Article

Cerebral Organization of Component Processes in Reading

Department of Applied Physics, Yale University, New Haven, Connecticut, United States
Brain (Impact Factor: 9.2). 09/1996; 119 ( Pt 4)(4):1221-38. DOI: 10.1093/brain/119.4.1221
Source: PubMed

ABSTRACT

The cerebral organization of word identification processes in reading was examined using functional magnetic resonance imaging (fMRI). Changes in fMRI signal intensities were measured in 38 subjects (19 males and 19 females) during visual (line judgement), orthographic (letter case judgement), phonological (nonword rhyme judgement) and semantic (semantic category judgement) tasks. A strategy of multiple subtractions was employed in order to validate relationships between structure and function. Orthographic processing made maximum demands on extrastriate sites, phonological processing on a number of frontal and temporal sites, and lexical-semantic processing was most strongly associated with middle and superior temporal sites. Significant sex differences in the cerebral organization of reading-related processes were also observed.

    • "This area is part of the semantic system (Graves, Binder, Desai, Conant, & Seidenberg, 2010; Lau, Phillips, & Poeppel, 2008). In reading, pMTG activation increases when meaningful materials are used or when participants focus on the semantic content of stimuli (Hoffman, Pobric, Drakesmith, & Lambon Ralph, 2012; Jobard et al., 2003; Simos et al., 2002; Pugh et al., 1996; Vandenberghe, Price, Wise, Josephs, & Frackowiak, 1996). The third area was the SMG. "
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    ABSTRACT: Cognitive theories on reading propose that the characteristics of written stimuli determine how they are processed in the brain. However, whether the brain distinguishes between regular words, irregular words, and pseudowords already at an early stage of the reading process is still subject to debate. Here we used chronometric TMS to address this issue. During the first 140 msec of regular word, irregular word, and pseudoword reading, TMS was used to disrupt the function of the ventral occipitotemporal, posterior middle temporal, and supramarginal gyri, which are key areas involved in orthographic, semantic, and phonological processing, respectively. Early TMS stimulation delivered on posterior middle temporal and supramarginal gyri affected regular and irregular word, but not pseudoword, reading. In contrast, ventral occipitotemporal disruption affected both word and pseudoword reading. We thus found evidence for an early distinction between word and pseudoword processing in the semantic and phonological systems, but not in the orthographic system.
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    • "In contrast, the ventral speech network is thought to mediate the processing of speech signals for comprehension. Taken together, there is overwhelming evidence that the dorsal neural network areas are biased toward phonologically-related processing, whereas the ventral neural network areas are biased toward semantically-related processing (Pugh et al., 1996; Sandak et al., 2004). However, as speech-based phonological experience becomes degraded by congenital deafness, it remains unclear how these respective reading networks would develop. "
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    ABSTRACT: The present work addresses the neural bases of sentence reading in deaf populations. To better understand the relative role of deafness and spoken language knowledge in shaping the neural networks that mediate sentence reading, three populations with different degrees of English knowledge and depth of hearing loss were included-deaf signers, oral deaf and hearing individuals. The three groups were matched for reading comprehension and scanned while reading sentences. A similar neural network of left perisylvian areas was observed, supporting the view of a shared network of areas for reading despite differences in hearing and English knowledge. However, differences were observed, in particular in the auditory cortex, with deaf signers and oral deaf showing greatest bilateral superior temporal gyrus (STG) recruitment as compared to hearing individuals. Importantly, within deaf individuals, the same STG area in the left hemisphere showed greater recruitment as hearing loss increased. To further understand the functional role of such auditory cortex re-organization after deafness, connectivity analyses were performed from the STG regions identified above. Connectivity from the left STG toward areas typically associated with semantic processing (BA45 and thalami) was greater in deaf signers and in oral deaf as compared to hearing. In contrast, connectivity from left STG toward areas identified with speech-based processing was greater in hearing and in oral deaf as compared to deaf signers. These results support the growing literature indicating recruitment of auditory areas after congenital deafness for visually-mediated language functions, and establish that both auditory deprivation and language experience shape its functional reorganization. Implications for differential reliance on semantic vs. phonological pathways during reading in the three groups is discussed.
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    • "On the basis of previous studies of aging, we hypothesized that older adults would show widespread brain activation, in comparison with younger adults, especially in right frontal areas homologous to left hemisphere language regions (Wierenga et al., 2008). On the basis of previous studies of aging, we focused on activations in (a) right IFG (Spreng, Wojtowicz, & Grady, 2010; Meinzer et al., 2009; Wierenga et al., 2008; theoretical models emphasize the importance of right hemispheric homologues, Cabeza, 2002; and of frontal regions, West, 1996) and left IFG, which has been found to be consistently active in fMRI studies of rhyme judgment where activation is often interpreted as related to phonological processing (Hoeft et al., 2007; Owen, Borowsky, & Sarty, 2004; Poldrack et al., 2001; Lurito, Kareken, Lowe, Chen, & Mathews, 2000; Pugh et al., 1996; Paulesu, Frith, & Frackowiak, 1993) and (b) the left insula (Shafto et al., 2007, 2010). 2. Both fMRI tasks (rhyme judgments on pictures and words) involve phonological retrieval but whereas the picture task is dependent on semantic retrieval, the word task is also supported by direct links between orthography and phonology. "
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    ABSTRACT: Age has a differential effect on cognition, with word retrieval being one of the cognitive domains most affected by aging. This study examined the functional and structural neural correlates of phonological word retrieval in younger and older adults using word and picture rhyme judgment tasks. Although the behavioral performance in the fMRI task was similar for the two age groups, the older adults had increased activation in the right pars triangularis across tasks and in the right pars orbitalis for the word task only. Increased activation together with preserved performance in the older participants would suggest that increased activation was related to compensatory processing. We validated this hypothesis by showing that right pars triangularis activation during correct rhyme judgments was highest in participants who made overall more errors, therefore being most error-prone. Our findings demonstrate that the effect of aging differ in adjacent but distinct right inferior frontal regions. The differential effect of age on word and picture tasks also provides new clues to the level of processing that is most affected by age in speech production tasks. Specifically, we suggest that right inferior frontal activation in older participants is needed to inhibit errors.
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