Studies of the Processing of Single Words Using Positron Tomographic Measures of Cerebral Blood Flow Change

摘要

Language is an essential characteristic of the human species, and as such has been a focal point for study in disciplines ranging from philosophy to neurology. Cognitive and neurological investigations of language often narrow the focus of study to the processing of individual words (lexical items). Lexical processing involves a network of several levels of internal coding that can be isolated by experiment. Examples of some of these separate codes include a visual image of the form of a spoken word (visual code), pronunciation of the word (phonological code) or the association of related words (semantic codes). Studies of the time course of activation of these internal codes of words and the roles they play in performance has been a central topic in the cognitive psychology of reading and listening. Behavioural neurologists have been concerned as well with issues in lexical processing, but the focus has been in correlating the internal stages of processing with different brain regions. Recent advances in activation techniques and data analysis strategies using position emission tomographic (PET) measurements of blood flow (BF) change have made it possible to address concerns relevant to both cognitive science and behavioral neurology. In this paper, the authors take advantage of these techniques to study words in normal subjects.