What is agnosia?

What is agnosia?

Agnosia is a condition that involves a lack of ability to interpret a sensory stimulus, although all our senses are preserved. That is, although we can see, smell or hear perfectly, when there is agnosia the person is unable to interpret and recognize what he is seeing, smelling or hearing. The person suffering from agnosia is unable to recognize objects, faces or voices despite not having any sensory problems.


  • 1 Causes of agnosia
  • 2 Types of agnosia
  • 3 What is the treatment for agnosia?

Causes of agnosia

The agnosia is caused by damage to certain brain pathways. These damages can be caused by injuries such as head injuries, encephalitis or strokes, among other conditions and these damages are usually located in the parietal and temporal lobes of the brain. When these brain pathways that connect the main areas of sensory processing and information storageThis deficit occurs in the recognition of external stimuli.

Types of agnosia

There are different types of agnosia depending on the location of the pathways that have been damaged in the brain. Next, we describe the main types of agnosia:

Visual agnosia

Visual agnosia occurs when the pathways that connect the occipital lobe, involved in receiving the new visual information, with the parietal and temporal lobes that allow the recognition of the meaning of this information. Visual agnosia may have different characteristics depending on the subtype we are talking about.

Thus, there is the aperceptive visual agnosia, which is characterized by causing great difficulty in joining parts of an object into an understandable whole. Although the person can recognize objects around him, he may have difficulty understanding the relationship between objects and the differences between similar objects. In addition, it will be very difficult to draw images or reconstruct these objects.

There is also the associative visual agnosia, which is based on the lack of ability to remember the information associated with the object. That is, in this case, the person cannot name an item or know what it is used for, even though he knows it perfectly.

Another type of visual agnosia is the prosopagnosia, which implies a lack of ability to recognize faces. This inability is usually caused by damage to the fusiform gyrus, a specific location in the brain that allows us to recognize faces.

There are also other types of visual agnosia such as acinetopsia, which implies inability to recognize movement, achromatopsia, in which we do not recognize the colors even though we can perceive them or the alexia, the inability to recognize written words.

Auditory agnosia

Auditory agnosia implies a inability to recognize sounds, although our hearing abilities are preserved. When a person suffers from auditory agnosia, he may not recognize the words, although he can read them, write them and speak them. This occurs when the secondary and tertiary auditory cortex of the temporal lobe of the brain is damaged.

Within auditory agnosia, different types such as verbal agnosia, in which people fail to interpret linguistic stimuli. There is also the nonverbal auditory agnosia, in which ambient sounds are not perceived correctly. The amusia, On the contrary, it is an inability to recognize and interpret music. We can also find the phonagnosia, a rare inability to recognize familiar voices.

Tactile agnosia

The tactile agnosia is the inability to recognize objects through touch. Although the affected patient may feel the weight of the object, he does not understand or recognize the object he is touching. This is related to injuries in the parietal lobe of the brain.

Within the tactile agnosia we can find the astereognosis, which is the inability to identify objects through touch and autotopagnosia, in which the person cannot correctly locate and orient the parts of their own body.

What is the treatment for agnosia?

There are no specific treatments for agnosia, since the treatments that are usually applied focus on heal the causes this. While some neurological damage can be remedied with surgery or other techniques, others can maintain agnosia permanently.

Treatments such as occupational therapy or speech therapy, which can help improve symptoms and make the patient adapt his lifestyle, as well as benefit from different supports that help him cope with these symptoms. If you or someone you know presents or thinks you may have symptoms of agnosia, feel free to consult a professional of neurological health.