phonological rules are used to spell nonwords. More recently, neuroimaging studies using positron emission tomography and fMRI have suggested a balanced model in which the reading of all word types begins in the visual word form area, but subsequently branches off into different routes depending upon whether or not access to lexical memory or semantic information is needed (which would be expected with irregular words under a dual-route model). A 2007 fMRI study found that subjects asked to produce regular words in a spelling task exhibited greater activation in the left posterior STG, an area used for phonological processing, while the spelling of irregular words produced greater activation of areas used for lexical memory and semantic processing, such as the left IFG and left SMG and both hemispheres of the MTG. Spelling nonwords was found to access members of both pathways, such as the left STG and bilateral MTG and ITG. Significantly, it was found that spelling induces activation in areas such as the left fusiform gyrus and left SMG that are also important in reading, suggesting that a similar pathway is used for both reading and writing. Far less information exists on the cognition and neurology of non-alphabetic and non-English scripts. Every language has a morphological and a phonological component, either of which can be recorded by a writing system. Scripts recording words and morphemes are considered logographic, while those recording phonological segments, such as syllabaries and alphabets, are phonographic. Most systems combine the two and have both logographic and phonographic characters. In terms of complexity, writing systems can be characterized as “transparent” or “opaque” and as “shallow” or “deep.” A “transparent” system exhibits an obvious correspondence between grapheme and sound, while in an “opaque” system this relationship is less obvious. The terms “shallow” and “deep” refer to the extent that a system’s orthography represents morphemes as opposed to phonological segments. Systems that record larger morphosyntactic or phonological segments, such as logographic systems and syllabaries put greater demand on the memory of users. It would thus be expected that an opaque or deep writing system would put greater demand on areas of the brain used for lexical memory than would a system with transparent or shallow orthography. See also Sign language Phonology Auditory processing disorder Brodmann area Cognitive science Developmental verbal dyspraxia FOXP2 Language disorder Neurobiology Neurolinguistics Neuropsychology Neuroscience Origin of language Visual word form area References Language acquisition