Why are language and number comprehension an important criterion for neuropsychology?

Disorders of the central nervous system or brain injury (e.g. after a stroke or focal trauma) can result in specific impairments of speech and language and of number processing. Language disorders can occur in various language modalities (e.g. spontaneous speech, naming, repeating words, reading, writing, speech comprehension, reading comprehension) and may involve different components of language (e.g. semantics, phonology, syntax) (Bartha, 2006). After brain injury various components and modalities of language comprehension are frequently impaired. These acquired combinations of language disorders that occur after language acquisition has been completed are classed as aspects of aphasia.

Number processing also involves complex cognitive mechanisms that may be impaired in various ways as a result of brain injury. There are two main aspects of dealing with numbers:

number processing (i.e., comprehension of numbers, reading numbers, the ability to write numbers, the ability to arrange numbers in sequence) and calculating and using arithmetical signs (Claros-Salinas, Nuerk & Willmes, 2006).