Brief Idea of Agnosia
What is Agnosia?
Agnosia is a rare neurological condition that targets recognition and identification of objects and/or persons. It is characterized by an inability to know, name, identify, and extract meaning from visual, auditory, or tactile impressions.Despite being able to see, hear, speak, and think normally, a person with agnosia cannot recognize something or someone he or she once knew. The loss of the ability to recognize cannot be explained by a generalized loss of knowledge or inadequate attention to the task. Agnosia is not due to memory loss.
Symptoms of agnosia may varies according to the area of brain that is affected. It is only limited to only one sensory modality, for example, visual or hearing or tactile. For instance, an individual with visual agnosia would not be able to visually recognize an object when asked to name it despite able to describe its visual characteristics (e.g. shape, colour). Another example, the auditory agnosia. He/she is not being able to identify whether a presented sound is a “cough”. Subsequently, if an individual is provided with the correct answer and then presented the stimulus again after an extend period of time, he/she with agnosia would still be unable to correctly identify the stimulus.
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CAUSES OF AGNOSIA
Agnosia can cause by strokes, traumatic brain injury (TBI), dementia, a tumor in the brain, developmental disorders, encephalitis, anoxia, overexposure to environmental toxins (e.g. carbon monoxide poisoning) and other neurological conditions. Agnosia can also be a result of degeneration of parts of the brain that are involved in the integration of experience, perception, and memory.
Agnosia occurs due to sensory perception of a perceived stimuli is disconnected from memories with the perceived stimuli. This means there is no deficit to memory but there is a disruption in the pathway that processes specific stimuli. In another words, he/she with agnosia can perceive a stimulus without its meaning associated.
Causes of agnosia result in damage to different regions of the cerebrum that integrates perceptions, memory and recognition. As a consequence, symptoms of agnosia develop due to the inability to retrieve information from those damaged areas of cerebrum. Individual with agnosia may retain their cognitive abilities in other areas. For example, people with visual agnosia can’t name an object when shown a picture of the object. However, he/she can immediately recognize the object if he/she can touch or hear a description of the object’s appearance. Besides, individual with tactile agnosia would not be able to recognize the same object with touch but can immediately name it if he/she sees the object.
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AGNOSIA 