The back of the beam is called the dorsal surface. This is covered by a thin gray coating. It is known as Indusium griseum. It is located in the cortical limbic areas.

Function & tasks

The corpus callosum plays an important role in connecting the two halves of the brain. The commissure system in it has the important task of transferring information to both hemispheres. The visual information of the left visual field is processed in the right occipital lobe.

The left occipital lobe processes the visual input from the right visual field analogously. The corpus callosum enables both occipital lobes to exchange what they have seen in the entire field of vision via a secondary communication path. The same applies to all other receptive and motor centers in the cortex of the cerebrum. Without the corpus callosum, this exchange would not exist. There is a coordination of the information from the respective hemispheres. The commissure fibers of the corpus callosum are both homotopic and heterotopic. This connects the areas of the cortex symmetrically as well as asymmetrically. This enables individual processes of information processing in the cerebrum to be divided into different regions and later put back together and coordinated with one another.

This means that objects that can be seen over the left half of the face or felt with the hands can only be named through the functional activity of the corpus callosum. The reason for this is that the associated sensory information is processed and interpreted in the right half of the brain. In the left half of the brain, however, the object being felt is named by the language centers. The connection between the hemispheres of the brain is very important for verbal-musical as well as verbal-analytical information transfer and processing. Thus, the scope of the beam goes far beyond a purely functional merging of the hemispheres.

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Diseases

Lesions in the area of ​​the corpus callosum lead to incorrect information processing, which is absorbed in the respective hemispheres of the brain. Objects felt or seen could not be recognized or named.

The information that is received by the senses can no longer be fully processed and put together in the individual sensorimotor areas. This leads to life-changing changes and has a major impact on how we cope with everyday life.

Clinically, the corpus callosum plays an important role in diseases such as epilepsy. Before there were good drugs used today to treat epilepsy, the corpus callosum was surgically cut through. This surgical procedure is called a callosotomy or "split-brain operation". Today it only occurs in isolated cases in very severe forms of epilepsy.

By cutting the corpus callosum, doctors want to prevent the pathogen from spreading from one hemisphere of the brain to the other. The severing of the interface between the two hemispheres should prevent the disease from worsening. In addition to illnesses such as severe epilepsy, surgery in the past was often performed after severe falls. The use of this method was also significantly reduced in these patients. Since the cognitive impairments of such an intervention are immense, the method is considered very controversial, although it has not yet been completely abandoned.