The corpus callosum is a muscle in the brain that connects the left and right hemispheres. The corpus callosum is believed to foster communication between the two hemispheres, which is often necessary when performing basic actions; for instance, a thought may emerge in one hemisphere, and then an action corresponding to that thought may be performed by the other hemisphere. Feeling hunger and then reaching for food would be one such example of this function.

When the corpus callosum is damaged, however, there may be maladaptive behaviors that ensue, as the communication between the two hemispheres is severed. The following research evaluates the role of the corpus callosum, then presents several instances of maladaptive psychological functioning if this area of the brain is underdeveloped, damaged, or severed. The research highlights how changes in psychological behavior and actions may ensue. Although the exact functioning of the corpus callosum has not been fully discovered by science, there is a clear correlation between the corpus callosum and the interaction between both hemispheres in the brain.

The corpus callosum is a muscle in the brain that connects the left and right hemispheres. The corpus callosum acts as a communication mechanism between the two hemispheres, which control different elements of behavior (Gazzaniga, 2000). Studies involving the corpus callosum generally focus on the ability of the hemispheres to communicate; in studies on brains of musicians and mathematicians, there is evidence to support that the corpus callosum in these individuals tend to be larger, while the corpus callosum in persons who are dyslexic have been shown to be smaller, on average, than those without dyslexia (Schlaug et al., 2005).

In some instances, due to brain damage or in order to reduce the frequency or severity of seizures in epileptics, where the corpus callosum has been surgically cut, behavioral changes have occurred. This evidence has given psychologists and physicians a better understanding of the corpus callosum’s impact on how psychological and behavioral functioning.

The two hemispheres of the brain have different functions; the left hemisphere of the brain is believed to impact how the brain reasons and considers logic and critical thought, while the right hemisphere of the brain influences one’s ability to think in abstract and nonverbal terms. Many everyday decisions would involve both hemispheres of the brain communicating with one another; for instance, if one becomes hungry and begins to consider where he or she should get dinner, a region of the right brain is signaling hunger, while a region of the left brain is critically evaluating the best place to get dinner. The connective function of the corpus callosum between the two hemispheres might also explain why there have been observable differences in size for musicians and mathematicians, which on average have a larger corpus callosum, and dyslexics, who have a smaller one.

For musicians and mathematicians, they are able to think clearly in abstract terms, which they can then express through various musical notations or equations. This would indicate that the communicative process between the two brain hemispheres is fluid, and what originates in the right hemisphere is being interpreted and expressed by the left hemisphere via the corpus callosum. In dyslexics, however, there is a demonstrable difficulty to express or identify abstract concepts or terms in a coherent manner. This is why dyslexics might see a word, but interpret it differently than how it appears. The smaller corpus callosum is having difficulty conveying information between the two hemispheres.

One condition, known as agenesis of the corpus callosum, is a brith disorder in which the corpus callosum fails to develop (Paul et al., 2007). This has been observed to cause delayed physical abilities, such as walking or speaking, when diagnosed in children. There may also be impairments to both memory and hand-eye coordination. In some instances, agenesis has been seen in those who are deemed savants, which is an ability to perform high abstract reasoning or mathematical calculations, but often at the cost of social impairment.

Agenesis has also been linked to a syndrome known as alien hand syndrome; this condition involves persons whose limbs perform actions that are not consciously controlled (Biran and Chatterjee, 2004). For instance, a person may with alien hand syndrome may grasp an object without even being aware the object is being grasped. Similarly, a leg might kick at an object, although the motion is unaware to the individual until he or she feels the foot striking the object. These instances identify how a non-developed corpus callosum can cause significant maladaptive psychological behaviors. While the exact method of how the corpus callosum works remains unknown, there is a clear link between the corpus callosum and behavior.

When the corpus callosum has been damaged, either through accident or to prevent reduce seizures in epileptics, maladaptive behaviors have been observed. These behaviors often involve a lack of awareness in one hemisphere on behaviors influenced by the other; in other words, the right side of the brain may literally not know what the left side is doing, or vice versa. As an example, someone with a corpus callosum who has been severed might be able to recognize a face shown to him or her in a photograph, but be unable to say who the person is.

This is because the right side of the brain is able to identify the face based on visual cognition, but unable to connect with the left side of the brain, which would be able to identify details associated with the individual, such as the person’s name or relationship to the individual. Another example might involve someone who is shopping for groceries, and eats directly while in the store: the right brain identifies hunger and the visibility of food, while the left side of the brain, which would be responsible for higher reasoning that would demonstrate this behavior to be appropriate is not able to communicate this reasoning to the right side. Other studies have involved patients being shown an image in the left eye, and being unable to describe the image verbally. This would be due to one part of the brain having a disconnect from the other side of brain.

Those with a split corpus callosum are identified as having split-brains. The general maladaptive psychological behaviors that occur are therefore based on an inability to reason. In other words, they are not able to always implement an ability to think critically, or evaluate the entirety of circumstances that another person would be able to. This can create confusion and potentially socially harmful behaviors, as there may be a tendency for people with split-brains to not always reason through a course of action before taking it. While the example of the person who ate in a grocery store is one such instance, another instance might involve someone who is unable to control anger: the feeling of anger would be experienced by the right side of the brain, while the left side of the brain, which would be able to reason an appropriate, socially acceptable response will in essence not be consulted by the other half of the brain.

The corpus callosum is therefore responsible for ensuring that all regions of the brain are able to essentially communicate with one another. Because the evidence has shown that those with a larger corpus callosum are able to more easily articulate abstract concepts, while simultaneously showing that those with a damaged or smaller corpus callosum have difficulty on these same tasks, it would appear that this region of the brain has a direct impact on both perception and behavior. Maladaptive psychological behaviors can result if the area is damaged or severed, so this would demonstrate how behavior can be physiologically influenced. The corpus callosum can best be understood as a communication hub between the regions of the brain. When everything is working correctly, the brain is able to balance impulses with critical reasoning. When there is damage to this region, or it is underdeveloped, certain behavioral issues might emerge. This is due to the inability of the brain to communicate efficiently between all regions. One part of the brain will literally have no idea what another part of the brain is doing. Damage to the corpus callosum cannot be cured, but with both mental and physical therapy, the maladaptive behavioral consequences of this condition can be managed.