Agnosia is the inability to recognise the import of sensory impressions despite the normal functioning of sense organs and nerves conducting sensation to the brain.
It can therefore apply to any of the sensory modalities, but most commonly vision is affected - the patient can see, but cannot interpret symbols such as letters. It may also apply to the loss of comprehension of time - time agnosia. Agnosia is frequently due to a lesion of the parietal lobe, in which case, for example, astereognosis can result.
Last reviewed 01/2018