Welcome to 2 minute neuroscience, where I explain neuroscience topics in 2 minutes or
In this installment I will discuss the corpus callosum.
To understand the role of the corpus callosum, it is first important to remember that the
brain is divided into two cerebral hemispheres (right and left), separated from another by
a long groove called the medial longitudinal fissure.
These two hemispheres are nearly mirror images of one another, but they do not function independently
and communication between the cerebral hemispheres is important for healthy brain function.
The importance of this communication can be seen with the processing of sensory information,
which is typically received first in one hemisphere and then must be shared with the other hemisphere.
When you type on your keyboard, for example, information about the feel of the keys is
sent up from your right hand to the primary somatosensory cortex on the left side of your
That information must then be shared with the right side of your brain as well.
That's where the corpus callosum comes into play.
It carries information received in one hemisphere over to the other and in general allows for
communication between the two hemispheres.
The corpus callosum is a large, C-shaped nerve fiber bundle that stretches across the midline
of the brain, connecting the left and right cerebral hemispheres.
It makes up the largest collection of white matter found in the brain.
The importance of the corpus callosum can be seen in patients who have had their corpus
callosum surgically severed--usually to stop the spread of epileptic seizures.
After the procedure, known as a corpus callosotomy, patients may display deficits representative
of decreased communication between the cerebral hemispheres such as the inability to name
an object if it is shown only in the left visual field.
This is thought to occur because information from the left visual field travels to the
right side of the brain, while language centers reside primarily on the left side of the brain.
Without the corpus callosum to connect the two hemispheres, the patient cannot place
a name to an otherwise very familiar object.