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Spatiotemporal dynamics of single-letter reading: a combined ERP-FMRI study

Casarotto, Silvia and Bianchi, A.M. and Ricciardi, Emiliano and Gentili, Claudio and Vanello, Nicola and Guazzelli, Mario and Pietrini, Pietro and Chiarenza, Giuseppe A. and Cerutti, Sergio Spatiotemporal dynamics of single-letter reading: a combined ERP-FMRI study. Archives Italiennes de Biologie. A journal of Neuroscience, 146 (2). pp. 83-105. ISSN 0003-9829 (2008)

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This work investigates the neural correlates of single-letter reading by combining event-related potentials (ERPs) and functional magnetic resonance imaging (fMRI), thus exploiting their complementary spatiotemporal resolutions. Three externally-paced reading tasks were administered with an event-related design: passive observation of letters and symbols and active reading aloud of letters. ERP and fMRI data were separately recorded from 8 healthy adults during the same experimental conditions. Due to the presence of artifacts in the EEG signals, two subjects were discarded from further analysis. Independent Component Analysis was applied to ERPs, after dimensionality reduction by Principal Component Analysis: some independent components were clearly related to specific reading functions and the associated current density distributions in the brain were estimated with Low Resolution Electromagnetic Tomography Analysis method (LORETA). The impulse hemodynamic response function was modeled as a linear combination of linear B-spline functions and fMRI statistical analysis was performed by multiple linear regression. fMRI and LORETA maps were superimposed in order to identify the overlapping activations and the activated regions specifically revealed by each modality. The results showed the existence of neuronal networks functionally specific for letter processing and for explicit verbal-motor articulation, including the temporo-parietal and frontal regions. Overlap between fMRI and LORETA results was observed in the inferior temporal-middle occipital gyrus, suggesting that this area has a crucial and multifunctional role for linguistic and reading processes, likely because its spatial location and strong interconnection with the main visual and auditory sensory systems may have favored its specialization in grapheme-phoneme matching.

Item Type: Article
Subjects: R Medicine > RC Internal medicine > RC0321 Neuroscience. Biological psychiatry. Neuropsychiatry
Research Area: Computer Science and Applications
Depositing User: Caterina Tangheroni
Date Deposited: 22 Feb 2016 10:26
Last Modified: 13 Sep 2016 09:58
URI: http://eprints.imtlucca.it/id/eprint/3098

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