Color vision is an important tool for distinguishing and identifying objects around us. Like other animals, humans can match, classify, identify, memorize, and imagine colors. However, these abilities can be lost when a person suffers from brain damage.
There are also instances when a person demonstrates selective color impairments, such as color agnosia. This condition refers to the failure to recognize colors despite a person's ability to show color perception, semantic memory for color information, and color naming.
A Rare Genetic Trait in the Family
The first and only case of developmental agnosia was reported in 2007. In most cases, color agnosia is acquired after experiencing brain damage, but in the Netherlands, family members in three generations demonstrated difficulty naming and recognizing colors, suggesting that it is genetic. Although they can display normal cognition and intact color perception, they cannot name colors or categorize them into general clusters of color. The researchers who conducted the previous study concluded that the disorder has a genetic origin resulting in abnormal cortical development.
The same team of scientists conducted further studies to identify the genetic origins of the disorder and gain more insight into the developmental mechanisms related to this medical condition.
In the current study, three affected and three unaffected family members underwent CGH-array testing and exam sequencing. The CGH chromosome profile array was used to perform linkage analysis, while the Dominant Mapper was used to calculate disease loci. Meanwhile, the developmental expression profiles of all candidate genes were also determined using comprehensive human brain transcript data sets.
The investigation resulted in the identification of 19 genomics regions and 11 rare coding variants found in affected family members with developmental color agnosia. The segregation pattern in the family also suggests that this disorder is inherited with complete penetrance.
This study is the first to locate the genomics regions and genetic variants in developmental color agnosia. Since this condition prevails in a single family, the number of subjects is limited, in addition to the assumption that it is inherited in an autosomal dominant manner. At this stage, the researchers still cannot pinpoint the causal variant because replication is not yet possible due to the uniqueness of the affected family. Although this is an explorative study, the researchers hope that the set of candidate genes they investigated could be the starting point for discovering the mechanisms of higher-level cognitive functions and cortical specialization.
READ ALSO: Why Do We See Colors Differently?
How Do We Recognize Colors?
Color recognition is a joint activity of the human eye and brain. As the light receptors in the eye deliver the messages to the brain, a familiar sensation of color is produced. It was Isaac Newton who observed that color is not inherent in objects. Instead, some of the colors are reflected on the surface of an object while the other dyes are absorbed. The reflected colors are the ones that reach our eyes and get interpreted in the brain.
Upon reaching the eyes, light travels to the retina, which is covered with millions of sensory cells called rods and cones. When these cells detect light, they make a combined response that creates a unique signal for each color. The rods and cones connect nerve cells and give the brain enough information for color interpretation and recognition.
Studies show that about 8% of men and 1% of women experience some form of color impairment. Most people who suffer from color deficiencies are unaware that the color they perceive is different from the ones that appear to other people. Other color-impaired persons perceive color but transmit colors to their brains differently.
RELATED ARTICLE: Electric Eye Designed for Microrobots Could Someday Give Artificial Vision to Colorblind and Blind People, Scientists Claim
Check out more news and information on Color Recognition in Science Times.
