Did You Know?
Both fusiform gyruses on the left and right side of the brain are interlinked, but they are thought to play very different roles. The left one recognizes face-specific features in objects that may or may not be an actual face. The right one recognizes whether these features actually belong to a real face.
What is the Fusiform Gyrus?
The fusiform gyrus is an important part of the brain, located in the Brodmann Area 37, between the lingual gyrus and the parahippocampal gyrus above it, and the inferior temporal gyrus below it, and is a part of the temporal and occipital lobe. It is recognized as an elongated ridge on both sides of the cerebrum. Although science has not conclusively proven the functions of this area, a general consensus by most researchers indicates essential high-level visual processing by this region of the brain.
Functions of the Fusiform Gyrus
- The fusiform gyrus is considered to be extremely important for face-specific processing functions in the human brain, as it uses it neurons to separate the color and shape of a face into generic categories. In a particular study, a subject reported that upon reviving artificial electrical stimulus to the fusiform gyrus, the faces of the researchers changed and acquired different features.
- Perceptions towards the recognition of emotions through facial expressions is also linked with the fusiform gyrus and the amygdala. It has however been noted that people with autism show low response in this area on being exposed to a human face, which is believed to be the reason why many autistic people are unable to recognize faces.
- The fusiform gyrus is seen to be activated whenever a person views anything that resembles a face, even if it is a non-living object.
- The occurrence of cartoonish or realistic hallucinations of faces is also often seen as a result of heightened neurophysical activity in this region.
- It is also believed that it helps in the recognition of designs and symbols used in a person's daily life, such as recognizing written words and numbers, or recognizing a particular brand and make of a popular car though its shape and color.
It is believed that the fusiform gyrus is responsible for a mental disorder called prosopagnosia/face blindness, where a person is unable to remember faces of people he/she has met, and instead relates to people through other stimuli, such as their clothes, hairstyle, voice, gait, etc. Although this hypothesis has not been conclusively proven, it is considered by most experts to be highly probable. This disorder can also lead to problems of recognizing colors, or recognizing places with the help of landmarks. The primary cause of this disorder is the occurrence of a stroke. However, people can also be born with this condition.
Another disorder related to prosopagnosia, called Williams syndrome, is also believed to occur partly due to abnormalities in the fusiform gyrus, where a person has slow mental development, and unusual cheerfulness and ease towards strangers.
This is a rare condition, where a person experiences stimuli with more than one sense of the body. For example, a person may associate colors with particular written languages, hear a particular sound when looking at a particular number, or see different colors when hearing various notes of music, etc. In these cases, the neurons of the fusiform gyrus have been noted to show high levels of activity. It is said to primarily occur when the boundaries between the fusiform gyrus and other parts of the brain are not well-defined, and merge into each other. In these cases, stimulus to one part of the brain may elicit reactions from an unrelated region.
As you can see, the fusiform gyrus plays an extremely important role in human psychology, and is vital in the effective functioning of people in a highly interactive human society.