Corpus Callosum and Brain Function

The corpus callosum is a thick band of nerve fibers that divides the cerebral cortex lobes into left and right hemispheres. It connects the left and right sides of the brain, allowing for communication between both hemispheres. The corpus callosum transfers motor, sensory, and cognitive information between the brain hemispheres.

Function

The corpus callosum is the largest fiber bundle in the brain, containing nearly 200 million axons. It is composed of white matter fiber tracts known as commissural fibers. It is involved in several functions of the body including:

• Communication between brain hemispheres
• Eye movement and vision
• Maintaining the balance of arousal and attention
• Tactile localization

From anterior (front) to posterior (back), the corpus callosum can be divided into regions known as the rostrum, genu, body, and splenium. The rostrum and genu connect the left and right frontal lobes of the brain. The body and splenium connect the hemispheres of the temporal lobes and the hemispheres of the occipital lobes.

The corpus callosum plays an important role in vision by combining the separate halves of our visual field, which process images separately in each hemisphere. It also allows us to identify the objects we see by connecting the visual cortex with the language centers of the brain. In addition, the corpus callosum transfers tactile information (processed in the parietal lobes) between the brain hemispheres to enable us to locate touch.

Location

Directionally, the corpus callosum is located underneath the cerebrum at the midline of the brain. It resides within the interhemispheric fissure, which is a deep furrow that separates the brain hemispheres.

Agenesis of the Corpus Callosum

Agenesis of the corpus callosum (AgCC) is a condition in which an individual is born with a partial corpus callosum or no corpus callosum at all. The corpus callosum typically develops between 12 and 20 weeks and continues to experience structural changes even into adulthood. AgCC can be caused by a number of factors including chromosome mutations, prenatal infections, exposure of the fetus to certain toxins or medications, and abnormal brain development due to cysts. Individuals with AgCC may experience cognitive developmental delays, and they may have difficulty understanding language and social cues. Other potential problems include hearing deficits, distorted head or facial features, spasms, and seizures.

How are people born without a corpus callosum able to function? How are both hemispheres of their brain able to communicate? Researchers have discovered that the resting-state brain activity in both those with healthy brains and those with AgCC look essentially the same. This indicates that the brain compensates for the missing corpus callosum by rewiring itself and establishing new nerve connections between the brain hemispheres. The actual process involved in establishing this communication is still unknown.