It is the loss of the ability to recognize objects, faces, voices, or places.
It is a weird mess. If you have this condition, you can still think, talk, and interact with the world. Agnosia generally affects only a single information pathway in the brain.
Agnosia occurs when the brain suffers damage along specific pathways. These routes connect the main areas of sensory processing—these parts of the brain store knowledge and information. Primary areas of sensory processing include visual and auditory cortices.
Lesions are usually caused in the parietal and temporal lobes of the brain. These lobes store information and semantic language. Strokes, head trauma, or encephalitis can cause injuries.
Other conditions that damage or deteriorate the brain can also cause agnosia. These conditions include:
- Poisoning by carbon monoxide.
Types and symptoms of agnosia
There are three different types of agnosia.
Visual agnosia occurs when there is brain damage along the pathways that connect the brain’s occipital lobe to the parietal and temporal lobes. The occipital lobe gathers incoming visual information. The parietal and temporal lobes allow you to understand the meaning of this information.
Apperceptive visual agnosia
Visual apperceptive agnosia causes difficulty assembling parts of an image into a comprehensible whole. This condition can make it difficult for him to understand the relationship between the objects.
You can, for example, try to copy an image of a circle and end up drawing a series of concentric scribbles.
You can still use vision to navigate your environment and pick up objects without problems. Lesions usually cause visual apperceptive agnosia in the parietal or temporal lobes on both sides of the brain.
Associative visual agnosia
Associative visual agnosia is the inability to remember information associated with an object. This can include the name, use, or origin of an object. This form of agnosia does not prevent you from drawing an object.
You may not be able to name the object in the drawing. You can recognize and use a thing shown to you, but you may not be able to tell what the object’s name is.
Prosopagnosia is the inability to recognize faces. It is caused by problems with the fusiform face area (FFA), a specific brain region that recognizes faces. The difficulty with facial recognition can also occur in Alzheimer’s disease. It happens because brain deterioration damages this region.
Autism can also cause difficulty in recognizing faces. A 2014 article discussed how children with autism spectrum disorders could learn to recognize faces differently. It may be harder for them to understand another person’s identity or emotional state.
Achromatopsia is the loss of color vision due to lesions in the V4 region of the brain. It is the inability to name colors despite being able to perceive them. Color anomia occurs when an injury separates the V4 areas of the brain from the language areas.
It is the inability to recognize words visually. It is not possible to read with pure alexia. In general, you can still speak and write without difficulty.
Akinetopsia is the inability to perceive movement. This condition can cause you to see moving objects as a series of still images, such as an object moving under a strobe light. If the disease is severe, you may not be able to see any movement.
Auditory agnosia is also known as deafness of pure words. It is the inability to recognize or process sounds despite intact hearing. It develops when the A1 sound processing region of the brain is disconnected from its language centers. He can still read, write and speak with deafness of pure words.
Phonagnosia is the inability to recognize and identify familiar voices. It develops when the brain damages a specific part of the sound association region.
This region is located in the right half of the brain. You can still understand the words that others speak if you have this condition. It can also recognize environmental sounds or sounds produced by objects.
Tactile agnosia is the inability to recognize objects through touch. You can feel the weight of the object. However, you may not be able to understand the meaning or use of the object. Lesions in the parietal lobe of the brain cause tactile agnosia.
Astereognosis is the inability to identify objects only by touch. This condition does not allow you to associate size, weight, and texture information with the correct words. You can still name objects by sight. You can also draw images of things, as well as reach them.
Autotopagnosia is when you lose the ability to orient the parts of your own body. Damage to the left parietal lobe of the brain causes this condition.
You know where your limbs are in space at all times, even with your eyes closed. However, this consciousness is distorted when the brain’s internal representation is damaged.