The role of the left Brodmann's areas 44 and 45 in reading words and pseudowords

Abstract

In this functional magnetic resonance imaging (fMRI) study, we investigated the influence of two task (lexical decision, LDT; phonological decision, PDT) on activation in Broca's region (left Brodmann's areas [BA] 44 and 45) during the processing of visually presented words and pseudowords. Reaction times were longer for pseudowords than words in LDT but did not differ in PDT. By combining the fMRI data with cytoarchitectonic anatomical probability maps, we demonstrated that the left BA 44 and BA 45 were stronger activated for pseudowords than for words. Separate analyses for LDT and PDT revealed that the left BA 44 was activated in both tasks, whereas left BA 45 was only involved in LDT. The results are interpreted within a dual-route model of reading with the left BA 44 supporting graphemeto-phoneme conversion and the left BA 45 being related to explicit lexical search. D

Developmental increases in effective connectivity to brain regions involved in phonological processing during tasks with orthographic demands

“…Although these studies suggest that dorsal inferior frontal gyrus may be generally related to maintenance/manipulation in verbal memory, other studies suggest that dorsal inferior frontal gyrus is more specifically involved in phonological segmentation. One of the most consistent findings is that pseudowords produce greater activation than words in dorsal inferior frontal gyrus for both the visual and auditory modalities (Burton et al, 2005;Fiebach et al, 2002;Heim et al, 2005;Ischebeck et al, 2004). Pseudo-words place large demands on segmentation because they must be decomposed and read by grapheme to phoneme correspondences.…”

Speed of lexical decision correlates with diffusion anisotropy in left parietal and frontal white matter: Evidence from diffusion tensor imaging

“…Confirmation of a role for the inferior parietal lobule, and demonstration of a role for left inferior frontal cortex, in phonology has come from modern functional neuroimaging studies (Pugh et al, 1996;Gold and Buckner, 2002;Sharp et al, 2005). In addition, left inferior frontal cortex has been reported to show strong activation associated with phonological components of visual word recognition (Rumsey et al, 1997;Heim et al, 2005). Although we looked for a possible lexicality effect, we found that both the speed of word acceptance and nonword rejection correlated negatively with FA in the same regions of inferior parietal and frontal WM.…”

“…In research settings, this skill is usually explored via the speeded visual lexical decision task, in which participants decide as quickly and accurately as possible whether visual letter strings represent words or nonwords. Results from studies using the visual lexical decision task have been influential in the development of models of visual word recognition (McClelland & Rumelhart, 1981;Coltheart et al, 2001), and mapping the neural correlates of visual word recognition processes (Rumsey et al, 1997;Binder et al, 2003;Heim et al, 2005).…”

Balanced bilinguals favor lexical processing in their opaque language and conversion system in their shallow language

“…More specifically, the left insula has been discussed to be part of the phonological loop and phonological working memory (Chee, Soon, Lee, & Pallier, 2004;Schulze, Zysset, Mueller, Friederici, & Koelsch, 2011). Left inferior frontal regions have been linked to phonological processing (Price, 2000), especially grapheme to phoneme conversion (Fiebach et al, 2002;Heim et al, 2005;Rodriguez-Fornells et al, 2006;Wheat et al, 2010) and enhanced short term memory capacities of phonological pathways compared to lexical pathways (Jobard et al, 2003;Nixon et al, 2004). Finally, left dorsolateral prefrontal regions were linked to phonological working memory and sublexical conversion (Pecini et al, 2008).…”