Agnosia
Agnosia is the inability to process sensory information. Often there is a loss of ability to recognize objects, persons, sounds, shapes, or smells while the specific sense is not defective nor is there any significant memory loss. It is usually associated with brain injury or neurological illness, particularly after damage to the occipitotemporal border, which is part of the ventral stream. Agnosia only affects a single modality, such as vision or hearing. More recently, a top-down interruption is considered to cause the disturbance of handling perceptual information.
Agnosia
The term 'agnosia' comes from the Ancient Greek ἀγνωσία ("agnosia"), "ignorance", "absence of knowledge". It was introduced by Sigmund Freud in 1891: "For disturbances in the recognition of objects, which Finkelnburg classes as asymbolia, I should like to propose the term 'agnosia'." Prior to Freud's introduction of the term, some of the first ideas about agnosia came from Carl Wernicke, who created theories about receptive aphasia in 1874. He noted that individuals with receptive aphasia did not possess the ability to understand speech or repeat words. He believed that receptive aphasia was due to lesions of the posterior third of the left superior temporal gyrus. Due to these lesions, Wernicke believed that individuals with receptive aphasia had a limited deafness for certain sounds and frequencies in speech.