Reading comprehension depends on neural processes supporting the access, understanding, and storage of words over time. Examinations of the neural activity correlated with reading have contributed to our understanding of reading comprehension, especially for the comprehension of sentences and short passages. However, the neural activity associated with comprehending an extended text is not well-understood. Here we describe a current-source-density (CSD) index that predicts individual differences in the comprehension of an extended text. The index is the difference in CSD-transformed event-related potentials (ERPs) to a target word between two conditions: a comprehension condition with words from a story presented in their original order, and a scrambled condition with the same words presented in a randomized order. In both conditions participants responded to the target word, and in the comprehension condition they also tried to follow the story in preparation for a comprehension test. We reasoned that the spatiotemporal pattern of difference-CSDs would reflect comprehension-related processes beyond word-level processing. We used a pattern-classification method to identify the component of the difference-CSDs that accurately (88%) discriminated good from poor comprehenders. The critical CSD index was focused at a frontal-midline scalp site, occurred 400–500 ms after target-word onset, and was strongly correlated with comprehension performance. Behavioral data indicated that group differences in effort or motor preparation could not explain these results. Further, our CSD index appears to be distinct from the well-known P300 and N400 components, and CSD transformation seems to be crucial for distinguishing good from poor comprehenders using our experimental paradigm. Once our CSD index is fully characterized, this neural signature of individual differences in extended-text comprehension may aid the diagnosis and remediation of reading comprehension deficits.
Keywords: reading comprehension, EEG/ERP, machine learning applied to neuroscience, current source density, working memory
Citation: Mossbridge JA, Grabowecky M, Paller KA and Suzuki S (2013) Neural activity tied to reading predicts individual differences in extended-text comprehension. Front. Hum. Neurosci. 7:655. doi: 10.3389/fnhum.2013.00655
Received: 22 April 2013; Accepted: 20 September 2013;
Published online: 06 November 2013.
Edited by:Hans-Jochen Heinze, University of Magdeburg, Germany
Reviewed by:Micah M. Murray, University Hospital Center and University of Lausanne, Switzerland
Copyright © 2013 Mossbridge, Grabowecky, Paller and Suzuki. This is an open-access article distributed under the terms of the Creative Commons Attribution License (CC BY). The use, distribution or reproduction in other forums is permitted, provided the original author(s) or licensor are credited and that the original publication in this journal is cited, in accordance with accepted academic practice. No use, distribution or reproduction is permitted which does not comply with these terms.
*Correspondence: Julia A. Mossbridge, Department of Psychology, Northwestern University, 2029 N. Sheridan Road, Evanston, IL 60208, USA e-mail: firstname.lastname@example.org