What is agnosia?
Agnosia is the inability to recognize objects despite adequate perception in the modality in which the object is presented.
The below table summarizes the comparison of the types of agnosias.
Forms of Agnosia or Neglect
| Definition | Associated Features | Anatomic Localization | |
|---|---|---|---|
| Topographagnosia | Inability to navigate complex layouts | Often unilateral neglect | Right occipitoparietal or bilateral temporo-parietal |
| Anosagnosia | Unawareness of impairment | Often left HP | Right parietal |
| Anosodiaphoria | Recognizes deficits, but is indifferent to them | Often an HP or hemisensory deficit | Right hemisphere |
| Prosopagnosia | Inability to recognize familiar faces | Inability to identify other specific members of a class, such as car brands; visual field defects | Bilateral inferior occipito-temporal |
| Simultanagnosia | Inability to interpret complex visual scenes | High occipitoparietal (e.g., posterior watershed) | |
| Achromatopsia | Lack of color vision | Quadrantanopia | Occipital cortex below the calcarine sulcus; inferotemporal |
| Hemineglect | Lack of attention to one-half of space | Posterior right parietal; then left frontal or left parietal |
HP , Hemiparesis.
