Editing Agnosia (section)

==Causes==
Agnosia can result from [[stroke]]s, [[dementia]], or other [[neurological disorder]]s. It may also be trauma-induced by a head injury, brain infection, or hereditary.  Additionally, some forms of agnosia may be the result of developmental disorders.<ref name="NINDS Agnosia Information Page" /> Damage causing agnosia usually occurs in either the occipital or parietal lobes of the brain.  Although one modality may be affected, cognitive abilities in other areas are preserved.<ref name="NINDS Agnosia Information Page" />

Patients who experience dramatic [[recovery from blindness]] experience significant to total agnosia.<ref>{{cite magazine
| url = http://www.newyorker.com/archive/content/articles/060619fr_archive01
 | title = The New Yorker: From the Archives: Content
| magazine = [[The New Yorker]]
| quote = mentally blind, or agnosic—able to see but not to decipher what he was seeing.
| access-date = 2010-05-05
|archive-url = https://web.archive.org/web/20060831124229/http://www.newyorker.com/archive/content/articles/060619fr_archive01 |archive-date = 2006-08-31}}</ref>

The effect of damage to the [[superior temporal sulcus]] is consistent with several types of neurolinguistic deficiencies, and some contend that agnosia is one of them. The superior temporal sulcus is vital for speech comprehension because the region is highly involved with the lexical interface. According to the 1985 TRACE II Model, the lexical interface associates sound waves (phonemes) with morphological features to produce meaningful words. This association process is accomplished by lateral inhibition/excitement of certain words within an individual's lexicon (vocabulary).<ref name="The superior temporal sulcus"/> For instance, if an experimenter were to say DOG aloud, the utterance would activate and inhibit various words within the subjects lexical interface:
* DOG activates 3, and inhibits 0 letters in '''DOG'''. – +3
* DOG activates 2, and inhibits 1 letters in F'''OG'''. – +2
* DOG activates 1, and inhibits 2 letters in '''D'''AN. – +1
The consistency of this model to agnosia is shown by evidence that bilateral lesions to the superior temporal sulcus produces 'pure word deafness' (Kussmaul, 1877), or as it is understood today, speech agnosia. Patients with pure word deafness demonstrate the inability to recognize and process speech sounds with normal auditory processing for non-speech sounds below the level of the cortex.<ref name="The superior temporal sulcus"/>