Open AccessThe neural response to changing semantic and perceptual complexity during language processing
Author(s) -
Sharp David J.,
Awad Malaka,
Warren Jane E.,
Wise Richard J.S.,
Vigliocco Gabriella,
Scott Sophie K.
Publication year - 2010
Publication title -
human brain mapping
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.005
H-Index - 191
eISSN - 1097-0193
pISSN - 1065-9471
DOI - 10.1002/hbm.20871
Subject(s) - semantic memory , comprehension , perception , psychology , speech perception , cognitive psychology , angular gyrus , superior temporal gyrus , inferior frontal gyrus , functional magnetic resonance imaging , speech recognition , computer science , neuroscience , cognition , programming language
Speech comprehension involves processing at different levels of analysis, such as acoustic, phonetic, and lexical. We investigated neural responses to manipulating the difficulty of processing at two of these levels. Twelve subjects underwent positron emission tomographic scanning while making decisions based upon the semantic relatedness between heard nouns. We manipulated perceptual difficulty by presenting either clear or acoustically degraded speech, and semantic difficulty by varying the degree of semantic relatedness between words. Increasing perceptual difficulty was associated with greater activation of the left superior temporal gyrus, an auditory‐perceptual region involved in speech processing. Increasing semantic difficulty was associated with reduced activity in both superior temporal gyri and increased activity within the left angular gyrus, a heteromodal region involved in accessing word meaning. Comparing across all the conditions, we also observed increased activation within the left inferior prefrontal cortex as the complexity of language processing increased. These results demonstrate a flexible system for language processing, where activity within distinct parts of the network is modulated as processing demands change. Hum Brain Mapp, 2010. © 2009 Wiley‐Liss, Inc.